Ch. 23 - Digital Equipment (Exp I & II) Flashcards
Digital radiography (DR) is characterized by…
The use of reusable receptors
Computers operate using a ______ language.
Binary machine
Each binary number is called a…
Bit
An eight-bit word is called a…
Byte
When the main power to the computer is turned off, ____ is erased.
RAM
When the main power to the computer is turned off, ____ is maintained.
ROM
Computed radiography is also referred to as…
PSP technology
Indirect DR uses _______ as the detector material.
Amorphous silicon
CR systems acquire clinical information by…
Laser scanning a PSP plate
The window width controls…
Image contrast
The window level controls…
Brightness
Window width changes are sometimes called…
- Gray scale expansion
- Enhancing visibility of detail
- Gray scale compression
Resolution is controlled by ____ size.
Pixel
A common feature between indirect and direct DR technology is…
Thin film technology (TFT)
Computerized digital images consist of a ____ of picture elements, each with a video display value or gray shade.
Matrix
Each pixel in a digital display matrix is located according to its…
Electronic address
In digital imagine, the limiting factor in spatial resolution is the…
Pixel size
A pixel that has an 8-bit depth displays ____ shades of gray.
256
Which of the choices below would produce the highest spatial frequency and contrast?
a. ) Gall bladder
b. ) Contrast filled urinary bladder
c. ) 3mm renal calculi (stone)
d. ) Contrast-filled appendix
c.) 3mm renal calculi (stone)
Which of the following is not related to the others?
a. ) Local processing
b. ) Manual processing
c. ) Point processing
d. ) Geometric processing
b.) Manual processing
In digital image processing, the digital data set is arranged into a histograph distribution in order to determine the…
a. ) Display matrix
b. ) Exposure index
c. ) Values of interest (VOI)
d. ) Both b ad c
d.) Both b and c
In digital image processing, an overexposed or underexposed image can be modified to achieve an acceptable “look” through a histogram analysis. This is the result of the digital processing technique of…
a. ) Histogram stretching
b. ) Histogram modification
c. ) Rescaling
d. ) All of the above
d.) All of the above
The purpose of LUT is to…
Apply a predetermined scale of contrast to the digital data set.
If the radiographer applied an ankle LUT to a chest radiograph data set, the image would demonstrate…
High contrast
All of the following are true of local area processing EXCEPT:
a. ) It relies on the application of kernels to pixels
b. ) Kernels are ultimately applied to the entire pixel data set
c. ) Spatial filtering is an example of local area processing
d. ) Electronic magnification of the image is an example of local area processing
d.) Electronic magnification of the image is an example of local area processing
the relationship between digital image resolution…
a. ) Is direct with matrix size
b. ) Is indirect with pixel size
c. ) Is direct with pixel bit depth
d. ) Both a and b
d.) Both a and b
When matrix size is increased ad pixel size goes down,
Spatial resolution increases
Of the many types of digital image procedures performed in a contemporary medical imaging department, the largest file sizes are typically generated by…
Digital fluoroscopy
Noise on a digital image is the summation of inherent electron system noise and quantum mottle noise. Of these two, the radiographer can improve the noise on an image by…
Increasing the exposure technique.
Of the following, the best S:N ratio is
a. ) 10:1
b. ) 100:1
c. ) 500:1
d. ) 1,000:1
d.) 1,000:1
When the quality of a digital detector is inspected for purchase, the preferred detector for purchase would have a…
a. ) DQE of 65% and MTF of 0.55
b. ) DQE of 40% and MTF of 0.80
c. ) DQE of 68% and MTF of 0.80
d. ) DQE of 55% and MTF of 0.35
c.) DQE of 68% and MTF of 0.80
The deviation index (DI)…
Compares entrance dose to the detector to a reference industry-standard target dose.
An S value of 200 represents…
An exposure to the IP of 1 mR
When changing the exposure technique from 9 mAs to 18 mAs using computed radiography, the radiographer should expect…
An EI number increase from 1500 to 1800.
The response to radiation exposure with a digital receptor is…
Linear
Grossly overexposed digital images will demonstrate…
A loss of contrast
When using CR technology, it is important to remember that…
a. ) The IP is extrasensitive to exposure after the initial x-ray exposure
b. ) The IP will lose about 25% of its signal in 8 hours if not processed
c. ) The IP is very sensitive to scatter, making grids very important
d. ) All of the above
d.) All of the above
An x-ray exposure taken at 80 kVp has an average energy of…
35 keV
In the technology of CR, the latent image is actually…
Electron “holes” in Europium
All of the following are true of pixel pitch EXCEPT:
a. ) It is defined as the distance between pixels
b. ) It is not related to spatial resolution
c. ) Is is determined by the size of the DEL in DR systems
d. ) It is measured from the center-to-center of the pixels
b.) It is not related to spatial resolution
All of the following impact digital image spatial resolution EXCEPT:
a. ) Pixel pitch
b. ) Bits/pixel
c. ) DEL dimension
d. ) Sampling frequency
b.) Bits/pixel
The size of the digital file size is determined by the:
a. ) Bit depth
b. ) Pixel size
c. ) Matrix
d. ) All of the above
d.) All of the above
In CR technology, pre-processing of data includes:
a. ) Histogram analysis
b. ) Gray scale analysis
c. ) Exposure data recognition (EDR)
d. ) All of the above
d.) All of the above
In digital image technology, once the image data is sent to PACS…
The data is fixed and not able to be reprocessed.
When using a Fuji CR system in the fixed-mode of operation:
a. ) Exposure techniques are variable and adjustable by the computer to adjust density and contrast
b. ) The system will not correct for exposure inadequacies and adjust for density problems
c. ) Your exposure techniques must be accurate, similar to film/screen technology
d. ) Both b and c
d.) Both b and c
All of the following are TRUE of Moire effect EXCEPT:
a. ) It results from a conflict in spatial frequencies between the grid frequency and laser scanning frequency
b. ) It produces useless diagonal dark lines across the finished image
c. ) It is most likely to occur with DR technology, particularly amorphous selenium
d. ) It is eliminated with ultra-high grid frequencies 178-200 lpi
c.) It is most likely to occur with DR technology, particularly amorphous selenium
