Study of a method based on TLD detectors for in-phantom dosimetry in BNCT.

A method has been developed, based on thermoluminescent dosemeters (TLD), aimed at measuring the absorbed dose in tissue-equivalent phantoms exposed to thermal or epithermal neutrons, separating the contributions of various secondary radiation generated by neutrons. The proposed method takes advantage of the very low sensitivity of CaF2:Tm (TLD-300) to low energy neutrons and to the different responses to thermal neutrons of LiF:Mg,Ti dosemeters with different 6Li percentage (TLD-100, TLD-700, TLD-600). The comparison of the results with those obtained by means of gel dosemeters and activation foils has confirmed the reliability of the method. The experimental modalities allowing reliable results have been studied. The glow curves of TLD-300 after gamma or neutron irradiation have been compared; moreover, both internal irradiation effect and energy dependence have been investigated. For TLD-600, TLD-100 and TLD-700, the suitable fluence limits have been determined in order to avoid radiation damage and loss of linearity.

Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT).

A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF2:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH3CH(NH2)COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT.

Characterisation of the TAPIRO BNCT epithermal facility.

A collimated epithermal beam for boron neutron capture therapy (BNCT) research has been designed and built at the TAPIRO fast research reactor. A complete experimental characterisation of the radiation field in the irradiation chamber has been performed, to verify agreement with IAEA requirements. Slow neutron fluxes have been measured by means of an activation technique and with thermoluminescent detectors (TLDs). The fast neutron dose has been determined with gel dosemeters, while the fast neutron spectrum has been acquired by means of a neutron spectrometer based on superheated drop detectors. The gamma-dose has been measured with gel dosemeters and TLDs. For an independent verification of the experimental results, fluxes, doses and neutron spectra have been calculated with Monte Carlo simulations using the codes MCNP4B and MCNPX_2.1.5 with the direct statistical approach (DSA). The results obtained confirm that the epithermal beams achievable at TAPIRO are of suitable quality for BNCT purposes.

Characterisation of the TAPIRO BNCT thermal facility.

Dosimetry and spectrometry measurements have been carried out in the thermal column of the research fast reactor RSV-TAPIRO (ENEA-Casaccia, Rome) in order to investigate its suitability for irradiation of cells or mice, with a view to research in the interests of boron neutron capture therapy (BNCT). The thermal column consists of a graphite moderator (40 cm thick) containing a lead shield (13 cm thick) in order to shield reactor background. The irradiation volume, inside this structure, has cubic shape (18 x 18 x 18 cm3). Besides measurements of fluence and dose rates in air or in phantom performed with thermoluminescence dosemeters (TLDs) and using the activation technique, dose and fluence profiles have been generated using a method based on gel dosemeters analysed with optical imaging. To check the consistency of the results, spectrometry measurements in the same irradiation volume have been performed by means of bubble detectors.

Development of educational tools to demonstrate the effects of hyper and microgravity on different test bodies.

Educational and outreach programs in space sciences have been a major concern since the beginning of the Space Era. Education curricula in Brazil rarely consider topics related to manned and unmanned space flight. This lack in the Brazilian education system has motivated the development of educational tools, used to demonstrate the effects of hyper- and microgravity on test bodies, both gravitational environments commonly found in aerospace missions. This paper presents the conception and development of a lift and a centrifuge for microgravity and hypergravity research use, respectively. Experiments were recorded via a digital camera and the images acquired were processed for better visualization of the effects of simulated variation in the gravitational force on test bodies. A CD-ROM was then produced for academic purposes. The final goal of this study is to motivate the insertion of space science related topics in the Brazilian elementary and high schools curricula.

Bone marrow percentage of plasma cells in the staging of monoclonal gammopathies.

In the present study, the relationships between percentage of bone marrow plasma cells (BMP%), tumor cell mass, stage, and survival are statistically analyzed in a large number (90) of monoclonal gammopathies (MG). Though BMP% has not been included among the criteria for the staging of multiple myeloma, our results indicate that the above mentioned parameters correlate at highly significant degrees. BMP% is therefore proposed as a new, useful parameter in the staging of MG.

[The nature of crystals in plasma cells present in a case of apparently benign biclonal gammapathy]. / Sulla natura dei cristalli endoplasmacellulari presenti in un caso di gammapatia biclonale apparentemente benigna.

A 77 years old white man presents, in his blood serum, a moderate gammapathy with 2 monoclonal peaks, IgAk and IgGlambda, and in his urine a little quantity of BJk, without any clinical or radiological manifestation. The sternal bone marrow showed 3-5% plasmacells, mostly containing many needlelike inclusions in the cytoplasm. These inclusions, red-violet at the May-Grünwald-Giemsa, were PAS and Sudan negative; positive at the Danielli reaction (for proteins). The alpha-naphtil-acetate-esterase and the acid phosphatase were present in one outer layer of the inclusions; ATP-ase was absent. At the electron microscopy, the inclusions were localized outside the rough endoplasmic reticulum; they exhibited a crystalline structure and were surrounded by an envelope which reminded the lysosomes. Basing on the morphological pattern, as well as on the presence of some lysosomal enzymes and on the lack of staining of crystals with fluorescinated anti-Ig sera, the hypothesis is stressed of an abnormal lysosomal hyperactivity, possibly leading to crystallization of the enzymatic proteins in the lysosomes.

Late appearance of an IgA (kappa) monoclonal protein in a patient with IgG (kappa) multiple myeloma: sharing of idiotypic specificities between the two serum proteins.

A patient with an IgG(chi) monoclonal serum protein developed in the course of the disease a second monoclonal spike of the same light chain type and of the IgA class. The latter monoclonal protein progressively increased and eventually exceeded the first IgG(chi) protein. Antigenic analysis of the two myeloma proteins demonstrated that they shared idiotypic determinants. Immunofluorescence studies, carried out with anti gamma and anti alpha reagents tagged with different fluorochromes revealed that the two isotypes were produced by different plasma cells. The data are discussed in the prospect of a possible transitional mechanism from IgG to IgA synthesis within a single B cell clone.

Ultrastructural aspects of crystal-like inclusions in a case of IgA plasma cell proliferation.

A case of apparently benign plasma cell proliferation is described. Needle-like paracrystalline inclusions were observed in numerous plasma cells outside the cisternae of the rough endoplasmic reticulum. They had a dense protein core surrounded by a layer of carbohydrate. They were found only in plasma cells secreting IgA-kappa immunoglobulin, but did not react with labelled specific antisera. A small amount of paraprotein IgA-kappa was found in the serum but no Bence-Jones protein could be detected in the urine. These observations suggest that these plasma cells synthesize normal IgA immunoglobulin and accumulate abnormal protein in the form of paracrystalline inclusions.