Deck 3: Computed Radiography: Physics and Technology

Question 1

Which of the following refers to the use of several digital operations for pre-processing and post-processing of the CR image data?

A)image acquisition
B)image plate scanning
C)image processing
D)image display

Answer 1

image processing

Question 2

In the past, gas lasers such as a helium-neon (He-Ne) laser were used; however, current CR readers use solid-state laser diodes that emit a red laser beam having wavelengths of about 670-690 nm.

Answer 2

True

Question 3

Which of the following refers to X-ray exposure of the phosphor plate storage, or imaging plate (IP)?

A)image acquisition
B)image plate scanning
C)image processing
D)image display

Answer 3

image acquisition

Question 4

Post-processing deals with shading corrections, pattern recognition, and exposure field recognition.

Question 5

Quality control involves a number of activities that are of significance to the administrator.

Question 6

What leads to image artifacts?

A)thick phosphor layers
B)backscatter
C)high resolution
D)thin phosphor layers

Question 7

The number of trapped electrons is proportional to the ____.

A)valence band
B)absorbed radiation
C)latent image
D)conduction band

Question 8

Which cycle basically consists of at least three steps: X-ray exposure of the IP, readout of the exposed IP, and erasure of the IP?

A)imaging
B)scanning
C)photodetection
D)reading

Question 9

While standard IPs have thick phosphor layers and absorb more radiation, high resolution IPs have thinner phosphor layers and provide sharper images compared to thick phosphors.

Question 10

X-ray exposure of the IP causes it to fluoresce (emit light when it is exposed to X-rays) for an extended duration.

Question 11

When is the PSP IP erased by exposing it to a high intensity light beam to get rid of any residual latent image?

A)before laser scanning
B)before image processing
C)after laser scanning
D)Before laser scanning

Question 12

Error correction ensures that equipment not meeting the performance criteria or tolerance limit established for specific QC tests must be replaced or repaired to meet specifications.

Question 13

To render the latent image visible, the PSP IP is taken to the CR reader/processor to be scanned by a laser beam. What is this process called?

A)photostimulated luminescence
B)absorption
C)florescence
D)photostimulated excitation

Question 14

When the radiation exposure is high, film is underexposed and the image is light and is not acceptable.

Question 15

What does X-ray exposure of the PSP IP create?

A)PSL
B)CR image
C)display image
D)latent image

Question 16

Which term refers to the time it takes for a latent image to disappear?

A)fading
B)absorption
C)conduction
D)imaging

Question 17

For the same FOV, the greater the matrix size, the smaller the pixels and the better the image sharpness.

Question 18

Which of the following CR systems incorporates a single fixed IP encased in a special housing that forms a stationary part of the unit?

A)cassette-based
B)photodetector
C)cassette-less
D)film-screen

Question 19

The emitted light from the CR is optically filtered and collected by the light channeling guide, or light collection optics.

Question 20

To render the latent image visible, the PSP must be scanned by a laser beam of a specific wavelength.

Question 21

The ____________________, or scanner, is a machine for scanning the exposed IP to render the latent image visible.

Question 22

Energy subtraction imaging can be done in CR using a special ____________________ to create separate images of bone and soft tissue.

Question 23

Which image quality descriptor of a digital image is related to the size of the pixels in the image matrix?

A)density resolution
B)DQE
C)spatial resolution
D)artifacts

Question 24

It was in 1983 that commercialization of CR imaging systems for use in diagnostic radiology began, when ____________________ introduced their FCR-101 unit.

Question 25

An image with a bit depth of ____ will have 256 (28) shades of gray per pixel.

A)4
B)8
C)12
D)18

Question 26

Which tool provides visual evaluation of high contrast resolution, low contrast resolution, and artifacts, using appropriate QC software?

A)FCR 1 shot Plus System
B)AAPM densitometer
C)Kodak CR System
D)Agfa CR System

Question 27

The digital detector used in CR imaging is the ____________________.

Question 28

Some IPs have a(n) ____________________ for easy identification.

Question 29

The movement of the IP is referred to as the ____ direction and the laser beam movement across the IP is called the ____ direction.

A)horizontal; vertical
B)fast-scan; slow-scan
C)vertical; horizontal
D)slow-scan; fast-scan

Question 30

The ____ descriptor takes into consideration not only the signal-to-noise ratio (SNR) but also the system noise, and therefore includes a measure of the amount of noise added.

A)PS
B)SID
C)EI
D)DQE

Question 31

Which of the following deals specifically with quality assessment, continuing education, the usefulness of quality control procedures, and the assessment of outcomes?

A)tolerance limits
B)quality control
C)acceptance testing
D)quality assurance

Question 32

Which of the following deals with the technical aspects (rather than the administrative aspects) of equipment performance?

A)CQI
B)QA
C)QC
D)AT

Question 33

Once the fixed stationary IP is exposed, the ____________________ image is acquired using a scanning technology appropriate to the system.

Question 34

Which of the following is a feature in an image that masks or mimics a clinical feature?

A)noise
B)artifact
C)density resolution
D)detective quantum efficiency

Question 35

The ____________________ allows the technologist to do any post-processing on images before they are communicated to the PACS for storage.

Question 36

Which CR QC test is used to assess the uniformity of the recorded signal from a uniformly exposed imaging plate?

A)dark noise
B)erasure thoroughness
C)spatial accuracy
D)CR imaging plate test for uniformity

Question 37

Given the negative feedback due to underexposures, what does a predictable and unfortunate use of higher exposures result in?

A)exposure creep
B)dose creep
C)optimum exposure
D)compensation

Question 38

Photostimulable phosphors have the property of creating and storing a(n) ____________________ when exposed to X-rays.

Question 39

Laser scanning produces a luminescence (light) that is proportional to the stored ____________________.

Question 40

The lasers used today for PSL in CR units are ____________________ lasers that produce light with a 680 nm wavelength compared to He Ne lasers that produce light with a 633 nm wavelength used in earlier CR units.

Question 41

The maintenance of equipment is an integral part of the daily activities in _____________________ since it is considered a component of a continuous quality improvement program.

Question 42

Quality control (QC) is a component of QA and refers specifically to the ___________________ of important variables that affect image quality and radiation dose.

Question 43

Routine performance involves conducting a QC test on the equipment on a regular basis with varying degrees of ____________________.

Question 44

____________________ involves both sampling the analog signal and quantization.

Question 45

A(n) ____________________ indicator is a numerical parameter used to monitor the radiation exposure to the IP in CR imaging.

Question 46

A(n) ____________________ can be defined as a distortion or error in an image that is unrelated to the subject being studied.

Question 47

____________________ testing is the first major step in a QC program and ensures that the equipment meets the specifications set by the manufacturers.

Question 48

The smaller the ____________________ size, the better the spatial resolution of the image.

Question 49

The fundamental problem with high exposures is that of increased ____________________ dose to the patient.

Question 50

In general, the greater the bit ____________________, the better the density resolution of the image.