Dose Course 2018_Flipping book
EPID CALIBRATION Correction factors (at this moment to be used for pretreat verifications and linac QA)
THE INTENSITY AT EACH POINT IN THE IMAGE MUST BE CALIBRATED IN A QUANTITATIVE SENSE
❑ The dose response of each pixel point must be known
❑ The effects of scattered radiation in the detector must be understood
❑ The temporal stability of the detector must be known.
DEPENDING ON THE DETECTOR: DIFFERENT CORRECTION FACTORS CAN BE EXPECTED
Field size
❑
❑ Backscatter from the EPID arm (Varian aS500, aS1000). Not needed for aS1200 (backscatter shielding added)
❑ EPID SAG if used at different gantry angles
Made with FlippingBook HTML5