Radiation Oncology Journal

The Korean Society for Radiation Oncology (대한방사선종양학회)
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The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer

  • Sung, Won-Mo (Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Park, Jong-Min (Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Choi, Chang-Heon (Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Ha, Sung-Whan (Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Ye, Sung-Joon (Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine)
  • Received : 2012.02.02
  • Accepted : 2012.03.09
  • Published : 2012.03.31
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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 $V_{20Gy}$ 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.

Keywords

References

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