外部被曝個人モニタによる測定値の評価に関する理論

抄録

The authors emphasized in the former paper that the measured values in the field of radiological protection are inevitably concerned with the uncertain factors which can never be dissolved by mere improvement of measurement techniques. A single value measured by an external personnel monitor attached on a certain position on the surface of human body does not carry the informations of incident direction of the exposed radiation, and therefore the organ dose can not be estimated correctly by a single measured value of the personnel monitor unless we get informations of irradiation pattern or special distribution of the incident radiation. The authors gave a basic matrix expression of the relationship between the measured value and the organ dose. In case as shown in Fig. 2 in the text, organ dose is given as follows;
Where D; organ dose
f_i; a measured value of the personnel monitor facing i-th direction. (In usual situation only one value of f₁……f_n is given as a measured value).
a_ij; contribution coefficient of the exposure from j-th direction to the measured value of the i-th monitor
b_j; contribution coefficient of the exposure from j-th direction to the organ dose
On the basis of this fundamental equation the authors developed a probabilistic investigation in estimating the organ dose from a single measured value and gave a quantitative expression of the uncertainty in dose estimation, introducing a concept of“Entropy”which is popularly used in information theory. The authors also made some discussions on the elimination of uncertainty when more than one measured values are obtained or some qualitative informations are additionally given about the spacial distribution of incident radiation