Background and purpose: Accelerator-Based Boron Neutron Capture Therapy is a radiotherapy based on compact accelerator neutron sources requiring an epithermal neutron field for tumour irradiations. Neutrons of 10 keV are considered as the maximum optimised energy to treat deep-seated tumours. We investigated, by means of Monte Carlo simulations, the epithermal range from 10 eV to 10 keV in order to optimise the maximum epithermal neutron energy as a function of the tumour depth.
Methods: A Snyder head phantom was simulated and mono-energetic neutrons with 4 different incident energies were used: 10 eV, 100 eV, 1 keV and 10 keV. $^{10}$B capture rates and absorbed dose composition on every tissue were calculated to describe and compare the effects of lowering the maximum epithermal energy. The Therapeutic Gain (TG) was estimated considering the whole brain volume.
Results: For tumours seated at 4 cm depth, 10 eV, 100 eV and 1 keV neutrons provided respectively 54 $\%$, 36 $\%$ and 18 $\%$ increase on the TG compared to 10 keV neutrons. Neutrons with energies between 10 eV and 1 keV provided higher TG than 10 keV neutrons for tumours seated up to 6.4 cm depth inside the head. The size of the tumour does not change these results.
Conclusions: Using lower epithermal energy neutrons for AB-BNCT tumour irradiation could improve treatment efficacy, delivering more therapeutic dose while reducing the dose in healthy tissues. This could lead to new Beam Shape Assembly designs in order to optimise the BNCT irradiation.
Distinct Radiobiological Responses to BNCT in SAS Oral Squamous Cell Carcinoma and MCF-7 Breast Cancer Cells
Key Laboratory of Radiation Physics and Technology of the Ministry of Education, Institute of Nuclear Science and Technology（教育部辐射物理与技术重点实验室，核科学与技术研究所）；West China School of Basic Medical Sciences and Forensic Medicine（华西基础医学与法医学院）
Boron Neutron Capture Therapy (BNCT) is a neutron radiotherapy used to treat tumours cells previously doping with Boron-10. This therapy requires an epithermal neutron beam for the treatment of deep tumours and a thermal beam for shallow ones. Thanks to recent high-current commercial accelerators, Accelerator-Based Neutron Sources (ABNS) are competitive option for providing therapeutic neutron beams in hospitals. In this work, the neutron field generated by the $^7$Li(p,n)$^7$Be reaction at $1950~$keV is studied as neutron source in ABNS, being measured by the Time-Of-Flight (TOF) technique at…
Selective accumulation of B-10 compound in tumour tissue is a fundamental condition for the achievement of BNCT (Boron Neutron Capture Therapy), since the effectiveness of therapy irradiation derives just from neutron capture reaction of B-10. Hence, the determination of the B-10 concentration ratio, between tumour and healthy tissue, and a control of this ratio, during the therapy, are essential to optimise the effectiveness of the BNCT, which it is known to be based on the selective uptake of B-10 compound. In this work, experimental methods are proposed and evaluated for the determination i…
Deep convolutional framelets for dose reconstruction in BNCT with Compton camera detector
Istituto Nazionale di Fisica Nucleare（国家核物理研究所）；Università degli Studi di Bari Aldo Moro（巴里阿尔多·莫罗大学）；Nanjing University of Science and Technology（南京理工大学）
Quantum Mechanical Analysis of Neutron Wavefunction Overlap and Nuclear Interaction Probability with Carborane Cage ($^{10}$B10) in Boron Neutron Capture Therapy
Previous measurements have shown large cross sections for the 11B(p,$α$)8Be reaction and K-shell ionization of boron from H+ ions. Past publications have shown that this reaction will likely increase the efficacy of proton therapy. This study investigates the size of boron particles for optimum treatment enhancement in proton therapy. Simulations of protons passing through varying sized boron particles were developed to compare energy outputs for alpha particles and low energy electrons. The results for the boron particle radius that produced the largest radiation output are presented in graph…
The proton boron fusion reaction, 11B(p, 3α), is investigated using MCNP6 to assess the viability for potential use in radiation therapy. The 11B(p, 3α) is theoretically desirable because it could combine the localized dose delivery protons exhibit (Bragg peak) with the creation of three high LET α particles that locally deposit energy in tumor regions. Simple simulations of a proton pencil beam incident upon a water phantom and a water phantom with an axial region also containing boron were modeled using MCNP6 in order to determine the extent of the impact boron had upon the calculated energy…
We present calculations and simulations on the role of the p+$^{11}$B$\to$3$α$ reaction in proton therapy. This reaction has been recently suggested to be responsible for a decrease in the survival probability of tumor cells, when they are irradiated with low-energy protons. However, at the concentration levels typical of the proposed boron carrier (sodium borocaptate, Na$_{2}$B$_{12}$H$_{11}$SH, in short BSH), i.e. less than 100 ppm, both calculations and Monte Carlo simulations suggest that the dose related to this reaction is orders of magnitude lower than the dose delivered by the primary …
The HANARO ex-core neutron irradiation facility was developed for various applications in the boron neutron capture therapy (BNCT) field, and its characteristics have been investigated. In order to obtain a sufficient thermal neutron flux with a low level contamination of fast neutrons and gamma-rays, a radiation filtering method is adopted. The radiation filter has been designed by using a silicon single crystal cooled by liquid nitrogen and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room are finished. Experimental measurements o…
