TITLE:
Biological Dose Comparison between a Fixed RBE and a Variable RBE in SFO and MFO IMPT with Various Multi-Beams for Brain Cancer
AUTHORS:
Ryosuke Kohno, Wenhua Cao, Pablo Yepes, Xuemin Bai, Falk Poenisch, David R. Grosshans, Tetsuo Akimoto, Radhe Mohan
KEYWORDS:
IMPT, Monte Carlo, Biological Dose, Variable RBE
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.8 No.1,
February
2,
2019
ABSTRACT: IMPT plans with various multi-angle
beams were planned by the Varian Eclipse treatment planning system for one case
of brain cancer. Dose distributions for each plan, along with the associated
linear energy transfer distributions, were recomputed using an in-house fast
Monte Carlo dose calculator with a FRBE of 1.1 or with a previously published
VRBE model. We then compared dosimetric parameters obtained by the VRBE with
those obtained by the FRBE. Biological doses obtained by the VRBE for the
clinical target volume in all plans were 1% - 2% larger than those obtained by
the FRBE. The minimum dose obtained by the VRBE for the right optic nerve in
the MFO IMPT with 4 fields was 70% larger than that obtained by the FRBE, but
the difference was only 18.1 cGy (RBE). The difference in maximum dose for the
right optic nerve in the MFO IMPT with 5 fields was less than 10.4%, but the
difference was 131.8 cGy (RBE). The mean difference in maximum dose was less
than 2% for all other organs at risk. We found that biological dose with the
FRBE had any dose errors in IMPT with various multi-angle beams.