Investigation of 131I radioactivity levels in soil around the nuclear medicine decay pool after the 7·20 extraordinary rainstorm disaster in Zhengzhou, Henan / 中华放射医学与防护杂志

Objective:To explore whether or not radioactive wastewater leakage or overflow exists in the nuclear medicine decay pool after the 7·20 extraordinary rainstorm disaster and to analyze its causes, so as to provide scientific basis for the design, construction and maintenance of the nuclear medicine decay pool and the radiation protection management of nuclear medicine in the future.Methods:Three hospitals A, B and C where 131I therapy are being performed were selected in Zhengzhou city, Henan province. Sampling points were set based on the monitoring result of the environmental radiation level around the nuclear medical decay pool in line with the relevent standard method. Soil samples were collected at different depths. The 131I radioactivity level in the soil was measured using HPGe gamma spectrometer, with the measured result being processed and analyzed. Results:Except for Hospital B where no 131I was detected, different 131I activity concentrations were detected in the soil samples collected around the nuclear medicine decay pool at Hospitals A and C. The 131I activity concentrations ranged from 16.4 to 98 111.8 Bq/kg at Hospital A and from 10.6 to 7 176.6 Bq/kg at Hospital C. After a time period of decay, the repeated detection has shown that the 131I activity concentrations ranged from 1.3 to 17.0 Bq/kg at Hospital A and from 3.9 to 7.1 Bq/kg at Hospital C. The 131I activity concentration in the soil at the depth of 0-5 cm was higher than that at the depth of 5-10 cm soil at the same sampling point. The ratios of activity concentration of 131I between different depths ranged from 1.3 to 13.1, with the median value of 5.9. Conclusions:After the 7·20 extraordinary rainstorm disaster, the surrounding environment of nuclear medicine decay pools at a few hospitals was contamminated by 131I to some extent. To prevent the risk of leakage of radioactive wastewater, the safety evaluation and management of radiation protection should be made better with increased awareness during the design, evaluation, construction and use of nuclear medicine decay pools.

Early versus delayed post-therapy whole body scintigraphy for well-differentiated thyroid carcinoma: A meta-analysis

Introduction@#No clear consensus exists as to the optimal timing for conducting whole body scintigraphy (WBS) after radioactive iodine (RAI) therapy for differentiated thyroid carcinoma. @*Objective@#This study aimed to compare the utility of early versus delayed post-therapy WBS in identifying residual lesions and metastases.@*Methods@#A systematic review of existing literature was done, yielding 6 observational studies relevant to the subject. Meta-analyses were done comparing lesion detecting rates of early (3-4 days post-RAI) and delayed (7-11 days post-RAI) post-therapy WBS for thyroid remnants and metastases in the lymph nodes, lungs, and bone using a random-effects model with odds ratios (OR) and 95% confidence intervals (CIs). A subgroup analysis was also done relating to the type of collimator used in imaging.

Evaluation of the therapeutic effect of deuterium depleted water on gastroenteritis induced by 131I radiation in thyroid cancer treatment / 中国辐射卫生

Objective To investigate the therapeutic effect of oral administration of deuterium depleted water on gastroenteritis induced by 131I radiation in thyroid cancer treatment. Methods Fifty patients with papillary thyroid cancer treated with 131I in the Department of Nuclear Medicine of Changshu No.2 People’s Hospital from May 2022 to February 2023 were divided into control group and experimental group (25 patients in each group). Data were continuously collected throughout the study duration. The control group was orally administrated omeprazole enteric-coated capsules and purified water at 660 mL tid for 5 days. The experimental group received the same basic treatment as the control group except that deuterium depleted water was used instead of purified water. The incidence and alleviation of 131I radiation-induced gastroenteritis were observed and compared between the two groups using the Fisher’s exact test and Kaplan-Meier analysis. Results The number of gastroenteritis cases from day 1 to day 5 after 131I administration was 2 (8%), 5 (20%), 2 (8%), 1 (4%), and 0 (0%), respectively, in the experimental group, and 2 (8%), 8 (32%), 4 (16%), 3 (12%), and 1 (4%), respectively, in the control group. The incidence of gastroenteritis was significantly different between the two groups (χ2=4.064, P=0.044). After 5 days of treatment, the overall response rate of patients in the experimental group was 96%, which was significantly higher than 76% in the control group (χ2=9.105, P=0.025). Conclusion Oral administration of deuterium depleted water is effective in the relief of clinical symptoms of 131I radiation-induced gastroenteritis in thyroid cancer treatment. The clinical application of deuterium depleted water should be further investigated.

