Inter-comparison of boron concentration measurements at INFN-University of Pavia (Italy) and CNEA (Argentina)

Portu, Agustina Mariana; Postuma, Ian; Gadan, Mario Alberto; Martin, G. Saint; Olivera, María Silvina; Altieri, S.; Protti, Nicoletta; Bortolussi, Silva

doi:10.1016/j.apradiso.2015.07.022

Cited by 11 publications

(9 citation statements)

References 18 publications

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“…They are around 2 ppm, as those previously calculated for individual samples of soft tissue (e.g. Portu et al, 2015a, Portu et al, 2015b. This correspondence is of great relevance because it allows the calibration curve constructed from powder samples to be used for the analysis of thin sections.…”

Section: Resultssupporting

confidence: 66%

Extending neutron autoradiography technique for boron concentration measurements in hard tissues

Provenzano

Olivera

Martin

et al. 2018

Applied Radiation and Isotopes

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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 B 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 10 cm 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 B 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.

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Section: Resultssupporting

confidence: 66%

Extending neutron autoradiography technique for boron concentration measurements in hard tissues

Provenzano

Olivera

Martin

et al. 2018

Applied Radiation and Isotopes

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“…Although the dynamics of the two mass curves as a function of time were different, the nal value of the CEv in both cases was equivalent to the historical value of 0.31 ± 0.02 (Portu, Postuma, et al, 2015). The equivalence between CEv values from TGA and the new methodology was also con rmed for lung samples (see Table II).…”

Section: Resultsmentioning

confidence: 63%

Measurement of an evaporation coefficient in tissue sections as a correction factor for 10B determination

Espector

Portu

Espain

et al. 2023

Histochem Cell Biol

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Boron Neutron Capture Therapy (BNCT) is a cancer treatment option that combines preferential uptake of a boron compound in tumor and irradiation with thermal neutrons. For treatment planning, boron concentration in different tissues must be considered. Neutron Autoradiography using Nuclear Track Detectors (NTD) can be applied to study both boron concentration and microdistribution in tissue samples. Histological sections are obtained from frozen tissue by cryosectioning. When they reach room temperature, they undergo an evaporation process, which leads to an increase of boron concentration in the sample. In order to take this effect into account, certain correction factors (Evaporation Coe cients, CEv) must be applied.With this aim, a protocol was established in order to register and analyze mass variation of tissue sections, measured with a semimicro scale. Values of ambient temperature, pressure and humidity were simultaneously recorded. Reproducible results of evaporation curves and CEv values were obtained for different tissue samples, which allowed the systematization of the procedure. This study contributes to a more precise determination of boron concentration in tissue samples through the Neutron Autoradiography technique, which is of great relevance to make dosimetric calculations in BNCT.

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“…Aqueous solutions prepared with 10 B enriched standards, ranging from 0 to 100 μ g.kg -1 [ 14 , 28 ].…”

Section: Methodsmentioning

confidence: 99%

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

Viglietti,

Espain,

Díaz

et al. 2023

PLoS ONE

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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.

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Inter-comparison of boron concentration measurements at INFN-University of Pavia (Italy) and CNEA (Argentina)

Cited by 11 publications

References 18 publications

Extending neutron autoradiography technique for boron concentration measurements in hard tissues

Extending neutron autoradiography technique for boron concentration measurements in hard tissues

Measurement of an evaporation coefficient in tissue sections as a correction factor for 10B determination

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

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