Tests on Application of Soil Magnetic and Integrated Gamma Ray TLD and TC Methods to the Exploration of Sandstone-Type Uranium Deposits

This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved that these approaches have yielded good results on classifying the sedimentary facies, defining the redox transitional zones and reflecting deep mineralization information. They may probably become new methods on searching for sandstone-type uranium deposits.

In vitro Dosimetric Study of Biliary Stent Loaded with Radioactive ^125I Seeds

Background： A novel radioactive ^125I seed-loaded biliary stent has been used for patients with malignant biliary obstruction. However, the dosimetric characteristics of the stents remain unclear. Therefore, we aimed to describe the dosimetry of the stents of different lengths -- with different number as well as activities of ^125I seeds. Methods： The radiation dosimetry of three representative radioactive stent models was evaluated using a treatment planning system （TPS）, thermoluminescent dosimeter （TLD） measurements, and Monte Carlo （MC） simulations. In the process of TPS calculation and TLD measurement, two different water-equivalent phantoms were designed to obtain cumulative radial dose distribution. Calibration procedures using TLD in the designed phantom were also conducted. MC simulations were performed using the Monte Carlo N-Particle extended version 2.5 general purpose code to calculate the radioactive stent＇s three-dimensional dose rate distribution in liquid water. Analysis of covariance was used to examine the factors influencing radial dose distribution of the radioactive stent. Results： The maximum reduction in cumulative radial dose was 26% when the seed activity changed from 0.5 mCi to 0,4 mCi for the same length of radioactive stents. The TLD＇s dose response in the range of 0-10 mGy irradiation by ^137Cs y-ray was linear： y = 182225x - 6651.9 （R2 = 0.99152; y is the irradiation dose in mGy, x is the TLDs＇ reading in nC）. When TLDs were irradiated by different energy radiation sources to a dose of 1 mGy, reading of TLDs was different. Doses at a distance of 0.1 cm from the three stents＇ surface simulated by MC were 79, 93, and 97 Gy. Conclusions： TPS calculation, TLD measurement, and MC simulation were performed and were found to be in good agreement. Although the whole experiment was conducted in water-equivalent phantom, data in our evaluation may provide a theoretical basis for dosimetry for the clinical application.

Study of whole-body occupational radiation exposure in the industrial radiography in Bangladesh

Objective:In order to understand the complete scenario of the effectiveness of radiation protection practice in the workplace,especially in the industrial radiography and also to analyze the trends with other related studies,epidemiological studies and legal purposes,the assessment and register of the effective dose plays a significant role.Therefore,efforts have been given in the assessment of collective effective dose,mean effective dose,prediction of lifetime cancer risk,and contribution of different age group workers in the collective effective dose.Methods:The occupational radiation exposures for 472 workers were investigated in industrial radiography throughout Bangladesh from 2015 to 2018 by using thermoluminescent dosimeter(TLD).By using a Harshaw TLD reader(Model-4500),the effective dose was measured in a quarterly basis throughout the year.Based on the value of personal dose equivalent Hp(10),database was prepared and recorded.Results:The collective effective dose was 36.1,40.7,28.8 and 37.5 man⋅mSv among 105,102,100 and 165 radiation workers in 2015,2016,2017 and 2018,respectively.The maximum effective dose received by radiation workers was 6.0,7.1,6.9 and 19.9 mSv in 2015,2016,2017 and 2018,respectively,which remained within the stipulated dose limits imposed by Nuclear Safety and Radiation Control(NSRC)Rules-1997,Bangladesh and International Commission on Radiological Protection(ICRP-103).Conclusion:This kind of monitoring would help to construct a national database that will be used by the end users to improve their implementation of optimization in occupational radiation protection in industrial radiography.