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Computed Tomography Review
Questions to study for CT review
351
Science
Professional
07/17/2021

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Cards

Term

Which of the following sets of reconstructed section widths and intervals would be best suited for a general CT study of the Abdomen and Pelvis in a patient with a history of lymphoma?

A. 0.625 mm x 0.625 mm

B. 1.25 mm x 2.5 mm

C. 5.0 mm x 5.0 mm

D. 10 mm x 15 mm

Definition

Answer: C. 5.0 mm x 5.0 mm

General Survey CT studies for lymphoma are typically performed contiguously with section widths ranging from 3.0 mm to 5.0 mm for routine review. Data acquistion with an MDCT system may involve the use of a thinner detector configuration, such as 0.625 mm. Thicker section widths are reconstructed for review, with thinner images used for multiplanar reformation (MPR) or for areas of specific concern.

Term

Which of the following is NOT an improvement in CT chest imaging due to the development of multidetector technology?

A. An overall reduction in patient radiation dose

B. Reduction in Partial Volume Artifact

C. Elimination of misregistration Artifact

D. Improved Contrast enhancement

Definition

Answer: A. An overall reduction in Patient radiation dose

The speed of MDCT systems allow for image s of the entire chest to be volumetrically acquired in just a few seconds. Fast, single-breath-hold acquistions greatly reduce artifact from breathing motion and allow for more efficient utilization of iodinated contrast agents. The ability to retrospectively reconstruct thin-section images can effectively eliminate the partial volume artifact on small areas of pathology. The drawback to MDCT is the potential for an increase in overall patient radiation dose. However, careful protocol optimization and continued technological advancements work to limit any increase in dose from MDCT exams.

Term

[image]

Number 3 Corresponds to which of the following?

A. External Iliac Artery

B. Femoral Artery

C. External Iliac Vein

D. Femoral Vein

Definition
Answer: A. External Iliac Artery
Term

An Agaston Score of 250 on an MDCT cardiac examination for Coronary Artery calcification is rated as:

A. Minimal

B. Mild

C. Moderate

D. Extensive

Definition

Answer: C. Moderate

The Agaston system quantifies coronary artery calcium as minimal (1-10), mild (11- 100), moderate (101-400), and extensive (>400).

Term

Number 2 corresponds to which of the following?

A. Anterior Cerebral Artery

B. Third Ventricle

C. Fourth Ventricle

D. Optic Tract

[image]

Definition
Answer: B. Third Ventricle
Term

Which of the following scan parameters is commonly used during a radiation therapy planning CT study of the prostate gland?
(1) Patient placed on flat table top

(2) Small DFOV used to include only the prostate gland

(3) CT scan performed with patient in exact position used for radiation treatment

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: B. 1 and 3 only

CT scans are commonly performed for radiation therapy planning. The purpose of the exam is to precisely locate the area of interest for therapeutic treatment with irradiation. It is important that the patient position during the CT exam is exactly the same as that used during radiation therapy. This includes using a flat table top, via a board or foam insert. Equally important is the DFOV chosen by the technologist. It must be large enough to include the entire surface of the anatomic part.

Term

In 1979, the scientists ___________ and ____________ shared the Nobel Prize for their research in Computed Tomography.

A. Watson and Crick

B. Olendorf and Hounsfield

C. Hounsfield and Cormack

D. Hounsfieild and Ambrose

Definition

Answer: C. Hounsfield and Cormack

Dr. Godfrey Hounsfield and Dr. Allan Cormack shared the Nobel prize for their work on the development of computed tomography in 1979.

Term

The portion of the primary beam interacting with a single detector is known as a:

A. Ray

B. View

C. Profile

D. Sample

Definition

Answer: A. Ray

The term ray is used to describe the portion of the xray beam that falls upon a single detector.

Term

The addition of _______ makes an auto clave more efficient at sterilization than an oven.

A. Antiseptic solution

B. moisture

C. Extreme pressure

D. Ultraviolet light

Definition

Answer: B. Moisture

An autoclave is a mechanical device used for sterilization. It involves the use of heat and steam under pressure to eliminate microbes. An oven only uses high heat and is not as efficient as an autoclave.

Term

Which of the following components of CT image quality is/are being evaluated?

(1) linearity

(2) section width

(3) spatial resolution

A. 1 only

B. 1 and 2 only

C. 3 and 3 only

D. 1, 2, and 3

[image]

Definition

Answer: B. 1 and 2 only

A linearity phantom contains 4 inserts of various materials surrounded by water. Known ranges or CT values are compared with those obtained by CT acquisition to ensure system accuracy and linearity. This American College of Radiology (ACR) phantom also contains two ramps consisting of a series of wires spaces 0.5 mm apart along the phantoms z-axis. The accuracy of the selected section width is evaluated by counting the number of wires visable in cross-section.

Term

Infection may occur indirectly through contact with contaminated objects known as:

A. Vectors

B. Fomites

C. Vehicles

D. hosts

Definition

Answer: B. Fomites

Fomites are objects that have been contaminated by an infectious organism or microbe. The spread of the infection may occur when someone comes in contact with the fomite. This is an indirect means of infection transmission.

Term

Which of the following units is used to quantify effective dose?

A. Roentgens (R)

B. Grays (Gy)

C. Sieverts (Sv)

D. Curies (Ci)

Definition

Answer: C. Sieverts (Sv)

Effective dose approximates the relative risk from exposure to ionizing radiation and is based on the radiosensitivity of a given tissue type. It is measured in Sieverts (Sv).

Term

The ability of a CT scanner to image a small high density object is controlled by the __________ of the scanner.

A. Contrast Resolution

B. Spatial Resolution

C. Sensitivity

D. Both A and C

Definition

Answer: B. Spatial Resolution

The spatial resolution of a CT scanner controls its ability to image small structures.

Term

The normal range of Cerebral blood volume (CBV) contained within 100 g of Brain Tissue is:

A: 0.6-1.0 mL/100 g

B. 4-5 mL/100 g

C. 15-19 mL/100 g

D. 30-40 mL/100 g

Definition

Answer: B. 4-5 mL/100 g

Term

Number 2 corresponds with which of the following?

A. Incus

B. Cochlea

C. Semicircular Canal

D. Vestibule

[image]

Definition
Answer: C. Semicircular Canal
Term

The type of MSCT detector array that contains midline narrow elements flanked by wider detectors is called a(n):

A. Uniform Matrix Array

B. Adaptive Array

C. Hybrid Array

D. Stationary Array

Definition

Answer: C. Hybrid Array

A hybrid array consists of two detector sizes. The narrower detectors are positioned midline, flanked by the wider detectors. For example, the central rows of a 16-channel MDCT system are 0.625 mm with the remaining peripheral rows at 1.25 mm.

Term

Number 1 corresponds with which of the following?

A. Ileum

B. Cecum

C. Jejunum

D. Duodenum

[image]

Definition
Answer: B. Cecum
Term

Which of the following azimuth settings was used to produce the localizer image?

A. 0 Degrees

B. 90 Degrees

C. 180 Degrees

D. 270 Degrees

[image]

Definition

Answer: A. 0 Degrees

The azimuth setting refers to the relationship between the x-ray tube and detectors during scout or localizer production. A 0-Degree azimuth describes the situation in which the x-ray tube and the detectors do not rotate but remain above and below the patient, providing a frontal projection.

Term

The role of computed tomography during combined PET-CT includes:

(1) anatomic location of tumor activity

(2) attenuation correction of emitted photons

(3) reduction in overall patient dose

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: B. 1 and 2 only

The process of attenuation correction utilizes the transmission data acquired in the corresponding CT analysis to account for the change in energy that occurs as annihilation photons emitted from decaying radionuclide travel through the patient. The CT image data is utilized for tumor localization and results in an increase in patient dose.

Term

Following the injection of intravenous contrast media during a CT examination of the brain, which of the following anatomic areas does not enhance?

A. Anterior communicating artery

B. Choroid plexus

C. Posterior horn of lateral ventricle

D. Dura Mater

Definition

Answer: C. Posterior Horn of Lateral Ventricle

The posterior horn of the lateral ventricle contains cerebrospinal fluid and does not enhance following the intravenous administration of contrast material. Areas with a good blood supply, such as the cranial blood vessels, choroid plexus, and dura mater do enhance during a contrast study of the brain.

Term

The degenerative pathologic process of the spine known as spondylolysis invloves a defect in the:

A. Spinous Process

B. Transverse Process

C. Pars interarticularis

D. Intervertebral disc

Definition

Answer: C. Pars Interarticularis

Spondylolysis involves a defect in the pars interarticularis commonly caused by osteophyte formation. The pars interarticularis is the area of the vertebrae between the inferior and superior articular processes ( neck of the "scotty dog").

Term

Which of the following term(s) is/are commonly used to describe a CT scanner's ability to differentiate objects with similar linear attenuation coefficients?

(1) spatial resolution

(2) sensitivity

(3) contrast resolution

A. 1 only

B. 3 only

C. 1 and 2 only

D. 2 and 3 only

Definition

Answer: D. 2 and 3 only

The ability of a CT scanner to accurately image objects with similar densities is termed contrast resolution or sensitivity. A CT scanner with poor contrast resolution or low sensitivity has difficulty seperating tissues whose linear attention coefficients are nearly equal.

Term

Normal unenhanced hepatic parenchyma exhibits CT densities within the range of:

A. -20 to 0 HU

B. +15 to +30 HU

C. +45 to +65 HU

D. +80 to +105 HU

Definition

Answer: C. +45 to +65 HU

Normal unenhanced hepatic parenchyma is homogenous in apperance with CT densities between +45 and +65 Hounsfield Units (HU). The CT density of the unenhanced liver is normally slightly greater than the densities of blood vessels and the splenic parenchyma.

Term

The approximate radiation dose measured during a scan of 100-mm pencil ionization chamber is termed the:

A. MSAD

B. Effective dose

C. CTDIvol

D. CTDI

Definition

Answer: D. CTDI

CTDI is a fixed measurement taken with a 100-mm long pencil ionization chamber inserted into an acrylic phantom. The CTDI standardized the dose measurement from a single axial scan and can be used to compare doses from different scan techniques.

Term

The stanford type B dissecting aneurysm affects which portion of the aorta?

A. Ascending Thoracic

B. Descending Thoracic

C. Abdominal

D. Birfurcation

Definition

Answer: B. Descending Aorta

Stanford type B dissecting aneurysms affect the descending aorta. Stanford Type A dissecting aneurysms affect the ascending aorta.

Term

Parenteral contrast administration refers to which of the following?

A. Oral Administration

B. Rectal administration

C. Intravenous administration

D. Nasogastric administration

Definition

Answer: C. Intravenous administration

The injection of a medication or contrast agent directly into the bloodstream is a type of parenteral administration. Other parenteral routes include intramuscular, subcutaneous, intradermal, and intrathecal.

Term

Which of the following is not a category of isolation technique?

A. Enteric precautions

B. gram-negative isolation

C. Contact isolation

D. Strict Isolation

Definition

Answer: B. gram-negative isolation

The categories of isolation technique are: Drainage-secretion precautions; acid-fast bacillus isolation; respiratory isolation; contact isolation; and strict isolation.

Term

A solitary pulmonary nodule can be assumed benign when its average density is within which of the following ranges?

A. 10-30 HU

B. 45-80 HU

C. 100-140 HU

D. 165-200 HU

Definition

Answer: D. 165-200 HU

Pulmonary Nodules appearing on CT examinations of the lungs may be determined as benign if their average density is more that 164+ HU. Although there have been conflicting studies in this area, researchers tend to agree that density values approaching +200 HU make the benign diagnosis more certain.

Term

Which of the following window settings would optimally display CT colonography images?

A. Level= -400, width= 1600

B. Level= +50, width= 400

C. Level= +150, width= 1000

D. Level= +250, width= 4000

Definition

Answer: A Level= -400, width= 1600

CT colonography images are best displayed in a wide "lung-type" window setting.

Term

Parenteral routes of medication administration include which of the following?

(1) subcutaneous

(2) intradermal

(3) transdermal

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: B. 1 and 2 only

Parenteral routes of medication administration include intramuscular, intravenous, intradermal, and subcutaneous.

Term

The portion of the male reproductive system responsible for the storage of the majority of mature sperm is the:

A. Seminal Vesicles

B. Vas Deferens

C. Testes

D. Prostate Gland

Definition

Answer: B. Vas Deferens

The majority of mature sperm is stored in the Vas Deferens. Sperm is produced in the seminiferous tubules and passes through the epididymus, where a small amount may be stored.

Term

A Stereotactic unit would be used for which of the following specialized CT examinations?

A. CT-guided fine-needle aspiration of an abdominal abscess

B. 3D CT angiogram

C. CT-guided biopsy of the brain

D. Dual window scanning

Definition

Answer: C. CT-guided biopsy of the brain

Steriotactic biopsy units are specialized units designed specifically for CT-guided biopsies. They are most commonly used for intercranial lesions, for which precision and accuracy are extremely important.

Term

Number 5 Corresponds to which of the following?

A. Duodenum

B. Descending Colon

C. Jejunum

D. Ascending Colon [image]

Definition
Answer: B. Descending Colon
Term

Which of the following vessels would not be used as a site for the injection of Iodinated contrast material?

A. Cephalic Vein

B. Brachial Artey

C. Antecubital vein

D. Basilic Vein

Definition

Answer: B. Brachial Artery

Common sites for intravenous contrast injection include the antecubital, basilic, cephalic, and accessory cephalic veins. Intrarterial injections of contrast material are not routinely performed for CT examinations. The only exceptions occur during hepatic CT portography, in which contrast agent may be administered through a catheter placed in the hepatic, superior mesentaric, or splenic artery.

Term

Which of the following is a typical protocol for a CT study of the brain for a patient with a history of dizziness?

A. 10-mm x 10-mm sections from the skull base through the vertex

B. 7-mm x 7-mm sections from the skull base through the posterior fossa

C. 2.5-mm x 2.5-mm sections through the posterior fossa, 5 mm x 5 mm to vertex

D. 1.5-mm x 1.5-mm sections from skull base to vertex

Definition

Answer: D. 2.5-mm x 2.5-mm sections through the posterior fossa, 5 mm x 5 mm to vertex

Patients with histories of headaches and/or dizziness should be evaluated for abnormalities of the inner ear. Thin sections (1-3 mm) are required throught the posterior fossa in order to best demonstrate the small anatomic structures and improve image quality.

Term

The spatial resolution of a CT scanner is usually given in the unit of measure:

A. HU

B. lp/cm

C. µ

D. Hz

Definition

Answer: B. lp/cm

The spatial resolution of a scanner quantifies its ability to visually seperate small objects in the image. The unit used to describe the spatial resolution is tested by scanning a phantom with an embedded resolution test pattern consisting of a series of small lead lines the decrease in size and spacing. The smallest, most closely spaces set of lead lines is said to be the spatial resolution of the CT scanner. A line pair (lp) consists of one lead line and a space immeiately next to it.

Term

The graph represents which of the following?

A. modulation transfer function (MTF)

B. signal-to-noise ratio (SNR)

C. views per rotation (VPR)

D. Slice Sensitivity profile (SSP) [image]

Definition

Answer: Slice Sensitivity profile (SSP)

The section width (slice) for a volumetric acquisition may be graphically displayed as a slice sensitivity profile (SSP). The SSP represents the degree of broadening that occurs along the z-axis during volumetric data acquisition.

Term

The typical range for possible pixel values in a modern CT system is between:

A. -512 HU and +512 HU

B. -1000 HU and +1000 HU

C. -1024 HU and +3071 HU

D. -4096 HU and +4096 HU

Definition

Answer: C. -1024 HU and +3071 HU

The typical range of Hounsfield scale CT numbers is -1024 to +3071 HU. This range equals the 4096 different values possible when one is using a 12-bit system. (212=4096)

Term

The duodenum is suspended from the diaphragm by the:

A. ligamentum teres

B. diaphragmatic crus

C. falciform ligament

D. ligament of Treitz

Definition

Answer: D. Ligament of Treitz

The suspensory ligament of the diaphragm is commonly referred to as the ligament of Treitz.

