chp2

Question 0

What is pixel?

Answer 0

picture element

smallest element in a digital image

Question 1

What is analog?

Answer 1

device or system that captures or measures continuously changing signal.

Question 2

What is pixel size?

Answer 2

the size of the pixel is directly proportional to the amount of spatial resolution or detail in the image.

Question 3

What is an example of pixel size?

Answer 3

the smaller the pixel the greater the detail

Question 4

What is pixel bit depth?

Answer 4

the number of bits within the pixel

Question 5

How many shades of grey can the eye see?

Answer 5

35

Question 6

What is a factor in determining the image contrast resolution?

Answer 6

grey level

Question 7

What is field of view (FOV)?

Answer 7

the amount of body part or patient included in the image

Question 8

What is exposure index?

Answer 8

the amount of exposure received by the IR (image receptor) not by the patient

Question 9

What is ALARA?

Answer 9

as low as reasonably acheivable

Question 10

What is air kerma?

Answer 10

unit of measurement of radiation energy absorbed in a unit of air

Question 11

How is air kerma expressed?

Answer 11

J/kg or gray (Gy)

Question 12

What is the indicated equivalent air kerma?

Answer 12

Measurement of radiation incident on the image receptor derived from pixel values produced by the exposure to an image receptor

Question 13

What is the target equivalent air kerma value?

Answer 13

set values, established by either the system manufacturer or the system user, that represents an optimal exposure for each specific body part and view

Question 14

What is the deviation index (DI)?

Answer 14

difference between the actual exposure and the target exposure it is expressed as a formula

Question 15

What are the some reasons you cannot solely determine image quality by the deviation index?

Answer 15

1. a prostheses within the image
2. gonadal shield within the image
3. failure of the system to recognize the collimated borders
4. unexpected body part in the image

Question 16

What is brightness?

Answer 16

amount of luminescence

Question 17

What is window level?

Answer 17

adjusting brightness of an image, this can also be used to make an image darker

Question 18

What is contrast resolution?

Answer 18

ability of the digital system to display subtle changes in the shade of gray

Question 19

What does contrast resolution depend on?

Answer 19

scatter

Question 20

What is spatial resolution?

Answer 20

the ability of the imaging system to demonstrate small details of an object

Question 21

What is dynamic range?

Answer 21

ability to respond to varying levels of exposure

Question 22

What equals more detail?

Answer 22

less lines

Question 23

What equals less detail?

Answer 23

more lines

Question 24

What is a matrix?

Answer 24

square arrangement of numbers in columns and rows

Question 25

What is modulation transfer?

Answer 25

the ability of a system to record available spatial frequencies

Question 26

What is noise?

Answer 26

anything that interferes with the image

Question 27

What is equipment noise and how does it affect the radiographer?

Answer 27

noise that is highly dependent on manufacturer; technology, and detector quality. This cannot be controlled by the radiographer

Question 28

What is latitude?

Answer 28

The amount of error that can be made in exposure factor choice and still result in the capture of the quality image

Question 29

What is latitude dependent on?

Answer 29

the image detector; the higher the dynamic range, the more values can be detected

Question 30

What is detective quantum efficiency(DQE)?

Answer 30

measurement of percentage of x-rays that is absorbed when it hit the detector

Question 31

What is modulation transfer function?

Answer 31

The ability of a system to record available spatial frequencies