ABSTRACT
Objective: To evaluate the radiation protection and performance test for the 192Ir brachytherapy apparatus. Methods: According to the national standard, radiation protection and its various properties of the 192Ir brachytherapy apparatus were tested. The radiation leakage dose of the 192Ir brachytherapy apparatus and the radiation scattered dose of the surrounding environment were tested with the ion chamber survey meter 451P. The activity of 192Ir radiation source was calibrated with the well chamber HDR1000 Plus. Results: The radiation leakage and scattered dose of the 192Ir source storage device and the surrounding environment are far below the national standard. The deviation of the activity calibration for 192Ir source is-2.07%, accordance with national standard±5%. Conclusion: Radiation protection and its various properties of the 192Ir brachytherapy apparatus should be regularly monitor for assuring the quality of the brachytherapy.
ABSTRACT
Daily dietary intakes of nitrate, nitrite and vitamin C were investigated in Chanle county, Fujian province, where gastric cancer was very common, with a marked geographic variation in mortality. The average daily intake of nitrate of residents in Zhanggang village (high risk area) was 132.75 mg, which was significantly higher than that (84.65 mg) in Shouzhan village (moderate risk area), but similar to that (113.12 mg) in Meihua village (low risk area). However, nitrite intake in Zhanggang village was greatly higher than that in Shouzhan and Meihua villages (3.36 mg vs 0.21 and 0.37 mg, respectively). The average daily intake of vitamin C in Shouzhan village was 56.37 mg, significantly lower than that in Zhanggang village (123.09 mg) and in Meihua village (105.90 mg). The molar ratio of vitamin C intake to nitrite in the three villages was 3.22, 3.30 and 4.33, respectively. It was invesely associated with the mortality of gastric cancer. The results suggested that nitrate and nitrite might be etiological factors of gastric cancer in the county.