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Existing and active low-energy Accelerator-Based BNCT programs worldwide will be reviewed and compared. In particular, the program in Argentina will be discussed which consists of the development of an Electro-Static-Quadrupole (ESQ) Accelerator-Based treatment facility. The facility is conceived to operate with the deuteron-induced reactions 9Be(d,n)10B and 13C(d,n)14N at 1.45 MeV deuteron energy, as neutron sources. Neutron production target development status is specified. The present status of the construction of the new accelerator development laboratory and future BNCT centre is shown.

In the present work we propose a fast and simple method, based on Laser Induced Breakdown Spectroscopy (LIBS), to evaluate Neutron Production Targets. Targets of interest consist of hydrogen (particularly deuterium or tritium) contained in a titanium matrix. The method aims to evaluate the relative content of hydrogen within the titanium matrix, in order to determine if the target is “accepted” or “rejected” according to this content. Several deuterium targets have been fabricated (TiD x ), with different deuterium concentrations, and different techniques have been used to characterize their surfaces. Optical Coherent Tomography has been used to characterize the size and shape of LIBS holes, in order to determine LIBS depth of analysis. Grazing Incidence X-ray Diffraction has been used to determine a range for deuterium relative content. Elastic Recoil Detection Analysis (ERDA) is proposed for future LIBS calibration, since it provides a single value for relative content, has a depth of analysis similar to LIBS and also allows to distinguish between different isotopes. ERDA first results are reported in comparison with LIBS results.

Low-income Hispanics are often identified as especially at risk for common chronic conditions like diabetes and are targeted for aggressive screening and treatment. Anthropologists and other social scientists have extensively explored barriers and facilitators to the management of chronic illnesses in minority populations but have not yet considered the impact of recently lowered diagnostic and treatment thresholds on such groups. In this paper, we critically review recent changes in diabetes, hypertension, and high cholesterol diagnostic and treatment standards that have dramatically increased the number of people being treated for these conditions. Drawing on an ethnographic study of chronic illness management in two Hispanic-serving clinics in the Midwest, we examine how these new standards are being applied and consider the resulting health care challenges their patients face. Our analysis leads us to question the value of promoting narrowly defined treatment goals, particularly when patients lack reliable access to the health care resources these goals require. While improving the health of low-income Hispanics is a worthwhile goal, it is important to consider whether these efforts may be promoting over-diagnosis and over-treatment, drawing them into an expensive chronic patient role with uncertain benefit.

Race, although an unscientific concept, remains prominent in health research and clinical guidelines, and is routinely invoked in clinical practice. In interviews with 58 primary care clinicians we explored how they understand and apply concepts of racial difference. We found wide agreement that race is important to consider in clinical care. They explained the effect of race on health, drawing on common assumptions about the biological, class, and cultural characteristics of racial minorities. They identified specific race-based clinical strategies for only a handful of conditions and were inconsistent in the details of what they said should be done for minority patients. We conclude that using race in clinical medicine promotes and maintains the illusion of inherent racial differences and may result in minority patients receiving care aimed at presumed racial group characteristics, rather than care selected as specifically appropriate for them as individuals. [race and genetics, primary care, health disparities, racial profiling]

Heavy elements with Z ≥ 30 are made by neutron capture reactions during stellar He burning and presumably in supernovae. This contribution deals mainly with the slow neutron capture (s) process which is responsible for about one half of the abundances in the mass region between Fe and Bi. The slow time scale implies that the reaction path of this process involves mostly stable isotopes which can be studied in detail in laboratory experiments. The neutron time of flight (n_TOF) facility at CERN is a neutron spallation source, its white neutron energy spectrum ranges from thermal to several MeV, covering the full energy range of interest for nuclear astrophysics, in particular for measurements of the neutron capture cross section required in s-process nucleosynthesis. This contribution gives an overview on the astrophysical program made at n_TOF facility, the results and the implications will be considered. European Commission (EC) FIKW-CT-2000-00107

Neutron induced fission cross sections of several isotopes have been measured at the CERN n_TOF spallation neutron facility. Between them some measurements involve isotopes (233U, 241Am, 243Am, 245Cm) relevant for applications to nuclear technologies. The n_TOF facility delivers neutrons with high instantaneous flux and in a wide energy range, from thermal up to 250 MeV. The experimental apparatus consists of an ionization chamber that discriminates fission fragments and α particles coming from natural radioactivity of the samples. All the measurements were performed referring to the standard cross section of 235U. European Commission Joint Research Centre European Community (EC) FIKW-CT-2000-00107