Outcomes and prognostic factors of differentiated thyroid cancer with bone metastasis / 中国辐射卫生

@#<b>Objective</b> To investigate the outcomes and prognostic factors of differentiated thyroid cancer (DTC) with bone metastasis. <b>Methods</b> A retrospective study was conducted on 108 DTC patients with bone metastasis who were treated in the Cancer Hospital of Chinese Academy of Medical Sciences. Kaplan-Meier survival curves were generated. Log-rank test and Cox proportional hazards model were used to screen the prognostic factors. The correlation between treatment and prognosis was analyzed. <b>Results</b> The median overall survival was 70 months. The 5-, 10-, 15-, and 20-year overall survival rates were 54.4%, 24.3%, 9.8%, and 4.3%, respectively. Univariate analysis showed improved prognosis in patients with single bone metastasis, without skeletal-relatedevents (SREs), and without cervical lymph node metastasis (<i>P </i>= 0.003-0.019). Patients who received combined treatments (<i>P</i> < 0.001) or ¹³¹I treatment alone (<i>P</i> = 0.109) showed better prognosis than those without ¹³¹I treatment. Multivariate analysis identified single bone metastases, SREs, and treatmentas independent prognostic factors. <b>Conclusion</b> In DTC patients with bone metastasis, good prognosis is significantly associated with single bone metastases, absence of SREs, and ¹³¹I therapy in combination with other therapeutic approaches.

Measurement of thyroid 131I activity in 162 iodine treatment workers in Hubei Province, China / 中国辐射卫生

Objective To determine the current status of occupational internal exposure to 131I in the thyroid of nuclear medicine workers, to explore the influencing factors for internal exposure, and to provide a basis for the radiation safety management of nuclear medicine. Methods The cluster sampling method was used to select 162 workers practicing 131I treatment in 24 hospitals in Hubei Province, China. Thyroid 131I activity levels were measured in vitro using a portable γ-spectrometer, and the committed effective dose was estimated. Results The thyroid 131I activity detected in 13 (54.17%) hospitals was above the lower limit of detection of the instrument. Two hospitals had the highest detection rates, 62.50% and 61.90%; the difference was significant compared with the remaining 11 hospitals (P < 0.0001). Thyroid 131I was detected in 34 workers in total, with a detection rate of 20.99% and a mean activity of 179.09 ± 138.71 (6.02-589.74) Bq. The highest detection rates were found in cleaners and nurses, which were 35.71% and 33.33%, respectively, with no significant difference in detection rate between positions (least P > 0.08). The mean value of the committed effective dose was 0.68 ± 0.52 (0.02-2.22) mSv/a in the 34 workers. Conclusion The 131I consumption and workplace ventilation may be important factors affecting the level of internal exposure. It is important to strengthen the training of nuclear medicine workers on radioprotection and workflow management, as well as the regular monitoring of occupational internal exposure for 131I treatment-related workers.

