CR

Question 1

IP

Answer 1

Imaging plate

Question 2

PSL

Answer 2

Photostimuable luminescence

Question 3

PSP

Answer 3

Photostimuable phosphor

Question 4

SP

Answer 4

Storage phosphor

Question 5

SPS

Answer 5

Storage phosphor screen

Question 6

PMT

Answer 6

Photomultiplier tube

Question 7

T/F
CR can be substituted for screen film radiography and used with any xray imaging system

Answer 7

True

Question 8

What are the 3 steps of the CR imaging process?

Answer 8

Image acquisition
Image processing
Image display

Question 9

Refers to xray interaction with the imaging plate, and results in the creation of a latent image

Answer 9

Image acquisition

Question 10

Insulates from handling trauma

Answer 10

Protective layer

Question 11

PSP in a binder
Stores meta stable electrons

Answer 11

Phosphor layer

Question 12

Grounds the plate
Absorbs light to increase sharpness

Answer 12

Conductor layer

Question 13

Serves as a base
Made of polyester

Answer 13

Support layer

Question 14

Prevents light from erasing data or leaking through the back

Answer 14

Light shield layer

Question 15

Made of lead, reduces backscatter

Answer 15

Backing layer

Question 16

What are computed radiography cassettes sometimes referred to as?

Answer 16

Filmless cassettes

Question 17

What is the material of the active layer (phosphor) in the cassette?

Answer 17

Barium Fluorobromide crystals doped with europium
BaFBr:Eu

Question 18

What is the atomic numbers of BaFBr?

Answer 18

56, 9, 35
Lower atomic numbers allow for k-edge attenuation between 35 and 50keV energies

Question 19

What is the problem with BaFBr?

Answer 19

Sensitive to scatter before and after exposure to the xray beam

Question 20

What happens when Compton and PE interactions occur with outer shell electrons?

Answer 20

The electrons are sent into a metastable state

Question 21

T/F
In CR, the responses to xray interaction are electrons trapped temporarily in a higher energy, metastable state, in the IR

Answer 21

True

Question 22

What happens when electrons return to their ground state?

Answer 22

They release light
(Photostimuable luminescence)
*this return can be stimulated by exposing the phosphor to intense infrared light from a laser

Question 23

T/F
Metastable electrons eventually return to their ground state on their own

Answer 23

True

Question 24

What is it called when the return to the ground state is accelerated or stimulated by exposing the phosphor to intense infrared light from a laser

Answer 24

Photostimuable luminescence

Question 25

Emission of visible light after excitation by laser light

Answer 25

Photostimulation

Question 26

What is the process called when the Photostimuable phosphor is exposed to a light source and emits light?

Answer 26

Photostimuable luminescence

Question 27

Mechanically stable Electrostatically protected Fashioned to optimize the intensity of stimulated light

Answer 27

Storage phosphor screens (SPS)

Question 28

T/F Screen phosphors can contain linear filaments that enhance the absorption of X-rays and limit the spread of stimulated emission

Answer 28

True

Question 29

What happens when the xray beam exposes the PSP?

Answer 29

The energy transfer results in excitation of electrons into a metastable state

Question 30

T/F Approximately 50% of electrons return to their ground state immediately resulting in prompt emission of light

Answer 30

True

Question 31

In the stimulating process of image acquisition, what determines the spatial resolution of the CR imaging system?

Answer 31

Laser Beam diameter

Question 32

What stage of the image acquisition system is the finely focused beam of infrared light with a beam of 50-100 um (approx. 70) directed at the PSP?

Answer 32

Stimulate

Question 33

T/F As laser beam intensity increases, so does the intensity of the emitted signal

Answer 33

True

Question 34

What does the laser light cause?

Answer 34

Metastable electrons to return to their ground state with the emission of a shorter wavelength in the blue region of the visible spectrum The latent image is made visible (read stage)

Question 35

What are the light detectors of choice for CR?

Answer 35

Photodiodes (PD)

Question 36

How is the residual latent image removed from the IR?

Answer 36

The phosphor is flooded with intense white light from a bank of specially designed lamps

Question 37

T/F If residual latent image remained, ghosting could appear on subsequent use of the IR

Answer 37

True

Question 38

T/F The laser light used to stimulate PSP is monochromatic

Answer 38

Trye

Question 39

What type of laser is the stimulating source of choice?

Answer 39

Solid state laser

Question 40

Why are solid state lasers less likely to interfere with emitted light?

Answer 40

They produce longer wavelength light

Question 41

CR reader Drive mechanism moves the IR slowly along the long axis of the IR

Answer 41

Slow scan *motor drive must be a constant speed, if not may result in banding artifacts

Question 42

CR reader During slow scan, a deflecting device deflects the laser back and forth across the short axis of the IR

Answer 42

Fast scan

Question 43

-Source of stimulating light -spreads as it travels to the oscillating mirror -scans in a raster pattern -focused by lens that keeps the beam diameter small (<100um)

Answer 43

Laser

Question 44

-the laser beam changes size and shape as it is deflected across the IR -the beam is shaped by optics that keep the beam size, shape, and speed largely independent of the beam position

Answer 44

Beam shaping optics

Question 45

Keeps the beam size, shape, speed, intensity constant

Answer 45

Special beam shaping optics

Question 46

T/F Laser beam diameter is critical for ensuring high spatial resolution

Answer 46

True

Question 47

What are the two processes of analog-to-digital conversion (ADC)

Answer 47

Sampling Quantization

Question 48

Analog signal is is converted to digital signal The digitized signals represent a specific location within the image matrix and is displayed as a specific brightness (shade of grey)

Answer 48

Analog to digital conversion (ADC)

Question 49

Which has a wider latitude, CR or screen film?

Answer 49

CR Screen film can only display approx. 30 shades of grey on a view box, CR can display approx. 100 000 grey levels

Question 50

What produces better spatial resolution, small or large IR/IP with a fixed matrix size?

Answer 50

Smaller (Smaller pixel size)

Question 51

What is spatial resolution affected by in CR?

Answer 51

Phosphor layer thickness Pixel size Laser beam size CR (2.5-5lpmm) Screen film (100lpmm)

Question 52

T/F If improper part is selected (technique) the image may be processed incorrectly and fail to display properly

Answer 52

True

Question 53

What is a major difference between film/screen receptors and digital receptors in regards to kvp?

Answer 53

Digital image contrast is no longer dependent on kvp

Question 54

Radiographic noise produced by the random interaction of X-rays with an intensifying screen. This effect is more noticeable when very high rare earth systems are used at high kvp

Answer 54

Quantum mottle

Question 55

What is the principal source of noise on an image?

Answer 55

-Mechanical defects (slow scan driver, fast scan driver) -optical defects (laser intensity, scatter) -computer defects (electronic noise, inadequate sampling/quantization)

Question 56

What are some advantage of CR over screen film?

Answer 56

-Fewer repeat due to wider exposure latitude -improved contrast resolution -lower technical factors -reduce patient dose

Question 57

Matrix sizes will change with differing plate sizes to maintain spatial resolution

Answer 57

Fixed sampling frequency

Question 58

Large IPs will result in poorer spatial resolution (larger pixel size) and small IPs will result in better spatial resolution (smaller pixel size)

Answer 58

Fixed matrix size