The low dose limit relative biological effectiveness (RBEm) and effective dose (previously reported by these authors) were used to compare 6, 15, and 18 MV conventional and IMRT radiotherapy for prostate cancer. In a comparison of the three beam energies used for the IMRT treatments, 6 MV resulted in the lowest effective dose, while 18 MV resulted in the highest effective dose. Comparing IMRT and conventional treatments of the same beam energy, IMRT resulted in increased equivalent dose to peripheral organs but lower effective doses. Dose to organs in close proximity to the treatment volume were orders of magnitude greater than dose to peripheral organs, thereby dominating the effective dose values. When RBEm is used to weight the doses to organs close to the treatment volume, IMRT resulted in lower Gy-equivalent doses compared to the conventional treatments, and thus lower deterministic effects for the colon, gonads, and bladder. The RBEm, does not consider the effects to peripheral organs, painting an incomplete picture for inter-comparison of different energies and different treatment techniques. Although the neutron radiation weighting factors are not fully applicable at some of the high organ doses, effective dose (and associated organ equivalent doses) still represents a useful measure for comparing radiation delivery methods. Perhaps it is reasonable (with full understanding of the limitations of each) to report both effective dose and RBEm weighted doses when comparing different radiation treatment techniques.
|Original language||English (US)|
|Number of pages||5|
|Journal||Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|
|Publication status||Published - Jun 23 2006|
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics