Neutron Autoradiography Combined With UV-C Sensitization: Toward the Intracellular Localization of Boron

Our group has reported the imprint formation of biological material on polycarbonate nuclear track detectors by UV-C exposure, which is used as an approach to simultaneously visualize cell imprints and nuclear tracks coming from the boron neutron capture reaction. Considering that the cell nucleus has a higher UV-C absorption than the cytoplasm and that hematoxylin preferentially stains the nucleus, we proposed to enhance the contrast between these two main cell structures by hematoxylin staining before UV-C sensitization. In this study, several experiments were performed in order to optimize UV-C exposure parameters and chemical etching conditions for cell imprint formation using the SK-BR-3 breast cancer cell line. The proposed method improves significantly the resolution of the cell imprints. It allows clear differentiation of the nucleus from the rest of the cell, together with nuclear tracks pits. Moreover, it reduces considerably the UV-C exposure time, an important experimental issue. The proposed methodology can be applied to study the boron distribution independently from the chosen cell line and/or boron compounds.Fil: Gadan, Mario Alberto. Comisión Nacional de Energía Atómica; ArgentinaFil: Lloyd, Rodrigo. Ministerio de Ciencia. Tecnología e Innovación Productiva. Agencia Nacional de Promoción Científica y Tecnológica; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica; ArgentinaFil: Olivera, María S.. Comisión Nacional de Energía Atómica; ArgentinaFil: Policastro, Lucia Laura. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes.; ArgentinaFil: Portu, Agustina Mariana. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Measurement of 10B concentration through autoradiography images in polycarbonate nuclear track detectors

The determination of the local concentration of boron in the different regions of tissue samples treated by Boron Neutron Capture Therapy (BNCT) could be made through the evaluation of the number of tracks forming autoradiography images. It is necessary to get a "standard" material containing a known amount of 10B, to correlate the number of tracks and boron concentration, i.e. to be used as a reference. Different systems were tested in order to find a suitable standard. Films made of 2% agarose in boron solutions showed a homogeneous distribution of the 10B atoms in the material structure. This system is easy handled and its physical properties are satisfactory. On the other hand, a small volume polycarbonate box was designed to contain 10B solutions of known concentration. This system showed a reduced number of background tracks and a promising behavior in many aspects. There is proportionality between track numbers per surface unit and 10B concentration, and between track numbers per surface unit and neutron fluence. Experimental results were compared to calculated values through formulas developed for thick samples autoradiography.Fil: Portu, Agustina Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Bernaola, Omar Alberto. Comisión Nacional de Energía Atómica. Gerencia de Area de Aplicaciones de la Tecnología Nuclear. Gerencia de Radiobiología (Centro Atómico Constituyentes); ArgentinaFil: Nievas, Susana Isabel. Comisión Nacional de Energía Atómica; ArgentinaFil: Liberman, Sara. Comisión Nacional de Energía Atómica; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica. Gerencia de Area de Aplicaciones de la Tecnología Nuclear. Gerencia de Radiobiología (Centro Atómico Constituyentes); Argentin

Reference systems for the determination of 10B through autoradiography images: Application to a melanoma experimental model

The amount of 10B in tissue samples may be determined by measuring the track density in the autoradiography image produced on a nuclear track detector. Different systems were evaluated as reference standards to be used for a quantitative evaluation of boron concentration. The obtained calibration curves were applied to evaluate the concentration of 10B in melanoma tumour of NIH nude mice after a biodistribution study. The histological features observed in the tissue sections were accurately reproduced by the autoradiography images.Fil: Portu, Agustina Mariana. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Carpano, M.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Dagrosa, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Nievas, S.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Pozzi, E.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Thorp, S.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Cabrini, R.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Liberman, S.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

From nuclear track characterization to machine learning based image classification in neutron autoradiography for boron neutron capture therapy

