Analog/Digital

Question 1

Describe Long Scale Contrast.

Answer 1

Low contrast
Small differences
Shades of gray
Abdomens/chest
Higher kVp

Question 2

Describe secondary factors for contrast.

Answer 2

Air gap- ^ OID, ^ contrast. Used for lateral c spines.
Body habitus- ^, decreases contrast.
Beam restriction- ^, ^ contrast, reduces scatter.
Grids- ^, ^ contrast, reduces scatter.

Question 3

Brightness?

Answer 3

Measurement of the luminance of a monitor calibrated in units of candela per square meter.

Question 4

Grayscale?

Answer 4

Grayscale is the difference of the densities on the digital image.

Question 5

Grayscale is manipulated by?

Answer 5

Window width.

Question 6

Brightness is manipulated by?

Answer 6

Window level.

Question 7

Contrast resolution.

Answer 7

The smallest exposure change or signal difference that can be detected in the IR.

Question 8

Contrast resolution is controlled by?

Answer 8

Dynamic range and bit depth (quantization)

Question 9

Dynamic range?

Answer 9

Range of exposures that may be captured by a detector.

Question 10

Bit depth (quantization)

Answer 10

The # of bits per pixel.

Question 11

Pixel size =?

Answer 11

Matrix.

Question 12

2 parts to spatial resolution?

Answer 12

Receptor (extraction)
Display Monitor (display)

Question 13

Exposure latitude?

Answer 13

Range of exposures which produce quality images.

Question 14

Image noise?

Answer 14

The deterioration of a radiographic image by unwanted interference in x ray signal detection.

Question 15

Describe the types of image noise.

Answer 15

Electronic noise- intrinsic within the system.
Quantum noise- insufficient signal strength
Scatter/fog- also increases noise.

Question 16

Best way to decrease scatter?

Answer 16

Collimation.

Question 17

Major controlling factor for recorded detail.

Answer 17

FSS.

Question 18

Secondary factors for recorded detail.

Answer 18

Body habitus- decreases detail. Higher OID increased magnification.
Motion- decreases detail.
OID- decreases detail, increases magnification
SID- increases detail, decreases magnification.
Film screen combination- decreases detail, increases phosphors size.

Question 19

Size distortion?

Answer 19

Magnification caused by excessive OID, or insufficient SID.

Question 20

Major controlling factor for distortion?

Answer 20

Patient positioning.

Question 21

Artifacts?

Answer 21

Distortion or error in a image.

Question 22

Describe artifacts secondary factors.

Answer 22

Image receptors- cassette based, cassette less.
Processing- cassette based
Software- in computer for digital imaging
Exposure- jewelry, clothing.

Question 23

Image blur?

Answer 23

Unfocused image.

Question 24

Describe secondary factors for image blur.

Answer 24

Receptor- cause within any receptor
Geometric- FSS, SID, OID
Motion- motion of patient, part, tube, IR.

Question 25

Describe short scale contrast.

Answer 25

High contrast
Sharp differences
Black and white
Bone work
Lower kVp.