177Lu-based radioligand therapy: A retrospective multicenter analysis to calculate the effective half-life and follow-up dose for the public.

20. Radiation protection following iodine-131 therapy for thyroid cancers: Comparison of two methods to calculate restriction times

The current research aims to assess the staff and patients’ effective doses during Nuclear medicine (NM) bone scans procedures. The administered activity was utilized to quantify the patients’ effective doses, while personnel’s effective doses were quantified using thermoluminescent detectors (TLD-100). The average administered activity was 650 (440 to 1440) MBq procedures using SPECT gamma camera system. The average annual staff effective dose (mSv) was estimated to be 2.3 (0.1 to 4.9). The typical patient’s effective dose was 4.9 (3.6 to 6.0) mSv per procedure. Staff exposure within the yearly effective dose limits. Patients’ exposure optimization is required based on patient weight. Estimating staff eye lens doses is suggested to confirm that the yearly effective radiation doses are within the safety range.

Aims: The study aimed at measuring the external radiation doses to workers from patients who were administered radiopharmaceuticals in the nuclear medicine department. The purpose of this study was to evaluate the radiation safety procedures in the department of nuclear medicine. Methods: A total of 80 patients were randomly selected for the study. These patients were injected with either 99mTcpertechnetate or 99mTc-MDP (methylene diphosphonate). The dose rate was measured in hot lab, waiting room and in the scanning room at distances of 10, 50 and 100 cm from the patient at different time intervals by using a radiation survey meter. The absorbed dose from radioactive patient to radiation workers was calculated by using RADAR software and mathematical formulae from the measured dose rate. Results: The mean dose rate from thyroid scan atients at a distance of 10, 50 and 100 cm, after administration of injection was found to be 41 μSv/h, 31 μSv/h and 22 μSv/h respectively; whereas the dose rate from bone scan patients was calculated at 62 μSv/h, 31 μSv/h and 28 μSv/h. The dose rate was also measured after 15 min and 30 min in waiting and scanning room for the same patients. The mean absorbed dose to nuclear medicine occupational workers calculated both manually and using RADAR software came out to be less than 1mSv/year. Conclusion: The external doses to radiation workers were within permissible level. The results obtained in the present study are comparable to the previous studies conducted world wide. The radiation dose level to occupational workers in our nuclear medicine department does not exceed the recommended dose limits for workers.

TL measurement of ambient dose at a Nuclear Medicine Department

The occupational radiation exposure of medical radiation workers at the Institute of Oncology, Vilnius University (IOVU) was analysed. Quartile dose measurements were collected and routinely analysed for a period of 8 y from 1 January 2004 to 31 December 2011. A total of 193 medical radiation workers were monitored, comprising 34 % physicians (radiologists and radiotherapists), 8 % physicists, 42 % radiological technologists and 16 % ancillary staff. A statistically significant decrease by 18 % has been detected when comparing the annual average effective doses (AAEDs) received by medical radiation workers at the IOVU during periods 2004-2007 and 2008-2011 (p < 0.0001). The main occupation categories responsible for this reduction were of Nuclear Medicine (p < 0.028) and Radiology (p < 0.0001) departments. The values of AAED in Radiology, Radiotherapy and Nuclear Medicine departments are quite low and well below the annual limit of 20 mSv, averaged over a period of 5 consecutive years.

In-vivo dosimetry in 3D conformal radiotherapy of breast and head and neck cancer

Preparation for postoperative radioiodine ablation for differentiated thyroid carcinoma is performed by either thyroid hormone withdrawal or recombinant human thyroid-stimulating hormone (rhTSH) administration. There is little information on the impact of the method of preparation with respect to whole-body effective I-131 half-life and its potential clinical implications in the Australian setting. A retrospective study was performed on patients admitted for adjuvant radioiodine ablation for non-metastatic differentiated thyroid carcinoma at the Royal Adelaide Hospital over a 4½-year period from 2009. Dose rate measurements were analysed for 19 rhTSH and 31 thyroid hormone withdrawal patients. The mean effective I-131 half-lives were 11.51 and 13.29 h for the rhTSH and thyroid hormone withdrawal groups, respectively, with no statistically significant difference between the two groups (P = 0.761). This result differs from previously published data where withdrawal periods were typically longer, resulting in slower renal clearance and longer half-lives for withdrawal patients. Our study did not demonstrate a significant difference in whole-body effective half-life of I-131 between the two methods of preparation for radioiodine ablation. This suggests that putative advantages of rhTSH over withdrawal in terms of whole-body radiation dose, duration of hospital admission and quality of life may be sensitive to duration of withdrawal.

