Comparison of ghosting effects for three commercial a-Si EPIDs.
van Herk, M
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Many studies have reported dosimetric characteristics of amorphous silicon electronic portal imaging devices (EPIDs). Some studies ascribed a non-linear signal to gain ghosting and image lag. Other reports, however, state the effect is negligible. This study compares the signal-to-monitor unit (MU) ratio for three different brands of EPID systems. The signal was measured for a wide range of monitor units (5-1000), dose-rates, and beam energies. All EPIDs exhibited a relative under-response for beams of few MUs; giving 4 to 10% lower signal-to-MU ratios relative to that of 1000 MUs. This under-response is consistent with ghosting effects due to charge trapping.
Radiographic Image Interpretation, Computer-Assisted
Reproducibility of Results
Image Processing, Computer-Assisted
Radiotherapy Physics Functional Imaging
License start date
Medical physics, 2006, 33 (7), pp. 2448 - 2451