A preliminary investigation on internal exposure dose of artificial radionuclides in nuclear medicine staff / 上海预防医学

ObjectiveTo tentatively understand the status of radioactive contamination in nuclear medicine personnel. MethodsA total of 34 radiation staff engaged in nuclear medicine diagnosis and treatment were selected from two hospitals in Shanghai as the survey subjects.Among the 34 medical staff， 8 were nuclear medicine doctors， 14 were nuclear medicine technicians and 12 were nuclear medicine nurses. After surface contamination monitoring was first carried out to confirm that they had no surface radioactivity contamination， whole body scanning was performed with a whole body counter to determine whether they were internally contaminated with artificial radionuclides. ResultsThe α surface contamination was not detected in the nuclear medical staff. The β surface contamination of the nuclear medicine doctors， technicians and nurses was （13.8±0.8）， （14.1±0.8） and （14.0±0.7） times per second， respectively. There were 2， 2， and 4 nuclear medicine doctors who were contaminated with 18F， 99mTc and 131I， 3， 5， and 2 nuclear medicine technicians who were contaminated with 18F， 99mTc and 131I， and 6， 8， and 5 nuclear medicine nurses who were contaminated with 18F， 99mTc and 131I， respectively. The 18F activity of nuclear medicine technicians was 1 997‒9 401 Bq， and the 99mTc activity of nuclear medicine technicians and nurses was 3 699‒18 692 and 652‒388 22 Bq， respectively. One nuclear medicine nurse had a 99mTc activity of 35 389 Bq. According to the preliminary estimation of 131I internal irradiation dose， the maximum committed effective dose of nuclear medicine doctors， technicians and nurses could reach 0.370， 0.018 and 0.584 mSv， respectively. ConclusionThe nuclear medicine staff are exposed to radioactive contamination， and it is important to monitor and evaluate their internal radiation doses.

Internal exposure levels of thyroid 131I in nuclear medical staff / 环境与职业医学

Background Based on numerous epidemiological studies, radionuclide 131I can result in thyroid disease. Objective To study the contamination level of thyroid 131I in 131I treatment associated radiation workers in nuclear medicine departments in Shanghai. Methods Based on a general survey on basic situation of nuclear medicine in Shanghai, the level of internal exposure of radiation workers involved in 131I treatment was assessed with questionnaires and on-site monitoring. A portable γ spectrometer was used for on-site detection, the intake and annual effective dose were estimated according to the measurement results. Physical examination reports were collected for radionuclide positive workers, and chromosome testing was performed. Results There were 579 nuclear medicine workers and 175 were engaged in 131I treatment in Shanghai. 131I was detected in thyroid of 18 workers, with a detection rate of 10.3%. Among them, the detection rates of thyroid 131I in nurses and cleaners were 23% and 25% respectively. The mean measured activity of thyroid 131I was 306.1 Bq and the maximum measured activity was 3716.9 Bq (nurse). The maximum intake was estimated at 37544 Bq and the median was 786.4 Bq. The average annual committed effective dose was 1.22 mSv and the maximum value was 14.87mSv. The chromosomal aberration rates of all detected workers were negative, and all blood indicators were normal except one with low hemoglobin. Conclusion The annual dose of nuclear medical staff engaged in 131I treatment does not exceed the national standard limit, but the internal exposure of nurses and cleaners should not be ignored. On the basis of strengthening protection and decontamination, routine internal exposure monitoring should be carried out.

Radioiodine (131I) treatment decision-making for low- and intermediate-risk differentiated thyroid cancer

