Simulation Study on the Feasibility of Current-mode SPECT for B-10 Concentration Estimation in Boron Neutron Capture Therapy

Abstract

Boron neutron caputure therapy (BNCT) is a promising treatment for invasive tumors. The BNCT utilizes the energy deposition by alpha particle and 7 Li created by the neutron capture reaction of 10 B. One of the problem of BNCT is the imaging of 10 B distribution during the treatment. The gamma rays with the energy of 0.478 MeV emitted by 7 Li can be exploited for this purpose. The photon counting of the gamma rays, however, is very difficult due to the high gamma ray background caused by 2.22 MeV gamma rays originated by the neutron reactions with 1 H. To overcome this difficulty, the authors propose a method to measure gamma rays as electric current by a "transXend" detector, which had been invented by them for energy-resolved X-ray computed tomography. In this paper, the feasibility study on 10 B distribution imaging in a water phantom with a tumor region is shown by simulation studies. For establishing the relationship between electric currents induced in the transXend detector by gamma rays and 10 B concentration, the attenuation of gamma rays by the phantom should be taken into account. For this purpose, a neural network was employed. The results showed good agreement with the training data used for the neural network. K: Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA); Medical-image reconstruction methods and algorithms, computer-aided diagnosis; Solid state detectors 1Corresponding author.

Clinical Viability of Boron Neutron Capture Therapy for Personalized Radiation Treatment

“…As pointed in the physical basis and dosimetry section, imaging 477 keV photon may serve also as a dosimetric tool. Unfortunately, there are also 2.2 MeV gammas originating from reactions with 1 H [ 109 ]. In a model paper [ 110 ] Goodman et al, studied the dose delivered to the patient using BSH in BNCT.…”

Research progress of ¹⁰B concentration and distribution measurement in boron neutron capture therapy

“…硼中子俘获治疗(boron neutron capture therapy, BNCT)是一种结合含硼靶向药物和重离子 治疗的二元肿瘤放射治疗方法 [1,2] . 其基本原理是 将含 10 B药物选择性富集于肿瘤细胞内, 然后热中 子照射肿瘤区域, 肿瘤细胞内的 10 B热中子俘获反 应截面较大(3835 barn, 1 barn=10 -28 m -2 ), 可俘 获大量热中子发生 10 B(n, a) 7 Li核反应, 产生高传 能线密度(linear energy transfer, LET)的a粒子 (1.47 MeV)和 7 Li反冲核(0.84 MeV), 反应式如下: 10 B + n → 11 B * → 7 Li + α + γ + 2.31 MeV, a粒子和 7 Li反冲核的射程分别约为9 µm和5 µm, 与所在肿瘤细胞的尺度相近, 所以杀伤作用仅限于 含 10 B的癌细胞及其紧邻细胞, 可在杀灭癌细胞的 同时几乎不损伤正常细胞, 实现细胞尺度的精确治 疗. 理论上BNCT是一种十分理想的肿瘤精准放 疗方法, 但经过近70年的发展, BNCT仍然未能 真正进入临床应用 [2] .…”

“…Kobayashi等 [9] 首次将SPECT用于BNCT治疗 过程中的瞬发 g 射线探测. 后来包括南京航空航天 大学陈达院士领导的实验室团队在内的各国研究 人员在BNCT专用SPECT的系统设计、探测器 及图像重建算法等方面做了大量研究工作 [7] . 素发生热中子俘获反应生成多种能量的 g 射线会 进一步降低图像质量 [10] .…”