As part of a project for developing Accelerator–Based Boron Neutron Capture Therapy (AB-BNCT), for which the generation of neutrons through nuclear reactions like 9Be(d,n) is necessary, a new material that preserves its physical and mechanical properties for a sufficient length of time under irradiation conditions and hydrogen damage is needed. In this work, a high entropy MoTaVWZr alloy (HEA) is considered for this task, because each one of the constituents is already good by itself under extreme irradiation condition. The structure, microstructure, density, Vickers hardness and melting temperature are reported for this HEA. Atomistic modeling results are in agreement with the experimental findings. Fil: Suarez Anzorena, María del Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina Fil: Bertolo, A. A.. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina Fil: Gagetti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Kreiner, Andres Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Mosca, Hugo Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina. Universidad Tecnológica Nacional; Argentina Fil: Bozzolo, Guillermo. University of Maryland; Estados Unidos Fil: del Grosso, Mariela Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Tecnológica Nacional; Argentina

Boron Neutron Capture Therapy (BNCT) requires neutron sources suitable for in-hospital siting. Low-energy particle accelerators working in conjunction with a neutron producing reaction are the most appropriate choice for this purpose. One of the possible nuclear reactions isA Beam Shaping Assembly design was computationally optimized. Depth dose profiles in a Snyder head phantom were simulated with the MCNP code for a number of BSA configurations. In order to optimize the treatment capabilities, the BSA configuration was determined as the one that allows maximizing both the tumor dose and the penetration depth while keeping doses to healthy tissues under the tolerance limits.Significant doses to tumor tissues were achieved up to ∼6cm in depth. Peak doses up to 57Gy-Eq can be delivered in a fractionated scheme of 2 irradiations of approximately 1h each. In a single 1h irradiation, lower but still acceptable doses to tumor are also feasible.Treatment capabilities obtained here are comparable to those achieved with other accelerator-based neutron sources, making of the

Many anticipate that expanding knowledge of genetic variations associated with disease risk and medication response will revolutionize clinical medicine, making possible genetically based Personalized Medicine where health care can be tailored to individuals, based on their genome scans. Pharmacogenetics has received especially strong interest, with many pharmaceutical developers avidly working to identify genetic variations associated with individual differences in drug response. While clinical applications of emerging genetic knowledge are becoming increasingly available, genetic tests for drug selection are not as yet widely accessible, and many primary care clinicians are unprepared to interpret genetic information. We conducted interviews with 58 primary care clinicians, exploring how they integrate emerging pharmacogenetic concepts into their practices. We found that in their current practices, pharmacogenetic innovations have not led to individually tailored treatment, but instead have encouraged use of essentialized racial/ethnic identity as a proxy for genetic heritage. Current manifestations of Personalized Medicine appear to be reinforcing entrenched notions of inherent biological differences between racial groups, and promoting the belief that racial profiling in health care is supported by cutting-edge scientific authority. Our findings raise concern for how pharmacogenetic innovations will actually affect diverse populations, and how unbiased treatment can be assured.

PURPOSE Recently, there has been dramatic increase in the diagnosis and pharmaceutical management of common chronic illnesses. Using qualitative data collected in primary care clinics, we assessed how these trends play out in clinical care. METHODS This qualitative study focused on management of type 2 diabetes and hypertension in 44 primary care clinics in Michigan and was based on interviews with 58 clinicians and 70 of their patients, and observations of 107 clinical consultations. We assessed clinicians’ treatment strategies and discussions of factors influencing treatment decisions, and patients’ understandings and experiences in managing these illnesses. RESULTS Clinicians focused on helping patients achieve test results recommended by national guidelines, and most reported combining 2 or more medications per condition to reach targets. Medication selection and management was the central focus of the consultations we observed. Polypharmacy was common among patients, with more than one-half taking 5 or more medications. Patient interviews indicated that heavy reliance on pharmaceuticals presents challenges to patient well-being, including financial costs and experiences of adverse health effects. CONCLUSIONS Factors promoting heavy use of pharmaceuticals include lower diagnostic and treatment thresholds, clinician-auditing and reward systems, and the prescribing cascade, whereby more medications are prescribed to control the effects of already-prescribed medications. We present a conceptual model, the inverse benefit law, to provide insight into the impact of pharmaceutical marketing efforts on the observed trends. We make recommendations about limiting the influence of the pharmaceutical industry on clinical practice, toward improving the well-being of patients with chronic illness.

