No abstract available

No abstract available

No abstract available

[en] Published in summary form only

[en] Optimization of neutron therapy requires nuclear cross section data for: (1) the selection of source reaction for neutron production, (2) the design of collimators and shields, (3) the calculation of absorbed dose in the irradiation tissues, including heterogeneity corrections, (4) microdosimetry, and (5) studies of the influence of radiation quality on biological effects. Under the auspices of the International Atomic Energy Agency (IAEA), a Coordinated Research Program (CRP) has been underway since 1987 to assess the status of these nuclear data, to coordinate research efforts, to report recent progress, and to recommend acceptance of appropriate data and further research where necessary. In this paper, we outline the results of the CRP's final report to be published and evaluate the status of the most critical nuclear data needs for therapy, i.e., kerma calculations and measurements, from low neutron energies to 70 MeV. Recommended values for (n,p) kerma and the carbon-to-oxygen neutron kerma factor ratios up to 70 MeV are given with estimates of their current uncertainties

[en] A study has been made about uncertainties in the dosimetry of sources for RALS (remotely controlled afterloading system). The intensity of source must be specified in terms of exposure rate to eliminate the need for accurate knowledge of exposure rate constant and filteration correction of source capsule. The regional Medical Dose Standard Centers of Japan Radiological Society can provide calibrated value of this exposure rate by commission. Among constants and correction terms in the equation for dose calculation, uncertainties due to corrections for the filtration of source capsule and the tissue attenuation were relatively large. A more precise estimation could be necessary about these two terms. Errors involved in the reconstruction of source position from radiographs are caused with the performance of simulator and computer digitizer and the method of handling. Appropriate standards must be established for performance, maintenance and handling of these devices. The overall uncertainty which was estimated assuming standard conditions and parameters was about 6 %. (author)

[en] Environ Matrix Operations are able to deliver usable and realizable optimization results even in cases where rectilinear mathematical methods fail. A general point of view of Environ Operations is to produce controlled variations of the initial parameters to render a complicated problem smoothly solvable. The permissibility of such operations is discussed on a mathematical and philosophical basis (clinical basis). 2 refs.; 4 figs

[en] The present report summarizes the results of a new series of biological intercomparisons of neutron therapy beams using mammalian cells cultured in vitro. Experiment design was based upon two important considerations: (a) It is a characteristic of cell culture experiments that variations within an experiment are much smaller than those between experiments. Consequently, neutron facilities were intercompared in pairs, within a given experiment, using cells from a common culture irradiated on the same day. (b) A standardized treatment fixture was used at all facilities, constructed of lucite, with space for 6 tissue culture flasks, and provision for an ionization chamber to be inserted into the jig to determine the dose received at the position occupied by the cells. Full build-up was ensured because the cells were overlaid with 2 cm of tissue culture medium. A substantial international effort to achieve compatible dosimetry was mounted by the physicists at the various installations engaged in neutron therapy, as a consequence of which there is agreement to within +-1.5% for dose measurements in air. The use of the standard treatment fixture was an attempt to extend the compatible dosimetry to a practical set-up for the irradiation of cell cultures

[en] Published in summary form only

[en] A mathematical optimization method will be discussed concerning the three dimensional radiation treatment planning of the HDR-afterloading technique. Program libraries of the EDV Center of the University of Essen were used. (orig.)