radiation physics QA tests

M5: retake analysis. what is the accepted reject rate

5%

Y3: accuracy of loading factors. kVp must not deviate from the selected value by more than __%

10

Y3: accuracy of loading factors. mA must not deviate from the selected value by more than __%

20

sY3: accuracy of loading factors. mA must not exceed __mAs for any exposure

600

Y3: accuracy of loading factors. backup timer accuracy: the timer must be within _____ of what is selected

10% + 1 ms

Y3: accuracy of loading factors. backup timer accuracy: the exposure must terminate at 600mAs or __s, whichever comes first

6s

Y3: accuracy of loading factors. minimum irradiation time: the control panel timer must be capable of exposures as small as ___ms or __mAs (whichever is greater)

16.6, 5

Y4: radiation output reproducibility. any variation between 10 exposures must be within __% of the average value

15

Y5: linearity. as we increase mAs, we expect the same increase in Air kerma. this must be accurate within __%

10

define HVL

the thickness of an absorber needed to reduce the beam intensity by half

Y7: AEC. for this test, we put different thicknesses of materials in front of the AEC chambers and it should be able to adapt the exposure to give the same optical density. the optical density of the different images must be within __%

20

Y8: xray field and light alignment (penny test). what is the acceptance limit

2% (or 2cm difference in all directions)

Y9: collimation and PBL devices. explain the perpendicularity test

plexiglass plate with a washer on the bottom and a screw at the top. the two should line up

Y9: collimation and PBL devices. the center of the beam must be within __% of the center of the plate

2

Y9: collimation and PBL devices. the dimensions of the collimated field must fall within __% of the SID

3

Y9: collimation and PBL devices. the area of collimation must be within __% of the area of the IR

4