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

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

• Sung W
• Park JM
• Choi CH
• Ha SW
• Ye SJ

• KMID: 2051109
• DOI: http://doi.org/10.3857/roj.2012.30.1.27

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.

Keyword

Intensity-modulated radiation therapy; Prostate cancer; Photon energy; Treatment planning; Integral dose

MeSH Terms

Head
Humans
Neutrons
Organs at Risk
Prostate
Prostatic Neoplasms
Retrospective Studies