Characteristics of a heavy water photoneutron source in boron neutron capture therapy

Abstract

Abstract: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 which energy spectrum shows an end point equal to the electron beam energy. By varying the target thickness, an optimum thickness exists for which, at the given electron energy, maximum photon flux is achievable. If a source of high-energy photons i.e. bremsstrahlung, is conveniently directed to a suitable D2O target, a novel approach for production of an acceptable flux of filterable photoneturons for boron neutron capture therapy (BNCT) application is possible. This study consists of two parts: 1. Comparison and assessment of deuterium photonuclear cross section data. 2. Evaluation of heavy water photonuclear source.

Gamma-radiation from the accretion of supernova envelope on compact remnant

“…Фотоядерные реакции и ядерный фотоэффект имеют пороговое значение энергии налетающего фотона, равное энергии связи последнего нейтрона, протона или нуклона в ядре. Например, для взаимодействия с легкими частицами (А<40) и образования в ходе этой реакции нейтрона энергия налетающего фотона должна быть в районе 10 ÷ 19 МэВ и 4 ÷ 6 МэВ для реакции с тяжелыми частицами [18]. Таким образом, эти эффекты не дают вклада в поглощение излучения с такой энергией.…”

Optimization of the photoneutron target geometry for e-accelerator based BNCT

“…In search for new sources, researchers have proposed using cyclotron accelerators, indirect production of neutrons and radioactive sources neutron emitters, each of which has its own advantages and disadvantages ( 4 – 9 ). Though, in developing countries, radiotherapy departments are often equipped with electron linear accelerators and some work is conducted to utilize this accelerator to produce epithermal neutrons ( 10 – 15 ). The benefits of electron linear accelerators are their low cost, small dimensions, high safety, and high social acceptability that make them a good choice to be utilized in hospitals ( 16 ).…”

Neutron beam optimization based on a 7 Li(p,n) 7 Be reaction for treatment of deep-seated brain tumors by BNCT

“…Boron Neutron Capture Therapy (BNCT) is an effective therapeutic modality for these tumors. This method benefits the thermal neutron capturing by 10 B, due to its large absorption cross section for a thermal neutron, and the breaking of 11 B excited nucleus into an alpha particle and a 7 Li ion. These particles deposit their energy over distances less than 10 µm -which is comparable to the cell diameter -and destroy tumor cells with negligible damage to the healthy tissue [1][2][3].…”

“…The advantages of using these sources are: simple application, high safety in hospital environments, relative low cost compared with reactors, easy turning off, providing sufficient neutron flux, and less overall risk than nuclear reactors. However, the most crucial aspects for accelerator-based neutron sources are the type and energies of incident particles, and target material selection [5][6][7][8].…”

“…The most common reaction for BNCT is 7 Li(p,n) 7 Be with a 1.644 MeV Q-value, and 1.881 MeV proton threshold energy. This source produces a high flux neutron with a relatively low energy.…”