Exam 2

Question 1

what is the phosphor layer made up of in a CR image plate?

Answer 1

barium fluorohalide

Question 2

what does the conductive layer in the CR image plate do?

Answer 2

eliminates the electrostatic problems

Question 3

what are the imaging plate layers from top to bottom?

Answer 3

protective layer
barium fluorohalide phosphor layer
reflective layer
conductive layer
polyester bas support layer
light shielding layer
backing layer

Question 4

what causes white lines to appear on the image parallel in the direction of the imaging plate?

Answer 4

dust, debris, or scratches on the light guide

Question 5

what is it called when the white border is eliminated during post processing?

Answer 5

shuttering

Question 6

this light is given off when the electrons move from a high energy state to the lower energy state

Answer 6

photostimulated luminescence

Question 7

you should always change the patient into a hospital gown
true or false

Answer 7

true

Question 8

what is the purpose of the photodetector?

Answer 8

to amplify the light and send it to the ADC

Question 9

how are residual images left on the image plate erased?

Answer 9

by flooding the plate with intense white light (fluorescent bulbs) and it pushes all the electrons in that higher energy state down into the ground state

Question 10

does direct or indirect imaging use a scintillator? and what is the scintillator made of?

Answer 10

indirect
gadolinium oxysulfide or cesium iodide

Question 11

does direct or indirect imaging use a photoconductor? and what is the photoconductor made of?

Answer 11

direct
amorphous selenium

Question 12

what does a photoconductor do?

Answer 12

converts x-ray photons directly into an electrical signal

Question 13

in the location domain what is needed to achieve better spatial resolution?

Answer 13

more pixels and smaller pixels

Question 14

in the frequency domain what is needed to achieve better spatial resolution?

Answer 14

more lines per mm

Question 15

isolates each pixel element, stores charges, acts as a switch to send electrical charges to the ADC and then the computer

Answer 15

thin film transistor (TFT)

Question 16

what is quantum model?

Answer 16

image noise, image is underexposed, means in needs for x-ray photons

Question 17

more lateral light spread =

Answer 17

worse spatial resolution

Question 18

what has crystals that are amorphous shapes the spread/refract light?

Answer 18

gallium oxysulfide

Question 19

what is more tubular/straw like and doesn’t cause a lot of lateral light spread?

Answer 19

cesium iodide

Question 20

which has results in better spatial resolution, gallium oxysulfide or cesium iodide?

Answer 20

cesium iodide

Question 21

what is the source of stimulating light?

Answer 21

the laser

Question 22

what uses a photodiode and what is it made of?

Answer 22

indirect
amorphous silicon

Question 23

what does a capacitor do?

Answer 23

holds charges

Question 24

what are the 3 main components in the active matrix array in a pixel? (flat panel detector)

Answer 24

TFT, capacitor, sensing area

Question 25

increased sensing area =

Answer 25

increased fill factor

Question 26

digital image contrast is not completely dependent on kVp true or false

Answer 26

true

Question 27

artifact reduction process that corrects for flow in the detector

Answer 27

gain calibration

Question 28

what is DQE?

Answer 28

the efficiency of the detector to convert an x-ray signal into a useful image signal

Question 29

how do you make up for a low DQE?

Answer 29

putting more x-ray photons into the system

Question 30

increased DQE =

Answer 30

decreased patient dose

Question 31

decreased DQE =

Answer 31

increased patient dose

Question 32

x-ray photons interact with the scintillator and light is emitted and it goes through fiber optics or lenses and mirrors to hit the ___

Answer 32

charge-coupled device (CCD)

Question 33

noise created by the lack of light photons from the scintillator

Answer 33

statistical noise

Question 34

the CCD chip operates without radiation stimulation, affected by temperature, cooler temperatures are better (less noise)

Answer 34

dark current noise

Question 35

the process of manufacturing each CCD chip is complicated and the response of each chip will vary across the array

Answer 35

amplification noise

Question 36

what size are typical CCD chips?

Answer 36

2-4 cm

Question 37

what is the insulator CCD layer made of?

Answer 37

silicon dioxide

Question 38

a solid chemical element or compound that conducts electricity under some conditions which makes it a good medium for control of electrical current

Answer 38

semiconductor

Question 39

Uses a scintillator, that when struck with x- ray photons, converts x-rays into light photons and stores them in capacitors. Each pixel or detector element has its own amplifier, which is switch off and on by circuitry within the pixel, converting the light photons into electrical charges

Answer 39

Complimentary Metal Oxide Semiconductor Systems (CMOS)