Introduction: Gastric emptying scintigraphy (GES) is a safe, noninvasive method for assessing the ability of the stomach to empty which has been used clinically for many years. It is considered as a “gold standard” to assess gastric emptying of both solids and liquids allowing assessment of early, mid and late emptying, each of which may be altered by pathology. The aim of the study was to analyse standard diagnostic approach and evaluate patients` radiation exposure, who underwent GES in Slovakia. Methods: A retrospective cohort study included 55 patients from 2 departments of nuclear medicine (department A, B). Patients’ radiation exposure was determined by dosimetry program IDAC-Dose2.1. The radiopharmaceutical 99mTc-DTPA, always with the same activity, was applied orally to patients at Department B. The applied activity of the radiopharmaceutical at GES was 185 MBq. The radiopharmaceutical 99mTc MAA, with various activity, was applied orally to patients at Department A. Results: According to ICRP60, the eff ective dose (ED) of every patient undergoing GES was 0.77 mSv and, according to ICRP103, the dose was 0.836 mSv at Department B. Patients at Department A were exposed to ionizing radiation with 5-times lower intensity, compared with patients at Department B. It was caused by radiopharmaceutical activity correction. The ED medians according to ICRP60, and according to ICRP103 were 0.167 mSv (range 0.105–0.208 mSv) and 0.181 mSv (range 0.113–0.226 mSv) at Department A, respectively. Discussion: Adequate correction of applied radiopharmaceutical activity is an essential part of GES guidelines and in accordance with ALARA principles. For the accuracy of GES examination, it is necessary to follow a standard 4-hour protocol and an approach which ensures full-featured utilization of the examination while decreasing patient`s radiation exposure. Conclusion: The results of our study show relatively low ED associated with GES, but also confi rm that the GES methodology significantly affects the patient`s radiation exposure

Should early post-stress imaging be performed on a routine clinical basis for myocardial perfusion studies?

Adjuvant radioiodine therapy (RITh) for differentiated thyroid carcinoma is performed either with thyroid hormone withdrawal or with administration of recombinant human thyroid-stimulating hormone (rhTSH). Heterogeneous results have been obtained on the impact of the method of patient preparation on thyroid uptake and whole-body effective half-life. A higher radiation exposure using thyroid hormone withdrawal for several weeks compared with rhTSH was reported in prior studies. It was the aim to examine whether these findings are reproducible in a modern protocol with a short interval between surgery and RITh. Methods: A retrospective study was performed on patients admitted for adjuvant RITh for differentiated thyroid carcinoma at the University Hospital of Cologne over a 5-y period from 2010. Dose rate measurements were analyzed for 366 patients, and subgroup analyses were performed for papillary thyroid cancer (n = 341) and follicular thyroid cancer (n = 25) patients, sex, length of hypothyroidism, and normal versus decreased glomerular filtration rate (GFR). Results: The median interval between surgery and RITh was 18 d for thyroid hormone withdrawal and 25 d for rhTSH (P < 0.01). The mean thyroid uptake was 4.2% ± 1.8% for the 300 hypothyroid patients versus 3.8% ± 1.6% (P = 0.12) for the 66 rhTSH patients. Whole-body half-life in the hypothyroid group was significantly longer at 19.3 ± 7.7 h versus 16.4 ± 4.6 h in the rhTSH group (P < 0.01). Results were predominantly influenced by data from the largest subgroup, that is, female papillary thyroid cancer patients. Within this group, whole-body half-life was significantly shorter in the rhTSH treatment arm. Duration of hypothyroidism and a decrease in GFR less than 60 mL/min/1.73 m2 significantly influenced results, with an increased whole-body half-life occurring in the hypothyroid group. When patients returned for whole-body scintigraphy, thyroid, half-life, and whole-body half-life were significantly shorter in the rhTSH groups, resulting in a low thyroid and remaining-body dose. Conclusion: With a shortening of the time between surgery and adjuvant RITh, thyroid uptake is not significantly changed but whole-body half-life becomes longer in the hypothyroid group. Radiation exposure for most patients is not significantly different. However, patients with a hypothyroid phase of more than 4 wk, and in particular those with a decreased GFR, experience higher radiation exposure.