ABSTRACT Objective: The purpose of this study was to investigate the effect and influencing factors of post-surgical radioactive iodine (RAI) therapy for patients with low- and intermediate-risk differentiated thyroid cancer (DTC). Subjects and methods: A retrospective analysis of 423 low- and intermediate-risk DTC patients admitted to the Department of Nuclear Medicine, Sichuan Provincial People's Hospital from January 2005 to December 2020 was performed. All patients were treated with surgery, had a postoperative pathological diagnosis, and were treated with RAI, including 89 males and 334 females. Recurrence risk stratification: 143 cases were low-risk, and 280 cases were intermediate-risk. Results: The excellent response (ER) rate for low- and intermediate-risk were 93.7% and 78.2%, respectively (P < 0.05). There were significant differences in age, cumulative dose of [131I], and pretreatment stimulated-Tg (pre-Tg) levels between the low- and intermediate-risk groups (P < 0.05). There were significant differences in the cumulative dose of 131I and pre-Tg levels between ER and the non-ER group (P < 0.05). The area under the curve (AUC) values were 0.799 in the low-risk group, and 0.747 in the intermediate-risk group for the ROC curve by ER status of pre-Tg. The ER rate with RAI treatment decreased with an increase in pre-Tg levels. Conclusion: Pre-Tg was an important factor for RAI treatment decision-making and prognostic evaluation and differed between low-risk and intermediate-risk DTC. Aggressive RAI therapy was recommended for low-risk DTC with pre-Tg ≥ 20.0 ng/mL and in intermediate-risk group with pre-Tg ≥ 10.0 ng/mL.

Measurement and evaluation of thyroid 131I activity in iodine treatment workers / 中华放射医学与防护杂志

Objective:To understand the 131I activity in thyroid of therapy workers in nuclear medicine department, and estimate the annual committed effective dose, in order to analyze the internal exposure of them. Methods:Six hospitals were investigated and 131I activity of thyroid was measured. The detection rate and activity value of thyroid 131I activity of therapy workers in nuclear medicine department were obtained from the six hospitals, and then the intake and annual committed effective dose were calculated. Results:A total of 63 iodine therapy workers from six hospitals were measured and 131I was detected for 52 workers among them, with the detection rate of 83% and 131I activities mostly lower than 200 Bq. The estimated annual committed effective dose ranged from 0.23 to 7.78 mSv. The annual committed effective dose to 84.6% of the workers was less than 2 mSv. Conclusions:Iodine therapy workers in nuclear medicine department should receive routine internal exposure personal monitoring, and the radiation protection system in all hospitals needs to be further improved.

Simulation of detection efficiency of a portable NaI(Tl) γ spectrometer for monitoring 131I in the thyroid / 中华放射医学与防护杂志

Objective:To simulate the effects of different thyroid-neck phantoms and monitoring positions on the detection efficiency of portable γ spectrometer, and to provide guidance for more accurate on-site measurement of 131I activity in the human thyroid. Methods:Based on the models of 4 typical thyroid-neck phantoms and a 3-inch NaI (TI) γ spectrometer used for the measurement of 131I in the thyroid and combined with the possible field monitoring scenarios, the Monte Carlo method was used to simulate and calculate the detection efficiency of the spectrometer under different conditions of monitoring distance, thyroid depth and thyroid volume. Results:The detection efficiency decreased significantly with the increase in the distance between the detector and the neck surface. The efficiency close to the neck surface was about 15 times that at 15 cm away from the neck surface. The detection efficiency decreased significantly with the increase in thyroid depth. When it was measured at the surface of the neck, the detection efficiency of thyroid at depth of 2 mm was about 3.6 times that of 30 mm. The detection efficiency decreases with the increase in thyroid volume. When it was measured at the neck surface, the detection efficiency of thyroid with 1 ml volume was 1.71 times that with 30 ml. The detection efficiency decreased with the center-point offset of the detector, especially at the neck surface, an offset of 2 cm would reduce the detection efficiency by about 15%.Conclusions:Not only the measurement distance used in calibration, but also the information of the depth and volume of thyroid in the neck-thyroid phantom, is important to know in advance for an accurate measurement of 131I activity in thyroid by using a portable gamma spectrometer.

