These obtained in vitro results are the first effectiveness factors determined for human melanoma at the RA-3 nuclear reactor and show that BNCT dosimetry planning for patients could be successfully performed using these new factors.

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BPA-BNCT could alter boron microlocalization of GB-10 administered subsequently. Boron targeting homogeneity is essential for therapeutic success.

background. We previously demonstrated the therapeutic success of sequential boron neutron capture therapy (Seq-BNCT) in the hamster cheek pouch oral cancer model. It consists of BPA-BNCT followed by GB-10-BNCT 24 or 48 hours later. Additionally, we proved that tumor blood vessel normalization with thalidomide prior to BPA-BNCT improves tumor control. The aim of the present study was to evaluate the therapeutic efficacy and explore potential boron microdistribution changes in Seq-BNCT preceded by tumor blood vessel normalization. Material and Methods. Tumor bearing animals were treated with thalidomide for tumor blood vessel normalization, followed by Seq-BNCT (Th Seq-BNCT) or Seq-Beam Only (Th Seq-BO) in the window of normalization. Boron microdistribution was assessed by neutron autoradiography. results. Th Seq-BNCT induced overall tumor response of 100%, with 87 (4)% complete tumor response. No cases of severe mucositis in dose-limiting precancerous tissue were observed. Differences in boron homogeneity between tumors pre-treated and not pre-treated with thalidomide were observed. conclusion. Th Seq-BNCT achieved, for the first time, response in all treated tumors. Increased homogeneity in tumor boron microdistribution is associated to an improvement in tumor control.

The distribution of boron in tissue samples coming from boron neutron capture therapy protocols can be determined through the analysis of its autoradiography image on a nuclear track detector. A more precise knowledge of boron atom location on the microscopic scale can be attained by the observation of nuclear tracks superimposed on the sample image on the detector. A method to produce an "imprint" of cells cultivated on a polycarbonate detector was developed, based on the photodegradation properties of UV-C radiation on this material. Optimal conditions to generate an appropriate monolayer of Mel-J cells incubated with boronophenylalanine were found. The best images of both cells and nuclear tracks were obtained for a neutron fluence of 1013 cm-2, 6 h UV-C (254 nm) exposure, and 4 min etching time with a KOH solution. The imprint morphology was analyzed by both light and scanning electron microscopy. Similar samples, exposed to UV-A (360 nm) revealed no cellular imprinting. Etch pits were present only inside the cell imprints, indicating a preferential boron uptake (about threefold the incubation concentration). Comparative studies of boron absorption in different cell lines and in vitro evaluation of the effect of diverse boron compounds are feasible with this methodology.

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.