Comparison of ghosting effects for three commercial a-Si EPIDs.

Research output: Contribution to journalArticle

  • External authors:
  • L N McDermott
  • S M J J G Nijsten
  • J-J Sonke
  • M Partridge
  • M van Herk
  • B J Mijnheer


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.

Bibliographical metadata

Original languageEnglish
JournalMedical Physics
Issue number7
Publication statusPublished - Jul 2006