Term

Number 5 corresponds to which of the following?

A. iliopsoas muscle

B. sartorius muscle

C. obtruator internus muscle

D. gluteus minimus muscle [image]

Definition
Answer: C. obtruator internus muscle
Term

The quantity of radiation dose recieved by the patient from a series of CT scans is reffered to as the:

A. MSAD

B. XCAL

C. CTDI

D. MTF

Definition

Answer: A. MSAD

The multiple-scan average dose (MSAD) is used to quantify the amount of exposure a patient recieves from a series of CT scans. It is calculated from the computed tomography dose index (CTDI) through a series of equations. The quantity of radiation per scan is measured with an ionization chamber.

Term

During a Coronary Artery CTA, single-segment reconstruction of a 400-msec rotation scan results in a temperal resolution of:

A. 100 msec

B. 200 msec

C. 400 msec

D. 800 msec

Definition

Answer: B. 200 msec

During single-segment, or half-scan reconstruction, data from only half a gantry rotation is used, resulting in a temperal resolution equal to one-half the gantry rotation time.

Term

The dimensions of a voxel may be calculated as the product of which of the following?

A. matrix size and pixel size

B. Pixel size and section width

C. DFOV and matrix size

D. DFOV and pixel size

Definition

Answer: B. pixel size and section width

The pixel is a two-dimensional representation of a vocel. The section width is equal to the length of the voel. To calculate the dimensions of a voxel, the pixel dimension must be multiplied by the section width.

Pixel x section width= voxel

Term

An injury to the brain at a location opposite to the site of tramatic impact is referred to as:

A. Coup

B. Contracoup

C. Subdural

D. Epidural

Definition

Answer: B. Contracoup

The contracoup type of acute brain injury occurs at a location on the opposite side of the head from the point of impact. As he moving skull rapidly decelerates prior to impact, the portion of the brain opposite to the impact site temporarily pulls away from the skull before forcibly recoiling back into its original position, resulting in tramatic injury. In comparison, coup injuries to the brain occur at the actual site of tramatic impact.

Term

Number 1 corresponds to which of the following?

A. renal artery

B. hepatic vein

C. superior mesenteric artery

D. celiac trunk

[image]

Definition
Answer: C. Superior mesenteric artery (SMA)
Term

Which of the following mathmatical functions may be used to quantify the spatial resolution of a CT scanner?

(1) PSF

(2) MTF

(3) LSF

A. 2 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: D. 1, 2, and 3

The line spread function (LSF), point spread function (PSF), and modulation transfer function (MTF) are each used to quantify the spatial resolution of a CT scanner. The LSF measures the ability of a CT scanner to clearly image an edge or a line. The PSF does the same for extremely small, point-like structures. The MTF examines the fidelity of the spatial frequency as it represents tissues with varying densities. The MTF is derived from the measurement of LSF and PSF.

Term

Which of the following is an advantage of automatic CO insufflation for CT- Colonography?

(1) cheaper cost

(2) lower risk of anaphylaxis

(3) lower risk of perforation

A. 1 only

B. 3 only

C. 1 and 2 only

D. 2 and 3 only

Definition

Answer: B. 3 only

Advantages of automatic CO insufflation include better overal distention and lower risk of perforation. Also, owing to the faster absorption rate of CO, there is a reduction in post-procederal discomfort in the patient.

Term

Number 1 corresponds to which of the following?

A. external iliac artery

B. femoral artery

C. External iliac vein

D. Femoral vein

[image]

Definition
Answer: C. External iliac vein
Term

Number 1 corresponds with which of the following?

A. corpus callosum

B. internal capsule

C. septum pellucidum

D. Putamen

[image]

Definition
Answer: C. septum pellucidum
Term

Which of the following technical adjustments may be employed to improve the temporal resolution of an MDCT system?

(1) decreased scan time

(2) decreased section width

(3) decreased DFOV

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: A. 1 only

Temporal resolution quantifies the CT system ability to freeze motion and provide an image free of blurring. The controlling factors of temporal resolution of a CT system are the gantry rotation speed and reconstructin method.

Term

Which of these numbers correspond to the genu of the corpus collosum?[image]

Definition
Answer: number 6
Term

The water-soluble oral contrast agents used for CT scans of the abdomen and pelvis should contain approximately__________ iodine.

A. 2%-5%

B. 8%-12%

C. 15%-20%

D. 25%-40%

Definition

Answer: A. 2%-5%

A solution of 2%-5% iodinated water-soluble contrast agent and water provides sufficient bowel opacification for CT studies of the abdomen and pelvis. Some institutions may use a flavoring agent to the solution or used a flavored contrast for ease of consumption. Common water-soluble contrast media include gastrografin and hypaque.

Term

The primary advantage of an isotropic MDCT data-set is:

A. reduced scan time

B. increased signal-to-noise ration (SNR)

C. improved raw data convolution

D. high-quality multiplanar reformations (MPR)

Definition

Answer: D. high-quality multiplanar reformations (MPR)

An isotropic volumetric data set yeilds high-quality images with equal resolution in any reconstucted plane. Reconstruction of isotropic, overlapping, thin-section MDCT images greatly reduces the "step" artifact that can negatively affect the quality of MPR and 3D CT images.

Term

The number, length, and organization of the individual detector elements in an MSCT system are referred to as the:

A. detector configuration

B. array pitch

C. CT generation

D. detector pitch

Definition

Answer. A. detector configuration

Detector configuration refers to the number, length, and organization of the individual detector elements in an MSCT system.

Term

Prospectively gated cardiac CT data acquisition occurs only durning the portion of the ECG termed the:

A. P wave

B. QRS complex

C. ST Segment

D. T wave

Definition

Answer: D. T wave

With prospective electrocardiography (ECG) monitoring, scanning only occurs during diastole, when the heart demonstrates the least motion. A user-defined percentage of the R-R intercal is set as the trigger for data acquisition to occur during the T wave of the ECG.

Term

High-resolutino CT examinations of the temporal bone and internal auditory canal should include which of the following technical parameters?

(1) 5- to 7-mm section width

(2) small (less than 10 cm) targeted DFOV

(3) soft-tissue kernel

A. 1 only

B. 2 only

C. 1 and 3 only

D. 1, 2, and 3

Definition

Answer: B. 2 only

Ct studies of the temporal bones and internal auditory canal require a high-resolution imaging technique. The tenets of high-resolution CT include thin sections (1-2 mm), a small targeted DFOV, and the use of high-resolution algorithm (kernel) for reconstruction.

Term

Which of the following statements most accurately describes the relationship between slice sensitivity profile (SSP) and dose profile?

A. The SSP is alway wider than the dose profile

B. The SSP is equal in width to the dose profile

C. The dose profile is always wider than the SSP

D. The SSP has no effect on the dose profile.

Definition

Answer: C. The dose profile is always wider than the SSP.

The term slice sensitivity profile (SSP) may be used to describe the reconstructed CT section. However, the section of tissue exposed to ionizing radiation, or dose profile, is greater in width than the SSP.

Term

Which of the following numbers: 6, 3, 7, or 2 does not branch off from the aortic arch?

[image]

Definition

Answer: A. 6

The subclavian (3), brachiocephalic (7), and common carotid (2) arteries all branch off the superior portion of the aortic arch. The left (1) and right (6) brachiocephalic veins originate from the superior vena cava.

Term

Number 1 corresponds to which of the following?

A. Iliacus muscle

B. gluteus minimus muscle

C. superior glueteal artery

D. psoas major muscle

[image]

Definition
Answer: D. psoas major muscle
Term

Which of the following window level and width settings were used to display this image?

A. Level=-700, Width=2000

B. Level=+50, Width=400

C. Level=+150, Width=1000

D. Level=+250, Width=4000

[image]

Definition

Answer: D. Level=+250, Width=4000

An extremely wide window should be used to display images containing tissues with varying density ranges. A width such as 4000 is sufficient to display the dense bone of the mastoid tip and internal auditory canals. The level is set at the approximate average value of the tissues displayed. A level of +250 is the approximate average of all tissues within this anatomic region.

Term

The average range for normal adult BUN levels is approximately:

A. 1-4 mg/dL

B.5-20 mg/dL

C. 23-30 mg/dL

D. 45-60 mg/dL

Definition

Answer: B. 5-20 mg/dL

The average range for normal adult blood urea nitrogen (BUN) levels is approximately 5-20 mg/dL.

Term

A Voxel may be defined as which of the following?

A. The portion of the CRT displaying the image

B. A miniature image

C. A volume element

D. An arrangement of pixels

Definition

Answer: C. A volume element

A Voxel may be defined as a volume element. It is represented within a matrix by a pixel.

Term

Which number corresponds with the left lobe of the liver?

[image]

Definition

Answer: Number 1

Term

The technique that allows the user to select the range of pixel values used in a 3D CT reformation is termed:

A. Thresholding

B. Windowing

C. Retrospective reconstruction

D. Targeting

Definition

Answer: A. Thresholding

The selected threshold allows the user to select the range of pixel values rendered in the 3D model. For example, a higher, bone threshold (>300 HU) can be chosen to build a skeletal model of the patient's skull. Decreasing the threshold to include voxels with lower attenuation values results ina 3D model with the patients soft tissues included.

Term

Which of the following sets of section widths and intervals is best suited for a CT examination of the cervical spine to rule out intervertebral disc herniation?

A. 5mm x 5mm

B. 1.25mm x 1.25mm

C. 5mm x 7mm

D. 10mm x 10mm

Definition

Answer: B. 1.25mm x 1.25mm

Contiguous acquisition with narrow slice thickness is preferred during CT examination of the cervical spine. Section widths of 1.25mm or less should be used with no gap or even an overlap, thus ensuring thorough evaluation of the relatively small intervertebral disc spaces.

Term

The oral administration of barium and iodinated contrast media prior to CT colonography serves the primary purpose of:

A. lesion enhancement

B. Insufflation

C. Catharsis

D. polyp tagging

Definition

Answer. D polyp tagging

Dual-agent tagging involves the oral administration of both barium and water-soluble iodinated contrast. The barium tags residual stool and coats the surface of polyps. The iodine contrast tags residual fluid. Tagged fluid and fecal matter exhibit high CT density and appear "white" on the CTC image. Tagging allows for differentation of polyp from fecal matter and improves the visualization of polyps that may be surrounding by residual fluid.

Term

Which of the following corresponds to the period of the cardiac cycle known as atrial systole?

A. Relaxation of the left and right atrial

B. Contraction of the left and right atria

C. Relaxation of the left and right ventricles

D. Contraction of the left and right venticles

Definition

Answer: B. Contraction of the left and right atria

Atrial systole describes the period of the cardiac cycle when the left and the right atria are contracting.

Term

The multiple-scan average dose (MSAD) is used to describe the:

A. Dose recieved in a single CT section

B. Amount of radiation absorbed in a quantity of air

C. Average dose to a single section within a scan of multiple sections

D. Cumulative dose for an entire helical scan

Definition

Answer: C. Average dose to a single section within a scan of multiple sections

The multiple-scan average dose (MSAD) is used to quantify the average cumulative dose to each section within the center of a scan consisting of multiple sections.

Term

Which Number corresponds to the common carotid artery?

[image]

Definition
Answer: Number 3
Term

Which of the following is a malignant tumor of the skeletal system?

A. Chondroblastoma

B. Osteochondroma

C. Enchondroma

D. Osteosarcoma

Definition

Answer: D. Osteosarcoma

Malignant tumors of the skeletal system include osteosarcoma, chondrosarcoma, and multiple myeloma.

Term

Which of the following is not a typical matrix size used with a modern CT scanner?

A. 80 x 80

B. 320 x 320

C. 512 x 512

D. 1024 x 1024

Definition

Answer: A. 80 x 80

Modern CT scanners are large matrices for image reconstruction and display. Typical sizes include 320 x 320, 512 x 512, and 1024 x 1024

Term

The type of compensating filter used at the x-ray tube of a CT scanner is called a:

A. Kernel

B. Water Bath

C. Bow-tie filter

D. Wedge filter

Definition

Answer: C. Bow-tie filter

The bow-tie filter used at the x-ray tube of a CT scanner absorbs a larger amount of radiation at the periphery of the patient, where the part thickness is reduced. The center of the patient is places at the center of the filter, where the largest amount of radiation is allowed to pass through. The use of this type of filter attempts to compensate for the differences in thickness of the often oval-shaped patient.

Term

Which of the following formulas may be used to calculate the dimensions of a pixel?

A. Pixel size= matrix size/DFOV

B. Pixel size=DFOV x matrix size

C. Pixel size= slice thickness/matrix size

D. Pixel size= DFOV/matrix size

Definition

Answer: D. Pixel Size=DFOV/matrix size

The dimensions of a pixel may be calculated by dividing the DFOV by the matrix size. Keep in mind that the pixel is a square with four equal sides and the dimension of one side is usually given in millimeters (mm). The area of the pixel is calculated by squaring the dimension, and the units are then adjusted to square millimetes (mm2).

Term

Number 1 corresponds with which atomic structure?

[image]

Definition
Answer: Duodenum
Term

Multiplanar reformation (MPR) images along the long axis of the optic nerve would be best describes by which of the following planes?

A. Sagittal

B. Coronal

C. Oblique Sagittal

D. Oblique Coronal

Definition

Answer: C. Oblique sagittal

The optic nerve runs along a lateral-to-medial path from the orbit anteriorly and to the optic chiasma posteriorly. Oblique sagittal MPR images will demonstrate the optic nerve in a profile parallel to its long axis.

Term

The primary indication for a non-contrast cardiac MDCT examinatuib is:

A. coronary artery stenosis

B. Aortic aneurysm

C. Coronary artery calcium quantification

D. Pulmonary embolism

Definition

Answer: C. Coronary Artery calcium quantification

The primary indication for non-contrast cardiac MDCT is coronary artery calcium (CAC) quantification for the assessment of atherosclerotic disease.

Term

Following the intravenous administration of iodinated contrast media, a hepatic hemangioma may become _________ and may no longer appear on the CT image.

A. Hypodense

B. Radiolucent

C. Isodense

D. Hyperdense

Definition

Answer: C. Isodense

The diagnosis of hemangioma is confirmed on CT by evaluation of its pattern of enhancement. Hemangiomas enhance from the periphery inward, until they become isodense with the surrounding hepatic tissue. Once isodense, the hemangioma attenuates the beam in the same way as the hepatic tissue. The CT numbers of the hemangioma and hepatic tissue become equal and the structures may become impossible to differentiate.

Term

After initiation of rapid bolus administratin of an iodinated contrast agent, the corticomedullary phase of renal contrast enhancement occurs at approximately:

A. 20-25 seconds

B. 30-40 seconds

C. 70-90 seconds

D. 3 to 5 minutes

Definition

Answer: B. 30-40 seconds

The corticomedullary phase is a late arterial phase beginning 30-40 seconds after the initiation of contrast agent administration. Optimal enhancement of the renal cortex and renal veins occurs during this period.

Term

Number 4 corresponds with which atomic structure?

[image]

Definition
Answer: Semicircular canal
Term

Which of the following aquistions may be characterized as noncontiguous?

A. 2.5 mm sections reconstructed every 1.25 mm

B. 5.0 mm sections reconstructed every 7.5 mm

C. 3.75 mm sections reconstructed every 3.75 mm

D. 20-second cine acquisition with 1.25 mm sections

Definition

Answer: B. 5.0 mm sectinos recontructed every 7.75

Noncontiguous images are images aquired with an interval greater than the section width. For example, 5.0 mm secions reconstructed every 7.5 mm fail to evaluate the intermittent 2.5 mm of tissue.