Measurement of 131I activity in thyroid of workers at the place of radioiodine therapy in six hospitals / 中华放射医学与防护杂志

Objective:To investigate 131I activity in thyroid of workers at the place of radioiodine therapy and its main influencing factors. Methods:In terms of the types of hospitals, six hospitals that performed radioiodine therapy procedure were selected by quota sampling in the provinces of Shandong and Shanxi. 131I activity in thyroids of 76 workers at the place of radioiodine therapy was measured directly, and their internal doses were estimated. Results:131I activity in thyroids was found to be above the detection limit for 29 subjects (38.16%) in five hospitals. The maximum value of 131I activity was 2 468.45 Bq for a doctor who was responsible for manual distribution of radioisotopes. In general 131I activities in thyroid of workers at the place of radioiodine therapy of six hospitals were not significantly different ( P>0.05). But the measurement result in the hospitals where radioiodine was distributed manually were significantly higher than that in the hospitals where radioiodine was distributed automatically ( Z=1.75, P<0.01). Thyroid measurement result of 12 workers in two hospitals where radioiodine was distributed manually were all above the detection limit, with medians of 324.59 Bq and 331.98 Bq, respectively. The medians of 131I activities in thyroid of 12 staff in the remaining 4 hospitals were all below the detection limit. The detection frequencies of 131I above dose limit were 32.61%, 25.00%, 10.00% and 0. The measurement result for the doctors who participated in distributing 131I and the relevent cleaners were significantly higher than for the doctors who did not participate in distributing 131I at the same hospital ( Z=2.44, 2.12, P<0.05). Conclusions:There was a significant difference in the internal exposure level among workers at the different places of radioiodine therapy. Using automatic loading device could reduce the internal exposure level of the workers at the place of radioiodine therapy. It is necessary to strengthen the radiological protection for workers at the control area of the place of radioiodine therapy.

Relationship between serum KLK11 and MK levels and the efficacy of the first 131I ablation after surgery for differentiated thyroid cancer / 中华内分泌外科杂志

Objective:To explore and analyze the relationship between serum KLK11 and MK levels and the effect of first iodine 131 ( 131I) ablation after operation for differentiated thyroid cancer. Method:108 patients with differentiated thyroid cancer who underwent total thyroidectomy in our hospital from Jun. 2020 to Jun. 2021 were consecutively selected, and received radioactive ablation after surgery. There were 37 males and 71 females. The age was (48.32±4.25) years, ranging from 28 to 79 years. The patients were divided into successful ablation according to whether the ablation was successful after treatment. There were 64 cases in the group and 44 cases in the unsuccessful group, and 60 healthy people with no abnormality in physical examination during the same period were selected as the control group. The patients were divided into a metastasis-positive group of 20 cases and a metastasis-negative group of 88 cases according to whether lymph nodes occurred. After surgery, serum samples of all subjects were taken, and enzyme-linked immunosorbent assay was used to detect the levels of serum kallikrein-related peptidases 11 (KLK11) and midkine (MK) , and the levels of serum KLK11 and MK were analyzed. Gender, age, BMI, TNM stage, TSH, maximum diameter of lesion, and duration of nail removal were collected. Univariate analysis and logistic regression analysis were used to analyze the independent risk factors of postoperative efficacy.Result:The levels of serum KLK11 and MK in the successful and unsuccessful groups were higher than those in the control group, while the levels of KLK11 and MK in the unsuccessful group were higher than those in the successful group (KLK11: t= 2.642, P<0.05; MK: t=11.906, P<0.05) . The serum levels of KLK11 and MK in the metastasis-positive group were higher than those in the metastasis-negative group (KLK11: t= 2.908, P<0.05; MK: t=14.907, P<0.05) . Univariate analysis showed that BMI ( χ2=6.780, P=0.009) , maximum diameter of lesions ( χ2=14.819, P=0.001) , TSH ( χ2=13.627, P=0.001) , serum KLK11 ( t=2.642, P=0.01) , and serum MK ( t=11.906, P<0.001) were associated with the effect of first 131I ablation after surgery for differentiated thyroid cancer ( P<0.05) . Taking the success of ablation as the dependent variable, a multivariate logistic regression analysis was performed. The results showed that the maximum diameter of the lesions greater than 2 cm ( OR=10.740, 95%CI: 7.033-16.401) , increased level of TSH ( OR=8.559, 95%CI: 2.812-26.057) , increased serum KLK11 level ( OR=16.710, 95%CI: .548-32.666) and increased serum MK level ( OR=10.580, 95%CI: 6.294-17.786) were the factors affecting the first 131I ablation effect after DTC surgery ( P<0.05) . Conclusion:The elevated levels of serum KLK11 and MK are independent risk factors affecting the efficacy of the first 131I ablation after surgery for differentiated thyroid cancer.

