Effect of small-doseγ-ray on endogenous antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT), was examined in brain and liver of mice. An increase ofCu/Zn-SOD activity was observed in both organs, particularly in brain, soon after irradiation with 50cGyofγ-ray. Mn-SODactivity was not altered in the brain, but contrary decreased in the liver post-irradiation. The activity of CAT was increased in both organs within 12hafter the irradiation. Moreover, MDA, a marker of lipid peroxidation, was siginicantly lowered in both organs, suggesting an induction of endogenous antioxidant potential following irradiation with a small dose ofγ-ray.
The radiation exposure rates were measured inside and outside a private house in the Tibetan Autonomous Region of China. As far as seen from the cosmic ray exposure rate and the gamma ray exposure rate, the indoor exposure rates can be classified into 3 groups: the 2nd floor, entrance to the 1st floor and in the rest of the 1st froor. In the 1st group, the mean cosmic ray exposure rate was 4.079nC/kg/h (15.81μR/h) and the mean gamma ray exposure rate was 4.515nC/kg/h (17.50μR/h) .In the 3rd group, the mean cosmic ray exposure rate was 2.740nC/kg/h (10.62μR/h) and the mean gamma ray exposure rate was 5.284nC/kg/h (20.48μR/h) .The reason why the cosmic ray exposure rate in the 3rd group is lower than in the 1st group is believed to be that cosmic rays are cut off by the construction materials. The reasons why the gamma ray exposure rate in the 3rd group is higher than in the 1st group are believed to be that the 3rd group is nearer to the ground than the 1st group and the stones of which the 1st floor walls are made have a higher concentration of natural radionuclides than the earth of which the 2nd floor walls are made. Both the cosmic ray exposure rate and the gamma ray exposure rate in the 2nd group are between those of the 1st group and the 3rd group. Futhermore, the authors calculated the air absorbed dose rates inside and outside a Tibetan private house and compared them with those of private houses in the world.
The trial apparatus manufactured for the decontamination of urine of patients treated with131Iconsists of two types of vessels, A and B. In the type of A, the urine is poured from the upper portion of the vessel and flows from the upper portion of the outer pipe of the vessel through a siphon. In the type of B, the urine is forced from the lower portion of the vessel and flows out from the upper portion. Type B vessel can be connected to B type vessel as well as to type A vessel. Seven litters of charcoal mixed with resin was put into the A type vessel and the absorption rate of131Iin water was almost 100 percent after treatment by this type A vessel. The 5.5 litters of ion exchange resin was put into the B type vessel with an absorption rate was 99.9 percent after treatment by the B type. These results show that this trial apparatus connecting vessels of type A and B can be practically used for the decontamination of urine of a large number of patients treated with131I.
We applied a new fingerprint checker for complete access control to the radiation controlled area and to the radioisotope storage room, and prepared softwares for the best use of this checker. This system consists of a personal computer, access controllers, a fingerprint register, fingerprint checkers, a tenkey and mat sensors, permits ten thousand users to register their fingerprints and its hard disk to keep more than a million records of user's access. Only 1 % of users could not register their fingerprints worn-out, registered four numbers for a fingerprint. The softwares automatically provide varieties of reports, caused a large reduction in manual works.