Quantification of prostate and seminal vesicle interfraction variation during IMRT.

Journal Article (Journal Article)

PURPOSE: To quantify the interfraction variability in prostate and seminal vesicle (SV) positions during a course of intensity-modulated radiotherapy (IMRT) using an integrated computed tomography (CT)-linear accelerator system and to assess the impact of rectal and bladder volume changes. METHODS AND MATERIALS: We studied 15 patients who had undergone IMRT for prostate carcinoma. Patients had one pretreatment planning CT scan followed by three in-room CT scans per week using a CT-on-rails system. The prostate, bladder, rectum, and pelvic bony anatomy were contoured in 369 CT scans. Using the planning CT scan as a reference, the volumetric and positional changes were analyzed in the subsequent CT scans. RESULTS: For all 15 patients, the mean systematic internal prostate and SV variation was 0.1 +/- 4.1 mm and 1.2 +/- 7.3 mm in the anteroposterior axis, -0.5 +/- 2.9 mm and -0.7 +/- 4.5 mm in the superoinferior axis, and 0.2 +/- 0.9 mm and -0.9 +/- 1.9 mm in the lateral axis, respectively. The mean magnitude of the three-dimensional displacement vector was 4.6 +/- 3.5 mm for the prostate and 7.6 +/- 4.7 mm for the SVs. The rectal and bladder volume changes during treatment correlated with the anterior and superior displacement of the prostate and SVs. CONCLUSION: The dominant prostate and SV variations occurred in the anteroposterior and superoinferior directions. The systematic prostate and SV variation between the treatment planning CT and daily therapy as a result of the rectal and bladder volume changes emphasizes the need for daily directed target localization and/or immobilization techniques.

Full Text

Duke Authors

Cited Authors

  • Frank, SJ; Dong, L; Kudchadker, RJ; De Crevoisier, R; Lee, AK; Cheung, R; Choi, S; O'Daniel, J; Tucker, SL; Wang, H; Kuban, DA

Published Date

  • July 1, 2008

Published In

Volume / Issue

  • 71 / 3

Start / End Page

  • 813 - 820

PubMed ID

  • 18207664

International Standard Serial Number (ISSN)

  • 0360-3016

Digital Object Identifier (DOI)

  • 10.1016/j.ijrobp.2007.10.028


  • eng

Conference Location

  • United States