Computed Radiography

Question 1

DR was introduced in _____ by _____

Answer 1

1981; Fuji

Question 2

Digital imaging began with __________ and ________

Answer 2

CT ; MRI

Question 3

PSL
PSP
SPS
IP

Answer 3

Photostimulable Luminescence
Photostimulable Phosphor
Storage Phosphor Screen
Imaging Plate

Question 4

SP
PMT
PD

Answer 4

Storage Phosphor
Photomultiplier Tube
Photodiode

Question 5

But in screen-film radiography the _____________ is a scintillator that emits light in response to an x-ray interaction.

Answer 5

radiographic intensifying screen

Question 6

Some materials such as ___________ emit some light promptly in the way that a scintillator does following x-ray exposure.

Answer 6

barium fluorohalide with europium (BaFBr:Eu or BaFI:Eu)

Question 7

They also emit light some time later when exposed to a different light source, which is called ___________

Answer 7

photostimulable luminescence (PSL).

Question 8

It is an activator and is responsible for the storage property of the PSL.

Answer 8

europium (Eu)

Question 9

ATOMIC NUMBER
Barium
Fluorine
Bromine

Answer 9

Barium - 56
Fluorine - 9
Bromine - 3

Question 10

ELECTRON BINDING ENERGY
Barium
Fluorine
Bromine

Answer 10

ELECTRON BINDING ENERGY
Barium - 37
Fluorine - 5
Bromine - 12

Question 11

Many Compton and photoelectric x-ray interactions occur with outer-shell electrons, sending them into an excited, metastable state. When these electrons return to the ground state, _________________

Answer 11

visible light is emitted

Question 12

Latent image occurs in the form of metastable electrons, such screens are called ______________

Answer 12

storage phosphor screens (SPSs).

Question 13

The SPS appears ______ because the small PSP particles (_________) scatter light excessively. Such scattering is called _______. PSP particles are randomly positioned throughout a _________

Answer 13

white ; 3 - 10 um ; turbid ; binder

Question 14

CR signal loss is objectionable after approximately _________

Answer 14

8 hours

Question 15

The IP has __________ that reduces backscatter x-rays. This improves the contrast resolution of the image receptor.

Answer 15

lead backing

Question 16

Main radiation detectors used for occupational radiation monitoring.

Answer 16

Thermoluminescent dosimetry (TLD) and optically stimulated luminescence (OSL)

Question 17

Light is emitted when a ______ heated. Light is emitted when an ________ is illuminated.

Answer 17

TLD crystal ; OSL crystal

Question 18

PSL is similar to _______

Answer 18

OSL

Question 19

4 steps producing PSL signal

Answer 19

Expose
Stimulation
Light Emission Read
Erase

Question 20

The laser light used to stimulate the PSP is __________

Answer 20

monochromatic.

Question 21

The resulting emission has a _______________.

Answer 21

polychromatic spectrum.

Question 22

These are necessary to allow only emitted light to reach the photodetector while blocking the intense stimulated light.

Answer 22

Optical filters

Question 23

It produce longer wavelength light and therefore are less likely to interfere with emitted light.

Answer 23

Solid - state laser

Question 24

It is the source of stimulating light; however, it spreads as it travels to the rotating or oscillating reflector.

Answer 24

Laser

Question 25

Small laser beam diameter is critical for ensuring ___________

Answer 25

high spatial resolution

Question 26

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

Answer 26

Image buffer

Question 27

The computer of the CR reader is in control of the slow scan and the fast scan. This control works off the computer clock in ________

Answer 27

gigahertz

Question 28

A 14-bit CR image has ___________ levels

Answer 28

16,384 gray

Question 29

Computed radiography imaging is characterized by extremely __________

Answer 29

wide latitude.

Question 30

the screen-film image can display only approximately _________ on a viewbox.

Answer 30

30 shades of gray

Question 31

Newer CR systems have ________ levels and therefore additional patient radiation dose reduction is possible.

Answer 31

lower noise

Question 32

__________ are the light detectors of choice for CR.

Answer 32

Photodiodes (PDs)

Question 33

Some signal is lost as the result of __________ and __________

Answer 33

(1) scattering of the emitted light and (2) the collection efficiency of the photodetector.

Question 34

It causes metastable electrons to return to the ground state with the emission of a shorter wavelength light in the blue region of the visible spectrum.

Answer 34

Laser beam