Clinical impact of dosimetric changes for volumetric modulated arc therapy in log file-based patient dose calculations

Yoshiyuki Katsuta, Noriyuki Kadoya, Yukio Fujita, Eiji Shimizu, Kenichi Matsunaga, Haruo Matsushita, Kazuhiro Majima, Keiichi Jingu

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Purpose A log file-based method cannot detect dosimetric changes due to linac component miscalibration because log files are insensitive to miscalibration. Herein, clinical impacts of dosimetric changes on a log file-based method were determined. Methods and materials Five head-and-neck and five prostate plans were applied. Miscalibration-simulated log files were generated by inducing a linac component miscalibration into the log file. Miscalibration magnitudes for leaf, gantry, and collimator at the general tolerance level were ±0.5 mm, ±1°, and ±1°, respectively, and at a tighter tolerance level achievable on current linac were ±0.3 mm, ±0.5°, and ±0.5°, respectively. Re-calculations were performed on patient anatomy using log file data. Results Changes in tumor control probability/normal tissue complication probability from treatment planning system dose to re-calculated dose at the general tolerance level was 1.8% on planning target volume (PTV) and 2.4% on organs at risk (OARs) in both plans. These changes at the tighter tolerance level were improved to 1.0% on PTV and to 1.5% on OARs, with a statistically significant difference. Conclusions We determined the clinical impacts of dosimetric changes on a log file-based method using a general tolerance level and a tighter tolerance level for linac miscalibration and found that a tighter tolerance level significantly improved the accuracy of the log file-based method.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalPhysica Medica
Volume42
DOIs
Publication statusPublished - 2017 Oct

Keywords

  • Log file
  • Patient-specific quality assurance
  • Radiotherapy
  • Volumetric modulated arc therapy

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • Physics and Astronomy(all)

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