Boron neutron capture therapy is a powerful anti-cancer treatment, the success of which depends heavily on the boron delivery agent. Enabling the real-time tracing of delivery agents as they move through the body is crucial to the further development of boron neutron therapy. In this study, we fabricate highly bio-compatible boron-10 embedded nanodiamonds using physical ion implantation in conjunction with a two-step annealing process. The red fluorescence of the nanodiamonds allows their use in fluorescence microscopy and in vivo imaging systems, thereby making it possible to conduct tracking…
Neutron relative effectiveness factors in Boron Neutron Capture Therapy: estimation of their values from the secondary charged particles and evaluation of weighted kerma factors for a standard tissue
This manuscript provides a response to a recent report by Mazzone et al. available online on arXiv that, in turn, tentatively aims at demonstrating the inefficacy of proton boron capture in hadrotherapy. We clarify that Mazzone et al. do not add any scientific or technical insights to the points extensively discussed in the original manuscript by Cirrone et al., and/or in the series of iterations had with the Referee, which ultimately lead to the publication of our original and pioneering experimental work. Here we summarize some of the key points of the long scientific debate we had during th…
A work recently published experimentally demonstrates an increase in the radiobiological efficacy of clinical proton beams when a tumour is treated in the presence of a concentration of 11B. The paper, for the first time, demonstrates the potential role of the p+11B to 3α (for brevity, p-B) reaction in the biological enhancement of proton therapy effectiveness. The work reports robust experimental data in terms of clonogenic cell survival and chromosomal aberrations and unambiguously shows the presence of an enhancement when cells were exposed to a clinical proton beam subject to treatment wit…
Bremsstrahlung photon beams produced by medical linear accelerators are currently the most commonly used method of radiation therapy for cancerous tumors. Photons with energies greater than 8-10 MeV potentially generate neutrons through photonuclear interactions in the accelerator's treatment head, patient's body, and treatment room ambient. Electrons impinging on a heavy target generate a cascade shower of bremsstrahlung photons, the energy spectrum of which shows an end point equal to the electron beam energy. By varying the target thickness, an optimum thickness exists for which, at the giv…
We propose a series of simulations about the potential use of Boron isotopes to trigger neutron-free (aneutronic) nuclear reactions in cancer cells through the interaction with an incoming energetic proton beam, thus resulting in the emission of characteristic prompt gamma radiation (429 keV, 718 keV and 1435 keV). Furthermore assuming that the Boron isotopes are absorbed in cancer cells, the three alpha-particles produced in each p-11B aneutronic nuclear fusion reactions can potentially result in the enhancement of the biological dose absorbed in the tumor region since these multi-MeV alpha-p…
The performance of the energy degrader in terms of beam properties directly impacts the design and cost of cyclotron-based proton therapy centers. The aim of this study is to evaluate the performances of different existing and novel degrader materials. The quantitative estimate is based on detailed GEANT4 simulations that analyze the beam-matter interaction and provide a determination of the beam emittance increase and transmission. Comparisons between existing (aluminum, graphite, beryllium) and novel (boron carbide and diamond) degrader materials are provided and evaluated against semi-analy…
We present the current status of our project of developing a photon counting detector for medical imaging. An example motivation lays in producing a monitoring and dosimetry device for boron neutron capture therapy, currently not commercially available. Our approach combines in-house developed detectors based on cadmium telluride or thick silicon with readout chip technology developed for particle physics experiments at CERN. Here we describe the manufacturing process of our sensors as well as the processing steps for the assembly of first prototypes. The prototypes use currently the PSI46digV…
Ion sources are key components of accelerators devoted to different types of medical applications: hadron-therapy facilities (accelerating protons or carbon ions), high-intensity accelerators for boron-neutron capture therapy (using intense proton beams), and facilities for isotope production (using different ion species). The three types of application present different requirements in terms of ion beam quality, reproducibility, and beam availability. Different characteristics of ion sources will be described, along with the reasons why they are particularly interesting or largely used.
We used the GEANT4 Monte Carlo MC Toolkit to simulate carbon ion beams incident on water, tissue, and bone, taking into account nuclear fragmentation reactions. Upon increasing the energy of the primary beam, the position of the Bragg-Peak transfers to a location deeper inside the phantom. For different materials, the peak is located at a shallower depth along the beam direction and becomes sharper with increasing electron density NZ. Subsequently, the generated depth dose of the Bragg curve is then benchmarked with experimental data from GSI in Germany. The results exhibit a reasonable correl…