Term

Number 1 corresponds to which of the following?

[image]

Definition

Answer: B. Fovea Capitis

Term

In effort to reduce radiation exposure to the orbits during a CT examination of the brain, the gantry may be angled:

A. perpendicular to the hard palate

B. Parallel to the hard palate

C. 15 degrees superior to the infraorbital meatal line (IOML)

D. 15 degrees inferior to the infraorbital meatal line (IOML)

Definition

Answer: C. 15 degrees superior to the infraorbital meatal line (IOML)

Aquisition for a brain CT may be preformed at an angle 15 degrees above the IOML, parallel to the skull base, to reduce orbital radiation dose and minimize beam hardening artifact.

Term

The IV administration of iodinated contrast media requires strict adherence to:

A. Contact isolation and sterile technique

B. Enteric precautions and aseptic technique

C. Contact isolation and aseptic technique

D. Standard precautions and aseptic technique

Definition

Answer: D. standard precautions and aseptic technique

Standard precautions refers to the principle that all blood, body fluids, and secretions may contain transmissible infectious disease. The practice of standard precautions applies to all patients recieving patient care, regardless of medical history. The technique and procedures constituting standard precautions are hand washing and the wearing of gloves, masks, goggles, gowns, etc. Similar in purpose aseptic technique refers to the specific procedures that a practioner employs to reduce the risk of infection during IV administraion of contrast agent. Examples are through hand washing between patients, wearing gloves, and cleansing the IV site with alcohol.

Term

Which of the following areas of the head commonly become calcified?

(1) Thalamus

(2) Pineal Gland

(3) Choroid plexus

A. 2 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: C. 2 and 3 only

The choroid plexus and pineal gland are common areas of calcification in the brain. These areas of increased attenuation and density are easily identified on the CT image.

Term

Which of the following is the correct order for the stages of infection?

A. Incubation, prodromal, active, convalescence

B. Convalescence, active, prodromal, incubation

C. Prodromal, incubation, convalesence, active

D. Incubation, convalescense, prodromal, active

Definition

Answer: A. incubation, prodromal, active, convalescence

The course of an infection can be divided into 4 stages. The incubation stage begins when a pathogenic organism enters the host. The prodromal stage is characterized by the appearance of early signs and symptoms fo the disease process. The active or full stage consists of the maximum appearance of the signs and symptoms of the disease. During the last stage, convalescence, the symptoms begin to diminish and may eventually completely subside.

Term

A CT scanner with a limiting resolution of 15 lp/cm can resolve an object as small as:

A. 0.1 mm

B. 0.3 mm

C. 0.6 mm

D. 1.0 mm

Definition

Answer: 0.3 mm

The minimum object size that a CT scanner can resolve may be calculated by taking the reciprocal value of the scanner's limiting resolution. The reciprocal of 15 lp/cm is 1/15 lp/cm. This is equivalent to 10/15 lp/cm, which equals 0.6 mm/lp. Because a line pair (lp) is equivalent to a line and space adjacent to it, this value may be divided in half to provide the minimum object that this scanner can resolve: 0.3

Term

By CT criteria, a solitary pulmonary nodule may be defined as a focal area of increased density in the lung that is smaller than:

A. 1 cm

B. 3 cm

C. 5 cm

D. 10 cm

Definition

Answer: B. 3 CM

Solitary pulmonary nodules are typically ovid focal areas of increased density that are less than 3 cm in diameter. Any lesion larger than 3 cm is reffered to as a focal mass, with an increase propensity for malignancy.

Term

Number 3 corresponds to which atomic structure?

[image]

Definition
Answer: Gluteus minimus muscle
Term

When one is choosing a window to display a CT image, the width defines the:

A. midpoint of the range of pixels displayed

B. range of CT numbers (pixels) to be displayed

C. Range of pixel values included in an ROI

D. Average CT number of the tissue of interest

Definition

Answer: B. Range of CT numbers (Pixels) to be displayed

The width of a CT window controls the range of pixel values that are assigned to a shade of gray. The width is centered to a level that is equal to the value of the tissue of interest.

Term

The ability of a CT scanner to image a small high-density object is controlled by the ____________ of the scanner.

A. Contrast Resolution

B. Spatial Resolution

C. Sensitivity

D. Both A and C

Definition

Answer: B. Spatial resolution

The spatial resolution of a CT scanner controls its ability to image small structures

Term

Which of the following is/are included in the signs and symptoms of hypovolemic shock?

(1) hypertension

(2) oliguria

(3) pallor

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: C. 2 and 3 only

Hypovolemic shock is caused by an insufficient volume of circulating blood. The common signs and symptoms of hypocolemic shock are pallor (absence of color in the skin), hypotension, tachycardia, and oliguria (decrease urine output)

Term

In 1917, Austrian mathematician _______ proved that it was possible to recontruct a three-dimensional object from the infinate set of all of its projections.

A. Radon

B. Tsien

C. Bracewell

D. Cormack

Definition

Answer: A. Radon

J. Radon, an Austrian mathematician was responsible for some of the earliest scientific research for the reconstruction principles used in computed tomography. In 1917 he proved that it was possible to build an image of an object through the use of an extremely large set of his projections.

Term

Which of the following may be used for the archival storage of CT images?

(1) CD-ROM

(2) VHS tape

(3) Magnetic optical disc

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: B. 1 and 3 only

CD-ROM and magnetic optical disc (MOD) are two media commonly employed for CT image archival.

Term

Which of the following methods may be used to determine the appropriate injection delay for optimal vessel enhancement during a CTA examination of the brain?

(1) measurement of the patient's pulse rate

(2) performing a bolus-timing sequence

(3) utilizing bolus-tracking software

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: C. 2 and 3 only

Although pulse rate may provide an indication of the patients overall cardiac function, it is not utilized to determine injection delays for angiographic procedures. Emperic delays, bolus timing squences, and bolus tracking software may all be used to accurately acquire CTA studies during peak vascularture enhancement.

Term

Which of the following corresponds to the longitudinal dimenion of the CT image voxel?

A. x-axis

B. Y-axis

C. z-axis

D. orthogonal axis

Definition

Answer: C. z-axis

The longitudinal dimension of the voxel corresponds to the z-axis of scanning, with a voxel depth equal to the reconstructed section width.

Term

________ is a term that refers to an excessive amount of nitrogenous materials in the blood and is a symptom of renal failure.

A. Hydronephrosis

B. Azotemia

C. Oliguria

D. Diuresis

Definition

Answer: B. Azotemia

Azotemia describes the condition excessive nitrogenous materials in the blood. This condition is also commonly called uremia. Azotemia is a symptom of renal insufficiency and may occur during chronic renal failure.

Term

Evaluation of the venous vascular structures of the brain is known as:

A. CT angiography

B. CT perfusion

C. CT Runoff

D. CT venography

Definition

Answer: D. CT Venography

CT Venography (CTV) of the brain is a cariation of the CTA technique whereby the timing of data acquisition is optimized for the period of peak venous opacification.

Term

Which of the following adjustments in technical factors will result in increase in spatial resolution?

A. increase in tube filament

B. increase in sampling frequency

C. Increase in section width

D. Increase in display field of view (DFOV)

Definition

Answer: B. increase in sampling frequency

The sampling frequency, or views per rotaion (VPM), controls the volume of transmission data acquired for each gantry rotation. Very small objects exhibit high spatial frequencies that only systems with high sampling rates will be capable of resolving.

Term

After initiation of rapid bolus administration of an iodinated contrast agent, the excretory phase of renal contrast enhancement occurs at approximately:

A. 20-25 seconds

B. 30-40 seconds

C. 70-90 seconds

D. 3-5 minutes

Definition

Answer: D. 3-5 minutes

The excretory phase is a delayed-imaging phase that begins approximately 3 minutes after the initiation of contrast agent administration. During this phase, contrast material has been excreted into the real calyces, opacifying the renal pelvis and the remainder of the urinary collecting system (ureters, bladder). The excretory phase best demonstrates the filling defects and potential lesions involving the urothelium, such as those from transitional cell carcinoma (TCC).

Term

Which number corresponds to the left brachiocephalic vein?

[image]

Definition
Answer: number 1
Term

The Propensity of a contrast agent to cause fluid to move from the extravascular space to the intravascular space is called:


A. Toxicity

B. Solubility

C. Concentration

D. Osmolality

Definition

Answer: D. Osmolality

An important characteristic of iodinated radiopaque contrast media, osmolality describes the propensity of the agent to cause fluid from outside the blood vessel (extravascular space) to move into the bloodstream (intravascular space).

Term

In multislice CT (MSCT), the beam pitch is equal to the table feed per rotation divided by the:

A. Number of detectors

B. Pre-patient collimation

C. Total collimation

D. Number of channels

Definition

Answer: C. Total collimation

The beam pitch, which is unique to multislice CT, is equal to the table feed per rotation divided by the total collimation. The total collimation is equal to the combined thickness of all of the sections that are simultaneously acquired with each gantry rotation.

Term

The full width at half maximum (FWHM) of a slice sensitivity profile diagram indicates the:

A. Limiting resolution

B. Signal-to-noise ratio (SNR)

C. Dose profile

D. Effective section width

Definition

Answer: D. Effective section width

The effective section width is defined as the full width at half maximum (FWHM) of the SSP. It is measured by examining the slice sensitivity profile at half of its maximum height.

Term

The detectors of a PET system absorb and measure what type of radiation?

A. Xray photons

B. Annihilation photons

C. Light photons

D. Ultraviolet photons

Definition

Answer: B. Annihilation photons

Annihilation photons are emitted from the radionuclide F-18-Fluorodeoxyglucose (FDG) that has been taken up by the tumor cells. PET detectors absorb the emitted photons, measuring the activity of a given area of potential malignancy.

Term

For a given CTA examination of the pulmonary arteries, 100 mL of a low-osmolar iodinated contrast agent is administered at a rate of 4 mL/sec. Peak pulmonary artery opacification should occur at approximately:

A. 5-10 sec

B. 20-25 sec

C. 50-60 sec

D. 80-90 sec

Definition

Answer: B. 20-25 sec

Empiric scan delays for CTA of the pulmonary arteries vary between 20 and 25 seconds. Peak contrast opacification of the pulmonary arteries depends heavily on the rate of injection and the cardiac output of the patient. Performing a test bolus sequence and utilizing bolus-tracking software are valuble methods of ensuring that acuisition occurs during the period of maximum vessel opacification.

Term

For a given CT acquisition, the calculated mAs applied to each reconstructed slice may be referred to as the:

A. effective mAs

B. peak mAs

C. absorbed mAs

D. constant mAs

Definition

Answer: A. effective mAs

Effective mAs describes the calculated mAs per acquired slice. The primary influencing factor for effective mAs is table speed, which is an important component controlled by the selected detector pitch. The detector pitch chosen by the CT operator directly affects the speed at which the patient travels through the gantry. The mAs divided by the pitch yields the effective mAs for each slice in a given CT acquisition.

Term

Number 2 corresponds to which anatomic structure?

[image]

Definition
Answer: Thalamus
Term

Number two corresponds to which anatomical structure?

[image]

Definition
Answer: Femoral artery
Term

Which of the following technical factor(s) play(s) a role in the production of an isotropic dataset?

(1) section width

(2) scan field of view (SFOV)

(3) display field of view (DFOV)

Definition

Answer: 1 and 3 only

Isotropic resolution is approached by choosing the thinnest detector collimation availible to to produce the thinnest slices availible and by reconstructing the acquired data with the smallest DFOV allowed according to the part of interest. Minimizing these two factors results in voxels approaching equal lengths in all directions.

Term

This Image of the Abdomen was most likely acquired in which phase of renal enhancement?[image]

Definition

Answer: Nephrographic Phase

The Neprographic phase occurs between 70-90 seconds after the start of the injection. Enhancement between renal cortex and medulla reaches equilibrium, providing optimal sensitivity for parenchymal lesions.

Term

The articulation between the dista tibia and fibula is called the:

A. Synarthrosis

B. Amphiarthrosis

C. Synostoses

D. Syndemosis

Definition
Answer: D. Syndemosis
Term

This type of image is referred to as a(n):

[image]

Definition

Answer: MPR image

Multiplanar reformation (MPR) describes the process of displaying CT images in a different orientation from the one used in the original reconstruction process. MPR images may be constructed in the coronal, sagitaal, or any other two dimensional plane. MPR images are typically formed from a vertical stack of contiguous, helically acquired axial CT images.

Term

This image of the abdomen was most likely acquired in which renal enhancement phase?

[image]

Definition

Answer: B. Corticomedullary phase

Beginning 30-40 seconds after initiation of contrast agent administration, the corticomedullary phase demonstrates optimal enhancement of the renal cortex with maximum differentiation from the renal medulla.

Term
Number 5 corresponds to what anatomic structure?[image]
Definition
Answer: Superior articular process
Term

Automatic tube current modulation (ATCM) software is utilized by the CT system in an effort to:

A. improve temporal resolution

B. decrease patient dose

C. save on energy costs

D. improve spatial resolution

Definition

Answer: B. decrease patient dose

Automatic tube current modulation (ATCM) is a form of automatic exposure control (AEC) for CT systems. This type of software automatically decreases applied dose on the basis of the size, density, and overall attenuation of the part being examined.

Term

After initiation of rapid bolus administration of an iodinated contrast agent, the hepatic venous phase of contrast enhancement occurs at approximately:

A. 15-20 seconds

B. 25-25 seconds

C. 60-70 seconds

D. 120-180 seconds

Definition

Answer: C. 60-70 seconds

The hepatic (or portal) venous phase is the period of peak hepatic parenchymal enhancement during which contrast material redistributes from the blood into the extravascular spaces. It occurs at approximately 60-70 seconds after the initiation of rapid bolus administration of a contrast agent.

Term

The ability of an object to attenuate the x-ray beam is assigned a value known as the:

A. Linear attenuation coefficient

B. Hounsfield value

C. CT number

D. ray sum

Definition

Answer: A. Linear attenuation coefficient

The ability of an object to attenuate the x-ray beam is assigned a value termed the linear attenuation coefficient. (μ).
Term

Number 7 corresponds to which anatomic structure?

[image]

Definition
Answer: Brachiocephalic artery
Term

The computer technique used to reduce size and storage requirements of digital CT image data is called:

A. Archival

B. Compression

C. Encryption

D. Rendering

Definition

Answer: B. Compression

Image compression is a complex computer technique that reduces the size of digital CT image data. Compression of CT images reduces the storage requirements and increases the speed at which the CT images may be transmitted across computer systems.

Term

A 64-slice MSCT system employs an array of 64 detectors, each with a dimension of 0.625 mm. What beam collimation is required to expose the middle 32 detectors of the array to transmitted x-radiation?

A. 10 mm

B. 20 mm

C. 32 mm

D. 64 mm

Definition

Answer: B. 20 mm

The selected detector configuration for a given acquisition determines the necessary beam collimation. The selected 32 detectors, each with an individual dimension of 0.625 mm. would require a beam collimation of 20 mm to expose each to transmitted radiation. (32 x 0.625= 20 mm).

Term

Which of the following is a correct difference between ionic and nonionic iodinated contrast media?

A. nonionic media have a higher osmolality than ionic media

B. ionic contrast media contain iodine, whereas nonionic media do not

C. nonionic contrast media have lower osmolality than ionic media

D. ionic contrast media are associated with a lower incidence of adverse reactions than nonionic media

Definition

Answer: C. nonionic contrast media have lower osmolality than ionic media

Nonionic iodinated contrast media have a lower osmolality and are associated with a lower incidence of adverse reaction than ionic contrast media. Both types of materials contain iodine in varying concentrations.

Term

Number 3 corresponds to which muscle?

[image]

Definition
Answer: Left pectoralis major muscle
Term

Number 4 corresponds to which structure?