The accelerator tubes are essential components of the accelerator. Their function is to transport and accelerate a very intense proton or deuteron beam through the machine, from the ion source to the neutron production target, without significant losses. In this contribution, we discuss materials selected for the tube construction, the procedures used for their assembly and the testing performed to meet the stringent requirements to which it is subjected.

In the range of low bombarding energies (less than about 1.5 MeV) the 9Be(d,n)10B reaction produces neutron spectra that can be moderated depending on the choice of the target thickness and the deuteron bombarding energy. In this work, a Monte Carlo simulation study to determine the capability of this reaction to deliver enough dose to efficiently control both skin and deep seated tumors has been performed by means of MCNP calculations using eight optimized 9Be targets.

This work reports on the characterisation of a neutron beam shaping assembly (BSA) prototype and on the preliminary modelling of a treatment room for BNCT within the framework of a research programme for the development and construction of an accelerator-based BNCT irradiation facility in Buenos Aires, Argentina. The BSA prototype constructed has been characterised by means of MCNP simulations as well as a set of experimental measurements performed at the Tandar accelerator at the National Atomic Energy Commission of Argentina.

Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT), we discuss here the electrostatic design of the machine, including the accelerator tubes with electrostatic quadrupoles and the simulations for the transport and acceleration of a high intensity beam.

This work discusses the development of online dosimetry of the boron dose via Single Photon Emission Computed Tomography (SPECT) during a BNCT treatment irradiation. Such a system will allow the online computation of boron dose maps without the large current uncertainties in the assessment of the boron concentration in different tissues. The first tomographic boron dose image with a SPECT prototype is shown.

We describe the present status of an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based (AB)-BNCT. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the (7)Li(p,n)(7)Be reaction. The machine currently being constructed is a folded TESQ with a high-voltage terminal at 0.6 MV. We report here on the progress achieved in a number of different areas.

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes.

A numerical optimization of a Beam Shaping Assembly (BSA) for Accelerator Based-Boron Neutron Capture Therapy (AB-BNCT) has been performed. The reaction (7)Li(p,n)(7)Be has been considered using a proton beam on a lithium fluoride target. Proton energy and the dimensions of a simple BSA geometry have been varied to obtain a set of different configurations. The optimal configuration of this set is shown.

In this work we describe the present status of an ongoing project to develop a tandem-electrostatic-quadrupole (TESQ) accelerator facility for accelerator-based (AB) BNCT at the Atomic Energy Commission of Argentina in Buenos Aires. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the (7)Li(p,n)(7)Be reaction slightly beyond its resonance at 2.25 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the (7)Li(p,n)(7)Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. An electrostatic machine is the technologically simplest and cheapest solution for optimized AB-BNCT. The machine being designed and constructed is a folded TESQ with a high-voltage terminal at 1.2 MV intended to work in air. Such a machine is conceptually shown to be capable of transporting and accelerating a 30 mA proton beam to 2.4 MeV. The general geometric layout, its associated electrostatic fields, and the acceleration tube are simulated using a 3D finite element procedure. The design and construction of the ESQ modules is discussed and their electrostatic fields are investigated. Beam transport calculations through the accelerator are briefly mentioned. Likewise, work related to neutron production targets, strippers, beam shaping assembly and patient treatment room is briefly described.

In this work 3D micromachining of x-cut lithium niobate crystals was performed using the high energy heavy ion microbeam (HIM) at the Tandar Laboratory, Buenos Aires. The samples were machined using 35 Cl beams at 70 MeV bombarding energy combined with wet etching with hydrofluoric acid solutions at room temperature. As the ion beam penetrates the sample, it induces lattice damage increasing dramatically the local etching rate of the material. This technique was applied to the fabrication of 3D waveguides with long control electrodes. The resulting structures indicate that well defined contours with nearly vertical sidewalls can be made. The results also show that with fluences of only 5 × 10 12 ions/cm 2 , this technique is suitable for the fabrication of different shapes of LiNbO 3 control-waveguides that can be used in different optical devices and matched with the existing optical fibers.

