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Objective To evaluate the current situation of radioactive contamination in the soil around a decommissioned uranium mine by combined determination of 210Pb and 210Po activity concentrations. Methods Soil samples were collected around a decommissioned uranium mine. 210Po and the 210Pb decay product 210Bi were plated on a copper sheet by self-deposition at a constant temperature. Gross α and gross β counts were measured using a low-background α/β counter. The activity concentrations of 210Pb and 210Po in soil were calculated. The radioactive contamination was evaluated using geological accumulation index. Results The activity concentrations of 210Pb and 210Po in the soil around the decommissioned uranium mine were 873.7-2315.5 and 956.0-2315 Bq·kg−1, respectively. The activity concentrations of 210Pb and 210Po in nearby farmland soil were 54.2-257.8 and 59.1-234.5 Bq·kg−1, respectively. Evaluation with the geological accumulation index showed that the level of nearby farmland contamination was 0-2, indicating zero to moderate radioactive contamination of the farmland. Conclusion The relatively high radioactivity around the decommissioned uranium mine requires attention to the transfer, diffusion, and ingestion of the uranium decay products 210Pb and 210Po in the surrounding soil to avoid radioactive contamination of the environment.
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Objective To study the radioactive concentration of 131I in the air of workplaces where sodium iodide [131I] oral solution was administrated for patients with differentiated thyroid cancer (DTC) in the Department of Nuclear Medicine, and to estimate the internal radiation dose to the staff. Methods Workplaces of radioiodine 131I therapy for DTC patients in the Department of Nuclear Medicine of a hospital were investigated. Air samples in 131I administration areas and treatment wards were collected respectively and were measured by low-background gamma-ray spectrometry to calculate the activity concentration of 131I in the air and to further estimate the internal radiation dose to staffs. Results The activity concentration in the 131I administration area within the first 3 h of administration was 3～187 Bq/m3. During administration and within the first 3 h of administration, the staff exposed in the administration area for 5～30 min received an internal radiation dose of 0.08～0.50 μSv and 0.00～0.04 μSv, respectively. The highest activity concentration of 131I in the air of the ward was measured on the day of administration, reaching 3091 Bq/m3. After patients were discharged, the activity concentration in the ward gradually decreased to 10～242 Bq/m3 within 48 h. Within 48 h after patients were discharged, the staff exposed in the ward for 5～30 min received an internal radiation dose of 0.01～14.11 μSv. Conclusion A high activity concentration of 131I in the air was recorded during administration for DTC patients in radioiodine 131I therapy, and thus we recommend remote instructed administration or administration through a shielded window. We also recommend that non-treatment related personnel except medical staffs should not enter the ward during patients’ hospitalization at which the activity concentration of 131I in the ward was the highest. After patients were discharged, a delayed entry into the ward is recommended to reduce the internal radiation dose.
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Objective To discuss 7Be and a 77.2 keV full-energy peak with short half-life found in the water sample from the 3D water phantom of a proton therapy system. Methods We measured the water sample from the 3D water phantom of a proton therapy system according to Determination of Radionuclides in Water by Gamma Spectrometry (GB/T 16140—2018). Results The activity concentration of 7Be in the water sample was 1.30 × 101 Bq·L−1 on December 24, 2018; 4.3 × 101 Bq·L−1 on March 22, 2019; and 1.41 × 101 Bq·L−1 at the time of sampling on December 19, 2018. On December 24, 2018, the net peak area of the 77.2 keV full-energy peak in the sample was 683 ± 45, and the measurement time was 26123.02 s; on March 22, 2019, the net peak area decreased to the background level of 194 ± 49, and the measurement time was 86400.00 s. Conclusion In the 3D water phantom of the proton therapy system, 7Be can be generated from the spallation reaction between high-energy neutrons and oxygen in water. In addition, we find a full-energy peak at 77.2 keV with short half-life. The activity concentration of 7Be in the water sample is lower than the exemption level, but the activity concentration at sampling may not be the maximum activity concentration in the process of quality control. The inductive radionuclide 7Be produced in the 3D water phantom should be identified and properly evaluated in the assessment of occupational radiation hazards of proton therapy system.
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Objective To understand the activity concentrations of natural radionuclides 40K, 226Ra, 232Th, and 238U in raw coal of coal mines in some regions of China, and to explore the correlation between ore with different activity concentrations and the concentration of radon and its progeny in the workplace. Methods Raw coal samples were collected in twelve coal mines in five provinces, and the activity concentrations of 40K, 226Ra, 232Th, and 238U were measured by a high-purity germanium γ-ray spectrometric system. Results The activity concentrations of four natural radionuclides in the raw coal samples of twelve coal mines were all lower than 1000 Bq/kg, and the activity concentration of 238U in one coal mine was close to 100 Bq/kg. The content of 40K, 226Ra, 232Th, and 238U in different coal mines varied greatly, but 226Ra, 232Th, and 238U were basically at the same level in the same coal mine. Conclusion None of the 12 coal mines belong to radio active mines. One of the coal mines investigated has the activity concentrations of 226Ra, 232Th, and 238U close to the standard limit for restricted-use management mines. It is suggested to study the correlation between the content of 226Ra in raw ore, intermediate products, tailings(slag), or other residues and the concentration of radon and its progeny in mines. Monitoring and protection of radon and its progeny in the decay chain should be strengthened for coal mines with high activity concentrations of natural radionuclides 226Ra, 232Th, and 238U.