[image]

Definition
Answer: Ischium
Term

Number 4 corresponds to which anatomic structure?

[image]

Definition
Answer: Sternocleidomastoid muscle
Term

Number 5 corresponds to which muscle?

[image]

Definition
Answer: Obturator internus muscle
Term

Which of the following technical facotors exhibits an effect upon longitudinal spatial resolution?

(1) detector pitch

(2) interpolation algorithm

(3) display field of view (DFOV)

A. 1 only

B. 3 only

C. 1 and 2 only

D. 1 and 3 only

Definition

Answer: C. 1 and 2 only

The factors that affect longitudinal spatial resolution and the SSP include the type of spiral interpolation algorithm inherent to the system and the selected detector pitch.

Term

Increasing the detector pitch during a spiral CT exam adversely affects the spatial resolution along which of the following?

A. axial plane

B. x-axis

C. y-axis

D. z-axis

Definition

Answer: D. Z-axis

The spatial resolution alond the z-axis is decreased when the detector pitch is increased. An increase in detector pitch causes less information to be acuired for each section reconstructed. The section sensitivity profile (SSP) is broadened, and the spatial resolution is reduces.

Term

When one is using a third-generation CT scanner, it is important that reference detectors positioned at the peripheral portions of the detector array be exposed to:

A. homogeneous radiation

B. unattenuated radiation

C. monochromatic radiation

D. remnant radiation

Definition

Answer: B. unattenuated radiation

Reference detectors are used to measure incident radiation intensity. This information is used by the computer during the calculation of the linear attenuation coefficient. If the patient is places incorrectly within the gantry, the reference detectors may be partially blocked causing an out-of-field artifact.

Term

The quantity of blood pumped out of the ventricle every heartbeat is termed the:

A. end-diastolic volume

B. ejection fraction

C. end-systolic volume

D. injection fraction

Definition

Answer: B. Ejection fraction

Ejection fraction describes the percentage of blood pumped out of a cardiac ventricle during each contraction. It is a measure of cardiac function and can be accurately determined during a cardiac CT examination. With system software, the ejection fraction can be calculated from a comparison between colume of blood within a ventricle at the end of filling (end-diastolic volume) and the volume at the end of contraction (end-systolic volume)

Term

The liver has dual blood supply and recieves 25% of its blood from the:

A. Hepatic artery

B. Superior mesenteric artery (SMA)

C. Portal vein

D. Superiod mesenteric vein (SMV)

Definition

Answer: A. Hepatic Artery

The liver has a dual blood supply, receiving 75% of its supply from the portal vein, and the remaining 25% from the hepatic artery.

Term

An IV contrast enhanced specialized CT evaluation of the small bowel after the oral administration of a low-density (0,1%) barium sulfate solution is termed:

A. CT enteroclysis

B. CT colonography

C. CT enterography

D. CT colonoscopy

Definition

Answer: C. CT enterography

CT enterography does not involve contrast agent administration through a nasogastric tube and is therefore less invasive than CT enteroclysis.

Term

The computerized communication system used by a PACS to transmit data is referred to as a:

A. Convolution

B. Hierarchy

C. Network

D. Matrix

Definition

Answer: C. Network

A PACS communicates with the CT system(s) and other modalities and peripherals via a computerized communication system, or network.

Term

Assuming a bolus injection of iodinated contrast agent at a rate of at least 4 mL/sec, an appropriate scan delay for a CTA examination of the mesenteric vasculature would be in the range of:

A.5-8 seconds

B. 20-30 seconds

C. 45-60 seconds

D. 70-90 seconds

Definition

Answer: B. 20-30 seconds.

Dual-phase imaging including the arterial phase (20-30 seconds) and portal venous phase (60-70 seconds) is typically performed for complete evaluation of the mesenteric vasculature. The use of bolus-tracking software or test bolus technique is recommended to ensure appropriate scan timing.

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: Ambient cistern
Term

The streaking artifact in the image is most likely due to:

[image]

Definition

Answer: Beam hardening

Streaking artifacts such as the one in the figure commonly occur during CT scanning of thick body parts like the shoulder. The x-ray beam changes in quality as it passes through different densities. These beam energy changes sometimes manifest as streak artifacts.

Term

Patients whose posterior descending artery branches from the right coronary atery, and whose left posterior ventricular branches arise from the left circumflex artery, are said to be:

A. Right dominant

B. Left dominant

C. Codominant

D. Posteriorly dominant

Definition

Answer: C. Codominant

7% of the population is said to be codominant, meanind the posterior descending artery (PDA) is supplied by the right coronary artey (RCA), and the left posterior ventricular branches arise from the Left circumflex artery (LCX)

Term

During post-contrast CT imahing of the abdomen, the degree of hepatic parenchymal enhancement depends on:

(1) the iodine concentration of the contrast agent

(2) the rate of contrast injected

(3) the osmolality of the contrast media

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1,2, and 3

Definition

Answer: B. 1 and 2 only

The extent of hepatic parenchymal enhancement depends on the overall dose of iodine delivered. The iodine dose may be increased directly by utilizing a contrast agent with a higher concentration, or indirectly by increasing the injection rate.

Term

Which of the following is NOT a component of the blood supply to the brain commonly referred to as the circle of willis (COW)?

A. Right middle cerebral artery

B. Left posterior communicating artery

C. Anterior communicating artery

D. Left posterior cerebral artery

Definition

Answer: A. Right middle cerebral artery

The circle of willis is composed of the anterior cerebral, anterior communicating, internal carotid, posterior cerebral, and posterior communicating arteries. The basilar and middle cerebral arteries are important vessels supplyaing blood to the brain, but they do not form a part of the circle of willis.

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: Right internal judular vein
Term

The type of hemorrhage that occurs between the skull and outer layer of the dura in traumatic brain injury is referred to as a(n):

A. Subdural hematoma

B. Epidural Hematoma

C. Subarachnoid Hematoma

D. Subcutaneous Hematoma

Definition

Answer: B. Epidural Hematoma

An epidural hematoma occurs between the skull and the outtermost meningeal covering of the brain called the dura mater. Subdural hematomas occur between the dura mater and the next inner layer of the meninges, known as the arachnoid. The innermost layer of the meninges is called the pia mater.

Term

Which of the following technical adjusments would decrease the quantum noise of a CT image?

(1) Increase mAs

(2) decrease section width

(3) Increase sectin width

A. 1 only

B. 1 and 2 only

C. 1 and 3 only

D. 1, 2, and 3

Definition

Answer: C. 1 and 3 only

The quantum noise of a CT image can be reduced by an increase in the number of x-ray photons reaching the detectore. This reduction may be accomplished by increasing mAs or section width (decreased collimation).

Term

Cerebrospinal fluid (CSF) is produces in the:

A. tentorium cerebelli

B. pineal gland

C. corpus callosum

D. choroid plexuses

Definition

Answer: D. Choroid plexuses

The cerebrospinal fluid is secreted by the choroid plexuses that are located in each of the four ventricles of the brain.

Term

Number 1 corresponds with which muscle?

[image]

Definition
Answer: Sartorius muscle
Term

After initiation of rapid bolus administratino of an iodinated contrast agent, the early arterial phase of hepatic contrast enhancement occurs at approximately:

A. 15-20 seconds

B. 25-35 seconds

C. 60-70 seconds

D. 120-180 seconds

Definition

Answer: A. 15-20 seconds

Occuring at 15-20 seconds after the initiation of contrast administration, the early arterial phase of contrast enhancement is the optimal phase for angiographic applications of liver CT. During the phase, the hepatic arterial supply is well opacified with little or no parenchymal enhancement.

Term

Which of the following manipulations involes the use of image data?

A. adjusting the width and level of a window

B. decreasing the DFOV

C. changing the algorithm selection

D. increasing the matrix size

Definition

Answer: A. adjusting the width and level of a window

The adjustment of the window width or level is a computer manipulation of the image data. The image has already been reconstructed from scan or "raw" data. The window changes only the range of pixel values that will be assigned a shad of gray. Adjustments in the algorithm, DFOV, or matrix require the raw data so that the image may be retrospectively reconstructed.

Term

Number 3 correspond with which anatomic structure?

[image]

Definition
Answer: Celiac trunk
Term

Which of the following components of CT image quality may be controlled by the technologist?

(1) Spatial resolution

(2) contrast resolution

(3) noise

A. 2 only

B. 3 only

C. 1 and 3 only

D. 1, 2, and 3

Definition

Answer: D. 1, 2, and 3

Each component of CT image quality may be affected-either positively or negatively-by the CT technologist. Spatial resolution is affected by geometric factors such as focal spot size and slice thickness. Contrast resolution may be altered by slice thickness, algorithm selection, and noise. The noise level on an image is dependent upon several facots, including patient dose and pixel dimension. Each of these factors must be considered by the CT technologist in an effort to provide high quality CT studies.

Term

Number 4 corresponds with which anatomic structure?

[image]

Definition
Answer: Cerebellum
Term

CT images of the abdomen should be acquired with the patient:

A. at full inspiration

B. breathing quietly

C. at full expiration

D. breathing normally

Definition

Answer: C. at full expiration

Suspended respiration at the end of full expiration is the most reproductable point in the respiratory cycle. It results in a less misregistration artifact during CT examinations of the abdomen.

Term

What is the display field-of-view used for a 3202matrix image with a pixel dimension of 0.75 mm x 0.75 mm?

A. 12 cm

B. 24 cm

C. 36 cm

D. 48 cm


Definition

Answer: B. 24 cm

The display field of view may be calculated by multiplying the pixel dimension by the matrix size. In this example, one side of the pixel measures 0.75 and the matrix used is 3202. The DFOV is 240mm or 24 cm.

Term

Coronal imaging through the paranasal sinuses is typically performed with the plane of imaging:

A. parallel to the infraorbital-meatal line

B. perpendicular to the gabellomeatal line

C. parallel to Reid's baseline

D. perpendicular to the hard palate

Definition

Answer: D. perpendicular to the hard palate

The imaging plane should be positioned perpendicular to the hard palate for coronal evaluation of the paranasal sinuses. This may be achieved by positioning the patient supine, head extended-back position, or with the patient in the prone position. In either case, appropriate angulation of the gantry can help achieve an aquisition angle that is perpendicular to the hard palate. Alternatively, multiplanar reformation (MPR) images may be produced at an angle perpendicular to the axial acquisition, also resulting in coronal images through the paranasal sinuses.

Term

Number 2 corresponds with which anatomic structure?

[image]

Definition
Answer: Sternocleidomastoid muscle
Term

The dimensions of a voxel may be calculated as the product of which of the following?

A. matrix size and pixel size

B. pixel size and section width

C. DFOV and matrix size

D. DFOV and pixel size

Definition

Answer: B. pixel size and section width

The pixel is a two-dimensional representation of a voxel. The section width is equal to the length of the voxel. To calculate the dimensions of a voxel, the pixel dimension must be multiplied by the section width.

Term

Which of the following would increase the noise apparent on a CT image?

A. increase in mAs

B. decrease in aperature size

C. increase in filtration

D. decrease in matrix size

Definition

Answer: B. decrease in aperature size

A decrease in aperature size reduces the amount of x-ray photons exposing the tissue. This will cause a decrease in the signal-to-noise ratio. Keep in mind that the collimators used to adjust the size of the aperature absorb radiation as they restrict the beam.

Term

Number 5 corresponds to which anatomical sturcture?

[image]

Definition

Answer: Petrous bone

Term

Which of the following units is used to quantify absorbed dose?

A. roentgens

B. grays (Gy)

C. sieverts (Sv)

D. curies (Ci)

Definition

Answer: B. grays (Gy)

Absorbed dose describes the amount of x-ray energy absorbed in a unit of mass. It is measured in grays (Gy).

Term

Number 2 correspons with which anatomical strucure?

[image]

Definition
Answer: Costovertebral articulation
Term

What scan field of view (SFOV) value was most likely used for the aquisition of this CT image?

[image]

A. 9.6 cm

B. 15.0 cm

C. 25.0 cm

D. 50.0 cm

Definition

Answer: D. 50.0 cm

The acquisition was most likely made with use of a large scan field of view (SFOV), 48-50 cm. Any smaller SFOV would result in out-of-field artifact, because portions of the upper shoulder area would lie beyond the range or the detector array. A smaller display field-of-view (DFOV) value was used for image reconstruction, targeting the side of interest.

Term

A CT image is reconstructed using a 5122 matrix and a display field of view of 17 cm. What is the linear dimension of each pixel?


A. 0.033 mm

B. 0.3 mm

C. 3.01 mm

D. 30.1 mm

Definition

Answer: B. 0.3 mm

The dimension of a pixel may be calculated by dividing the field of view by the matrix size. The DFOV of 17 cm must first be converted into 170 mm. This is then divided by 512 mm, for a pixel dimension of 0.33 mm. Keep in mind that the pixel is a two-dimensional item, square in shape, and the measurement of 0.33 mm corresponds to only one side.

Term

The portion of the nephron responsible for filtration of unwanted materials from the blood plasma is called the:

A. afferent arteriole

B. Proximal tubule

C. efferent arteriole

D. glomerulus

Definition

Answer: D. glomerulus

The glomerulus is the portion of the nephron responsible for filtering unwanted substances from blood plasma. The blood enters into the glomerulus through the afferent arteriole and exits through the efferent arteriole. The waste fluid leaves the glomerulus through the proximal tubule.

Term

The ability of an MDCT system to freeze heart motion during a cardiac CT is described by its:

A. detector resolution

B. spatial resolution

C. temporal resolution

D. contrast resolution

Definition

Answer: C. temporal resolution

The temporal resolution of an MDCT system describes its ability to freeze the motion of the heart as well as the arterial motion velocity within the coronary vasculature.

Term

Number 2 corresponds with which anatomical structure?

[image]

Definition
Answer: Hyoid bone
Term

Which of the following types of image noise can be most easily reduced by the CT technologist?

A. electronic noise

B. artifactual noise

C. quantum noise

D. detector noise

Definition

Answer: C. quantum noise

The quantum or statistical noise of a CT image can be reduced by increasing the number of x-ray photons absorbed by the detectors for each voxel of tissue. This can be accomplished with increased in technique (mAs) and with increases in the pixel and voxel and dimensions.

Term

In multislice CT (MSCT), the beam pitch is equal to the table feed per rotation divided by the:

A. number of detectors

B. pre-patient collimators

C. total collimation

D. number of channels

Definition

Answer: C. total collimation

The beam pitch, which is unique to multislice CT, is equal to the table feed per rotation divided by the total collimation. The total collimation is equal to the combined thickness of all of the sections that are simultaneously acquired with each gantry rotation.

Term

The term beam hardening is used to describe which of the following physical phenomena?

A. the decrease in average photon energy of a heterogenous x-ray beam

B. the increase in average photon energy of a homogenous x-ray beam

C. the increase in average photon energy of a heterogenous x-ray beam

D. the decrease in average photon energy of a homogenous x-ray beam

Definition

Answer: C. the increase in average photon energy of a heterogenous x-ray beam

Beam hardening occurs as the x-ray beam traverses the patient. The x-ray beam used in CT is composed of x-ray photons with numerous different energies. The heterogenous beam undergoes an increase in average photon energy as it passes through the patient and the lower-energy photons are absorbed.

Term

During IV contrast agent administration for peripheral CTA examinations, the bolus duration should be equal to the scan time minus:

A. 0 seconds

B. 5 seconds

C. 15 seconds

D. 30 seconds

Definition

Answer: B. 5 seconds

The duration of scan acquisition for peripheral CTA will be based on the anatomic length of the study and the capabilities of the particular CT system in use. Faster scanners run the risk of "outrunning" the bolus by completing the acquisition before the entire contrast volume has been administered. Bolus duration, or the time required to inject a specific volume of contrast, may be calculated as the product of injection flow rate and total contrast agent volume. The subtraction of 5 seconds allows the scanner to maintain pace with the contrast agent as it moves down the aorta and results in the cessation of contrast agent administration just prior (5 sec) to the end of data acquisition.

