Towards the final BSA modeling for the accelerator-driven BNCT facility at INFN LNL

Some remarkable advances have been made in the last years on the SPES-BNCT project of the Istituto Nazionale di Fisica Nucleare (INFN) towards the development of the accelerator-driven thermal neutron beam facility at the Legnaro National Laboratories (LNL), aimed at the BNCT experimental treatment of extended skin melanoma. The compact neutron source will be produced via the ⁹Be(p,xn) reactions using the 5 MeV, 30 mA beam driven by the RFQ accelerator, whose modules construction has been recently completed, into a thick beryllium target prototype already available. The Beam Shaping Assembly (BSA) final modeling, using both neutron converter and the new, detailed, Be(p,xn) neutron yield spectra at 5 MeV energy recently measured at the CN Van de Graaff accelerator at LNL, is summarized here.     

Production of no-carrier-added Be from target cooling water

Beryllium-7, a monoenergetic photon emitter, is present as a by-product in a no-carrier-added (NCA) form at the BLIP from proton activation of the water which is used to cool targets. This report describes its recovery and purification.     

Beryllium exposure: dermal and immunological considerations

Objective: People exposed to beryllium compounds are at increased risk of developing beryllium sensitization and chronic beryllium disease (CBD). The purpose of this short communication is to present information regarding the potential importance of skin exposure to beryllium, an exposure and alternate immune response pathway to the respiratory tract, which has been largely overlooked in epidemiologic and exposure assessment studies. Methods: We reviewed the published literature, including epidemiologic, immunologic, genetic, and laboratory-based studies of in vivo and in vitro models, to assess the state of knowledge concerning skin exposure to beryllium. Results: Reduction in inhalation exposure to beryllium has not resulted in a concomitant reduction in the occurrence of beryllium sensitization or CBD, suggesting that continued prevalence may be due, in part, to unchecked skin exposure to beryllium-containing particles. Conclusions: Recent developments in our understanding of the multiple exposure pathways that may lead to beryllium sensitization and CBD suggest that a prudent approach to worker protection is to assess and minimize both skin and inhalation exposures to beryllium.     

Stimulatory and cytotoxic effects of beryllium on proliferation of mouse spleen lymphocytes in vitro

Low concentrations (1–5 μM) of beryllium (Be) salts were weakly mitogenic to mouse spleen cells in vitro as measured by an hydroxyurea-sensitive 2–3fold increase in pulse labelled [³H]-thymidine incorporation into lymphocyte DNA. It is proposed the activation may be induced by a direct interaction of Be²⁺ with the lymphocyte membranes. Higher concentrations of Be²⁺ (5–20 μM) produced a gradual loss of the stimulatory response, possibly as the result of either a limited cytotoxic effect or by the established property of intracellularly-accumulated Be²⁺ to inhibit cell division. In contrast, Concanavalin A-stimulated lymphocyte mitogenesis was markedly decreased by a 20-h preincubation of splenocytes with micromolar concentrations of Be²⁺, whereas similar pretreatment with lower concentrations (0.1 μM) actually enchanced the subsequent proliferative response. In both cases, supplementary addition of 0.1–1% peritoneal macrophages increased the level of Concanavalin A stimulation. It is concluded, therefore, that inhibition of the proliferative response to accessory cell-dependent mitogens may result from a dose-dependent destruction by Be²⁺ of the macrophage/adherent cell population.     

实验性铍病支气管肺泡灌洗液中细胞免疫学观察

以氧化铍气道染毒豚鼠，观察铍病豚鼠支气管肺泡灌洗液细胞成分、淋巴细胞对铍盐的增殖反应及肺泡巨噬细胞产生白细胞介素－１（ＩＬ－１）的变化。发现铍染毒早期ＢＡＬＦ中多形核粒细胞显著增加，后期则淋巴细胞增加明显。与外周血铍淋转比较，ＢＡＬＦ淋巴细胞对铍盐刺激的增殖反应更为第三。     

作业场所空气中铍的石墨炉原子吸收光谱检测法

目的建立工作场所空气中铍及其化合物的测定方法。方法参考《NIOSH分析方法手册》，研究用石墨炉原子吸收光谱法测定空气中微量的铍。内容包括石墨炉条件的选择、方法线形范围、特征浓度和检出限、方法精密度和回收率。结果该法线形范围为0～4μg／L；回归方程相关系数为0．999，特征浓度为0．034μg／L，检出限为0．024μg／L，精密度RSD为1．0％～7．7％，回收率为90．8％～100％。结论该方法适用于工作场所空气中铍及其化合物的测定。     

Project for the development of the linac based NCT facility in University of Tsukuba

A project team headed by University of Tsukuba launched the development of a new accelerator based BNCT facility. In the project, we have adopted Radio-Frequency Quadrupole (RFQ)+Drift Tube Linac (DTL) type linac as proton accelerators. Proton energy generated from the linac was set to 8 MeV and average current was 10 mA. The linac tube has been constructed by Mitsubishi Heavy Industry Co. For neutron generator device, beryllium is selected as neutron target material; high intensity neutrons are generated by the reaction with beryllium and the 80 kW proton beam.Our team chose beryllium as the neutron target material. At present beryllium target system is being designed with Monte-Carlo estimations and heat analysis with ANSYS. The neutron generator consists of moderator, collimator and shielding. It is being designed together with the beryllium target system. We also acquired a building in Tokai village; the building has been renovated for use as BNCT treatment facility. It is noteworthy that the linac tube had been installed in the facility in September 2012.In BNCT procedure, several medical devices are required for BNCT treatment such as treatment planning system, patient positioning device and radiation monitors. Thus these are being developed together with the linac based neutron source. For treatment planning system, we are now developing a new multi-modal Monte-Carlo treatment planning system based on JCDS. The system allows us to perform dose estimation for BNCT as well as particle radiotherapy and X-ray therapy. And the patient positioning device can navigate a patient to irradiation position quickly and properly. Furthermore the device is able to monitor movement of the patient׳s position during irradiation.