crdr 3

Question 1

at this time, it is the most widely used DR modality

Answer 1

computed radiography (CR)

Question 2

Digital Radiography (DR) is introduced in?

Answer 2

1981 by Fuji

Question 3

Digital imaging began with?

Answer 3

CT and MRI

Question 4

IP

Answer 4

imaging plate

Question 5

PMT

Answer 5

photomultiplier tube

Question 5

PD

Answer 5

photodiode

Question 6

PSL

Answer 6

photostimulable luminescence

Question 7

PSP

Answer 7

photostimulable phosphor

Question 7

SP

Answer 7

storage phosphor

Question 8

SPS

Answer 8

storage phosphorscreen

Question 9

Similarities between screen-film imaging and CR imaging

Answer 9

• both use as IR an x-ray sensitive plate
• both can be used interchangeably with any x-ray imaging system
• both produce latent image

Question 10

Differences between screen film radiography and CR

Answer 10

• in screen-film, IS is scintillator that emits light in response to an x-ray interaction
• in CR, the response to x-ray interaction is seen as trapped electrons in a higher energy metastable state

Question 11

emit light promptly in the way that a scintillator does following x-ray exposure

Answer 11

barium fluorohalide with europium

Question 11

also emit light some time later when exposed to a different light source

Answer 11

photostimuable luminescence (PSL)

Question 12

occur with outer-shell electrons, sending them into an excited, metastable state

Answer 12

Compton and photoelectric x-ray interaction

Question 12

barium fluorobromide atomic numbers

Answer 12

56, 9, 35 respectively

Question 13

when metastable electrons return to their ground state, visible light is emitted (no answer)

Answer 13

this return to the ground state can be accelerated or stimulated by exposing the phosphor to intense infrared light from a laser

Question 14

phosphor used in PSP

Answer 14

barium fluorohalide

Question 15

SPS appears white because the small PSP particles (3–10 μm) scatter light excessively, such scattering is called?

Answer 15

turbid

Question 15

mechanically stable, electrostatically protected, and fashioned to optimize the intensity of stimulated light

Answer 15

SPS

Question 16

PSP screen-film cassette

Answer 16

IP

Question 17

housed in a rugged cassette that appears similar to a screen- film cassette.

Answer 17

PSP screen

Question 18

principal advantage of CR

Answer 18

CR can be substituted for screen-film radiography and used with x-ray imaging system

Question 19

TLD

Answer 19

thermoluminescent dosimetry

Question 20

OSL

Answer 20

optically stimulated luminescence

Question 20

PSP screen of the IP is not loaded and unloaded in a darkroom. (no answer)

Answer 20

Rather, it is handled in the manner of a screen-film daylight loader.

Question 21

main radiation detectors used for occupational radiation monitoring

Answer 21

TLD and OSL

Question 22

Light is emitted when TLD crystal is

Answer 22

heated

Question 23

Light is emitted when an OSL crystal is

Answer 23

illuminated

Question 24

1st step of events engaged in producing a PSL signal

Answer 24

Expose

Question 24

induced image-forming signal

Answer 24

1st step (Expose)

Question 25

2nd step of events engaged in producing a PSL signal

Answer 25

Stimulate

Question 26

3rd step of events engaged in producing a PSL signal

Answer 26

Read

Question 26

4th step of events engaged in producing a PSL signal

Answer 26

Erase

Question 27

Stimulation of the latent image results from the interaction of an infrared laser beam with the PSP

Answer 27

2nd step (stimulate)

Question 28

The light signal emitted after stimulation is detected and measured.

Answer 28

3rd step (Read)

Question 29

Before reuse, any residual metastable electrons are moved to the ground state by an intense light.

Answer 29

4th step (Erase)

Question 30

xray beam exposes a PSP, energy transfer realist in excitation. 50% of these electrons return to ground state, resulting in emission of light. remaining 50% return to ground state over time. causes latent image to fade

Answer 30

1st step

Question 31

diameter of the laser beam affects the ____ of the CR imaging system

Answer 31

spatial resolution

Question 31

detecting the stimulated emission

Answer 31

3rd step

Question 32

as the laser beam penetrates, it spreads. The amount of spread increases with PSP thickness

Answer 32

--

Question 33

some signal is lost as the result of:

Answer 33

- scattering of emitted light - collection of efficiency of photodetector

Question 34

the light detectors of choice for CR

Answer 34

PD

Question 34

if residual latent image remained, ghosting could appear on subsequent use of IP (no ans)

Answer 34

any residual is removed by flooding the phosphor with very intense white light from bank of specially designed fluorescent lamps

Question 35

represents the marriage of mechanical, optical, and computer modules

Answer 35

CR reader

Question 35

challenge to the CR reader is to precisely interrogate each metastable electron of the latent image in a precise fashion

Answer 35

optical features

Question 36

Components of the optical subsystem

Answer 36

1. Laser 2. Beam-Shaping Optics 3. Light-Collecting Optics 4. Optical Filters 5. Photodetector

Question 36

source of stimulating light

Answer 36

laser

Question 36

The output of the photodetector is a ___ that is transmitted to a computer system that has multiple functions. It is processed for amplitude, scale, and compression. This shapes the signal before the final image is formed

Answer 36

time-varying analog signal

Question 36

it is usually a hard disc and is place where a completed image can be stored temporarily until it is transferred to a workstation for interpretation or to an archival computer.

Answer 36

image buffer

Question 37

in control of the slow scan and the fast scan.

Answer 37

computer of CR reader

Question 37

it is exposed with an existing x-ray imaging system to form a latent image. inserted into an automatic processor (reader), and the latent image is made visible

Answer 37

cassette

Question 38

Four principal characteristics of any medical image:

Answer 38

1. Spatial resolution 2. Contrast resolution 3. Noise 4. Artifacts

Question 38

The principal source of noise on a radiographic image is

Answer 38

scatter radiation

Question 39

The transition from screen-film radiography to CR brings several significant changes.

Answer 39

- fewer repeat examination - contrast resolution is improved - patient radiation dose is reduced

Question 39

CR image contrast is constant regardless of radiation exposure, images can be made at higher kVp and lower mAs, resulting in additional reduction in patient radiation dose.

Answer 39

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