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Objective:To monitor and analyze the activity concentrations of 7Be and 210Pb in atmospheric aerosol in Beijing from 2017 to 2020. Methods:Totally 1 074 atmospheric aerosol samples were collected by high flow air sampler (SnowWhite) including 275 in spring, 266 in summer, 262 in autumn and 271 in winter and subjected to analysis by low background high-purity germanium gamma-ray spectrometery (ORTEC) to determine the activity concentrations of 7Be and 210Pb. Results:The activity concentrations of 7Be in atmospheric aerosol were from 0.56 to 14.84 mBq/m 3, with an avearage of 6.84 mBq/m 3, and from 0.01 to 9.37 mBq/m 3 for 210Pb, with an avearage 3.19 mBq/m 3. The differences in activity concentrations of 7Be and 210Pb in atmospheric aerosol among differernt seasons were statistically significant ( F=32.66, 93.93, P<0.05). Activity concentration of 7Be was highest in spring, followed by autumn, and lowest in summer and winter. Activity concentration of 210Pb ranged from winter, autumn, spring to summer in descending order. Conclusions:The activity concentrations of 7Be and 210Pb in atmospheric aerosol in Beijing from 2017 to 2020 fluctated within the range of normal level.
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Objective To ascertain the dose levels to personnel from the activation products in the radiotherapy place of a proton acceterator and to provide technical basis for protection design of the treatment place and the personnel's radiation protection.Methods A PROTEUS 235 proton therapy system was analyzed for the potentials to produce activated nuclides in the air during its operation.The concentrations of the main radionuclides and the resultant personnel doses were estimated.Results The activity concentrations of activated nuclides were 15O 4.1 × 10-2,13N 3.3 × 10-2,41 Ar 6.2 × 10-3 and 11 C 2.0 × 10-2 Bq · cm-3,respectively,in proton accelerator hall,whereas those in the proton beam radiotherapy room were only about 5％ of the corresponding values in the proton accelerator hall.The annual doses to the radiation workers from immersion external exposure due to air activation were less than 1 and 0.1 mSv,respectively,when entering the proton accelerator hall 5 and 30 min after beam stopping;whereas those were 1.3-2.0,0.7-1.2 and 0.3-0.6 mSv,respectively,when entering the therapy hall 0,5 and 15 min after beam stopping.Conclusions The personnel doses received from activated nuclides in the air in the radiotherapy place of a proton acceterator are unignorable.The contribution to doses from immersed external exposure of 15O,13N,41Ar and 11C should be taken into full considerations,with necessary protection measures needed.
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Radioactivity measurements were carried out in and around Warri Refining and Petrochemical Company in the Niger Delta region of Nigeria for the naturally occurring radionuclides of 40K, 238U and 232Th. The values were used to determine the excess lifetime cancer risk (ELCR) and the radiation health hazard indices. Results show that the ELCR value within the company premises is 0.12×10-3 while the highest value was 0.17×10-3 from Ugborikoko Community. The internal health hazard index ranged from 0.02 – to 0.64 and the external health hazard index ranged from 0.02 – 0.33. All these values were less than the world permissible standards. It could be concluded that the potential carcinogenic risk from gamma radiation doses to the population in and around the refining and petrochemical company is low.
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Studies on natural and anthropogenic radioactivity assume greater importance in the context of human health and development. Hence two species of seaweeds viz: Gracilaria edulis and Ulva lactuca, from three high background radiation areas (Arockiapuram, Kadiapattinam and Kurumpanai) on the southwest coast of Tamil Nadu, and Mandapam as low background radiation area of the southeast coast of Tamil Nadu were studied for variations in activity concentration of 228 Ra, 40 K, 238 U and 228 Th. Among these radionuclides, 40K recorded significant inter-species variation while 238 U and 228 Th showed significant association. The overall mean concentration of radionuclides was found high in G.edulis (5.31, 57.49, 36.05, 356.55 Bq kg-1 for 228 Ra, 40K, 238U, 228 Th respectively), while the mean concentrations for U.lactuca were 4.88, 42.35, 34.40, 347.70 Bqkg-1 for 228 Ra, 40K, 238U, 228 Th respectively. The mean concentration of radionuclides was uniformly found low during northeast monsoon season in both the seaweed species.
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Objective To evaluate the factors affecting the measurement of lung tumor activity concentration (AC) with FDG-PET. Methods High count Monte-Carlo simulations,based on VIP-Man (marked VHP atlas) added with spherical lung tumors of different diameter and activity,were performed to generate the essentially noiseless projection data for PET. The factors related with the measurement of tumor AC were evaluated. Results Using the maximum value in the tumor region of interest (ROI) generally resulted in the over-estimation of AC,and the degree of over-estimation would also increase as the noise became severer. For the small tumors with low AC,the proper partial volume correction was needed. Drawing ROI after post-reconstruction filtering could improve the reproducibility of AC measurement compared with no filtering first. Conclusion The accuracy and reliability of AC measurement depends strongly on factors including tumor size,post-reconstruction filter,noise level,ROI definition,PVE correction,etc.