Ch 16 Digital Radiography

Question 1

screen-film requires _____

Answer 1

chemical processing

Question 2

DR is more efficient in ________ than screen-film

Answer 2

time, ,space, and personnel

Question 3

the capture element is that which:

Answer 3

captures the x-ray

Question 4

the coupling element is that which:

Answer 4

transfers the x-ray generated signal to the collection element

Question 5

the collection element may be:

Answer 5

a photodiode, a charge-coupled device CCD, or a thin-film transistor TFT

Question 6

the photodiode collects ______
the CCD collects ____
the TFT collects _____

Answer 6

photodiode: light photons
CCD: light photons
TFT: electrons

Question 7

SPR

Answer 7

scanned projection radiography

Question 8

DRT

Answer 8

digital radiographic tomosynthesis

Question 9

a CCD is a _____ sensing element, advantages are ______, it is a ________ semiconductor

Answer 9

light sensing, advantages are sensitivity, dynamic range, and size, silicon-based semiconductor

Question 10

sensitivity of the CCD allows it to:

Answer 10

detect and respond to very low levels of visible light

Question 11

dynamic range of the CCD allows it to:

Answer 11

respond to a wide range of light intensity, from very dim to very bright

Question 12

CCD’s radiation response is ______

screen-film’s radiation response is _____

Answer 12

CCD: linear

screen-film: H&D curve response

Question 13

CsI/CCD is an indirect DR process by which:

Answer 13

x-rays are converted first to light then to electric signal

Question 14

CsI/a-Si is an indirect DR process by which:

Answer 14

x-rays are converted first to light and then to electric signal

Question 15

fill factor:

Answer 15

the percentage of the pixel face that is sensitive to x-rays, approximately 80% (20% of the x-ray beam does not contribute to the image)

Question 16

in DR as pixel size reduces, _______

Answer 16

spacial resolution increases but at the expense of the patient dose

Question 17

spacial resolution in DR is:

Answer 17

pixel limited

Question 18

in DR it is considered direct because:

Answer 18

there is no coupling element, the a-Se is both the capturing element and the coupling element

Question 19

a-Se is a direct DR process by which _____ are converted to _____

Answer 19

x-rays are converted to electric signal

Question 20

for soft tissue radiography ____ is more important than _____

Answer 20

contrast resolution is more important than spatial resolution

Question 21

spatial resolution is limited to _____ and _____ is more important

Answer 21

pixel size in DR and contrast resolution is more important

Question 22

CR uses ____ to generate a latent image; the visible image results when _______

Answer 22

PSP; the PSL is scanned with a laser beam