Knowledge of the 10B microdistribution is of great relevance in BNCT studies. Since 10B concentration assesment through neutron autoradiography depends on the correct quantification of tracks in a nuclear track detector, image acquisition and processing conditions should be controlled and verified, in order to obtain accurate results to be applied in the frame of BNCT. With this aim, an image verification process was proposed, based on parameters extracted from the quantified nuclear tracks. Track characterization was performed by selecting a set of morphological and pixel-intensity uniformity parameters from the quantified objects (area, diameter, roundness, aspect ratio, heterogeneity and clumpiness). Their distributions were studied, leading to the observation of varying behaviours in images generated by different samples and acquisition conditions. The distributions corresponding to samples coming from the BNC reaction showed similar attributes in each analyzed parameter, proving to be robust to the experimental process, but sensitive to light and focus conditions. Considering those observations, a manual feature extraction was performed as a pre-processing step. A Support Vector Machine (SVM) and a fully dense Neural Network (NN) were optimized, trained, and tested. The final performance metrics were similar for both models: 93%-93% for the SVM, vs 94%-95% for the NN in accuracy and precision respectively. Based on the distribution of the predicted class probabilities, the latter had a better capacity to reject inadequate images, so the NN was selected to perform the image verification step prior to quantification. The trained NN was able to correctly classify the images regardless of their track density. The exhaustive characterization of the nuclear tracks provided new knowledge related to the autoradiographic images generation. The inclusion of machine learning in the analysis workflow proves to optimize the boron determination process and paves the way for further applications in the field of boron imaging.Fil: Viglietti, Julia S.. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; ArgentinaFil: Espain, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; ArgentinaFil: Díaz, Rodrigo Fernando. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología. Centro Internacional de Estudios Avanzados; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Fisicas. - Universidad Nacional de San Martin. Instituto de Ciencias Fisicas.; ArgentinaFil: Nieto, Luis Agustin. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología. Centro Internacional de Estudios Avanzados; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Fisicas. - Universidad Nacional de San Martin. Instituto de Ciencias Fisicas.; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Szewc, Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Cincinnati; Estados UnidosFil: Bernardi, Guillermo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Rodríguez, Luis M.. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fregenal, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; ArgentinaFil: Portu, Agustina Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; Argentin

Extending neutron autoradiography technique for boron concentration measurements in hard tissues

The neutron autoradiography technique using polycarbonate nuclear track detectors (NTD) has been extended to quantify the boron concentration in hard tissues, an application of special interest in Boron Neutron Capture Therapy (BNCT). Chemical and mechanical processing methods to prepare thin tissue sections as required by this technique have been explored. Four different decalcification methods governed by slow and fast kinetics were tested in boron-loaded bones. Due to the significant loss of the boron content, this technique was discarded. On the contrary, mechanical manipulation to obtain bone powder and tissue sections of tens of microns thick proved reproducible and suitable, ensuring a proper conservation of the boron content in the samples. A calibration curve that relates the 10B concentration of a bone sample and the track density in a Lexan NTD is presented. Bone powder embedded in boric acid solution with known boron concentrations between 0 and 100 ppm was used as a standard material. The samples, contained in slim Lexan cases, were exposed to a neutron fluence of 1012 cm−2 at the thermal column central facility of the RA-3 reactor (Argentina). The revealed tracks in the NTD were counted with an image processing software. The effect of track overlapping was studied and corresponding corrections were implemented in the presented calibration curve. Stochastic simulations of the track densities produced by the products of the 10B thermal neutron capture reaction for different boron concentrations in bone were performed and compared with the experimental results. The remarkable agreement between the two curves suggested the suitability of the obtained experimental calibration curve. This neutron autoradiography technique was finally applied to determine the boron concentration in pulverized and compact bone samples coming from a sheep experimental model. The obtained results for both type of samples agreed with boron measurements carried out by ICP-OES within experimental uncertainties. The fact that the histological structure of bone sections remains preserved allows for future boron microdistribution analysis.Fil: Provenzano, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Olivera, María Silvina. Comisión Nacional de Energía Atómica; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica; ArgentinaFil: Rodriguez, Luis Miguel. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Fregenal, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Thorp, Silvia Inés. Comisión Nacional de Energía Atómica; ArgentinaFil: Pozzi, Emiliano César Cayetano. Comisión Nacional de Energía Atómica; ArgentinaFil: Curotto, Paula. Comisión Nacional de Energía Atómica; ArgentinaFil: Postuma, Ian. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Altieri, Saverio. Istituto Nazionale di Fisica Nucleare; Italia. Universita Degli Studi Di Pavia; ItaliaFil: González, Sara Josefina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bortolussi, Silva. Istituto Nazionale di Fisica Nucleare; Italia. Universita Degli Studi Di Pavia; ItaliaFil: Portu, Agustina Mariana. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Qualitative autoradiography with polycarbonate foils enables histological and track analyses on the same section

