Microdosimetry spectra and RBE of H-1, He-4, Li-7 and C-12 nuclei in water studied with Geant4

Abstract

A Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT) is used to study radiation fields of H-1, He-4, Li-7 and C-12 beams with similar ranges (~160-180 mm) in water. Microdosimetry spectra are simulated for wall-less and walled Tissue Equivalent Proportional Counters (TEPCs) placed outside or inside a phantom, as in experiments performed, respectively, at NIRS, Japan and GSI, Germany. The impact of fragmentation reactions on microdosimetry spectra is investigated for He-4, Li-7 and C-12, and contributions from nuclear fragments of different charge are evaluated for various TEPC positions in the phantom. The microdosimetry spectra measured on the beam axis are well described by MCHIT, in particular, in the vicinity of the Bragg peak. However, the simulated spectra for the walled TEPC far from the beam axis are underestimated. Relative Biological Effectiveness (RBE) of the considered beams is estimated using a modified microdosimetric-kinetic model. Calculations show a similar rise of the RBE up to 2.2-2.9 close to the Bragg peak for helium, lithium and carbon beams compared to the modest values of 1-1.2 at the plateau region. Our results suggest that helium and lithium beams are also promising options for cancer therapy.

References in corpus (5)

• Distributions of positron-emitting nuclei in proton and carbon-ion therapy studied with GEANT4
• Nuclear fragmentation reactions in extended media studied with Geant4 toolkit
• Comparative study of depth-dose distributions for beams of light and heavy nuclei in tissue-like media
• PET monitoring of cancer therapy with He-3 and C-12 beams: a study with the GEANT4 toolkit
• Microdosimetry of radiation field from therapeutic C-12 beam in water: a study with Geant4 toolkit

Cited by in corpus (1)

• Comparative study of RBE and cell survival fractions for ${}^1$H, ${}^4$He, ${}^{12}$C and ${}^{16}$O beams using Geant4 and Microdosimetric Kinetic model