99m Technetium Pertechnetate Thyroid Scan for remnant thyroid tissue detection among post-thyroidectomy patients at Jose R. Reyes Memorial Medical Center: A retrospective analysis

@#This study aims to determine the diagnostic value of a 99mTc-pertechnetate (99m TcO-4) thyroid scan among patients with DTC who underwent thyroidectomy to assess functioning thyroid remnants before radioactive iodine therapy. A retrospective non-experimental cross-sectional design was done to compare the results of the 99m TcO-4 thyroid scan with the patient's post-RAI scan. A review of all our patients' charts was done for eight years, and after excluding those that did not fit the criteria, 70 patients were included in the study. Data collected was analyzed on a "per patient" basis– where patients either had a "positive scan" or "negative scan", and on a "per lesion" basis – where every lesion's presence and size were compared on both modalities. 99m TcO-4 thyroid scan in the "per patient" analysis showed a sensitivity of 73.91%, specificity of 100%, positive predictive value (PPV) or 100%, and accuracy of 74.29%, however, negative predictive value was determined to be 5.26%. In the "per lesion" analysis, the scan had a less favorable performance with the computed sensitivity of 61.69%, PPV of 94.93%, and accuracy at 59.41%. It was then concluded that 99mTc-pertechnetate scan may be useful in determining functioning remnant thyroid tissue and subsequent management of DTC patients after thyroidectomy, but must take note of its low negative predictive value.

Investigation of two types of portable γ spectrometer applicability for measurement of thyroid 131I activity and internal doses to radiation workers / 中华放射医学与防护杂志

Objective:To investigate the differences in applicability of both the portable high-purity germanium (HPGe) γ spectrometer and the portable lanthanum bromide (LaBr) γ spectrometer for measuring thyroid 131I activity and internal exposure monitoring for radiation workers. Method:Both DETECTIVE-DX100-KT portable HPGe γ spectrometer and InSpector 1000 portable LaBr γ spectrometer were used to measure the 131I content in thyroid of radiation workers for comparison of the measuring result, minimum detectable activity (MDA) and corresponding annual committed effective doses between two types of spectrometers. Results:The detection rate of 131I in thyroid of radiation workers was 67.7% for HPGe γ spectrometer and 26.2% for LaBr γ spectrometer, respectively. The MDA was 12.26-14.74 Bq (measuring time: 3-5 min) for HPGe γ spectrometer and 56.56-80.37 Bq for LaBr γ spectrometer (measuring time: 2-4 min). The annual committed effective dose corresponding to MDA was 0.07-0.08 mSv (3-5 min) for HPGe and 0.31-0.45 mSv (2-4 min) for LaBr, respectively, in the case of using chronic continuous intake mode and 7 d monitoring period. Conclusions:The minimum detectable activity (MDA) of the two types of portable spectrometers could meet the requirements specified in GBZ 129-2016 Specifications for individual monitoring of occupational internal exposure for thyroid monitoring equipment. The two types of spectrometers could be used for routine monitoring of internal contamination. The difference between the monitoring result of LaBr γ and HPGe γ spectrometers might be due to such factors as large uncertainty in short measuring time and low activity concentrations, incomplete identical of distance between probe and neck, probe angle setting, different response of equipment to the environment, background deduction method.

