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Clinical trials for boron neutron capture therapy (BNCT) by using the medical irradiation facility installed in Japan Research Reactor No. 4 (JRR-4) at Japan Atomic Energy Research Institute (JAERI) have been performed since 1999. To carry out the BNCT procedure based on proper treatment planning and its precise implementation, the JAERI computational dosimetry system (JCDS) which is applicable to dose planning has been developed in JAERI. The aim of this study was to verify the performance of JCDS. The experimental data with a cylindrical water phantom were compared with the calculation results using JCDS. Data of measurements obtained from IOBNCT cases at JRR-4 were also compared with retrospective evaluation data with JCDS. In comparison with phantom experiments, the calculations and the measurements for thermal neutron flux and gamma-ray dose were in a good agreement, except at the surface of the phantom. Against the measurements of clinical cases, the discrepancy of JCDS's calculations was approximately 10%. These basic and clinical verifications demonstrated that JCDS has enough performance for the BNCT dosimetry. Further investigations are recommended for precise dose distribution and faster calculation environment.

We have developed an ultra-high resolution charged particle radiography technique using CR-39 solid state track detectors and an atomic force microscope (AFM). Very small etch pits about 80 nm in diameter were measured with the AFM. We planned to apply this technique to high resolution autoradiography. Such practical applications often require accurate positioning between the sample mounted on a CR-39 detector and particle tracks recorded in the CR-39 in order to determine the radiation dose distribution inside the sample. As a fiducial marker for the positioning, aluminum patterns were deposited on the CR-39 surface using a photolithography technique. The aluminum patterns were dissolved through a typical etching process for CR-39 detectors and pattern-shaped steps were left on the surface. Using these patterns should ensure accurate positioning between the sample and the etch pits in autoradiography. This method provides a new technique for radiation imaging of biological samples at a subcellular scale.