Comparison of ghosting effects for three commercial a-Si EPIDs.
Date
2006-07ICR Author
Author
McDermott, LN
Nijsten, SMJJG
Sonke, J-J
Partridge, M
van Herk, M
Mijnheer, BJ
Type
Journal Article
Metadata
Show full item recordAbstract
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.
Collections
Subject
Humans
Silicon
Radiographic Image Interpretation, Computer-Assisted
Radiotherapy Dosage
Calibration
Reproducibility of Results
Equipment Design
Radiometry
Phantoms, Imaging
Time Factors
Image Processing, Computer-Assisted
Software
Research team
Radiotherapy Physics Functional Imaging
Language
eng
License start date
2006-07
Citation
Medical physics, 2006, 33 (7), pp. 2448 - 2451