arrt review: image production / fluoroscopy

Question 1

Flux gain is the ______________ gained during acceleration from _____________ to the ______________

Answer 1

kinetic energy, photocathode, output phosphor

Question 2

Minification gain is the _____________________ from the _______________ to the __________________

Answer 2

concentration of photoelectrons, input phosphor, output phosphor

Question 3

Brightness is the ability of the ___________________ to increase the _______________ level of the image

Answer 3

image intensifier, brightness

Question 4

percentage that measures the efficiency of the image intensifier

Answer 4

conversion factor

Question 5

What is the Input phosphor made of? what does it do?

Answer 5

Cesium iodide
converts x-rays to light photons (1 to 1,000 light photons)

Question 6

What is the output phosphor made of? what does it do?

Answer 6

Zinc cadmium sulfide
converts e- to light photons

Question 7

What is the photocathode made of? what does it do?

Answer 7

Cesium and antimony compounds
converts light photons to photoelectrons (e-)

Question 8

Why are lower grid ratios used in fluoroscopic imaging?

Answer 8

Using higher kVp and lower mAs (using contrast is the reason behind these technical factors)

Question 9

Only __________ grids used in conventional fluoro (____________________________________)

Answer 9

linear, (crossed in interventional)

Question 10

how do you calculate brightness gain?

Answer 10

Brightness gain = flux gain x minification gain

Question 11

how do you calculate flux gain?

Answer 11

output light photons/input x-ray photons

Question 12

how do you calculate minification gain?

Answer 12

diameter of input phosphor^2/diameter of output phosphor^2

Question 13

what is the order of components in an image intensifier?

Answer 13

(anti-scatter grid)
input phosphor
photocathode
electrostatic focusing lenses
anode
output phosphor

Question 14

what converts x-rays to light in the image intensifier?

Answer 14

input phosphor

Question 15

which comes first in the image intensifier: photocathode or input phosphor?

Answer 15

input phosphor

Question 16

what converts light photons to electrons in the image intensifier?

Answer 16

photocathode

Question 17

what converts electrons to light photons in the image intensifier?

Answer 17

output phosphor

Question 18

what does a CCD/video camera do in the image intensifier?

Answer 18

convert light photons to electrical (analog) signal

Question 19

what does an ADC do in the image intensifier?

Answer 19

converts electrical (analog) signal to a digital signal

Question 20

the ABC prevents fluctuations in the _______

Answer 20

SNR

Question 21

how does Automatic Brightness Control work?

Answer 21

Feedback loop from image intensifier or flat panel detector to adjust exposure factors

Question 22

what is an example of another name for ABC?

Answer 22

automatic exposure rate control (AERC)

Question 23

what is vignetting?

Answer 23

decrease in image brightness around the edges of the image

Question 24

what is vignetting caused by?

Answer 24

caused by OID or curved edge of input phosphor

Question 25

what is pincushion artifact?

Answer 25

Parts of the image appear curved or bent inward toward the center of the image

Question 26

what is pincushion artifact caused by?

Answer 26

curved shape of input phosphor, external magnetic fields

Question 27

what is S-shape artifact?

Answer 27

parts of the image appear curved or bent inward toward the center of the image

Question 28

what is S-shape artifact caused by?

Answer 28

external magnetic fields, mis-angulation of the x-ray beam

Question 29

what is blooming?

Answer 29

parts of the image white out causing a loss of visual sharpness

Question 30

what is blooming caused by?

Answer 30

high energy x-rays hitting the input phosphor, creating intense light production

Question 31

what is veiling glare artifact?

Answer 31

type of blooming, contrast recuing haze on the fluoro image

Question 32

what is veiling glare artifact caused by?

Answer 32

scattering of x-ray, light, and e- energies inside the image intensifier

Question 33

what is lag?

Answer 33

delay in the response tie of the image intensifier to changes in beam intensity

Question 34

what is noise?

Answer 34

grainy or mottled image

Question 35

how can you reduce lag?

Answer 35

use frame averaging or high-speed image intensifiers

Question 36

older image intensifier systems used _____ to send to a TV; modern image intensifiers use ________

Answer 36

vidicon, CCD

Question 37

image intensifiers with CCDs have __________________ and __________________ compared to vidicon tube systems

Answer 37

higher spatial resolution, less image blooming and lag

Question 38

order of parts in flat panel detectors

Answer 38

Indirect (scintillation → photodiode → TFT)

Question 39

What kind of digital conversion is used in FPD’s in fluoro? Indirect or direct?

Answer 39

Indirect (scintillation → photodiode → TFT)

Question 40

flat panel vs. image intensifiers flat panels = (more/fewer) energy conversions (higher/lower) patient dose (more/less) artifacts (wider/narrower) dynamic range

Answer 40

fewer energy conversions lower patient dose less artifacts wider dynamic range

Question 41

what is the scintillation layer made of in a flat panel detector?

Answer 41

cesium iodide or gadolinium

Question 42

what is the photodiode layer made of in a flat panel detector?

Answer 42

amorphous silicon

Question 43

overall conversion process of flat panel detectors

Answer 43

xrays --> light --> electrical signal ---> digital signal

Question 44

with pulsed fluoroscopy, the higher the frame rate, the ____________

Answer 44

more seamless the image appears

Question 45

which is a setting/mode, and which is operator controlled? Pulsed fluoro, intermittent fluoro

Answer 45

pulsed = mode, intermittent = operator

Question 46

what occurs in frame averaging?

Answer 46

pixels are averaged and compared for the most common elements

Question 47

what is the effect of frame averaging on patient dose?

Answer 47

Does not impact patient exposure or tube heat

Question 48

what is the effect of frame averaging on fluoro image quality?

Answer 48

Decreases noise, makes image clearer

Question 49

Static fluorograph made during fluoro exam is a ________

Answer 49

spot image

Question 50

Spot imaging = (higher/lower/no effect) on patient dose

Answer 50

higher

Question 51

Last image hold = (higher/lower/no effect) on patient dose

Answer 51

no effect

Question 52

spot imaging is like a _______ and last image hold is like a ____________

Answer 52

static xray, screenshot

Question 53

federally mandated limit for the exposure rates of conventional fluoro

Answer 53

100 mGy/minute

Question 54

where is ghost imaging seen, CR or DR?

Answer 54

CR only