Presented paper describes the results of the individual doses measurements for ionizing radiation, carried out by the Laboratory of Individual and Environmental Doses Monitoring (PDIS) of the Central Laboratory for Radiological Protection in Warsaw (CLOR) for the medical staff employees in several nuclear medicine (NM) departments across Poland. In total there are48 NM departments in operation in Poland [1] (consultation in Nuclear Atomic Agency). Presented results were collected over the period from January 2011 to December 2011 at eight NM departments located in Krakow, Warszawa (two departments), Rzeszow (two departments), Opole, Przemysl and Gorzow Wielkopolski. For radiation monitoring three kinds of thermo luminescence dosimeters (TLD) were used. The first TLD h collected information about whole body (C) effective dose, the second dosimeter was mounted in the ring (P) meanwhile the third on the wrist (N) of the tested person. Reading of TLDs was performed in quarterly periods. As a good approximation of effective and equivalent dose assessment of operational quantities both the individual dose equivalent Hp(10) and the Hp(0.07) were used. The analysis of the data was performed using two methods The first method was based on quarterly estimations of Hp(10)q and Hp(0.07)q while the second measured cumulative annual doses Hp(10)a and Hp(0.07)a. The highest recorded value of the radiation dose for quarterly assessments reached 24.4 mSv and was recorded by the wrist type dosimeter worn by a worker involved in source preparation procedure. The mean values of Hp(10)q(C type dosimeter) and Hp(0.07)q (P and N type dosimeter) for all monitored departments were respectively 0.46 mSv and 3.29 mSv. There was a strong correlation between the performed job and the value of the received dose. The highest doses always were absorbed by those staff members who were involved in sources preparation. The highest annual cumulative dose for a particular worker in the considered time period was 4.22 mSv for Hp(10)a and 67.7 mSv for Hp(0.07)a. In 2011 no case of exceeding the allowed dose limits was noted.

In this study, the occupational radiation dose, radon gas, and non-ionizing radiation doses originating from electromagnetic fields (EMF) to which radiation workers are exposed were monitored and evaluated for 1 y. Using electronic personnel dosimeters (EPD), average daily radiation doses based on the number of patients and annual average effective dose results of radiation workers were obtained over a period of 1 y. Also, the annual effective dose and risk values were calculated for 8 h and 24 h by taking radon gas measurements at 2-mo intervals in the nuclear medicine department. Finally, electric field measurements were made one day a week in the selected areas. All the results obtained were compared with national and international dose limits. The results obtained as a result of EPD, radon gas, and EMF measurements made in the nuclear medicine department were found to be far below the international and national legal dose limits.

Occupational exposure in Bosnia and Herzegovina is regulated by the national regulation on radiation protection for occupational and public exposure. All radiation workers are required to be monitored using whole body passive thermoluminescent dosemeters and, in case of non-uniform external exposures, by dosemeters that would indicate dose to the most affected body parts. Exposed workers are almost exclusively employed in the medical field, and some of them work in nuclear medicine departments where they handle unsealed radioactive sources. Introduction of the positron emission tomography-computed tomography (PET-CT) in two largest clinical centers in the country was expected to cause the increase of equivalent doses to hands received by staff handling the positron emitting radionuclides. Hence, routine monitoring of finger doses became a necessity. The purpose of this study was to evaluate the available data on monitoring with ring dosemeters during PET-CT procedure in two hospitals in Bosnia and Herzegovina and compare them with other practices in the nuclear medicine department, as well as with the results of monitoring in other countries. In general, results confirm that effective doses, as well as equivalent doses to hands, are well below annual dose limits. Finger dosemeters have been proven to be an invaluable asset in the incidental situations that sometimes occur in nuclear medicine departments. Different number of patients and differences in injection methodologies are identified as a possible source of differences between doses in two hospitals. Overall, routine evaluation of doses to hands provides a sound basis for possible optimization processes, as well as confirmation of good practices.

BackgroundThe control of the delivery of radiopharmaceuticals is the first activity for the staff of radiopharmacy.PurposeFor a secure process of delivery and for staff, we set up controls for parcels...

Occupational radiation exposure in nuclear medicine department in Kuwait