RESUMO
Objective:To perform dosimetric audits on medical accelerators in radiotherapy institutions in Jiangsu province by using a radiophoto luminescent glass dosimeter (RPLGD) and to evaluate both the accuracy of radiotherapy doses and the effectiveness of RPLGD as an auditing tool.Methods:Firstly, the purposive sampling method was used to select three prefecture-level cities in Jiangsu province with good cooperation between radiotherapy institutions and a large number of patients treated by medical accelerators. Secondly, a simple random sampling method was used to select 31 radiotherapy institutions from all radiotherapy institutions in the selected three cities. Finally, one medical accelerator was selected from each institution for dose audit. A dose audit was performed by using RPLGD combined with a 30 cm × 30 cm × 30 cm standard phantom. The dosimeter was placed 10 cm underwater in the center of a 10 cm × 10 cm field with a 100 cm source skin distance. The dosimeter was irradiated with absorbed dose of 2 Gy. After the completion of irradiation, the dosimeter was read by the reader and the deviation was calculated. The acceptance level of the present research was ±5%. A non-parametric test was used to test the significance of differences between different manufacturers, installation years, and geographic distribution.Results:The dose deviation of 31 accelerators was from -16.9% to 2.0%. Of these, 28 accelerators pass the audit with pass rate of 90.3%. A follow-up audit was conducted on the only accelerator whose dose deviation exceeds±10%, also with discrepancy within ±5%. Two accelerators with a dose deviation larger than ±5% were re-measured using ionization chambers, both with dose deviation within ±3%. The non-parametric test result showed that there were no significant statistical differences in dose deviation for accelerators with different manufacturers, installation years, and geographic distribution( P>0.05). Conclusions:The levels of dose deviation for accelerators in Jiangsu province are consistent with those in the previous studies. However, there is still a difference with developed countries. RPLGD is feasible as a dose audit tool. The coverage of the RPLGD audit should be expanded to promote the quality of the radiotherapy through dose aduit.
RESUMO
Objective:To investigate the current situation of radiotherapy resources in medical institutions at all levels in Jiangsu province.Methods:The survey was initiated with the subproject " Medical Radiation Protection Monitoring" of the National Key Occupational Disease Monitoring Project. Unified electronic questionnaires were designed based on the survey content, distributed and recycled through the network, to investigate all medical institutions (excluding military hospitals) conducting radiotherapy in Jiangsu province in 2020.Results:By the end of 2020, there were 113 medical institutions (excluding military hospitals) carrying out radiotherapy in Jiangsu Province, including 86 hospitals Level Ⅲ, 23 hospitals Level Ⅱ, 2 hospitals Level I, and 2 unrated hospitals, with the largest number of hospitals in northern Jiangsu. A total of 2 033 workers were engaged in radiotherapy, with inclusion of 319 medical physicists, accounting for 15.69% of the total, slightly higher than the national average. There were 195 sets of radiotherapy equipment, including 153 medical linear accelerators and 31 afterloading units, 9 Gamma Knife and 2 60Co therapeutic machines, respectively. The number of accelerators per million population was 1.80, more than nationwide average, 1.45, in 2018. The annual number of patients treated with radiotherapy was 92 441, with an annual treatment frequency of 1.090 per 1 000 population, lower than international health-care level I. Conclusions:Radiotherapy resources in Jiangsu province exceed the national average, but may not fully meet the medical requirements of existing patients, and there is still a significant gap from international health-care level I.
RESUMO
Objective:To assess impact of radiation from nuclear power on the surrounding environment, a dose assessment model was constructed and relevant dose coefficients were determined through refined animal models.Methods:Zebrafish is one of the most important aquatic model animals in the radiation hazard assessment of nuclear power liquid effluent. A geometric model of zebrafish containing internal bones and visceral organ was established for dose estimation. The internal and external dose coefficients (DC) of the zebrafish model were calculated by Monte Carlo method with seven nuclides as the source term, 3H, 40K, 58Co, 60Co, 110Ag, 134Cs, 137Cs, which are common in nuclear liquid effluents and environmental monitoring. Results:The level of nuclide gamma energy determines dose coefficients for external radiation. The dose coefficients of most nuclides in internal organs was higher than that in whole body, and the internal organ dose of 58Co was 165% higher than that in whole body. The internal radiation dose coefficients of the model established in this study was relatively high, and the internal radiation dose coefficients caused by 60Co was 2.6 times of existing ellipsoid model, which suggested that the different internal materials and the choice of different particle types would affect the energy deposition. Conclusions:Refining of model animals is important. Accurate assessment of the organs dose coefficients of model animals is helpful to assess the radiation effects on non-human species.