ABSTRACT
Objective To investigate the radiation dose to operators in the process of 241Am-Be neutron source logging, and discuss neutron source management and protective measures for operators in well logging. Methods Through on-site observation and measurement of 241Am-Be neutron source logging in a company, we obtained the surface γ dose rate and neutron dose rate of the neutron source, as well as the operating time and distance of various processes including source taking, transfer, and loading, calculated the radiation dose to operators in various processes, and analyzed the source and proportion of the personal effective dose to operators. Results The effective doses of neutron irradiation and γ irradiation were 94.17 μSv and 2.72 μSv, respectively, for the combined processes of source tank inspection, transfer, and detection; 36.66 μSv and 24.08 μSv, respectively, for source loading and unloading; and 130.83 μSv and 26.80 μSv, respectively, for the whole neutron source logging process. The total annual effective dose of neutron source logging was 15.78 mSv, as estimated by logging 100 times per year. Conclusion In the process of 241Am-Be neutron source logging in the company, the effective dose to operators mainly arises from neutron irradiation. Therefore, it is necessary to strengthen neutron source management and take effective protective measures against neutron radiation.
ABSTRACT
Objective To collect and analyze the radiation dose to patients in cardiovascular interventional procedures and the radiation dose-related indicators,in order to provide a basis for improving radiation protection of patients.MethodsThe clinical data of 26 cases of complete cardiovascular interventional procedures was collected in the municipal Grade A Class Three hospitals,including coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA),and the patient-received radiation doses and other related factors was studied.TLD personal dosimeter radiation field matrix method was used to measure fluorescence time,the entrance skin dose (ESD),the peak skin dose (PSD),dosearea product (DAP) and other indicators.TLD was used to measure the organ dose of the phantom under the cardiovascular interventional procedure condition.ResultsThe fluoroscopy time was (17.7 ±15.6) min during the range of 0.80-42.4 min.The average entrance skin dose (ESD) was (159 ± 138)mGy during the range of 4.40-459 mGy.The peak skin dose (PSD) was (769 ± 705) mGy during the range of 22.6 - 2.43 × 103mGy.The fluorescence time,entrance skin dose (ESD) ,peak skin dose (PSD) of the group CA + PTCA are greater than the group CA and the difference has statistical significan.The peak skin dose and the fluoroscopy time have good linear correlation (r = 0.84,P ＜ 0.01 ).Conclusion The peak skin dose the patient received in cardiovascular interventional radiological operation can be estimated through the fluoroscopy time.
ABSTRACT
Objective To study the dose distribution of the radioactive 125Ⅰ seeds sources in the treatment of prostate cancer and also to explore the more effective method for improving treatment planning system (TPS).Methods Choose the designated TPS and use TLDs dosimeter based on a prostate cancer model.Finally stimulated measurement was focused on dose distribution in prostate cancer.The number of 125Ⅰ seed sources implanted was 89, each with 1.37 × 107 ( ± 5% ) Bq.Results Maximum dose of every layer ranged from 151 to 241 Gy, by 4.1% to 66.0% higher than the prescribed dose (145 Gy).The Minimum dose of every layer ranged from 101 to 128 Gy, by 12% to 30% higher than the prescribed dose.The maximum dose of normal tissue at 10 mm from the edge of model ranged from 46 to 91 Gy.The deviation was 44% -63% compared with the prescribed dose.Conclusions The designated TPS shows that it could be used as a practical guide for treatment of prostate cancer with the radioactive 125Ⅰ seed sources.The research methods offered by the study can provide evaluation of the TPS.