In this work the D(d,n)3He and 9Be(d,n)10B reactions have been studied in a low-energy regime as neutron sources for skin tumor treatment in the frame of accelerator-based BNCT (AB-BNCT). The total neutron production and the energy and angular distributions for each reaction at different bombarding energies and for the thick targets considered (TiD2, Be) have been determined using the available data in the literature. From this information, a feasibility study has been performed by means of MCNP simulations. The thermal, epithermal and fast neutron fluxes and doses at skin tumor positions (loaded with 40 ppm 10B) which are located on a whole-body human phantom have been simulated for different D2O moderator depths. The best-case performance shows that a high tumor control probability (TCP) of 99% corresponding to a weighted dose in tumor of 40 Gy can be reached at the tumor position keeping the weighted dose in healthy tissue below 12.5 Gy, by means of the 9Be(d,n)10B reaction at 1.1 MeV for a deuteron current of 20 mA and a 30 cm D2O moderator in 52 min. The availability of low-energy neutrons in the 9Be(d,n)10B reaction from the population of excited levels between 5.1 to 5.2 MeV in 10B and the convenience of a thin beryllium target are discussed. As a complement concerning alternatives to the Li(metal) + p reaction, the neutron yield of refractory lithium compounds (LiH, Li3N and Li2O) were calculated and compared with a Li metal target.

In this work, the performance of an accelerator-based neutron source design has been compared with that of a modern fluoride-filtered reactor-based epithermal beam having near-optimal quality for treatment of deep seated tumors in relation to its applicability for BNCT. The accelerator is a Tandem-Electrostatic-Quadrupole (TESQ) accelerator which is a design under development at the National Atomic Energy Commission (CNEA) in Buenos Aires, Argentina based on the 7Li(p,n)7Be reaction, relatively close to its energy threshold. The reactor is the Massachusetts Institute of Technology reactor upgraded with a Fission Converter Beam (MIT-FCB) and improved with an 8 mm thick 6Li filter. The comparison has been done by means of data reported on the MIT-FCB + 6Li filter performance and MCNP simulations on our TESQ design considering the neutron fluxes provided by the two sources and the doses delivered in a human phantom by both devices. The results show a deeper advantage depth (AD) for the TESQ which turns out to be a promising alternative to a reactor-based BNCT treatment.

A project to develop a Tandem-electrostatic-quadrupole (TESQ) accelerator for accelerator-based boron neutron capture therapy (AB-BNCT) is described. A folded Tandem, with 1.25 MV terminal voltage, combined with an electrostatic quadrupole (ESQ) chain is being proposed. The project goal is a machine capable of delivering 30 mA of 2.5 MeV protons to be used in conjunction with a neutron production target based on the 7Li(p, n)7Be reaction slightly beyond its resonance at 2.25 MeV. This machine is conceptually shown to be capable of accelerating a 30 mA proton beam to 2.5 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the 7Li(p, n)7Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. This electrostatic machine is the technologically simplest and cheapest solution for optimized AB-BNCT.

In this work we provide some information on the present status of accelerator-based BNCT (AB-BNCT) worldwide and subsequently concentrate on the recent accelerator technology developments in Argentina. Fil: Cartelli, Daniel Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Capoulat, Maria Eugenia. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Bergueiro, Rodolfo Javier. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gagetti, Leonardo. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Suárez Anzorena, M.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: del Grosso, Mariela Fernanda. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Baldo, M.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Castell, W.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Padulo, J.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Suárez Sandín, J.C.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Igarzabal, M.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Erhardt, J.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Mercuri, Dario Martin. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Minsky, Daniel Mauricio. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Valda, A.A.. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Debray, Mario Ernesto. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Somacal, Héctor Rubén. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Cánepa, Natalia Mabel. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Real, N.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Gun, M.. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina Fil: Herrera, M. S. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina Fil: Tacca, Hernán Emilio. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina Fil: Kreiner, Andres Juan. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina

7Li(p,n)7Be is an endothermic reaction and working near its threshold (1.88MeV) has the advantage of neutron spectra with maximum energies of about 100keV, considerably lower than at higher beam energies, or than using other neutron-producing reactions or as for the uranium fission spectrum, relevant for BNCT based on nuclear reactors. With this primary energy it is much easier to obtain the energies needed for treating deep seated tumors by BNCT (about 10keV). This work studies bombarding energies up to 2.05MeV,different beam incidence angles and the effect of the undesirable gamma production via the 7Li(p,γp?) 7Li reaction. Fil: Minsky, Daniel Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Kreiner, Andres Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina

In this work a complete description of the 7Li(p, n)7Be reaction near threshold is given using center-of-mass and relative coordinates. It is shown that this standard approach, not used before in this context, leads to a simple mathematical representation which gives easy access to all relevant quantities in the reaction and allows a precise numerical implementation. It also allows in a simple way to include proton beam-energy spread affects. The method, implemented as a C++ code, was validated both with numerical and experimental data finding a good agreement. This tool is also used here to analyze scattered published measurements such as (p, n) cross sections, differential and total neutron yields for thick targets. Using these data we derive a consistent set of parameters to evaluate neutron production near threshold. Sensitivity of the results to data uncertainty and the possibility of incorporating new measurements are also discussed. Fil: Herrera, Maria Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Moreno, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. YPF - Tecnología; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina Fil: Kreiner, Andres Juan. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina

