QC Digital

Question 1

Half-value measurement for testing filtration/quality of beam

Answer 1

Minimum amount at 70kvp is 2.5 mm of aluminum equivalent

Question 2

Light field to radiation field alignment - accuracy of collimator

Answer 2

Must be accurate to +- 2% of SID

Question 3

Positive beam limitation (testing collimation)

Answer 3

Primary beam should not be allowed to be larger than the IR when activated

Question 4

Central ray alignment

Answer 4

centering mark should be +- 1% of the light field central ray

Question 5

Focal spot size

Answer 5

size should be within +- 50% of equipment specifications

Question 6

kVp accuracy

Answer 6

should be within +- 3-5 kVp on control panel OR +- 10% of kVp indicated

Question 7

Timer accuracy

Answer 7

should be within +- 5% for exposure longer than 10 milliseconds
OR +- 20% for exposures less than 10 milliseconds

Question 8

mA linearity

Answer 8

should be within +- 10%

Question 9

mA reproducability

Answer 9

should be within +- 5%

Question 10

mA reciprocity

Answer 10

should be within +- 10%

Question 11

AEC Ion chamber sensitivity

Answer 11

should be w/in +- 10%

Question 12

IR Exposure Variation (density adjustment)

Answer 12

vary per unit

Question 13

AEC response capabilities

Answer 13

should be w/in +- 10%

Question 14

backup timer verification

Answer 14

backup timer should terminate exposure after prolonged on time (tested by placing lead on the detector and waiting for the backup timer to kick in)

Question 15

Fluoroscopy exposure rate

Answer 15

No more than 100 mgy/min and no more than 10 R/min

Question 16

Automatic Brightness Control

Answer 16

Checked to make sure the radiation dose hitting the input phosphor is constant. Use phantoms to measure if dose is adjusted.

Question 17

Plate uniformity

Answer 17

Numbers on plate should be similar in value. Less than 20 value difference should be seen amongst the measured areas.

Question 18

Spacial resolution line pairs of digital imaging systems

Answer 18

2.5 lp/mm

Question 19

Grayscale standard display function

Answer 19

Should not vary more than 10% as recommended by American Association of Physicists in Medicine task group 18

Question 20

Average luminance of primary display monitors

Answer 20

300-500 cd/m2

Question 21

How often should aprons be checked?

Answer 21

Visually every 6 mths

Checked fluoroscopically annually