Boron neutron capture therapy design calculation of a 3H(p,n) reaction based BSA for brain cancer setup

Bassem Elshahat,Bassem Elshahat,Nabil Maalej,Nabil Maalej,Akhtar Naqvi

doi:10.14319/ijcto.33.10

Abstract

Purpose: Boron neutron capture therapy (BNCT) is a promising technique for the treatment of malignant disease targeting organs of the human body. Monte Carlo simulations were carried out to calculate optimum design parameters of an accelerator based beam shaping assembly (BSA) for BNCT of brain cancer setup. Methods: Epithermal beam of neutrons were obtained through moderation of fast neutrons from 3 H(p,n) reaction in a high density polyethylene moderator and a graphite reflector. The dimensions of the moderator and the reflector were optimized through optimization of epithermal / fast neutron intensity ratio as a function of geometric parameters of the setup. Results: The results of our calculation showed the capability of our setup to treat the tumor within 4 cm of the head surface. The calculated peak therapeutic ratio for the setup was found to be 2.15. Conclusion: With further improvement in the polyethylene moderator design and brain phantom irradiation arrangement, the setup capabilities can be improved to reach further deep-seated tumor.

Highlights

Boron neutron capture therapy (BNCT) is a binary radiation therapy modality proposed as an alternative treatment for brain tumors.[1,2,3,4,5,6,7,8,9]
This paper describes the Corresponding author: Bassem Elshahat; Department of Medical Imaging, Royal Jubilee Hospital, Vancouver Island Health Authority, Victoria, BC, Canada
Dosimeteric conversion factors and 10B concentrations followed generally accepted standards when using BPA for brain glioma’s.2. Any adjustment of these relative biological effectiveness (RBE) values will change all three figures of merit defined above, and inter-comparisons of the results presented here with published results for other neutron beams must take this into account

Summary

Introduction

Boron neutron capture therapy (BNCT) is a binary radiation therapy modality proposed as an alternative treatment for brain tumors.[1,2,3,4,5,6,7,8,9] The two major components of the therapy are a stable isotope 10B of boron that can be concentrated preferentially in tumor cells and a beam of low energy neutrons.[2,3, 8] Initially the BNCT treatment was proposed using the thermal neutrons beams. Due to low penetrating power of thermal neutrons it was necessary to open the human scalp and irradiate the tumor with the thermal neutron beam. Later it was proposed to use the epithermal neutron beam, which has enough penetrating power to reach the deep-seated tumor in the brain without opening the scalp.[2, 8]. There are several techniques to produce epithermal beams of neutrons either using nuclear reactors[1, 6] or a particle accelerator as a neutron source.[2,3,4,5, 7,8,9] Epithermal beams of neutrons from nuclear reactors have been tested to treat patients with a glioblastom multiforme, and intracranial metastatic and subcutaneous melanoma.[1, 6] The accelerator based neutron sources have certain advantages over reactor based neutron sources such as low gamma ray background associated with neutrons, low cost, ease of placing an accelerator in or near hospitals etc

Methods

Results

Conclusion