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A Shiragai

Publications and source records attributed to A Shiragai.

8 recordsLinked to original sources
PubMed1991

A formulation for high-energy photon and electron beam dosimetry.

A formalism is derived to estimate the absorbed dose to a medium irradiated by high-energy photon and electron beams using an ionization chamber calibrated in terms of the exposure and this is compared with those in particular NACP and AAPM protocols. The influence of the humidity in air on the response of the chamber is taken into account in combination with various correction factors. In the present proposal, the fundamental factors needed for converting the reading of a chamber, calibrated in exposure (or air kerma), into absorbed dose are calculated for dry air in the calibration beam. For the user's beam, correction factors depending on the atmospheric conditions prevailing in the laboratory are given.

Calibration↗
PubMed1978

A proposal concerning the absorbed dose conversion factor.

New definitions of the absorbed dose conversion factors Clambda and CE are proposed. The absorbed dose in water is given by the product of absorbed dose conversion factor, exposure calibration factor, ionisation chamber reading, cap displacement correction factor and perturbation correction factor. At exposure calibration the material of the build-up cap must be the same as that of the chamber wall. An ionisation chamber of which the wall material is water-equivalent or air-equivalent may be used. In the latter case the wall must be thin. For these two cases absorbed dose conversion factors are introduced and it is recommended that either of the two sets should be adopted. Furthermore, if the chamber wall is neither water- nor air-equivalent, the factor by which these currently defines values should be mutliplied is also given: again the wall must be thin. The ICRU definitions of Clambda and CE are inconsistent, as recently pointed out, while the definitions presented here are consistent.

Electrons↗
PubMed1977

An approach to an analysis of the energy response of LiF-TLD to high energy electrons.

Responses of LiF-TLD to high energy electrons relative to 60Co gamma-rays were investigated experimentally and theoretically. The Burlin et al. theory, its modified version by Almond and McCray and the Holt et al. semi-empirical theory were examined in comparison with each experiment. An approximate approach to theoretical analysis of energy response of LiF-TLD was attempted and compared with some experimental results.

Cobalt Radioisotopes↗
PubMed1975

The transformation method for the MIRD absorbed fraction as applied to various physiques.

A transformation method was investigated for applying the MIRD absorbed fraction to internal dose calculations for an individual. The transformation method consists of two parts, transformation of the target organ mass, and of the distance between source and target organs. The variation of the specific absorbed fraction with distance in the human body was approximated with the traditional exponential form. To examine the transformation method, experiments were carried out for cobalt-60 gamma rays, using LiF-TLD, with the thyroid and ovaries as source organs. The transformed values of the MIRD absorbed fractions agreed well with the experimental values. Some results obtained from the MIRD values by these transformation methods were also compared with those for younger age groups calculated by Snyder.

Adolescent↗