CH 7

Question 1

Attenuation

Answer 1

Process by which a beam of radiation is reduced in energy when passing through tissue or other materials
EX: Radiopaque- light/white bone
Radiolucent- dark/black

Question 2

Automatic rescaling

Answer 2

Process by which images are produced with uniform brightness and contrast, regardless of the amount of exposure

Question 3

Computed radiography (CR)

Answer 3

• first version of digital imaging
• uses storage phosphor plates to produce images
• placed in a reader that scans the plate and transferred it’s energy into an image on the monitor

Question 4

Contrast

Answer 4

Difference between ranges of adjacent IR exposures represented as gray tones in an image

Question 5

Contrast resolution

Answer 5

Ability to distinguish between very subtle differences in image receptor exposures and differentiate them from the noise in the image

Question 6

Data drop

Answer 6

Condition due to extreme overexposure which causes digital detector elements to become overwhelmed with photon energy and leads to drop of data during image reconstruction

Question 7

Detector element (DEL)

Answer 7

Pixel size element of the DR IR that has a fixed dimension in x- or y- orientation

Question 8

Detector saturation

Answer 8

Data drop that involves areas or regions of the digital detector

Question 9

Digital radiography (DR)

Answer 9

Digital image acquisition systems that convert x-ray energy into a digital electronic signal for manipulation and display using direct or indirect (turns I are until light then converted into image) conversion

Question 10

Primary radiation

Answer 10

Exiting X-ray tube

Question 11

Scatter radiation

Answer 11

Bounces off patient

Question 12

Absorbed radiation

Answer 12

Stays in patient

Question 13

Remnant radiation

Answer 13

Strikes image receptor

Question 14

Radiographic exposure factors

Answer 14

mAs- milliampere seconds, directly controls quantity of X-ray photons
kVp- kilovoltage peak, controls penetrating ability of X-ray beam
SID- affects relative intensity of beam

Question 15

Factors that affect radiographic quality

Answer 15

Image signal: visibility of image
image resolution: sharpness/accuracy
Balance between the two required for optimum image quality

Question 16

Two types of image signal

Answer 16

1. IR exposure: signal value, numerical value assigned to the amount of x-ray exposure IR receives (brightness)
2. Contrast: signal difference, difference in adjacent structures on image

Question 17

Two types of image resolution

Answer 17

1. Spatial resolution: sharpness, describes the degree of accuracy of structural lines recorded
2. Contrast resolution: ability to distinguish between very subtle differences and signal values and differentiate them from noise

Question 18

What are factors that affect signal value?

Answer 18

• mAs/kVp/SID
• patient size/thickness, Atomic number of anatomy, Pathology
• beam modification: filtration/collimating
• grids
• type of IR: CR/DR indirect and direct

Question 19

Subject contrast

Answer 19

Differences in the intensity of x-ray beam after it has been attenuated or absorbed by patient

Question 20

Radiographic contrast

Answer 20

Difference between adjacent exposure values on the radiographic image

Question 21

Image contrast

Answer 21

brightness

Question 22

Contrast media

Answer 22

Substance that’s injected into or ingested by patient to better visualize structures

Question 23

Spatial resolution factors

Answer 23

Temporal resolution: motion distortion
Beam, geometry: object unsharpness due to shape of an atomic structure, use a small focal spot for better resolution, greater SID, smaller OID

Question 24

Fluoroscopy

Answer 24

Use of x-rays to create a real time image of patient anatomy and function
- need image intensifier and flat panel digital fluoroscopic detector