Term

Two adjacent pixels are measured to have a difference of 1 HU. This amounts to a tissue density difference of approximately:

A. 0.1%

B. 1.0%

C. 10%

D. 25%

Definition

Answer: A. 0.1%

Pixels that differ by only 1 Hounsfield unit represent tissue whose attenuation coefficient differ by only 0.1%

Term

Which of the following types of algorithms would be best suited to demonstrate the bony details of the shoulder joint in the figure?

A. high spatial frequency

B. soft tissue

C. standard

D. low spatial frequency

Definition

Answer: A. high spatial frequency

Hugh spatial frequency algorithms demonstrate the greatest spatial resolution and are best suited for imaging sharp density changes, such as those occuring with bone tissue. Bone, edge, and detail are names commonly given to high spatial frequency algorithms.

Term

Which of the following technical adjustments may be emplayed to improve the temporal resolution of an MDCT system?

(1) decreased scan time

(2) decrease section width

(3) decreased DFOV

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: A. 1 only

Temporal resolution quantifies the CT system's ability to freeze motion and to provide an image free of blurring. The controlling factors of the temporal resolution of a CT system are the gantry rotation speed and reconstruction method.

Term

Which of the following technical characteristics of a CT system does NOT directly affect patient dose?

A. source-to-detector distance

B. filtration

C. detector efficiency

D. filament size

Definition

Answer: D. filament size

Although they are beyond the control of the operator, the source-to-detector distance, filtration, and detector efficiency of a CT system all directly affect patient dose. The selected filament size does have geometric ramifications with regard to spatial resolution. A smaller filament results in improved spatial resolution. Patient dose is not affected by filament selection, provided that the mAs value remains constant.

Term

Number 6 corresponds to which anatomical structure?

[image]

Definition
Answer: Pedicle
Term

Severe reactions to intravenous iodinated contrast material occur in approximately ________ of all patients.

A. less than 1%

B. 3%

C. 5%

D. 10%

Definition

Answer: A. less than 1%

Severe reactions to intravenous iodinated contrast media occur in less than 1% of all patients. Examples of severe reactions are shock, myocardial infarction, and death.

Term

In which of the following cranial nerves would an acoustic neuroma be found?

A. third

B. eighth

C. tenth

D. twelfth

Definition

Answer: B. Eighth

An acoustic neuroma (Schwannoma) arises from the schwann cells of the eighth cranial nerve, or the vestibulocochlear nerve. This type of cranial mass may be imaged with CT examinations of the internal auditory canals.

Term

Because of its excessive density, barium sulfate may be used in CT only in suspensions with concentrations of:

A. 1-3% barium sulfate

B. 5-7% barium sulfate

C. 10-13% barium sulfate

D. 25-30% barium sulfate

Definition

Answer: A. 1-3% barium sulfate

Barium sulfate is normally too dense to be useful in CT imaging. Even when diluted with water, barium's high attenuation characteristics can cause streaking artifacts on the CT image. Some commercially availible CT oral contrast media preperations do contain barium sulfate in 1-3% suspensions. The suspension contains additives that are designed to prevent settling of barium sulfate, which could cause inhomogenous opacification of the gastrointestinal system.

Term

Which of the following statements accurately describes the effects of administering an iodinated IV contrast agent during imaging procedures of the brain?

(1) The contrast agent increases attenuation values for normal gray metter.

(2) The contrast agent improves the differentiation of subtle hemorrhage

(3) The contrast agent enhances neoplasms that have disrupted the blood-brain barrier.

Definition

Answer: 1 and 3 only

During CT imaging for suspected intracranial bleeding, contrast administration is initially contraindicated because the associated enhancement may mask subtle signs of hemorrhage.

Term

Phantom measurement of the uniformity of a CT system is performed primarily to assess the negative effects of:

A. partial volume averaging

B. noise

C. detector drift

D. beam hardening

Definition

Answer: D. beam hardening

The uniformity of a CT system describes its ability to maintain relatively consistent CT values acress the entire image of an object of equal density, such as a water-filled phantom. Beam hardening occurs as low-energy x-ray photons are absorbed when the beam passes through the patient. The average photon energy of the beam increases along the path and may result in a loss of system uniformity.

Term

Which of the following correctly illustrates the central volume principle of cerebral perfusion?

A. CBF=CBV/MTT

B. CBF=CBV MTT

C. MTT=CBV CBF

D. CBF=MTT/CBV

Definition

Answer: A. CBF=CBV/MTT

The central volume principle is described by the formula CBF=CBV/MTT. It illustrates the relationship of cerebral blood flow as a factor of the colume of blood within a given area of brain tissue and the time it takes for that blood to pass through the area. Reduces CBF may indicate ischemia due to stroke or other brain abnormalities.

Term

Number 1 corresponds with which anatomic structure?

[image]

Definition
Answer: portal vein
Term

In this image at the level of the L4-L5 disc space, number 6 corresponds to which anatomical strucure?

[image]

Definition

Answer: Cauda Equina

The spinal cord extends inferiorly from the brain's medulla and terminates at approximately the level of T12-L1. At its distal end, the spinal cord tapers into the conus medullaris. The cauda equina is the nerve bundle extending inferiorly from the spinal cord.

Term

The image is displayed in which anatomic plane?

[image]

Definition

Answer: Axial

The axial plane divides the body into inferior and superior portions. The section bisects the foot perpendicular to its long axis and is said to be an axial image in referrence to the standard anatomic position.

Term

Which of the following components of the CT system is the most common cause of ring artifacts on the reconstructed CT image?

A. x-ray tube

B. collimator

C. slip ring

D. detector

Definition

Answer: D. detector

Ring artifacts are typically cause by faulty detectors. An error in a detecor results in back-projection of an incorrect ring of density on the reconstructed CT image.

Term

Which of the following correctly describes the position of the seminal vesicles in the male pelvis?

A. posterior to the bladder and anterior to the rectum

B. superior to the rectum and inferior to the bladder

C. anterior to the bladder and superior to the prostate

D. inferior to the bladder and posterior to the rectum

Definition

Answer: A. posterior to the bladder and anterior to the rectum

The seminal vesicles are located posterior to the bladder and anterior to the rectum on a cross section of the male pelvis.

Term

Cardiac CT images are typically acquired during which phase of the heart's cycle?

A. systolic phase

B. equilibrium phase

C. diastolic phase

D. ejection phase

Definition

Answer: C diastolic phase

The heart optimally imaged with the least artifact from motion during its period of relaxation, otherwise known as the diastolic phase of the cardiac cycle.

Term
The spatial resolution of a CT scanner is often measured using the MTF of the system, which is an acronym for:
Definition

Answer: Modulation transfer function

The modulation transfer function (MTF) is a mathmatical method of quantifying the spatial resolution of a CT scanner.

Term

Each iliac artery bifurcates into the internal and external iliac arteries at about the level of:

A. L4

B. L5-S1

C. the pubic symphysis

D. the patella

Definition
Answer: B. L5-S1
Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: Stomach
Term

Which of the following technical considerations is necessary to differentiate hydronephrosis from parapelvic cysts on CT examination?

A. administration of an iodinated IV contrast

B. prone acquisition

C. administration of an oral contrast agent

D. Valsalva maneuver

Definition

Answer: A. administration of an iodinated IV contrast

Parapelvis cysts are simple cysts arising within the renal pelvis. They are similar in appearance to the distention of the pelvis and calyces known as hydronephrosis. Delayed imaging after IV contrast agent administration opacifies the renal pelvis, clearly differentiating hydronephrosis from parapelvic cysts.

Term

Where should the tourniquet be positioned during preparation of a patient for intravenous contrast administration?

A. directly over the injection site

B. proximal to the injection site

C. distal to the injection site

D. below the injection site

Definition

Answer: B. proximal to the injection site

Prior to the intravenous injection of contrast media, a tourniquet is placed proximal to the injection site. The tourniquet helps distend the vein, making needle insertion easier.

Term

During combined PET-CT imaging, abnormal physiologic uptake of radiopharmaceuticals can occur in patient muscle due to:

A. low blood glucose

B. pre-examination fasting

C. strenuous activity

D. high blood pressure

Definition

Answer: C. strenuous activity

Strenuous physical activity can cause abnormal physiological uptake of FDG in muscle. Therefore, the patient is instructed to avoid such activity prior to the injection and during the delay for imaging. In addition, all patient activity and speech are limited for up to 60 minutes after the injection of FDG.

Term

The volume of a voxel may be calculated by multiplying the pixel dimension (mm2) by the:


A. Display field of view (DFOV)

B. section width

C. pitch

D. scan field of view (SFOV)

Definition

Answer: B. Section width

As a geometric cuboid, the volume of a voxel may be calculated as the product of the pixel area dimension (mm2) and the section width (mm). The pixel dimension (d) must be first calculated by dividing the display field of view (DFOV) by the matrix size. The area of the pixel may then be found by squaring the value of d (mm). The unit of measurement for voxel of volume is mm3.

Term

Which of the following is the primary interaction between x-ray photons and tissue during computed tomography?

A. bremsstrahlung

B. Characteristic

C. Compton effect

D. coherent scatter

Definition

Answer: C. Compton effect

Owing to the high-energy beam used in CT the compton effect is the predominant interaction between x-ray and matter. CT scanners use between 120 and 140 kVp, yielding x-ray energies with averages between 70 and 80 KeV.

Term

Number 3 corresponds to which anatomic structure?

[image]

Definition
Answer: Seminal vesicles
Term

Which of the following technical adjustments would result in a decrease in patient dose?

(1) decrease mAs

(2) increase detector pitch

(3) decrease kVp

A. 2 only

B. 1 and 2 only

C. 1 and 3 only

D. 1, 2, and 3

Definition

Answer: D. 1, 2, and 3

The relationship between mAs and dose is directly proportional. Any reduction in mAs results in a reduction in dose when all other factors remain equal. Increasing detector pitch raises the rate at which the patient moves through the gantry during data acquisition; when all other factors remain constant, increases in detector pitch reduce patient dose. A decrease in kVp also results in lower patient dose primarily through the reduction in overall beam energy at lower tube potentials. This may seem counterintuitive to those who recall the use of high-kVp techniques in radiography as a means of lowering required mAs and the associated patient dose. When we reduce kVp to reduce patient dose in CT.

Term

The normal pulse rate range in a child is:

A. 30-50 beats per minute

B. 60-100 beats per minute

C. 70-120 beats per minute

D. 110-150 beats per minute

Definition

Answer: C. 70-120 beats per minute

The normal range for pulse rate in a child is 70-120 beats per minute. This is slightly higher than the range of 60-100 beats per minute for an adult.

Term

The normal range of respirations for an adult is:

A. 5-10 breaths per minute

B. 12-20 breaths per minute

C. 20-30 breaths per minute

D. 35-50 breaths per minute

Definition
Answer: B. 12-20 breaths per minute
Term

The process of scanning a phantom device of known density to improve the accuracy of CT attenuation measurement may be referred to as:

A. Hounsfield correction

B. linearity

C. uniformity

D. calibration

Definition

Answer: D. calibration

During the process of calibration, CT acquisitions are made of a phantom of a known density (i.e. water) or an empty gantry field (air). The CT system makes corrections of the data acquired, ensuring that the calculations of linear attenuation and Hounsfield values during clinical procedures are accurate.

Term

Number 4 corresponds to which anatomic structure?

[image]

Definition
Answer: Ethmoid sinus
Term

The average range for normal prothombin (PT) time is approximately:

A. 3-5 seconds

B. 7-9 seconds

C. 12-15 seconds

D. 18-23 seconds

Definition

Answer: C. 12-15 seconds

Normal prothrombin (PT) times are lab-specific and range between approximately 11 and 15 seconds. This test is used to evaluate the coagulation ability of a patient scheduled to undergo an invasive CT procedure.

Term

A high-osmolar contrast material has an average osmolality of:

A. 100-300 mOsm/kg water

B. 600-850 mOsm/kg water

C. 1000-2400 mOsm/kg water

D. 4000-7000 mOsm/kg water

Definition

Answer: C. 1000-2400 mOsm/kg water

The osmolality of a contrast material is a measure of the number of particles per kg of water. Osmolality is factor in determining the potential for adverse reactions to iodinated contrast material. Ionic contrast media, which dissolves into a large number of anions and cations in solution, have an average osmolality between 1000 and 2400 mOsm/kg.

Term

The technique that provides the detail of the outer portions of the 3D model while maintaining the typical CT detail of the lungs inside is called:

A. Maximum intensity projection (MIP)

B. Surface rendering

C. Summed projection

D. Voxel gradient

Definition

Answer: B. surface rendering

Computer programs are capable of constructing 3D models of anatomy with several different types of rendering techniques. A surface-rendered 3D model provides excellent surface anatomy while maintaining the normal cross-sectional anatomy apperance of the volume inside the model.

Term

Which of the following display fields-of-view (DFOV) should be chosen for a CT examination of the thoracic soine of a patient whose thorax measures 40 cm?

A. 15 cm

B. 25 cm

C. 32 cm

D. 42 cm

Definition

Answer: A. 15 cm

During a CT examination of the spine, the display field-of-view should be one that displays the spine enlarged on the monitor. Commonly referred to as targeting, this technique provides the viewer with an enlarged image of the spine without the loss of detail that accompanies magnigication of the CT image. Although in this patient measures 40 cm, the DFOV of 15 cm will be suffivient to target the spine and enlarge its image on the viewing monitor.

Term

Number 1 corresponds with which anatomic structure?

[image]

Definition
Answer: Coracoid process
Term

The Hounsfield value of a pixel is directly related to which of the following?

A. Window width

B. Field of view size

C. μ of HO

D. Window Level

Definition

Answer: C. μ of HO


The value of a pixel in Hounsfield units is calculated through a comparison of the linear attenuation coefficient (μ) of a voxel of a tissue to that of water.

Term

Which of the following is an advantage of nonionic contrast media of ionic media?

A. lower cost

B. decreased nephrotoxicity

C. decreased enhancement

D. reduced incidence of adverse reaction

Definition

Answer: D. reduced incidence of adverse reaction

Nonionic contrast material is associated with a lower incidence of adverse reactions than ionic media. Nonionic media are also higher is cost but unfortunately offer no reduction in renal toxicity.

Term

Which of the following CT image archival media is capable of storing the greatest amount of information?

A. magnetic tape

B. 5-inch floppy disk

C. 3-inch floppy disk

D. magnetic optical disk

Definition

Answer: D. magnetic optical disk

With storage capabilities of severeal gigabytes (GB) of digital information, the magnetic optical disk has the highest storage capacity of the acrhival media listed.

Term

During CT perfusion studies, the quanity of blood (in mL) contained within 100g of brain tissue is termed the:

A. mean transit time (MTT)

B. cerebral blood flow (CBF)

C. cerebral blood volume (CBV)

D. percent-washout value (PWV)

Definition

Answer: C. cerebral blood volume (CBV)

Cerebral blood volume (CBV) describes the quantity of blood (in mL) contained within 100-g volume of brain tissue. Normal range is 4-5mL/100g.

Term

The graph is used to evaluate which component of CT image quality?

[image]

Definition

Answer: Spatial resolution

The MTF of a CT system is an objective measurment of a system's in-plane spatial resolution. By evaluating an MTF curve of the particular image, the operator can assess the spatial resolution of a CT system and appraise changes in spatial resolution due to adjustments in technical factors.

Term

Number 3 corresponds with whcih anatomic structure?

[image]

Definition
Answer: Anterior horn of the lateral ventricle
Term

Number 4 corresponds to what anatomic structure?

[image]

Definition
Answer: Scapula
Term

Number 4 corresponds to which anatomic structure?

