Shared Flashcard Set

Details

Radio Ch 7
Digital Imaging
30
Health Care
Graduate
10/21/2010

Additional Health Care Flashcards

 


 

Cards

Term
Advantages of Digital Imaging
Definition
elimination of chemical processing
elimination of hazardous wastes
images can be electronically transferred to other health care providers without altering the image
receptors require less radiation than film - lowering pt. exposure
Term
Disadvantages of Digital Imaging
Definition
Initial expense is high
digital systems have new or immature technologies and the systems could do out of business
intraoral systems are susceptible to rough handling and are expense to replace
Term
What makes film x-rays competitive with digital?
Definition
low cost and excellent image quality
Term
What are the two ways in which digital imaging is numeric and discrete?
Definition
1. in terms of the spatial distribution of the pixels
2. in terms if the different shades of gray of each of the pixels.
Term
What type of medium are film images considered to be in?
Definition
analog
Term
What does it mean to be in an analog medium?
Definition
differences in the size and distribution of black metallic silver results in a continuous density spectrum
Term
What does ADC stand for? What does it consist of?
Definition
Analog-to-digital conversion
Two steps: sampling and quantitizing
Term
Sampling and quantitized are steps of what process?
Definition
ADC (analog to digital conversion)
Sampling - small range of voltage values are grouped as a single value
Quantitized- every sample signal is assigned a value
Term
What does the quantitized value represent?
Definition
intensity of the image(grey level)
Term
Two main technologies of digital image receptors are _______ and _________.
Definition
Solid- State technology
Photostimulate phosphor technology
Term
The use of solid-state detectors is referred to as different things in medicine and dentistry. What are they?
Definition
In medicine they are referred to as digital radiography
In dentistry they are called sensors
Term
What does Photostimulable phosphor consist of?
Definition
A phosphor coated on top of a plate in which an image is formed after x-ray exposure.
This technology is sometimes thought as storage phosphor bc the image is temporarily stored within the phosphor
Term
What does Photostimulable phosphor consist of?
Definition
A phosphor coated on top of a plate in which an image is formed after x-ray exposure.
This technology is sometimes thought as storage phosphor bc the image is temporarily stored within the phosphor
Term
Computed Radiology is another term for what?
Definition
The use of PSP (photostimulable phosphor technology) plates in medical radiology
Term
What are analog images composed of vs. digital images?
Definition
Analog are composed of a continuous gradient
Digital are composed of pixels of numerical info that are organized into a matrix.
Term
T/F The intensity of the voltage (when a photon strikes the pixel area on the sensor) produces a gradient
Definition
true
Term
T/F The expense of the detector increases with decreasing number of pixels
Definition
FALSE. The expense increases with an increasing number of pixels (matrix size)
pixel size varies from 20 to 70 micrometers
Term
How many solid-state sensors are commonly used?
Definition
3
Term
What are the three types of solid-state sensors?
Definition
Charge coupled device (ccd)
Complementary metal oxide semiconductors
Flat panel detectors
Term
T/F The charge coupled device was the last type of digital receptor to be used in dentistry ( of the 3 types)
Definition
False - 1st type
Term
Thin silicon wafer, pixels read in a continuous chain (bucket bridage style), more bulky than other receptor types - what type of sensor is described?
Definition
Charge coupled device (CCD)
Term
Describe Complementary metal Oxide Semiconductors (CMOS)
Definition
Use silicon detector with same mechanism as CCD
Pixels read ONE at a time, isolated from neighbors (unlike CCD)
Term
What do both CCD and CMOS have in common? What is an advantage of CMOS?
Definition
Both generate electron-hole pairs within the pixel in proportion to the amount of x-ray energy that is absorbed.
CMOS are less expensive than CCDs
Term
t/f CCD detectors are more sensitive to light than to x-rays
Definition
True. Bc of this, manufacturers use a layer of scintillating material (cesium iodide or gadolinium oxybromide) coated on the CCD surface or coupled to the surface by fiberoptics - increasing the x-ray absorption efficiency of the detector
Term
What are CCD, CMOS, and Flat Panel detectors each used for?
Definition
CCD- intraoral imaging
CMOS- video cameras
Flat panel - extraoral imaging
Term
t/f flat panel detectors provide small matrix areas
Definition
False - large matrix areas with pixel sizes less than 100 micrometers
Term
What does the large matrix area in Flat panel detectors allow?
Definition
Imaging of larger areas of the body - head
Term
What are two approaches of Flat panel detectors?
Definition
Indirect and Direct

Indirect - sensitive to visible light, use an intensifying screen to convert x-ray energy into light (thicket screens use less radiation but yield lower quality images)

Direct - use photoconductor material selenium)which permits more efficient absorption of x-rays
Term
Are Flat panel detectors afforable and used often?
Definition
No, they are expensive and limited to specialized imaging such as cone beam imaging
Term
Compare Indirect intensifying screens and Direct photoconductor material in Flat panel detectors
Definition
Direct use selenium and provide higher resolution but lower efficiency compared to Indirect using intensifying screens with galdolinium or cesium.
Supporting users have an ad free experience!