Inter- and Intrafractional Movement-Induced Dose Reduction of Prostate Target Volume in Proton Beam Treatment

Myonggeun Yoon, Dongwook Kim, Dong Ho Shin, Sung Yong Park, Se Byeong Lee, Dae Yong Kim, Joo Young Kim, Hong Ryull Pyo, Kwan Ho Cho

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Purpose: To quantify proton radiotherapy dose reduction in the prostate target volume because of the three-dimensional movement of the prostate based on an analysis of dose-volume histograms (DVHs). Methods and Materials: Twelve prostate cancer patients underwent scanning in supine position, and a target contour was delineated for each using a proton treatment planning system. To simulate target movement, the contour was displaced from 3 to 15 mm in 3-mm intervals in the superior-to-inferior (SI), inferior-to-superior (IS), anterior-to-posterior (AP), posterior-to-anterior (PA), and left-to-right (LR) directions. Results: For both intra- and interfractional movements, the average coverage index and conformity index of the target were reduced in all directions. For interfractional movements, the magnitude of dose reduction was greater in the LR direction than in the AP, PA, SI. and IS directions. Although the reduction of target dose was proportional to the magnitude of intrafractional movement in all directions, a proportionality between dose reduction and the magnitude of interfractional target movement was clear only in the LR direction. Like the coverage index and conformity index, the equivalent uniform dose and homogeneity index showed similar reductions for both types of target movements. Conclusions: Small target movements can significantly reduce target proton radiotherapy dose during treatment of prostate cancer patients. Attention should be given to interfractional target movement along the longitudinal direction, as image-guided radiotherapy may be ineffective if margins are not sufficient.

Original languageEnglish
Pages (from-to)1091-1102
Number of pages12
JournalInternational Journal of Radiation Oncology Biology Physics
Volume71
Issue number4
DOIs
Publication statusPublished - 2008 Jul 15
Externally publishedYes

Keywords

  • Dose-volume histogram
  • Prostate cancer
  • Prostate movement
  • Proton radiotherapy

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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