[image]

Definition
Answer: Anterior superior iliac spine (ASIS)
Term

Number 1 corresponds to which anatomic stucture?

[image]

Definition
Answer: Sphenoid sinus
Term

The approximate inherent filtration of the CT x-ray amounts to an aluminum equivalent of:

A. 1.2 mm

B. 3.0 mm

C. 5.8 mm

D. 10.0 mm

Definition

Answer: 3.0 mm

The tube housing, cooling oil, and so on, consitite the inherent filtration, which amounts to approximately 3.0 mm of aluminum equivalent filtration.

Term

The branches of the left coronary artery include the:

(1) sinus node artery

(2) left anterior descending artery

(3) left circumflex artery

A. 2 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition
Answer: C. 2 and 3
Term

The purpose of intravenous contrast agent administration during a CT study is to:

(1) increase the contrast between adjacent structures

(2) increase the overall image density

(3) increase beam attenuation of enhanced structures

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 3 only

Definition

Answer: B. 1 and 3 only

Iodinated intravenous contrast agents alter the CT image by increasing the density of enhanced structures. Organs, blood vessels, and so on, containing iodine attenuate a greater portion of the primary beam, thereby increasing their attenuation value. This permits greater differentiation of anatomic structures and pathologic processes. Any "enhanced" structure has an increased attenuation value (and subsequent image density) that its normal, unenhanced state.

Term

Ischemic brain tissue identified as an infarct core when cerebral blood volume (CBV) falls below:

A. 2.5 mL/100g

B. 5.0 mL/100g

C. 10.0 mL/100g

D. 50.0mL/100g

Definition

Answer: A. 2.5 mL/100g

Brain parenchyma with a CBV less than 2.5 mL/100g is identified as the infarct core.

Term

A CT system measures the average linear attenuation coefficient of a voxel of tissue to be 0.189. The linear attenuation coefficient of water for this scanner equals 0.181. The CT number assigned to the pixel representing this voxel of tissue equals:

A. -956 HU

B. -173 HU

C. +44 HU

D. +1044 HU

Definition

Answer: C. +44 HU

The CT number of a pixel may be calculated by subtracting the linear attenuation coefficient of water from the linear attenuation coefficent of the tissue within the voxel. This number is divided by the linear attenuation coefficient of water. The quotient is multiplied by a contrast factor of 1000 to yield the value of the pixel in Hounsfield units.

0.189-0.181=.008

.008/0.181=0,044

0.044x1000=44

Term

The exaggeration of displayed calcification within the coronary arteries during a cardiac MDCT study is reffered to as:

A. aliasing

B. blooming

C. star artifact

D. penumbra

Definition

Answer: B. blooming

Blooming refers to the potential overestimation of vessel calcification due to partial volume artifact. During cardiac MDCT studies, blooming may be somewhat mitigated by improving the spatial resolution of a given acquisition or choosing an appropriately wide window setting (1500 HU) to reduce the apperace of the artifact.

Term

The typical dose of the radiopharmaceutical F-18-fluorodeoxyglucose (FDG) for combined PET-CT examination is within the range of:

A. 0.3 to 0.8 millicuries (mCi)

B. 1.5 to 3.0 mCi

C. 5.0 to 7.0 mCi

D. 10.0 to 15.0 mCi

Definition

Answer: D. 10.0 to 15.0 millicuries

Typical dose consistes of 10-15 millicuris (mCi) of FDG administered intravenously.

Term

This image of the pelvis was most likely acquired in which phase of IV enhancement?

[image]

Definition

Answer: excretory phase

The well-opacified ureters indicate that the acquisition of this image occured during the excretory phase of IV contrast enhancement.

Term

Which of the following may be used to reduce metal streak artifact on coronal plane CT images of the orbits?

(1) retrospective recontruction of targeted images with reduces display field-of-view (DFOV)

(2) metallic artifact reduction (MAR) software to improve image quality

(3) construction of coronal multiplanar reformation (MPR) images from the acquired axial-plane images

A. 1 only

B. 3 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: C. 2 and 3 only

Volumetric MDCT axial acquisition through the orbit, sinuses, and so on, allows for high quality coroanl MPR imaged without metal streaking artifact. CT manufactuers may offer metallic artifact reduction (MAR) software in an effort to reduce streaking artifact from metal substances. Targeted reconstructions would eliminate only the streak artifact at the periphery of the field and would not remove unwanted streak artifact appearing through the area(s) of interest.

Term

Which of the following would be a suitable range for contrast agent volume for an intrathecal injection during a postmyelogram CT examination of the lumbar spine in an adult patient?

A. 1-3 mL

B. 5-9 mL

C. 12-14 mL

D. 18-22 mL

Definition

Answer: C. 12-14 mL

A common range of contrast agent volume for an intrathecal injectin during post-myelographic CT is 12-14 mL in an adult patient. The total volume should not exceed approximately 17 mL, so as to keep the iodine dose below 3 g.

Term

Which of the following oral contrast agents offers the best visualization of the enhancing GI wall on post-IV contrast CT examination?

A. low-osmolar water-soluble iodinated contrast

B. high-osmolar water-soluble iodinated contrast

C. water
D. barium sulfate suspension

Definition

Answer: C. water

Water as a negative oral contrast agent improves visualization of the enhancing enteral wall when an IV contrast agent is administered. Other agents such as VoLumen and milk, may also be effective as agents capable of distending the bowel while allowing for wall visualization.

Term

Number 2 corresponds to which anatomic structure?

[image]

Definition
Answer: Pharyngeal constrictor muscle
Term

The maximum dose of intravenous iodinated contrast for a child should not exceed:

A. 1 mg/kg body weight

B. 3 mg/kg body weight

C. 5 mg/kg body weight

D. 10 mg/kg body weight

Definition

Answer: B. 3 mg/kg body weight

The maximum dose of intravenous iodinated contrast agent should not exceed 3 mg per kg of body weight during pediatric CT examinations. Contrast loads in excess of this limit have been reported to cause acute osmolar poisoning in children.

Term

The component of the DAS responsible for strengthening the signal emitted from the detector is termed the:

A. digital-to-analog converter (DAC)

B. preamplifier

C. high-resolution comb

D. bow-tie filter

Definition

Answer: B. preamplifier

The weak electronic signal emitted from the detectors in response to the measurement of transmitted radiation must be strengthened before it is utilized for image reconstruction. The preamplifier is the component of the data acquisition system (DAS) responsible for amplifying the detector signal.

Term

Number 5 corresponds to which anatomic structure?

[image]

Definition
Answer: appendix
Term

Which of the following matrices would provide the greatest spatial resolution?

A. 256x256

B. 320x320

C. 512x512

D.1024x1024

Definition

Answer: D. 1024x1024

A larger matrix size consists of an increased number of pixels. The computer is then able to assign less information into each pixel, allowing the image to display extremely small objects seperately from one another. This increases the spatial resolution of the CT scanner.

Term

The human eye is capable of differentiating approximately _________ shades of gray.

A. 10-25

B. 60-80

C.100-120

D. 250-256

Definition

Answer: B. 60-80

The human eye is capable of differentiating only about 60-80 individual shades of gray. The 256 shades utilized in CT are therefore sufficient to represent the total range of pixel values possible in a 12-bit system.

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: posterior clinoid process
Term

A dermoid tumor of the ovary may also be referred to as a :

A. leiomyoma

B. cystic teratoma

C. germ cell tumor

D. hemorrhagic cyst

Definition

Answer: B. cystic teratoma

A dermoid cyst is a mature cystic teratoma that is characterized on CT imaging by areas of widely varying densities including fat, fluid, and calcifications.

Term

After initiation of rapif bolus administration of an iodinated contrasr agent, the equilibrium phase of hepatic contrast enhancement occurs at approximately:

A. 15-20 seconds

B. 25-35 seconfs

C. 60-70 seconds

D. 120-180 seconds

Definition

Answer: D. 120-180 seconds

The equilibrium phase of hepatic contrast enhancement usually occurs 2-3 minutes after the initiation of contrast agent administration. During this phase, hepatic parenchymal enhancement dissipates and there is minimal difference in contrast enhancement beterrn the intravascular and extravascular spaces.

Term

Which of the following technologic advances has led to the develpment of spiral/helical CT scanning?

(1) slip-ring technology

(2) electron beam technology

(3) high-efficiency x-ray tubes

A. 1 only

B. 1 and 2 only

C. 1 and 3 only

D. 1,2, and 3

Definition

Answer: C. 1 and 3 only

Spiral/helical CT scanners are a recent development in computed tomography technology. The advents of slip-ring technology and improvements in the x-ray tube design have made this innovation possible. Slip-rings have taken place of the cumbersome cables previously used to transmit the CT signal and supply power to the tube and detectors. This develpment enables the tube and detectors to rotate continuously around the patient, acquiring data in the form of a helix. The longer exposure times of up to 60 seconds require extremely efficient x-ray tubes with enormous heat capacities.

Term

The following formula is used to calculate the linear coefficient:

I=I0e- μx

The symbol "x" identifies:

A. Euler's constant
B. absorber thickness

C. the unknown

D. transmitted photons

Definition

Answer: B. absorber thickness

The lambert-beer law,

I=I0e- μx

is used to calculate the attenuation coefficient of a volume of material. The symbol "x" represents the thickness of the absorber attenuating the radiation.

Term

Number 3 corresponds to which anatomic structure?

[image]

Definition
Answer: External auditory meatus
Term

The largest deterrent of a CT scanner's contrast resolution is:

A. patient motion

B. noise

C. hardware malfunction

D. beam hardening

Definition

Answer: B. noise

The largest enemy of contrast resolution is noise. Noise appears as a graininess that can obscure the outline and delineation of structures, thus limiting the scanner's ability to seperate them.

Term

Number 7 corresponds with which anatomic structure?

[image]

Definition
Answer: Glueteus medius muscle
Term

The average CT value for blood is approximately:

A. -50 HU

B. 0 HU

C. +45 HU

D. +100 HU

Definition
Answer: C. +45 HU
Term

CT images that have been reconstructed from a portion of the data acquisition process in the hopes of reducing patient motion artifacts are called:

A. dynamic images

B. subtraction images

C. segmented images

D. filtered images

Definition

Answer: C. segmented images

CT images are usually constructed from transmission data acquired during a 360-degree rotation of the x-ray tube. A CT image can also be constructed from a portion of the data acquisition phase. For example, if a patient moves dueing the last third of a 2-second scan, an image can be contructed from the first 240 degrees of tube rotation, yielding an image free of motion. This process referred to as segmentation, is a software capability of many modern CT scanners.

Term

Which of the following methods of oral contrast agent administration would be suitable for the CT scan of the abdomen depicted in this figure?

[image]

A. 1500 mL 90-120 minutes prior to scanning

B. 1200 ml enema immediately prior to scanning

C. 100 mL 3 hours prior to scanning with an additional 50 mL given just before the study

D. 450 mL 30 minutes prior to scanning with an additional 250 mL given just before the study

Definition

Answer: D. 450 mL 30 minutes prior to scanning with an additional 250 mL given just before the study.

For a CT examination of the abdomen, an oral contrast agent should be administered in a volume of approximately 450 mL 15 to 30 minutes prior to the exam. An additional 250 mL should be given just prior to the study. This method of administration should provide adequate opacification of the stomach and small bowel.

Term

The normal range of glomerular filtration rate (GFR) for women is:

A. 50 +or- 14mL/min/m2

B. 60 +or- 10mL/min/m2

C. 70 +or- 14mL/min/m2

D. 80 +or- 10mL/min/m2

Definition

Answer: B. 60 +or- 10mL/min/m2


Normal range of GFR is 60 +/- 10mL/min/m2 for women and 70 +/- 14mL/min/m2 for men.

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: Right external carotid artery
Term

Quantitive computed tomography (QCT) is a specialized technique used most often for the diagnosis of:

A. lymphoma

B. osteoporosis

C. renal cyst

D. hemangioma

Definition

Answer: B. osteoporosis

Quantitive computed tomography (QCT) is used to measure the mineral content of bone. Density measurements of the patient's bone are compared with density measurements of reference phantom. The bone mineral density (BMD) values are compared with normal values to assess osteoporosis.

Term
The normal range of respirations for a child is:
Definition
Answer: 20-3o breaths per minute
Term

Which of the following is not an iterative method of CT image reconstruction?

A. point-by-point correction

B. Fourier transform

C. simultaneous reconstruction

D. ray-by-ray correction

Definition

Answer: B. Fourier transform

The interative methods of CT image reconstruction include simultaneous reconstruction, ray-by-ray correction, and point-by-point correction. The fourier transform method is an analystic method of CT image reconstruction.

Term

Iodine is commonly used in radiopaque contrast media because of its:

A. radiolucency

B. viscosity

C. osmolality

D. high atomic number

Definition

Answer: D. high atomic number

Iodine's high atomic number cause it to attenuate a large portion of the primary beam. Introducing iodine into tissue changes the subject contrast of the enhances anatomic area.

Term

Which of the following contrast media may be used during a CT examination of the chest?

(1) diatrizoate meglumine

(2) barium sulfate

(3) iopamidol

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition
Answer: D. Diatrizoate meglumine is an ionic intravenous contrast material, and iopamidal is a nonionic one. Both may be used for soft tissue enhancement during CT of the chest. A brium sulfate contrast agent, usually in the form of a paste, may also be used to outline the esophagus, when necessary.
Term

At its dista end, the spinal cord tapers into the:

A. bulbus cordis

B. caudate nucleus

C. conus elasticus

D. conus medullaris

Definition

Answer: D. conus medullaris

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: Thyroid gland
Term

A portion of a herniated intervertebral disc that has migrated from its normal position is called a(n):

A. bulging disc

B. sequestered disc

C. osteophyte

D. protrusion

Definition

Answer: B. sequestered disc

Sequestered disc or free fragment is used when a portion of the disc nucleus completely breaks free and migrates from its normal posistion.

Term

Important characteristics of a quality control program include:

(1) consistent test frequency

(2) prompt corrective actions when necessary

(3) accurate record-keeping

A. 1 only

B. 1 and 2 only

C. 1 and 3 only

D. 1, 2, and 3

Definition

Answer: D. 1, 2, and 3

The hallmarks of a superior QC program are routine frequency of testing, prompt corrective actions as necessary, and accurate record-keeping.

Term

The primary indication for CT perfusion of the brain is:

A. status-post trauma

B. acute stroke

C. mass lesion

D. hydrocephalus

Definition

Answer: B. Acute stroke

CT perfusion (CTP) evaluates cerebral perfusion by monitoring the initial passing of iodinated contrast media through the vasculature of the brain. The primary indication of CTP is in the evaluation of acute stroke.

Term

The areas indicated by number 2 correspond to which of the following?

[image]

Definition
Answer: Corpus callosum
Term

The interaction between x-ray and matter that is responsible for the production of the scatter radiation absorbed by the patient and detectors is:

A. compton effect
B. bremsstrahlung

C. photoelectric

D. characteristic

Definition

Answer: A. compton effect

In the compton interaction, an x-ray photon ejects an outer-shell electron of an atom. The photon loses some of its energy in the collision and then continues on in a different, scattered direction. This interaction is the major source of scatter radiation involved in the formation of the CT image.

Term

In patients who are right dominant, the posterior descending artery branches from the:

A. ramus intermedius

B. conus artery

C. right coronary artery

D. right ventricular branch

Definition

Answer: C. Right coronary artery

85% of the population is said to be right dominant, meaning that the posterior descending artery (PDA) branches from the right coronary artery (RCA).

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: Acromion
Term

Number 4 corresponds to the:

[image]

Definition
Answer: Ilium
Term

Which of the following imaging planes best demonstrates spondyloisthesis of the spine?

A. axial

B. coronal

C. sagittal

D. oblique axial

Definition

Answer: C. sagittal

Spondylolisthesis refers to the forward "slipping" of an upper vertebral body over the lower because of degenerative changes of the facet joints. It is best demonstrated on sagittal MPR images of the spine.

