A simple approach for EPID dosimetric calibration to overcome the effect of image-lag and ghosting

EPID dosimetry has known drawbacks. The main issue is that a measurable residual signal is observed after the end of irradiation for prolonged periods of time, thus making measurement difficult. We present a detailed analysis of EPID response and suggest a simple, yet accurate approach for calibration that avoids the complexity of incorporating ghosting and image-lag using the maximum integrated signal instead of the total integrated signal. This approach is linear with dose and independent of dose rate.

► Image-lag and ghosting effects dosimetric accuracy.
► Image-lag and ghosting result in the reduction of total integrated signal for low doses.
► Residual signal is the most significant result for the image-lag and ghosting effects.
► Image-lag and ghosting can result in under-dosing of up to 2.5%.