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Infomatics
Chapter 5
81
Medical
Post-Graduate
08/03/2016

Additional Medical Flashcards

 


 

Cards

Term
How many bits are in a byte?
Definition
8
Term
N bits can represent what range of numbers?
Definition
0 to 2N-1
Term
One byte can store integer values from
Definition
0 - 255
Term
What is the major disadvantage of the transmission of information in analog form.
Definition
The signals can become distorted, causing a loss of fidelity of the information and the errors can accumulate.
Term
Most transducers, sensors, or detectors produce ______ data.
Definition
analog
Term
ADC
Definition
Analog-to-digital converter - used to convert analog signals to digital signals
Term
Converting an analog signal to a digital signal is called ________.   This process requires two steps, _____ and ______.
Definition
digitization, sampling and quantization
Term
The conversion of an analog signal to a digital signal does not result in a loss of data, T/F.
Definition
False
Term
The pixel size should be ________ the size of the smallest object to be seen.
Definition
less than half
Term
The number of bits per pixel determines the
Definition
contrast resolution.
Term
Total number of bytes required to store an image is
Definition
the number of pixels (rows * columns) multiplied by the number of bytes per pixel.
Term
Types of information storage devices
Definition
magnetic disks, flash memory, magnetic tape, optical disks
Term
RAID
Definition
Redundant Array of Independent disks - used for large amounts of on-line storage.  Basically, a RAID is several hard disk drives that are linked together.
Term
What types of images benefit from being displayed in color.
Definition
Co-registered dual modality images, false color images, volume rendered images.
Term
In grayscale, each pixel is represented by _____ value.  In color, each pixel is represented by _____ values.
Definition
Grayscale - one value, color - 3 values (red, green, and blue intensities)
Term
What type of monitor is most commonly used today?
Definition
Flat panel, liquid crystal displays (LCD)
Term
Briefly, how does an LCD monitor work.
Definition
A backlight source is passed through a horizontal polarizing filter.  A voltage is applied to the LC layer that causes the molecules to twist which changes the polarity of the light passing through it.  This allows the light to then pass through a vertical polarizing filter.  If no voltage is applied, the molecule doesn't twist and the polarity of the light doesn't change, so the light for that pixel gets blocked by the vertical polarizing filter.
Term
Luminance
Definition
Rate of light energy emitted or reflected from a surface per unit area, per unit solid angle.  Units are cd/m2.
Term
Required maximal luminance for an interpretation workstation?
Definition
171 cd/m2
Term
Black level
Definition
Minimal luminance, measured with the entire screen black.
Term
Contrast ratio for a monitor
Definition
Maximal luminance divided by the black level.
Term
Veiling glare
Definition
Stray light from the face of the monitor that occurs when an image is displayed.
Term
Problems with LCD monitors include
Definition
bad pixels and limited viewing angle.
Term
Pixel pitch
Definition
Distance from the center of a pixel to the center of an adjacent pixel.
Term
In terms of luminance for a monitor, contrast may be defined as
Definition
C = (Lmax - Lmin) / Lavg
Term
The smallest luminance difference (Lmax-Lmin) that is detectable by half a group of human observers?
Definition
JND - just noticeable difference
Term
Common pixel format for monitors used to display radiographs.
Definition

2560 pixels x 2048 pixels

Called a 5 megapixel monitor

Term
Typical pitch of a 5 megapixel monitor?
Definition
0.165 mm
Term
Lookup tables are used to affect the display of image ______.
Definition
contrast
Term
What does the "level" control?
Definition
The midpoint of the pixel values to be displayed.
Term
What does the "window" control?
Definition
The range of pixel values about the level to be displayed.
Term
The signal sent to a display system that produces a luminance is called the
Definition
digital driving level
Term
What is the display function?
Definition
It describes the luminance produced by the monitor as a function of the magnitude of the digital signal sent to the monitor.
Term
Users adjust medical imaging monitors using the "brightness" and "contrast" controls. T/F
Definition
false
Term
DICOM stands for
Definition
Digital Imaging and Communication in Medicine
Term
GSDF stands for
Definition
Grayscale Standard Display Function
Term
The LUT in a display system converts  _____ to ____ so the net display function will conform to the __________.
Definition

Presentation Values or P-values to Digital Driving Levels

conform to the DICOM GSDF

Term
Output values from the LUT that are provided to the display system are called
Definition
digital driving levels
Term
What does the DICOM GSDF do?
Definition
It provides a predictable relationship between "presentation values" and the luminance displayed by a monitor.
Term
Advantages of Diagnostic Monitors vs Consumer Grade Monitors?
Definition
1) higher maximal luminance, 2) more uniform luminance, 3) smaller pixels - better spatial resolution, 4) wider viewing angles
Term
PACS stands for
Definition
Picture Archiving and Communications System
Term
PACS is a system for the ______, _______, and _______ of radiological images.
Definition
storage, transfer, and display
Term
What is Teleradiology?
Definition
The transmission of radiological images for reviewing at remote sites.
Term
HIS stands for
Definition
Hospital Information System
Term
RIS stands for
Definition
Radiology Information System
Term

EMR stands for

What does it do?

