Detection of IMRT delivery errors based on a simple constancy check of transit dose by using an EPID

Tae Seong Baek, Eun Ji Chung, Jaeman Son, Myonggeun Yoon

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Beam delivery errors during intensity modulated radiotherapy (IMRT) were detected based on a simple constancy check of the transit dose by using an electronic portal imaging device (EPID). Twenty-one IMRT plans were selected from various treatment sites, and the transit doses during treatment were measured by using an EPID. Transit doses were measured 11 times for each course of treatment, and the constancy check was based on gamma index (3%/3 mm) comparisons between a reference dose map (the first measured transit dose) and test dose maps (the following ten measured dose maps). In a simulation using an anthropomorphic phantom, the average passing rate of the tested transit dose was 100% for three representative treatment sites (head & neck, chest, and pelvis), indicating that IMRT was highly constant for normal beam delivery. The average passing rate of the transit dose for 1224 IMRT fields from 21 actual patients was 97.6% ± 2.5%, with the lower rate possibly being due to inaccuracies of patient positioning or anatomic changes. An EPIDbased simple constancy check may provide information about IMRT beam delivery errors during treatment.

Original languageEnglish
Pages (from-to)1876-1881
Number of pages6
JournalJournal of the Korean Physical Society
Issue number10
Publication statusPublished - 2015 Nov 1

Bibliographical note

Publisher Copyright:
© 2015, The Korean Physical Society.


  • EPID
  • In vivo dosimetry
  • Intensity modulated radiation therapy
  • Transit dose

ASJC Scopus subject areas

  • General Physics and Astronomy


Dive into the research topics of 'Detection of IMRT delivery errors based on a simple constancy check of transit dose by using an EPID'. Together they form a unique fingerprint.

Cite this