Neutron autoradiography is an imaging methodology that enables analysis of the spatial distribution of heavy ion emitters in a given material. In particular, it allows localization of 10 B in a tissue section put in contact with a nuclear track detector. Boron imaging is essential when considering boron neutron capture therapy as an option for treating cancerous tumors. A description of the autoradiography method is presented together with specific characteristics and technical details developed in our laboratory. We propose a new mounting technique to compare autoradiography images with the same section that gave rise to the latent tracks. The solid state nuclear track detector is polycarbonate, because it can be processed rapidly to obtain the autoradiographic results. It is a transparent material, which allows visualization of the sections mounted on it. Tissue can be removed easily and background is minimal.Fil: Portu, Agustina Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Carpano, Marina. Comisión Nacional de Energía Atómica; ArgentinaFil: Dagrosa, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Cabrini, Rómulo L.. Comisión Nacional de Energía Atómica; Argentina. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica; Argentin

UV-C radiation effect on nuclear tracks of different ions in polycarbonate

The neutron autoradiography technique was developed in our laboratory using polycarbonate nuclear track detectors, to qualitatively and quantitatively analyze boron distribution and concentration in biological samples from experimental models coming from Boron Neutron Capture Therapy research. Spatial resolution was later improved by generating an imprint of the biological sample (e.g. cellular culture, tissue sections) on the detector surface, which can be microscopically observed together with nuclear tracks originated by 10B capture products. This methodology was developed for polycarbonate detectors and involves UV-C light irradiation of the sample-detector assembly. The chemical etching process of the detector, usually performed to enlarge the nuclear tracks, also “reveals” the imprint of the sample. In this work we report a fading effect in nuclear tracks due to UV-C exposure. Significant differences in track density produced by alpha ions and Li recoils coming from the neutron capture reaction, 10B(n,α)7Li, were found between exposed and unexposed to UV-C light (254 nm wavelength) polycarbonate foils. A decreasing relation between track density and exposure time to UV-C radiation could also be observed for these ions. To analyze the effect produced by UV-C radiation on nuclear tracks of different ions, polycarbonate detectors irradiated with 7Li, 12C, 16O, 32S, 127I, 197Au beams and air degraded alpha particles from a241Am source were also studied. A wavelength dependent photodegradation mechanism affecting the polycarbonate detector would be altering the nuclear tracks development in different ways, according to ion damage characteristics.Fil: Saint Martin, María Laura Gisela. Universidad Nacional de San Martín. Instituto Sabato; ArgentinaFil: Portu, Agustina Mariana. Comisión Nacional de Energía Atómica. Gerencia de Area de Aplicaciones de la Tecnología Nuclear. Gerencia de Radiobiología (Centro Atómico Constituyentes); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ibarra, M. L.. Comisión Nacional de Energía Atómica. Gerencia de Area de Aplicaciones de la Tecnología Nuclear. Gerencia de Radiobiología (Centro Atómico Constituyentes); Argentina. Universidad Nacional de San Martín; ArgentinaFil: Alurralde, Martín Alejo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina. Comisión Nacional de Energía Atómica; Argentin

