Purpose: This study investigates the enhanced conformality of neutron dose distributions obtainable through the application of intensity modulated neutron radiotherapy (IMNRT) to the treatment of prostate adenocarcinoma. Methods and Materials: An in-house algorithm was used to optimize individual segments for IMNRT generated using an organ-at-risk (OAR) avoidance approach. A number of beam orientation schemes were investigated in an attempt to approach an optimum solution. The IMNRT plans were created retrospectively for 5 patients previously treated for prostate adenocarcinoma using fast neutron therapy (FNT), and a comparison of these plans is presented. Dose distributions and dose-volume histograms (DVHs) were analyzed and plans were evaluated based on percentage volumes of rectum and bladder receiving 95%, 80%, and 50% (V95, V80, V50) of the prescription dose, and on V60 for both the femoral heads and GMmuscle group. Results: Plans were normalized such that the IMNRT DVHs for prostate and seminal vesicles were nearly identical to those for conventional FNT plans. Use of IMNRT provided reductions in rectum V95 and V80 of 10% (2-27%) and 13% (5-28%), respectively, and reductions in bladder V95 and V80 of 12% (3-26%) and 4% (7-10%), respectively. The average decrease in V60 for the femoral heads was 4.5% (1-18%), with no significant change in V60 for the GMmuscle group. Conclusions: This study provides the first analysis of the application of intensity modulation to neutron radiotherapy. The IMNRT technique provides a substantial reduction in normal tissue dose in the treatment of prostate cancer. This reduction should result in a significant clinical advantage for this and other treatment sites.
|Number of pages||11|
|Journal||International Journal of Radiation Oncology Biology Physics|
|State||Published - Aug 1 2007|
- Fast neutron radiotherapy
- Intensity-modulated neutron radiotherapy
- Prostate radiotherapy