Term

Number 2 corresponds to which anatomic structure?

[image]

Definition
Answer: Left common carotid artery
Term

Number 8 corresponds to which anatomic structure?

[image]

Definition
Answer: Ethmoid sinus
Term

For a given CT acquisition, the calculated mAs applied to each reconstructed slice may be referred to as the:

A. effective mAs

B. peak mAs

C. absorbed mAs

D. constant mAs

Definition

Answer: A. effective mAs

Effective mAs describes the calculated mAs per acquired slice. The primary influencing factor for effective mAs is table speed, which is an important component controlled by the selected detector pitch. The detector pitch chosen by the CT operator directly affects the speed at which the patient travels through the gantry. The mAs divided by the pitch yields the effective mAs for each slice in a given CT acquisition.

Term

Which of the following technical changes may increase the partial volume effect present on a spiral CT scan?

A. decrease in pitch

B. decrease in section width

C. increase in matrix size

D. increase in pitch

Definition

Answer: D. increase in pitch

When the pitch is increase during a spiral CT scan, either the section width or the table speed has been increased. The effects of increased section width on the partial volume effect are obvious. The increased table speed also plays a role in increasing partial volume averaging. Because the table moves through the gantry at a faster rate, each rotation of the tube and detectors is responsible for recording more information. This causes a broadening of the section sensitivity profile (SSP), which manifests as partial volume averaging.

Term

Which of the following phases of IV contrast agent administration provides the best gastric and intestinal wall enhancement?

A. early arterial

B. corticomedullary

C. portal venous

D. excretory

Definition

Answer: C. portal venous phase

For indications involving the GI tract, acquisition is typically obtained during the portal venous phase for optimal gastric and intestinal wall enhancement.

Term

Malignant neoplasms of the liver include which of the following?

(1) focal nodular hyperplasia (FNH)

(2) cavernous hemangioma

(3) hepatocellular carcinoma (HCC)

A. 3 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: A. 3 only

Hepatocellular carcinoma (HCC) and metastases are the most common malignant neoplasms of the liver. Hemangiomas and focal nodular hyperplasia (FNH) are both examples of a benign hepatic tumor.

Term

The anatomical plane of the image can be described as the:

[image]

Definition

Answer: oblique axial plane

The oblique axial plane is parallel to the metatarsals, approximately 20 to 30 degrees caudal to the direct axial plane. MPR images such as these are used to assess the tarsal-metatarsal joint.

Term

Which of the following will serve to decrease the noise of a CT image?

A. decrease in dose
B. decrease in slice thickness

C. increase in matrix size

D. decrease in matrix size

Definition

Answer: D. decrease in matrix size

A decrease in matrix size will cause a subsequent increase in pixel dimension. This larger size caused an increase in the number of x-rays passing though each pixel, thereby increasing the signal-to-noise ratio.

Term

Which of the following bones is found within the hindfoot?

A. talus

B. metatarsals

C. navicular

D. cuboid

Definition

Answer: A. Talus

The talus and calcaneous constitute the hindfoot. The navicular, cuboid, and cuneiforms make up the midfoot, and the forefoot consists of the metatarsals and phalanges.

Term

An image was produced with a 1.0-mm aperature size and was displayed using a 5122 matrix and a 15-cm DFOV. The voxel dimension for this image would be:


A. 0.29 mm x 0.29 mm x 1.0 mm

B. 02.9 mm x 2.9 mm x 1.0 mm

C. 3.4 mm x 3.4 mm x 1.0 mm

D. 0.29 mm x 0.29 mm x 1.0 cm

Definition

Answer: A. 0.29 mm x 0.29 mm x 1.0 mm

The pixel dimension may be calculated by dividing the DFOV by matrix size. This two dimensional pixel size is then multiplied by the length of the voxel.

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: Optic nerve
Term

Number 3 corresponds to which anatomic structure?

[image]

Definition
Answer: Ischium
Term

Which artifact manifests as a streaking effect at areas of extremely-high-density interfaces?

A. edge gradient

B. Gibbs phenomenon

C. density gradient

D. partial volume

Definition
Answer: A. edge gradient
Term

The tortuous S-shaped portion of the internal carotid artery as it enters the bony skull may be referred to as the carotid:

A. lordosis

B. kyphosis

C. siphon

D. sinus

Definition

Answer: C. siphon

Carotid siphon refers to the portion of the internal carotid artery as it enters the bony skull and bifurcates into the anterior cerebral and middle cerebral arteries.

Term

An acquisition is made on a 4-slice mSCT system with a detector array of 16 1.25-mm detector elements along the z-axis. With a selected beam width of 20 mm, what beam pitch would result in the table movie 35.00 mm for each rotation of the gantry?

A. 1.0

B. 1.5

C. 1.75

D. 2.0

Definition

Answer: C. 1.75

The beam pitch for a given acquisition is equal to the table feed per rotation divided by the total collimation. The total collimation for this acquisition is equal to the total number of sections (detectors) multiplied by the detector dimension, or 16 multiplied by 1.25 mm. The beam pitch may be therefore calculated by dividing 35.00 by 20, or 1.75

Term

The normal range for the international normalized ratio (INR) for prothrombin time (PT) results is:

A. 0.2-0.5

B. 0.8-1.2

C. 2.2-3.5

D. 6.1-8.6

Definition

Answer: B. 0.8-1.2

The INR compares a patient's PT with a control sample for a more accurate result. The normal range for INR is 0.8-1.2.

Term

Which of the following section widths would cause the greatest amount of partial volume averaging?

A. 1 mm

B. 3 mm

C. 5 mm

D. 10 mm

Definition

Answer: D. 10 mm

Large section widths result in long voxel lengths with possibly several tissue types accounted for within the voxel. When a CT number is assigned to the representative pixel, the density of all of the tissue types is averaged, yielding one attenuation coefficient. Narrow section widths tend to decrease the partial volume effect.

Term

Which of the following technical factors exhibit an effect upon longitudinal spatial resolution?

(1) detector collimation

(2) detector pitch

(3) interpolation algorithm

A. 1 only

B. 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

D. 1,2, and 3

The factors that affect longitudinal spatial resolution and the SSP include the type of spiral interpolation algorithm inherent to the system and the selected detector pitch. Thin-section image reconstruction reduces or completely eliminates broadening of the SSP and also improves longitudinal spatial resolution.

Term

During a CT scan, each sample of ray sum measurements made by the data aquisition system (DAS) is called a:

A. signal

B. view

C. projection

D. ray

Definition

Answer: view

The term view is used to describe each data sample made by the DAS. During the process of data acquisition, views are acquired by the DAS hundreds of times per second, according to the system's individual sampling rate.

Term

The best method of reducing the risk of contrast-induced nephrotoxicity (CIN) is:

A. premedication with costocosteroids

B. adequate patient hydration.

C. reduction of the contrast reduction rate

D. utilization of a biphasic injection technique

Definition

Answer: B. adequate patient hydration

Adequate hydration of the patient is the best method of CIN prevention. In the well-hydrated patient with normal renal function, the risk for develpment of CIN is extremely low.

Term

The primary advantage of prospective ECG gating for cardiac CT over retrospective ECG gating is:

A. the ability to scan patients with severe arrhythmia

B. the ability to evaluate cardiac function

C. a reduction in required contrast dose

D. a reduction in patient radiation dose

Definition

Answer: D. a reduction in patient radiation dose

The main benefit of prospective ECG gating is the potential for up to a 70% reduction in patient radiation dose. Prospective ECG gating required a steady heartbeat to limit motion artifact, and the evaluation of cardiac funtion is not possible because data is acquired only during diastole.

Term

A pixel may be defined as:

A. the portion of the CRT displaying the image

B. a volume element

C. a picture element

D. a miniature image

Definition

Answer: C. a picture element

A pixel is an element of the digital image. It is located in a matrix and is a two-dimensional representation of a voxel. When CT numbers are calculated for voxels (volume elements) of tissue, the pixel is assigned the calculated number and a subsequent shade of gray. The pixel may be defined as a picture element, or the smallest component of the digital image.

Term

The normal range of cerebral blood flow (CBF) through 100 g of the brain's gray matter is:

A. 2-4 mL/100g/min

B. 15-25 mL/100g/min

C. 50-60 mL/100g/min

D. 110-135 mL/100g/min

Definition
Answer: C. 50-60 mL/100g/min
Term

Number 5 corresponds to which anatomic structure?

[image]

Definition
Answer: Internal auditory canal
Term

The normal platelet count range for an adult is:

A. 30,000-45,000/mL of blood

B. 75,000-125,000/mL of blood

C. 140,000-440,000/mL of blood

D. 450,000-700,000/mL of blood

Definition
Answer: C. 140,000-440,000/mL of blood
Term

The most common indication for CT-guided Radiofrequency ablation (RFA) is in treatment of neoplasms involving the:

A. internal auditory canal (IAC)

B. uterus

C. lungs

D. liver

Definition

Answer: D. liver

The most common indication for CT-guided RFA is in treatment of hepatic neoplasm.

Term

A patient is required to have the following radiographic examinations: CT of the abdomen, GI series, and a Barium enema. The correct order for the scheduling of these procedures would be:

Definition
Answer: CT of the abdomen, Barium enema, GI series
Term

For MDCT, identified areas of calcium must demonstrate relative attenuation values greater than:

A. +20 HU

B. +130 HU

C. +450 HU

D. +1000 HU

Definition

Answer: B. +130 HU

On MDCT cardiac exams for coronary artery calcification (CAC) quantification, areas of calcium are identified as those greater than 1mm2 in area with Hounsfield values above 130.

Term

A patient has a severe vagal reaction to iodinated contrast material that includes bradycardia. Initial treatment mat consist of:

A. atropine

B. diazepam

C. Zantac

D. proventil

Definition

Answer: A. atropine

Patients suffering from vagal reactions to iodinated contrast agents present with hypotension and bradycardia. Treatment includes increasing blood pressure with IV fluids and intravenous administration of atropine to block vagal stimulation of the heart.

Term

A straight line appearing vertically on the scanogram (pilot) of a fourth generation CT scanner is an artifact most likely caused by:

A. edge gradient

B. detector malfunction

C. tube arcing

D. beam hardening

Definition

Answer: B. detector malfunction

A straight line artifact on a scanogram (pilot) image is most likely caused by a malfunctioning detector in both third- and fourth- generation scanners. As the patient travels through the gantry, the faulty detector does not record any information, leading to the blank line that appears on the image.

Term

Which of the following letters in the graph corresponds to full width at half maximum?

[image]

Definition

Answer: C.

The full width at half maximum (FWHM) of the SSP curve demonstrates the effective section width of a volumetric CT acquistion. It is measured by examining the slice sensitivity profile at half of its maximum height.

Term

What is the dimension of each pixel in the matrix of an image with the following parameters?

FOV=25.6 cm

Matrix=512 mm x 512 mm

A. 0.5 mm

B. 0.5 cm

C. 0.05 cm

D. both A and C

Definition

Answer: D. both A and C

The dimensions of a pixel may be calculated by dividing the FOV by the matrix size. The DFOV, 25.6 must first be converted into 256 mm. This is then divided by 512 mm for a pixel dimension of 0.5 mm.

Term

For trauma indications, CT examinations of the pelvis and hips may include which of the following advanced applications?

(1) CT enteroclysis

(2) CT angiography

(3) CT cystography

A. 2 only

B. 3 only

C. 1 and 2 only

D. 2 and 3 only

Definition

Answer: D. 2 and 3 only

Contrast-enhanced MDCT acquisitions of the post-traumatic pelvis may include CTA evaluation for vascular injury as well as assessment of the bladder via cystography.

Term

Which of the following technical factor(s) play(s) a role in the production of an isotropic dataset?

(1) section width

(2) scan field of view (SFOV)

(3) display field of view (DFOV)

A. 1 only

B. 1 and 2 only

C. 1 and 3 only

D. 2 and 3 only

Definition

Answer: C. 1 and 3 only

Isotropic resolution is approached by choosing the thinnest detector collimation availible to produce the thinnest slices availible and by reconstructing the acquired data with the smallest DFOV allowed according to the part of interest. Minimizing these two factors results in voxels approaching equal lengths in all directions.

Term

An MDCT image is reconstructed using a 512 x 512 matrix and a display field of view of 44cm. If the detector collimation is set to a section width of 2.5 mm, what is the volume of each voxel?

Definition

Answer: 1.85 mm3


44cm=440mm

440mm/512= .859375

.859375 x .859375= 0.73852539

.73852539 x 2.5=1.84631

1.85 mm3

Term

What anatomic structure corresponds to number 3?

[image]

Definition
Answer: Retromandibular vein
Term

Which layer of the uterine wall brightly enhances after IV administration of an iodinated contrast agent?

A. mesometrium

B. perimetrium

C. myometrium

D. endometrium

Definition

Answer: C. myometrium

The myometrium enhances brightly after IV contrast agent administration owing to its highly vascular composition.

Term

Number 3 corresponds to which anatomic structure?

[image]

Definition
Answer: Medial rectus muscle
Term

Which of the following phases of renal contrast enhancement provides maximum sensitivity for parenchymal lesions?

A. early arterial

B. corticomedullary

C. nephrographic

D. excretory

Definition

Answer: C. nephrographic

During the nephrographic phase, enhancement between renal cortex and medulla reaches equillibrium, providing optimal sensitivity for parenchymal lesions. The nephrographic phase occures between 70 and 90 seconds aftwe the start of the injection.

Term

Number 6 corresponds to which muscle?

[image]

Definition
Answer: Erector spinae muscle
Term

Portal venous phase imaging of the liver is used to optimally demonstrate which of the following?

A. hepatocellular carcinoma (HCC)

B. hypovascular hepatic metastases

C. hepatic artery aneurysm

D. focal nodular hyperplasia (FNH)

Definition

Answer: B. hypovascular hepatic metastases

Portal venous phase imaging is the phase during which hypovascular lesions are most conspicuous because of their density difference in comparrison with the enhancing hepatic parenchyma. Hepatocellular carcinoma (HCC), hepatic artery aneurysm, and focal nodular hyperplasia (FNH) are all hypervascular in nature and be be best demonstrated in an arterial phase imaging.

Term

The ______ gland is located in the anterior portion of the mediastinum and is often identified with CT during scanning of younger patients.

A. thyroid

B. Luschka

C. thymus

D. parathyroid

Definition

Answer: C. thymus

The Thymus gland may be found in the anterosuperior portion of the mediastinum. It is most easily visable prior to puberty. After puberty it becomes increasingly infiltrated with fat, so it is more difficult to image with computed tomography.

Term
A normal range for systolic blood pressure in an adult is:
Definition

Answer: 95-140 mm Hg

Term

During CT perfusion studies, the measured time (in seconds) required for blood to pass through an area of brain tissue is termed the:

Definition

Answer: mean transit time (MTT)

Term
The degree of CT section broadening that occurs along the z-axis during volumetric data acquisition is represented graphically by the:
Definition

Answer: Slice sensitivity profile (SSP)

Term

Which of the following mathematical techniques is used for reconstruction of vollumetric MDCT images?

A. 180-degree interpolation (180LI)

B. 360-degree interpolation (360LI)

C. back-projection

D. Fourier reconstruction

Definition

Answer: A. 280-degree interpolation (180LI)

The 180-degree linear interpolation technique (180LI) is commonly used for current MDCT image reconstruction. This method interpolates data acquired at a distance only 180 degrees away from the location of the reconstructed slice.

Term

Which of the following contrast agents may be used for the purpose of colon insufflation during a CT colonography examination?

(1) room air

(2) CO

(3) normal (0.9%) saline

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Definition

Answer: B. 1 and 2 only

Colon isufflation involves the introduction of room air or carbon dioxide into the colon for the purpose of bowel wall distention.

