Health physics最新文献

This study aims to assess the residual radioactivity produced in the human head phantom following irradiation from a boron neutron capture therapy neutron source based on a 2.8 MeV proton accelerator. Using Monte Carlo software to simulate irradiation on a head phantom based on ICRP Publication 110, it was found that, in addition to the nuclides 24 Na, 38 Cl, and 42 K reported in other literature, 32 P is the nuclide that contributes the most to the internal exposure dose in patients post-BNCT. Calculations indicate that the effective dose resulting from 60 min of irradiation activation ranges between 148 and 401 μSv, which is relatively low. This study also analyzed the dose rate at a distance of 60 cm from the activated head. Approximately 5 min after irradiation ends, short-lived nuclides such as 19 O and 20 F decay completely, reducing the dose rate to below 1 μSv h -1 . Although nuclides like 24 Na will continue to emit radiation, the dose rate remains at a safe level.

Iodine-131 ( 131 I) has been used widely in diagnosing and treating thyroid disorders, but its radioactive nature poses risks of gamma radiation exposure to those near the patient. To mitigate this, radiation protection measures are needed, among which is the provision of optimal structural shielding. In the Philippines, achieving this involves using minimum shielding thickness to meet safety limits from national regulations. Widely used conventional methods, like those based on the tenth-value layer (TVLs) measurements, may yield poor estimates, while computational simulations are precise but impractical to use due to their complexity. Archer's fitting method offers a simple and accurate alternative for designing optimal shielding in medical imaging and radiotherapy facilities based on multiple studies. However, little to no data is available regarding the use of Archer's fitting method in providing better accuracy in shielding calculations in isolation rooms of 131 I therapy facilities. A comparison of the transmission factors calculated using different calculation methods was done, and their effect on the minimum shielding thicknesses was investigated. Transmission curves generated with broad-beam TVLs reported from previous studies yielded the closest agreement with ANS/ANSI 6.4.3 buildup factors for lead barriers. On the other hand, results showed the closest agreement among the transmission curves and shielding thicknesses acquired with the American National Standard (ANSI/ANS) 6.4.3. buildup factors, Archer's fitting method, and Monte Carlo simulation through Particle Heavy Ion Transport System (PHITS) ver. 3.28 code for ordinary concrete barriers. Poor agreement was seen with the curves generated with the Narrow-Beam and Ideal Broad Beam TVL methods and the curve generated with ANSI/ANS 6.4.3. buildup factor data. Broad-Beam TVLs from previous studies, Monte Carlo Simulation, and Archer's fit can be alternative options for shielding design. An experimental study is proposed for verification.

To characterize awareness of radiation-related knowledge (RRK) and nuclear energy-related knowledge (NERK) among students and teachers living and working around nuclear power plants (NPPs), a survey of 546 teachers and students in two schools (one middle school and one high school) within 30 km of an NPP in Liaoning Province was conducted via paper questionnaires, web-based surveys, and face-to-face interviews. The data were entered using EpiData 3.1, and the result was analyzed using R Version 3.2.2. The analytical methods used included utilization and composition ratios, as well as mean-χ ± SD to statistically describe the data, and χ2 (Fisher's and Pearson's tests) as well as Student's t -test to draw comparisons. The results showed that the RRK and NERK scores (14 questions in total) of the teachers and students (546 individuals in total) were 75.6% and 57.4%, respectively. In the radiation knowledge section of the survey, the RRK of the students plus teachers was 67.8%, while the NERK score was 55.9%. The teachers' attitudes toward the benefits of nuclear energy was more positive, which may be attributable to their higher educational levels, their occupations, or their backgrounds. The survey results also indicated that teachers and students trusted nuclear science experts and authoritative media more than other non-authoritative media. This indicates that the ways in which relevant knowledge related to nuclear energy is disseminated should be carefully considered.