The impact of stool and gas volume on intrafraction prostate motion in patients undergoing radiotherapy with daily endorectal balloon

Ken Kang Hsin Wang, Neha Vapiwala, Viet Bui, Curtiland Deville, John P. Plastaras, Voichita Bar-Ad, Zelig Tochner, Stefan Both

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Purpose: The aim of this study was to quantify the impact of rectal stool/gas volumes on intrafraction prostate motion for patients undergoing prostate radiotherapy with daily endorectal balloon (ERB). Methods: Total and anterior stool/gas rectal volumes were quantified in 30 patients treated with daily ERB. Real-time intrafraction prostate motion from 494 treatment sessions, at most 6 min in length, was evaluated using Calypso® tracking system. Results: The deviation of prostate intrafraction motion distribution was a function of stool/gas volume, especially when stool/gas is located in the anterior part of the rectum. Compared to patients with small anterior stool/gas volumes (<10 cm3), those with large volume (10-60 cm3) had a twofold increase in 3D prostate motion and interquartile data range within the 6th minute of treatment time. The 10% of the overall CBCT session where large anterior rectal volumes were observed demonstrated larger percentage of time at displacement greater than our proposed internal margin 3 mm. Conclusion: Volume and location of stool/gas can directly impact the ERB's intrafraction immobilization ability. Although our patient preparation protocol and the 100 cm3 daily ERB effectively stabilized prostate motion for 90% of the fractions, a larger-sized ERB may improve prostate fixation for patients with greater and/or variable daily rectal volume.

Original languageEnglish (US)
Pages (from-to)89-94
Number of pages6
JournalRadiotherapy and Oncology
Volume112
Issue number1
DOIs
StatePublished - Jul 1 2014
Externally publishedYes

Keywords

  • Endorectal balloon
  • Intrafraction motion
  • Prostate
  • Rectal filling

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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