Definition

Electronic Medical Record System

Used to register patients, send a request for a radiology study, store the radiologist's report.

Term
MWL stands for
Definition
Modality Worklists
Term
What is DICOM
Definition

Digital Imaging and Communications in Medicine

A set of standards to facilitate the transfer of medical images and related information.

Term
What are some of the standards for that DICOM includes.
Definition
Standards for the transfer of images, standards for image formats being transfered, and standards for exchange of information regarding workflow
Term
What are examples of DICOM information objects?
Definition
"patients", "images", and "studies"
Term
What are examples of DICOM composite information objects?
Definition
CT image object, CR image object, DX image object, etc.
Term
What is a DICOM conformance statement?
Definition
A formal statement, provided by a vendor, describing a specific implementation of the DICOM standard.
Term
What are the functions of the RIS?
Definition

Ordering and scheduling procedures, protocol descriptions, maintaining patient database, transcription, reporting, and bill preparation.

It supports the entry, use, and storage of text based data.

Term
What is the standard for communicating between the RIS, HIS, EMR, and PACS?
Definition
HL7 - Health Level 7
Term
In a PACS, each study is typically identified by a unique number.  What is it called?
Definition
The accession number.
Term
IHE stands for
Definition
Integrating the Healthcare Enterprise
Term
The IHE develops documents called _______ and the collection of them is called the _______.
Definition

Integration Profiles,

Technical Framework

Term
What do IHE integration profiles do?
Definition
Integration profiles describe solutions to clinical problems using existing standards such as DICOM and HL7.
Term
Two categories of image compression?
Definition
reversible (lossless) and irreversible (lossy)
Term
Reversible compression of medical images results in compression ratios of about ____?
Definition
2:1 to 3:1
Term
Irreversible compression results in compression ratios of _____?
Definition
15:1 or greater
Term
A typical interpretation workstation consists of
Definition
Two high-luminance 54 cm diagonal 3 or 5 megapixel grayscale monitors in portrait orientation and a navigation monitor.
Term
What is a hanging protocol?
Definition
It's the way in which a program arranges images for presentation and display.
Term
What controls should the viewer have for manipulating images?
Definition
window, level, pan and zoom
Term
What is illuminance?  What are the units?
Definition
It is the light energy impinging on a surface (as opposed to luminance - light coming from the surface).  Units are lux.
Term
What is the range of illuminance for viewing clinical images?
Definition
20-40 lux
Term
What is a common test pattern used for evaluating monitors?
Definition
SMPTE - Society of Motion Picture and Television Engineers
Term
What is image co-registration?
Definition
Super-imposing an image from one modality onto an image from another modality.
Term
What is CAD?  Where might it be found?
Definition
Computer Aided detection or diagnosis.  It is sometimes used in mammography.
Term
What is a MIP image?
Definition
Maximum Intensity Projection - formed by passing a set of rays through a volume dataset and selecting the maximum pixel value along each ray.
Term
What are two approaches to viewing a 2D image as a 3D object?
Definition
Shaded surface display (SSD), also called surface rendering, and volume rendering
Term
Five main goals of information security.
Definition
1) privacy, 2) integrity, 3) authentication, 4) nonrepudiation, and 5) availability
Term
HIPAA stands for
Definition
Health Insurance Portability and Accountability Act
Term
What is a firewall.
Definition
A giant massive wall of fire that burns everything that tries to cross it.  I'm done.
Term
Give an overview of the workflow when imaging a patient.
Definition
Patient is registered with the EMR.  EMR sends a request for a study to the RIS.  The RIS schedules the study.  Patient and exam info go onto a modality worklist.  The study is performed.  Images are transfered to PACS for storage and review.  The PACS/RIS developes an interpretation worklist.  Radiologist reviews images and dictates a report.  The report goes to the EMR.
Term
What is DICOM Metadata
Definition
It is the information contained in the header of a DICOM file.  The information includes patient identity, technical info about the image size, content, and how it was created.
Term
What is each data value in a DICOM header identified with.  Describe it.
Definition
A tag.  Each tag has two numbers.  The first is a group number that groups similar types of information together.  The second is unique to the group and identifies a data value.
Term
What is a DICOM object that doesn't contain an image.  Give an example.
Definition

Structured reports

ex. X-ray radiation dose structured report

Term
What is CPT.  Describe it.
Definition
Current Procedural Terminology - it is coding for the description of radiologic procedures performed.
Term
What is RadLex?  How is it being used in CT?
Definition
RadLex is a unified language created by RSNA for use in Radiology.  By giving CT studies a uniform set of names, dose metrics can be compared through the ACR Dose Index Registry.
Term
What are 4 different types of worklists used in Radiology?
Definition

1) Protocol - list of requested studies that need an assigned protocol

2) Interpretation - list of acquired exams that need reviewed

3) Modality - list of exams to be performed on a given modality

4) Billing - list of exams that need to be coded and released for charging

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