Basing on some formulas of Lagrange interpolation derived in this paper, acomputer program for table calculations has been prepared. Main features of the program are as follows; 1) maximumdegree of polynomial in Lagrange interpolationis 10, 2) tables with both one variable and two variables can be applied, 3) logarithmic transformations of function and/or variable values can be included and 4) tables with discontinuities and cusps can be applied. The program has been carefully tested by using the data tables in the manual of shielding calculation for radiation facilities. For all available tables in the manual, calculations with the program have been reasonably performed under conditions of 1) logarithmic transformation of both function and variable values and 2) degree 4 or 5 of the polynomial.
In order to give an accurate measurement for ambient dose monitoring, the residual dose should be reduced to an order of 0.1 mSv and Al203: C dosemeters are to be annealed by users just before service operation. An easy new annealingprocess for this purpose has been studied by using common fluorescent lamps with films that cut ultraviolet components. We made a series of annealing tests of Al203: C detectors by this method. The average residual dose by exposing to bare lamps was 0.13 mGy, while it decreased to one tenth; i. e. 0.01 mSv, by using the ultraviolet cut films. The test results show that use of common fluorescent lamps with ultraviolet cut films provides an easy and practical annealing method for measuring ambient doses by Al203: C detectors.
The PSL value-radioactivity conversion factor and the detection limit of a thyroid 131I in vivo monitoring system using an imaging plate (IP) were investigated by using thyroid-neck phantom loaded aqueous 131I solution. The conversion factor of the IP system was approximately constant for the thyroid volume between 7.7 and 20.5ml and neck diameter between 10cm and 14cm. The conversion factor linearly decreased with increasing the tissue thickness. The detection limits ranged from 311 to 506 Bq depending on the combinations of neck diameter, thyroid volume and prethyroid tissue thickness. The detection limit of the IP system was less than 1/60 of the screening level of 30 kBq in cases of public emergencies. The IP system is a new option for thyroid 131I monitoring method.
As a measure of harmful effect of radiation, radiation exposure index (REXI) is proposed. It is an integer expression of logarithmic ratio of radiation dose to a standard value. REXI is a dimensionless quantity and is free from the requirementof additivity, in contrast with dose. Not a few kinds of doses are used in the field of radiation protection and among them the effective dose plays main role, since the main target of radiation control is of the so-called stochastic effect and the effective dose is used as the controlling quantity. Effective dose is a radiation dose, namely, a quantity of cause to describe the effect, but it cannot be a representation of the effect itself. It is nothing but a measure of possibility of the effect. In addition, the LNT (linearity and non threshold) Postulation adopted by ICRP makes it difficult to understandthe foreseen associated effect quantitatively.
Upon the proposals of Prof. T. Sugahara that the system of radiation protection should be designed in the direction of so-called inverse problem, considerations are made. It seems hard to formulate the issues mathematically. The proposalsare to be understood as the pointing out of importance of the direction of thinking or considering in designing or modifying radiation protection.