Feasibility study of predicting dose of radioiodine in hyperthyroidism patients based on neural network / 中华放射医学与防护杂志

Objective:To construct back propagation (BP) neural network model to predict the dose required for 131I therapy for hyperthyroidism and to calculate the personalized dose plan for patients. Methods:A complete set of data of patients treated for hyperthyroidism radioaiodine was collected from the nuclear medicine departments of several medical colleges in Shanghai, including history, examination result, treatment course, etc. As a result, a prediction model was established. The predicated result for BP neural network, radial basis function (RBF) neural network and Support Vector Machine (SVM) were compared by means of small sample data. The optimal model was selected to predict administrated dose and to finally test the accuracy of the model.Results:The average errors in BP neural network, RBF neural network and SVM model based on small samples were 5.53%, 7.09% and 9.64%, respectively. After comparison, BP neural network was selected to build the prediction model. 30 cases of data were selected by random sampling to verify the BP neural network. The mean error, mean square error, minimum error and maximum error of the prediction result were 7.22%, 0.053, 0.57% and 13.78%, respectively.Conclusions:In this study, a neural network prediction method was proposed to provide a more accurate dose for patients in need of radioiodine therap for hyperthyroidism, and to reduce the possibility of radiation damage or the unsatisfactory therapeutic effect caused by insufficient dose. It has clinical practical significance in providing the reference for clinicians to evaluate the administrated dose.

An investigation of hospitalization management and radiation protection in 131I treatment for thyroid cancer / 中国辐射卫生

Objective To investigate the status and problems of hospitalization management and radiation protection in 131I treatment for thyroid cancer, and to provide suggestions for medical institutions to implement relevant standards. Methods We investigated the status of radiation protection and management in 10 medical institutions conducting 131I treatment for thyroid cancer (6 in Shanghai, 2 in Zhejiang Province, and 2 in Jiangsu Province, China) by consulting written materials, expert interviews, and on-site inspection and testing. Results The average activity of 131I therapy for thyroid cancer in the 10 medical institutions was 110~120 mCi (4.07~4.44 GBq). All patients who received the treatment were hospitalized, with a stay of 3~7 days. Seven institutions carried out 131I dispensing, 6 of which used automatic 131I dispensing instruments. Nine institutions had an independent ventilation system in the wards, 8 of which regularly changed the filters. All the 10 institutions set special toilets and shower rooms in the wards, and had shielding facilities between sickbeds, with the lead equivalent from 0.5 mm Pb (lowest) to 10 mm Pb (highest). All the 10 institutions had intercom and monitoring facilities in the wards, 9 of which had a one-way access control system, and 4 of which had dose monitoring equipment. Nine institutions carried out surface pollution monitoring in the workplace, but none performed air pollution testing. All the 10 institutions required the radioactivity in the body of patients be less than 400 MBq before discharge, and five of them estimated the activity by measuring the dose rate at a certain distance from the body surface of patients. All the 10 institutions had radioactive sewage decay ponds, but none of them conducted regular monitoring. Rapid on-site surface pollution testing in the wards showed that highest value was 31.9 Bq/cm2. Conclusion The 10 medical institutions carried out 131I treatment for thyroid cancer basically according to the requirements of national laws, regulations, and standards, but there are still some problems in ward construction, radiation protection facilities, and patient hospitalization management, which should be further standardized.

Radioactive concentration of 131I in the air of treatment workplaces for differentiated thyroid cancer with sodium iodide 131I oral solution / 中国辐射卫生

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.

Investigation on the radiation of 131I in treatment site of a grade A tertiary hospital / 中国辐射卫生