Evaporation process in histological tissue sections for neutron autoradiography

The analysis of the distribution and density of nuclear tracks forming an autoradiography in a nuclear track detector (NTD) allows the determination of 10B atoms concentration and location in tissue samples from Boron Neutron Capture Therapy (BNCT) protocols. This knowledge is of great importance for BNCT dosimetry and treatment planning. Tissue sections studied with this technique are obtained by cryosectioning frozen tissue specimens. After the slicing procedure, the tissue section is put on the NTD and the sample starts drying. The thickness varies from its original value allowing more particles to reach the detector and, as the mass of the sample decreases, the boron concentration in the sample increases. So in order to determine the concentration present in the hydrated tissue, the application of corrective coefficients is required. Evaporation mechanisms as well as various factors that could affect the process of mass variation are outlined in this work. Mass evolution for tissue samples coming from BDIX rats was registered with a semimicro analytical scale and measurements were analyzed with software developed to that end. Ambient conditions were simultaneously recorded, obtaining reproducible evaporation curves. Mathematical models found in the literature were applied for the first time to this type of samples and the best fit of the experimental data was determined. The correlation coefficients and the variability of the parameters were evaluated, pointing to Page’s model as the one that best represented the evaporation curves. These studies will contribute to a more precise assessment of boron concentration in tissue samples by the Neutron Autoradiography technique.Fil: Espector, Natalia. Universidad Favaloro; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Portu, Agustina Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Santa Cruz, Gustavo Alberto. Comisión Nacional de Energía Atómica; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentin

Optical density analysis in autoradiographic images from BNCT protocols

In Boron Neutron Capture Therapy (BNCT) research, information on spatial distribution and concentration of boron in tissues is essential for the treatment planning and for dose determination. Neutron autoradiography technique offers the possibility to gain insight into boron biodistribution in tissues. The irradiation of tissue sections deposited on nuclear track detectors produces damages in the latter, which can be visualized by microscope imaging and that are spatially correlated with the boron localization in the biological section. We had previously developed a methodology for the quantification of boron concentration in tissue samples by nuclear track density determination (QTA). In this work we analyzed the optical density (OD) in autoradiographic images where track density is too high to be quantified by track counting. OD was determined from grey level measurements on low magnification micrographs and proved to be a suitable parameter to quantify boron concentration. The images were originated by placing polycarbonate detectors in contact with samples containing 10B atoms, irradiated with thermal neutrons and finally chemically attacked. Reference standards were developed from aqueous solutions prepared with known boron concentrations in order to construct calibration curves. The obtained optical density values were compared with curves proposed by other authors, showing similar tendencies. The calibration curve was used to make preliminary boron concentration determinations in histological tissue sections of animals infused with boron compounds, which agreed with measurements realized by the QTA approach. The methodology proposed in this work would allow a fast preliminary analysis of histological and autoradiographic images in samples of interest for BNCT.Fil: Vidal, C.. Universidad Favaloro. Facultad de Ingeniería y Ciencias Exactas y Naturales; ArgentinaFil: Portu, Agustina Mariana. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Thorp, Silvia Inés. Comisión Nacional de Energía Atómica; ArgentinaFil: Curotto, Paula. Comisión Nacional de Energía Atómica; ArgentinaFil: Pozzi, E.. Comisión Nacional de Energía Atómica; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentin

A facility for the study of Single Event Effects in the TANDAR accelerator

Semiconductor devices used in space applications suffer degradation due to the space radiation environment, which affects their electric parameters, eventually reducing the in-orbit lifetime. This relatively slow behavior is due to cumulative total dose effects. On the other hand, radiation can destroy information or even damage electronic parts of the device in a sudden way. These processes are known as Single Event Effects (SEE). Heavy ion beams from electrostatic tandem or other accelerators can be used to test and characterize the response of the electronics to SEE. Two conditions are necessary for this purpose: to use very low fluxes of only a few hundred to hundreds of thousand particles/(cm2·s), and to browse over a wide Linear Energy Transfer (LET) interval by changing the energy and/or the type of the impinging particles. In this work we describe the facility developed at the Argentine tandem accelerator (Tandar) to study SEE, and especially the fabrication and use of a perforated Ta foil to reduce the beam current to the required values. The determination of the resulting beam uniformity over the area of irradiation is also reported. The system has been tested by a SEE experiment on a webcam sensor.Fil: Ibarra, M. L.. Comisión Nacional de Energía Atómica; ArgentinaFil: Portu, Agustina Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; ArgentinaFil: Barrera, Marcela Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Filevich, Alberto. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alurralde, M.. Universidad Nacional de San Martín. Instituto Sabato; Argentina. Comisión Nacional de Energía Atómica; Argentin