Different materials and proton beam energies have been studied in order to search for an optimized neutron production target and beam shaping assembly for accelerator-based BNCT. The solution proposed in this work consists of successive stacks of Al, polytetrafluoroethylene, commercially known as Teflon®, and LiF as moderator and neutron absorber, and Pb as reflector. This assembly is easy to build and its cost is relatively low. An exhaustive Monte Carlo simulation study has been performed evaluating the doses delivered to a Snyder model head phantom by a neutron production Li-metal target based on the 7Li(p,n)7Be reaction for proton bombarding energies of 1.92, 2.0, 2.3 and 2.5 MeV. Three moderator thicknesses have been studied and the figures of merit show the advantage of irradiating with near-resonance-energy protons (2.3 MeV) because of the relatively high neutron yield at this energy, which at the same time keeps the fast neutron healthy tissue dose limited and leads to the lowest treatment times. A moderator of 34 cm length has shown the best performance among the studied cases.

Microdistributions of the prospective BNCT-compound CuTCPH, a carborane-containing tetraphenylporphyrin with one Cu atom in its molecular structure, have been obtained in tissue sections of different organs of tumor-bearing and normal Syrian hamsters injected with the boron compound by employing a heavy ion microbeam. High resolution X-ray spectroscopy following micro-PIXE (Particle Induced X-ray Emission with micrometer-sized beams) with a focused 16O ion beam was used. Focusing was performed with a heavy-ion scanning high-precision magnetic quadrupole triplet microprobe. Squamous Cell Carcinomas were induced on the right Cheek Pouch of Syrian Hamsters (HCP), sampled, cryo-sectioned and freeze-dried. Two-dimensional maps of elemental concentration were obtained by scanning the beam over the samples. Very non-uniform Cu concentrations were found in all sections.

The effects of copper and cadmium on metabolism through the pentose phosphate pathway were evaluated in Bufo arenarum toad ovary. The effects of the two metals on dehydrogenases from this pathway were evaluated by three experiments: (1) in samples obtained from control females with addition of the metals to the reaction mixture (in vitro), (2) in samples obtained from control females and after long-term exposure of females to 4 and 100 microg/L of Cu or Cd in the incubation media (in vitro after exposure to the metals in vivo), and (3) 14CO2 production through the pentose phosphate pathway was evaluated after [U-14C]glucose microinjection on ovulated oocytes (in vivo after microinjection of the metals). Results from (1) evidenced inhibition of both enzyme activities but only above 1.5 mM Cu and Cd added to the reaction mixture. In (2) both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities decreased in samples from the ovaries of females exposed in vivo to Cu, in a concentration-dependent manner (up to 90% in females exposed to 100 microg/L Cu: 2.12 +/- 1.57 NADPH micromol/min microg protein x 10(-5) vs 19.97 +/- 8.54 in control females). Cd treatment of the toads only rendered an inhibitory effect on 6-phosphogluconate dehydrogenase activity after exposure to 4 microg/L of the bivalent cation. (3) In vivo 14CO2 evolution significantly decreased in oocytes coinjected with 6.3 x 10(-3) mM Cu (calculated intracellular final concentration of the metal injected) and radioactive glucose. Cu and Cd concentration in samples from exposed females were always under detection limit by particle-induced X-ray emission. The results presented here are in agreement with a role for both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities determination as biomarkers of effect and exposure for Cu but not for Cd toxicity.

In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator‐Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte‐Carlo simulations and measurements. The neutrons were generated via the 7Li(p, n)7Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

In boron neutron capture therapy (BNCT) the delivered dose to the patient depends both on the neutron beam characteristics and on the {sup 10}B body distribution which, in turn, is governed by the tumor specificity of the {sup 10}B drug-carrier. BNCT dosimetry is a complex matter due to the several interactions that neutrons can undergo with the different nuclei present in tissue. However the boron capture reaction {sup 10}B(n,{alpha}){sup 7}Li accounts for about 80 % of the total dose in a tumor with 40 ppm in {sup 10}B concentration. Present dosimetric methods are indirect, based on drug biodistribution statistical data and subjected to inter and intra-patient variability. In order to overcome the consequences of the concomitant high dosimetric uncertainties, we propose a SPECT (Single Photon Emission Tomography) approach based on the detection of the prompt gamma-ray (478 keV) emitted in 94 % of the cases from {sup 7}Li. For this purpose we designed, built and tested a prototype based on LaBr{sub 3}(Ce) scintillators. Measurements on a head and tumor phantom were performed in the accelerator-based BNCT facility of the University of Birmingham (UK). They result in the first tomographic image of the 10B capture distribution obtained in a BNCT facility.

