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Flashcards in Analog/Digital Deck (25):
1

Describe Long Scale Contrast.

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

2

Describe secondary factors for contrast.

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

3

Brightness?

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

4

Grayscale?

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

5

Grayscale is manipulated by?

Window width.

6

Brightness is manipulated by?

Window level.

7

Contrast resolution.

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

8

Contrast resolution is controlled by?

Dynamic range and bit depth (quantization)

9

Dynamic range?

Range of exposures that may be captured by a detector.

10

Bit depth (quantization)

The # of bits per pixel.

11

Pixel size =?

FOV
-----
Matrix.

12

2 parts to spatial resolution?

Receptor (extraction)
Display Monitor (display)

13

Exposure latitude?

Range of exposures which produce quality images.

14

Image noise?

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

15

Describe the types of image noise.

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

16

Best way to decrease scatter?

Collimation.

17

Major controlling factor for recorded detail.

FSS.

18

Secondary factors for recorded detail.

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.

19

Size distortion?

Magnification caused by excessive OID, or insufficient SID.

20

Major controlling factor for distortion?

Patient positioning.

21

Artifacts?

Distortion or error in a image.

22

Describe artifacts secondary factors.

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

23

Image blur?

Unfocused image.

24

Describe secondary factors for image blur.

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

25

Describe short scale contrast.

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