Studies on Radiation Dosimetry by a Solid Color Changing Substance (Solid Color Radiation Dosimetry)

A study on the solid chemical dosimeter was made to improve the sensitivity to x-ray and the stability to ultravioletray . According to the results obtained with gelatin, cellulose, plastic, paraffin and fat , the best material as a base was as paraffin . The small amount of vaseline was added into paraffin to prevent the crack and flake forming . The results of the screening of about 100 dyes showed that methyl yellow was the best dye of those to detect the effect of x-ray irradiat ion in chloroform-paraffin system. Dinthizon was sensitive dye in carbon tetrachloride-paraffin system. Many kinds of organic or inorganic compounds were blended into the chloroform-paraffin-vaseline system to sensitive the response to ionizing radiation and stabilize to ultravioletray. Para-hydroxy azo benzene was most effective as a sensitizer and stabilizer . Several halogenated hydrocarbons were mixed into the methyl yellow-paraffin vaseline system to check the degree of color change produced by x-ray irradiation, and it was found that chloroform was the best of these for methyl yellow system. From these experiments, the practical dosimeter was made by mixing of methyl yellow, p-hydroxy azo benzene, paraffin and vaseline. Three methods with electric, optical and pH meter were tried in order to measure the amount of chemical products in the dosimeter, but the measurement with pH meter was most applicable. The amount of acid produced by x-ray irradiation was directly proportional to the ex posure dose up to 5000 r. The multi color changes proportional to changed dose were made by the combination of dithizon and methyl yellow added into carbon-tetrachloride-chloroform mixture.