The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer - Abstract

PURPOSE: To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients.

MATERIALS AND METHODS: Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose.

RESULTS: Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The V20 Gy of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%.

CONCLUSION: In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

Written by:
Sung W, Park JM, Choi CH, Ha SW, Ye SJ.   Are you the author?
Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea; Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.

Reference: Radiat Oncol J. 2012 Mar;30(1):27-35.
doi: 10.3857/roj.2012.30.1.27

PubMed Abstract
PMID: 23120741 Prostate Cancer Section