The use of proton and heavy ion beams for radiotherapy is a well established cancer treatment modality in the first world, which is becoming increasingly widespread, due to its clear advantages over conventional photon-based treatments. This strategy is suitable when the tumor is spatially well localized. Also the use of neutrons has tradition. Here Boron Neutron Capture Therapy (BNCT) stands out, though on a much smaller scale, being a promising alternative for tumors which are diffuse and infiltrating. On this sector, so far only nuclear reactors have been used as neutron sources. In this paper we briefly describe the situation in Latin America and in particular we discuss the present status of an ongoing project to develop a folded Tandem-ElectroStatic-Quadrupole (TESQ) accelerator for Accelerator-Based (AB)-Boron Neutron Capture Therapy (BNCT) at the Atomic Energy Commission of Argentina. The project goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the {sup 7}Li(p,n){sup 7}Be reaction. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams to perform BNCT for deep-seated tumors in less than an hour. The machine being currently designed and constructedmore » is a folded TESQ with a terminal at 0.6 MV as a smaller scale prototype. Since the concept is modular the same structure will be used for the 1.2 MV final accelerator.« less

Glioblastoma multiforme and metastatic melanoma are frequent brain tumors in adults and presently still incurable diseases. Boron Neutron Capture Therapy (BNCT) is a promising alternative for this kind of pathologies. Accelerators have been proposed for BNCT as a way to circumvent the problem of siting reactors in hospitals and for their relative simplicity and lower cost among other advantages. Considerable effort is going into the development of accelerator‐based BNCT neutron sources in Argentina. Epithermal neutron beams will be produced through appropriate proton‐induced nuclear reactions and optimized beam shaping assemblies. Using these sources, computational dose distributions were evaluated in a real patient with diagnosed glioblastoma treated with BNCT. The simulated irradiation was delivered in order to optimize dose to the tumors within the normal tissue constraints. Using Monte Carlo radiation transport calculations, dose distributions were generated for brain, skin and tumor. Also, the dosimetry was studied by computing cumulative dose‐volume histograms for volumes of interest. The results suggest acceptable skin average dose and a significant dose delivered to tumor with low average whole brain dose for irradiation times less than 60 minutes, indicating a good performance of an accelerator‐based BNCT treatment.

(7)Li(p,n)(7)Be is an endothermic reaction and working near its threshold (1.88 MeV) has the advantage of neutron spectra with maximum energies of about 100 keV, considerably lower than at higher beam energies, or than using other neutron-producing reactions or as for the uranium fission spectrum, relevant for BNCT based on nuclear reactors. With this primary energy it is much easier to obtain the energies needed for treating deep seated tumors by BNCT (about 10 keV). This work studies bombarding energies up to 2.05 MeV, different beam incidence angles and the effect of the undesirable gamma production via the (7)Li(p,γp') (7)Li reaction.

Charged hadrons (protons and heavier ions) have very definite advantages over photons as far as radiotherapy applications are concerned. They allow for much better spatial dose localization due to their charge, relatively high mass and nature of the energy deposition process. In the frame of an attempt to promote the introduction of hadrontherapy in Argentina we have installed and started using an external beam facility at our tandem accelerator TANDAR. The advantages of heavy ions can only be fully exploited for tumors of well defined localization. In certain types of malignancies, however, the region infiltrated by tumor cells is diffuse, with no sharp boundaries and with microscopic ramifications. In such cases (particularly in certain brain cancers) a more sophisticated scheme has been suggested called boron neutron capture therapy (BNCT). In this work, the use of the Tandar accelerator to produce neutrons for feasibility studies for BNCT through low-energy proton beams on a thick LiF target is being briefly described. Studies on the 13C(d,n) reaction and a comparison with other neutron-producing reactions are also mentioned. Simulation work to optimize an accelerator-based neutron production target is discussed. A project is being prepared to develop a small proton accelerator in Argentina. Technical specifications of this machine will be briefly discussed.