Term

The broadening of the slice sensitivity profile inherent to helical CT acquisition is said to negatively affect the:

A. in-plane spatial resolution

B. longitudinal spatial resolution

C. contrast resolution

D. temporal resolution

Definition

Answer: B. longitudinal spatial resolution

Longitudinal spatial resolution describes the degree to which patient movement during volumetric acquisition can negatively affect image detail.

Term

The soft center of each intervertebral disc is called the:

A. nucleus pulposus

B. nucleus prepositus

C. annulus fibrosus

D. annulus stapedius

Definition
Answer: A nucleus pulposus
Term

Number 3 corresponds to which anatomic structure?

[image]

Definition
Answer: Vermis of cerebellum
Term

Which of the following terms describes a condition in which cerebral ischemia is caused by systemic hypertension?

A. vasovagal reaction

B. myocardial infarction

C. transient ischemic attack

D. hydrocephalus

Definition
Answer: A. vasovagal reaction
Term

A voxel's dimension may be decreased by which of the following?

A. decreasing the section width

B. decreasing the matrix size

C. increasing the section width

D. increasing DFOV

Definition

Answer: A. decreasing the section width

The section width of a CT image controls the length of the voxel. The dimensions of a voxel may also be reduced through decreases in the size of the pixel. Increases in matrix size and decreases in DFOV serve to decrease the dimensions of the pixel and voxel.

Term

Which of the following would most likely require the intravenous injection of an iodinated contrast agent for accurate differentiation during a CT study of the abdomen?

A. angiomyolipoma

B. renal stone

C. diverticulitis

D. renal cyst

Definition

Answer: D. renal cyst

The diagnosis of a simple cyst is accurately made with proper CT examination. Pre- and post- contrast images must be obtained to measure enhancement. The attenuation values for the cystic area should be at or near zero. The diagnoses of angio,yolipoma, diverticulitis, and renal stones can be made without the intravenous injection of contrast media.

Term

Number 4 corresponds to which anatomic structure?

[image]

Definition
Answer: internal auditory canal
Term

prior to and after contact with each pateint, a proper hand-washing technique requires that the technologist use warm soap and water with a cirrcular rubbing motion for at least:

A. 10 seconds

B. 30 seconds

C. 2 minutes

D. 5 minutes

Definition

Answer: B. 30 seconds

Term

Number 4 corresponds to which anatomic structure?

[image]

Definition
Answer: Rt. lateral pterygoid plate.
Term

Number 5 corresponds to which anatomic structure?

[image]

Definition
Answer: Putamen
Term

Which of the following is an example of a hypovascular hepatic mass?

A. hemangioma

B. hepatic cyst

C. hepatocellular carcinoma (HCC)
D. focal nodular hyerplasia

Definition

Answer: B. hepatic cyst

The hallmark CT finding for a cyst is lack of enhancement with IV contrast agent administration. Cysts are therefore charachterized hypovascular. Hemangiomas, hepatocellular carcinomas (HCC), focal nodular hyperplasia (FNH), and certain metastatic lesions are all examples of hypervascular tumors of the liver.

Term

Which of the following phases of contrast enhancement optimally demonstrates the relationship between pancreatic neoplasm and the surround structure?

A. pre-contrast

B. arterial phase
C. pancreatic phase

D. portal venous phase

Definition

Answer: B. arterial phase

During arterial phase acquisition through the pancreas, there is a maximum opacification of the surrounding vasculature, including the aorta and superior mesenteric artery. An important goal of pancreatic CT is to evaluate the involvement of surrounding vessels by pancreatic neoplasm.

Term

Which of the following statements regarding the pituitary gland is false?

A. it is sometimes referred to as the hypophysis cerebri

B. it is seated within the sella turcica

C. the infundibulum attaches it to the hypothalamus

D. it is responsible for the production of epinephrine

Definition

Answer: D. it is responsible for the production of epinephrine.

The pituitary gland is responsible for the production of several hormones, including somatotropin and prolactin. It is the adrenal glands that play a rold in the production and secretion of epiephrine (adrenaline).

Term

Which of the following types of contrast material may be used during CT evaluation of the pelvis?

(1) an intravenous iodinated contrast agen

(2) low dense barium sulfate solutions

(3) oil-soluble contrast material

A. 1 only

B. 2 only

C. 1 and 2 only

D. 1,2, and 3

Definition

Answer: C. 1 and 2 only

During CT examination of the pelvis, both intravenous and oral contrast agents are commonly administered. An intravenous contrast agent is important in differentiating pelvis blood vessels for lymph nodes. An oral contrast agent serves to opacify the small and large colon and greatly improves their visualization. Oil-based contrast media are not commonly used for CT procedures.

Term

In an MSCT system, the detector array is composed of multiple rows of individual detector elements alond the:

A. x-axis

B. y-axis

C. z-axis

D. entire circumference of the gantry

Definition

Answer: C. z-axis

A multislice CT (MSCT) system utilizes a third generation curvilinear detector array with multiple rows of individual detector elements segmented along the longitudinal axis, or z-axis.

Term

Number 5 corresponds to which muscle?

[image]

Definition
Answer: piriformis muscle
Term

Number 2 corresponds to which muscle?

[image]

Definition
Answer: Lateral rectus muscle
Term

The full width at half maximum (FWHM) of a slice sensitivity profile diagram indicates the:

A. limiting resolution

B. signal-to-noise ratio

C. dose profile

D. effective section width

Definition

Answer: D. effective section width

The effective section width is defined at the full width at half maximum (FWHM) of the SSP. It is measured by examining the slice sensitivity profile at half of its maximum height.

Term

High-resolution computed tomography (HRCT) of the chest incorporates which of the following protocols?

A. 10-mm sections, standard algorithm

B. 10-mm sections, bone algorithm

C. 3-mm sections, standard algorithm

D. 1-mm sections, bone algorithm

Definition

Answer: D. 1-mm sections, bone algorithm

High-resolution computed tomography (HRCT) of the chest is used to examine diffuse pulmonary disease. The technique offers excellent visualization of the lungs, airways, and pulmonary hilum. HRCT involves the use of narrow sections (1-3mm) and a high-resolution algorithm.

Term

A test phantom containing water is scanned and five region of interest measurements are performed. THe subsequent density measurements are compared and demonstrate a maximum deviation of less than 2 HU. This quality assurance test was performed to evaluate the scanner's:

A. spatial resolution

B. cross-field uniformity

C. signal-to-noise ratio

D. contrast resolution

Definition

Answer: B. cross-field uniformity

The test described is used to evaluate cross-feild uniformity of a CT scanner. The ROI measurements are arranged with one at the center of the image and the others rotated about the periphery. Each of the 5 ROI measurements taken from the water phantom should yield relatively the same CT number value.

Term

Which of the following would increase the signal-to-noise ratio of a CT image?

A. decreased aperature size

B. decreased mAs

C. increased filtration

D. increased aperature size

Definition

Answer: D. increased aperature size

The signal-to-noise ratio of a CT image is increased when a larger amount of x-ray photons are absorbed by the detectors. From the choices given, only an increase in aperature size (beam width) would accomplish that.

Term

Which of the following statements is true regarding patients recieving metformin therapy for type 2 diabetes and IV contrast-enhanced CT examinations?

(1) metformin therapy is a direct contraindication to administration of IV contrast agents

(2) the patient should not take metformin for up to 2 days following administration of an IV contrast agent

(3) after administration of an IV contrast agent, the patient may need renal function testing before resuming metformin therapy

Definition

Answer: 2 and 3 only

Metformin, also known by its most common proprietary name, Glucophage, is a drug used to treat type 2 diabetes. Patients are typically instructed not to take metformin for up to 2 days adter a contrast-enhanced CT examination. The patient should refer to the referring physician for instructions before resuming metformin treatment because a blood test to check renal function may be needed first.

Term

A CT scanner capable of producing an image that is a perfect reproduction of the actual anatomic section is said to have an MTF of:

A. 0

B. 1

C. 10

D. 100

Definition

Answer: B. 1

The modulation transfer function (MTF) of a CT scanner measures the ability of the system to faithfully reproduce the area of anatomy. It can be thought od as a comparison of the actual anatomy with the image produces. If the two are exactly alike, the MTF of the scanner is 1. If the image produced contains no useful information, the MTF is 0. The MTF of most CT scanners falls somewhere in between.

Term

Which of the following reduces the scatter radiation reaching the detectors?

A. post-patient collimation

B. pre-patient collimation

C. pre-detector collimation

D. both a and c

Definition

Answer: D. both a and c

Pre-detector collimation and post-patient collimation are synonymous. Both terms describe a device designed to remove scatter radiation before it reached the detector.

Term

Which of these numbers corresponds to the vestibule?

[image]

Definition
Answer: number 4
Term

Each 1.0% in contrast between adjacent objects amounts to a difference in pixel value of approximately:

A. 3 HU

B. 10 HU

C. 25 HU

D. 60 HU

Definition

Answer: B. 10 HU

Each 1.0% in contrast between adjacent objects amounts to a difference in pixel value of approximately 10 HU. MDCT systems are typically capable of differentiating adjacent objects with attenuation differences as small as 3 HU.

Term

The plasma half-life of intravenously administered iodinated contrast material is approximately:

A. 30 minutes

B. 60 minutes

C. 2 hours

D. 12 hours

Definition

Answer: C. 2 hours

After approximately 2 hours, the percentage of iodinated contrast material in blood plasma is reduced to hald of the administered volume.

Term

Which of the following types of image reconstruction was used in the first prototype CT scanner?

A. convolution method

B. iterative technique

C. Fourier transform

D. back-projection

Definition

Answer: B. iterative technique

The first-generation prototype CT scanner designed by Dr. Godfrey Hounsfield used and iterative from of image reconstruction.

Term

Areas of a CT image containing abrupt changes in tissue density are electronically represented by:

A. positive CT numbers

B. high spatial frequencies

C. negative CT numbers

D. low spatial frequencies

Definition

Answer: B. high spatial frequencies

The contrast of a CT image is controlled by the spatial frequencies of the tissue(s) within the section. Tissues of differing densities are represented electronically by different spatial frequencies. Adjacent tissues with large differences in density are represented by a high spatial frequency signal.

Term

Number 3 corrseponds to which anatomic structure?

[image]

Definition
Answer: external iliac artery
Term

The rights of the patient include which of the following?

(1) the patient has the right to considerate and respectful care

(2) the patient has the right to recieve a copy of the diagnostic procedure performed

(3) the patient has the right to refuse medical treatment

A. 1 only

B. 1 and 2 only

C. 1 and 3 only

D. 1, 2, and 3

Definition

Answer: C. 1 and 3 only

The american hospital association drafted A Patient's Bil of Rights in 1973. Included amoung the 12 "rights" are the patient's right to considerate and respectful care and the right to refuse treatment. Release of the patient's diagnostic examination results is not an inherent right and is at the discretion of the physician(s) involved.

Term

What is the maximum allowable blood glucose measurement for patients scheduled to undergo PET-CT examination?

A. 25 mg/dL

B. 75 mg/dL

C. 150 mg/dL

D. 500 mg/dL

Definition

Answser: C. 150 mg/dL

The patient's blood glucose may be measured prior to the injection of F-18-fluorodeoxyglucose (FDG). It should be below 150 mg/dL to prevent FDG uptake inhibition by glucose circulating the bloodstream.

Term

A CT scanner measures the linear attenuation coefficient of a voxel of tissue as 0.40. The linear coefficient of water for this scanner equals 0.20. The CT number assigned to the pixel representing this voxel of tissue equals:

A. -1000 HU

B. 0 HU

C. 1 HU

D. +1000 HU

Definition

Answer: D. +1000 HU

The CT number of a pixel may be calculated by subtracting the linear coefficient of water from the linear attenuation coefficient of the tissue within the voxel. This number is divided by the linear coefficient of water. The quotent is multiplied by a contrast factor of 1000 to yield the value of the pixel in Hounsfield units.

.4-.2=.2

.2/.2=1

1x1000=+1000HU

Term

_______ is the term used to describe the ability of a PACS to transmit data from the imaging facility to an off-site location.

A. encryption

B. DICOM

C. HL7

D. teleradiology

Definition

Answer: D. teleradiology

Teleradiology refers to the ability of a PACS to transmit image data across a local area network (LAN) or wide area network (WAN) from the imaging facility to an off-site location.

Term

Number 2 corresponds with which anatomic structure?

[image]

Definition
Answer: stomach
Term

Glioma is a general term used to describe a group of primary tumors. Consisting of malignany glial cells, gliomas occur in the:

A. oral cavity

B. kidney

C. brain

D. liver

Definition

Answer: C. brain

The term glioma refers to a group of glial tumors that occur in the brain. Glial cells are connective neural cells that play a supportive role in the brain. There are several common types of gliomas, including astrocytomas, and glioblastomas.

Term

The hallmark CT finding for focal nodular hyperplasia (FNH) of the liver is:

A. Lack of enhancement with IV contrast administration

B. CT density approximately 10 HU less than the spleen

C. Peripheral globular enhancement during initial contrast agent administraion

D. Central scar that remains hypodense after initial contrast agent administraion

Definition

Answer: D. Central scar that remains hypodense after initial contrast agent administraion

Focal nodular hyperplasia (FNH) is a common vascular lesion often identified along the surface of the liver. It is characterized by intense homogenous enhancement with contrast agent administraion. There is usually a central scar that remains hypodense until delayed imaging, when it my also enhance.

Term

The excretion half-time of intracenous iodinated contrast media in a patient with normal renal function is between:

A. 1 and 2 hours

B. 18 and 24 hours

C. 1 and 2 days

D. 5 and 7 days

Definition

Answer: A. 1 and 2 hours

Excretion half-time is a value describing the amount of time necessary for 50% of the contrast agent administered to be filtered by the renal system. In patients with normal renal function, the half-time is usually between 1 and 2 hours.

Term

As a solid-state CT detector measures transmitted radiation, it emits a proportional response in the form of a(n):

A. digital signal
B. quantity of gas

C. analog signal

D. modulation transfer function

Definition

Answer: C. analog signal

The detector emits an electronic analog signal in proportionate response to the transmitted radiation it absorbs. As the detector array rotates about the patient, the signal varies according to the measured x-ray energy flux.

Term

Which of the following factors has NO measurable effect on spatial resolution?

A. focal spot size

B. kVp

C. detector sampling frequency

D. matrix size

Definition

Answer: B. kVp

The spatial resolution of a CT image depends on several factors, including focal spot size, detector size and spacing, field of view, pixel dimension, and detector sampling rate.

Term

During prospectively ECG-gated cardiac CTA studies, the scanning acquisition mode may be best described as:

A. axial "step-and-shoot"

B. helical volumetric

C. axial cine

D. multiplanar reconstruction

Definition

Answer: A. axial "step-and-shoot"

During prospective ECG-gated cardiac CTA, data are acquired in an axial "step-and-shoot" mode. The x-ray and data acquisition systems are activated only during the diastolic portion of the R-R interval. Retrospective ECG gating involves a volumetric helical acquisition with only the diastolic portion of the data used for image reconstruction. Cine CT involves a series of acquisitions of a limited area over time. Routinely used in perfusion CT studies, cine acquisitions may have certain cardiac applications, such as the evaluation of valves, specific vessels, and cardiac perfusion.

Term

The acronym PTT is used for which of the following labratory tests?

A. prothrombin time

B. passive tachycardia test

C. partial prothrombin time

D. partial thromboplastin time

Definition

Answer: D. partial thromboplastin time.

The partial thromboplastin time indicates the coagulation time of a patient's blood. It is often abbreviated as PTT.

Term

Number 1 corresponds to which anatomic structure?

[image]

Definition
Answer: External iliac vein
Term

Number 2 corresponds to which anatomic structure?

[image]

Definition
Answer: trochlea of humerus
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