Objective To detect the radiation of 131I in treatment site of a grade A tertiary hospital. Methods A total of 25 patients with thyroid cancer were administrated 131I at a total dose of 82880 MBq. After administration, the ambient dose equivalent rate of the ward was detected with X- and γ-ray detectors. After patient discharge, surface contamination of the ward was detected with α/β surface contamination meter. During patient hospitalization and on the day of discharge, air samples were collected from 131I treatment site and office area. The air samples were measured using a HPGe γ-ray spectrometer and the concentration of 131I in air was calculated. Results The ambient dose equivalent rate in the ward ranged from 0.15 to 0.46 μSv/h. Before ward cleaning, surface contamination ranged from 0.53 to 40.1 Bq/cm2 and the highest value was recorded on the toilet. Within 4 h after administration, the concentrations of 131I in air in treatment site and the corridor of the office area were 1.74 Bq/m3 and 0.66 Bq/m3, respectively. The ventilation air flow rate in the treatment site was 0.50 m/s. Ventilation decreased the concentration of 131I in air by 29.7%, 79.7%, and 53.3% compared with the previous day during hospitalization and on the day of discharge. Conclusion The radiation of external exposure of 131I in the treatment site is low and the shielding is effective. Before ward cleaning, the surface contamination is lower than the required limits except for the toilet. Ventilation is the primary way to reduce the concentration of 131I in air.

Monitoring results and analysis of 131I in the air of workplace treated with iodine / 中华放射医学与防护杂志

Objective:To understand the activity concentration of 131I aerosol in the air of the iodine treatment workplace and estimate the internal dose of 131I inhaled by medical staff in nuclear medicine. Methods:Using CF-1001BRL portable large capacity air sampler, the 131I aerosol in the iodine treatment workplace of nuclear medicine department of 6 hospitals in Shandong province was collected by iodine box, and the HPGe-γ energy spectrometer was used to measure the samples. The 131I activity concentration in iodine treatment workplace at 6 hospitals was obtained, and the internal dose to medical staff was estimated. Results:The 131I activity concentration in the air in iodine treatment workplaces at 6 hospitals ranged from 3.64 to 2.94×10 3 Bq/m 3. The 131I activity concentration in the controlled area (ward, patient passageway, subpacking room, operation administration room) was significantly higher than that in the supervised area. The highest 131I activity concentration, 2.62×10 2 Bq/m 3, in the supervised area was found in the medical care passageway. The estimated effective dose to nuclear medicine workers was 0.07-5.68 mSv, not exceeding the national limit. Conclusions:The phenomenon of 131I aerosol contamination still exists in the iodine treatment workplaces of nuclear medicine departments in hospitals, so it is necessary to carry out internal radiation monitoring for nuclear medicine departments all around the country, and explore more reasonable protection standards and methods.

Preliminary study on assessment of internal dose to workers exposed to 131I radionuclide / 中华放射医学与防护杂志

Objective:To explore the assessment methodology for internal dose to workers exposed to 131I radionuclide. Methods:Workers were chosen in a 131I radiopharmaceutial manufacturer and a nuclear medicine department in a hospital using 131I to treat hyperthyroidism and thyroid cancer. A portable high purity germanium (HPGe) gamma spectrometer was used to measure the content of 131I in the thyroid for 4 consecutive times in a period of 7 d. The internal dose was estimated combining with the work rotation mode for workers dealing with 131I. Results:When the monitoring month was used as a typical month to estimate the internal dose, the annual committed effective dose was 0.09-1.93 mSv for the production staff engaged in the repackaging of 131I radiopharmaceuticals in the surveyed enterprise, and 0.06-0.58 mSv for the nuclear medicine staff in the surveyed hospital. After adjusting the monitoring result of the current monitoring period based on the rotation mode, the annual committed effective dose was estimated to be 0.06-1.22 mSv for radiopharmaceutical production workers and 0.03-0.15 mSv for nuclear medicine workers, respectively. Conclusions:In the assessment of internal dose to radiation workers exposed to 131I, using a single time measurement result to estimate the annual dose would lead to a larger error. In the case of continuous monitoring, the result of subsequent monitoring periods should be corrected according to the result of previous monitoring periods. In order to accurately estimate the internal dose of workers exposed to 131I, it is necessary to take full account of the 131I exposure pattern, time and frequency and the internal contamination route. For workers who may be exposed to 131I with potential internal dose greater than 1 mSv/year, a 14 day-routine monitoring period was appropriate.