Technique

Question 1

What is a technique chart?

Answer 1

· Legally required
· Specific to your system
· Fixed kVp
· Measurement and shielding information

Question 2

What is the fixed or optimum kVp system?

Answer 2

· Use optimum kVp for each body part
· mAs is varied for changes in part size
· most desirable for consistent quality

Question 3

How does screen speed relate to exposure?

Answer 3

· Greater efficacy = less exposure necessary = faster screen
· Relative screen speed of 100 is industry standard
· A screen with a speed of 200 would be twice as fast as a 100-speed screen, and require only ½ as much exposure
· General purpose radiography: 300-400
· Extremity radiography: 100
· Large crystals and a thick phosphor layer produce more film exposure from a given amount of x-ray exposure (greater speed) but provide less radiographic detail

Question 4

What is a detail screen?

Answer 4

·     Rare earth crystals
·     Small crystal size
·     Thin phosphor thickness
·     Reflective layer
·     Relative speed: 50-100
·     Extremities
·     Non-bucky use

Question 5

What factors are used to change density

Answer 5

o Increased mA increases density
o Increased time increases density
o Increased kVp increases density
o Adding a grid or increasing the grid ratio decreases density
o Increased film sensitivity (speed) increases density
o Increased screen speed increases density
o Increased size of patient or body part decreases density
o Increased developer temperature increases density
o Increased developing time increases density
o Moderate increase in developer strength increases density
o Developer that is exceptionally strong may decrease density
o Increase SID decreases density
o Increase OID decreases density
o Major reduction in field size decreases density due to decreased secondary radiation

Question 6

kVp affects length of scale of contrast - Low kVp

Answer 6

§     Short scale
§     High contrast
§     Low latitude
§     “black and white” appearance
§     Best for subjects with similar tissue densities

Question 7

kVp affects length of scale of contrast§ - High kVp

Answer 7

§     Long scale
§     Low contrast
§     Wide latitude
§     “gray” appearance
§     Best for subjects with widely varying tissue densities

Question 8

Fog reduces?

Answer 8

contrast

Question 9

as patient size increases

Answer 9

Contrast suffers (decreases)

Question 10

Secondary radiation control increases contrast by reducing fog

Answer 10

§ Increased OID creates an air gap, reducing the quantity of scatter reaching the film and increasing contrast
§ Use of grid increases contrast
§ Increase in grid ration increases contrast

Question 11

How does Film processing affects contrast?

Answer 11

Contrast is greatest when developer time, temperature and strength are optimal

Question 12

How does Film type affects contrast?

Answer 12

§ High or medium contrast film preferred for bone imaging
§ High latitude (long scale contrast) film is desirable for chest radiography