Occupational radiation exposure among the staff of departments of nuclear medicine and diagnostic radiology in Kuwait

Radiation dose to health care workers measured by thermoluminescent dosimetry

AIM

To evaluate radiation dose among physicians, nurses, nuclear medicine (NM) technicians, and radiographers at a single institution and to compare the difference in the measured dose during COVID-19 with other periods.

MATERIALS AND METHODS

A retrospective analysis of the occupational radiation doses received by all workers in diagnostic radiography and NM departments at a single institution during a 5-year period (2018-2022) was performed. Dose measurements were recorded for 94 radiology personnel: radiographers, NM technicians, physicians, and nurses. In addition to descriptive statistics, the Mann-Whitney U-test was used to compare the average annual effective dose between male and female workers and between the periods before and during COVID-19. Kruskal-Wallis test was used to compare effective radiation doses from different quadrants.

RESULTS

The annual average effective doses were found to be between 0.58 and 0.72 mSv for males and 0.68 and 0.85 mSv for females. All radiographers, 86% of nurses, and 69% of physicians have received annual average effective doses below 0.99 mSv. The average annual effective doses for all radiation workers were similar in the period before COVID-19 when compared to the period during COVID-19 except for nurses who had significantly lower (P<0.05) doses before COVID-19.

CONCLUSION

The average annual effective doses of radiation workers during 2018-2022 were well below the annual dose limit. A relatively higher average effective dose was received among NM technicians compared with other radiation occupational workers. While the caseload during the COVID-19 pandemic was lower due to government policies, the radiation dose to healthcare workers during the pandemic was similar to that before the pandemic.

Assessment of Occupational Radiation Exposures at Ghana Research Reactor-1 Facility

The annual occupational doses for workers at the Ghana Research Reactor-1 facility were assessed for the period 2018-2021. The dose records of monitored staff were retrieved and analysis done for dose distribution and collective effective doses. Thermoluminiscent dosimeters were used to monitor the occupational exposures. The dosimeters were evaluated for the cumulative radiation dose levels using the Harshaw 6600 TLD reader system. Annual dose of 1.52 mSv/year was the maximum acquired by an individual. An annual average effective dose range of 0.20-1.36 mSv was determined for all workers. The annual total collective effective dose was established to be in the range of 0.40-10.08 man-Sv. The 20 mSv annual limit for occupational exposure was not exceeded for monitored workers. The assessment shows that the GHARR-1 facility, in terms of radiation health effects, is a favorable environment for workers since exposures are mostly below occupational exposure limit.

Evaluation of personal dose equivalents during positron emission tomography and computed tomography imaging

This study aimed to evaluate the annual occupational radiation exposure of technologists during PET/CT imaging in 2020 and 2021. Eleven nuclear medicine technologists were monitored at the PET/CT department. The personal dose equivalents (PDEs) for staff members, measured in terms of Hp (10) and Hp (0.07), were assessed annually, considering both deep and surface doses. PDEs were quantified using a thermoluminescent detector (LiF:Mg:Ti)). The average and range of PDEs and extremity doses (mSv) for the technologists were as follows: 4.5 (0.1-13.4) for Hp (10), 4.63 (0.1-13.9) for Hp (0.07), and 2.5 (0.2-17.5) for extremity, respectively. The results indicated that staff members are exposed to high-energy gamma rays while preparing radiopharmaceuticals, injections, and image acquisition. Therefore, proper handling of radiopharmaceuticals and patient management during the acquisition of parameters are crucial for maintaining the occupational dose within the defined limit.

Evaluation of institutional whole-body and extremity occupational radiation doses in nuclear medicine

This study evaluated nuclear medicine occupational radiation doses at Sultan Qaboos University Hospital, a 700-bed tertiary care teaching hospital in Oman. Personal effective whole-body doses, Hp(10), and extremity doses, Hp(0.07), were collected for 19 medical radiation workers over a 7-year period (2015-2021). Personal doses for four professional groups were measured using calibrated thermo-luminescence dosemeters ((LiF:Mg,Ti) TLD-100). The average, median and maximum cumulative doses were compared against the annual whole-body and extremity dose limits (20 mSv and 500 mSv y-1, respectively) and local dose investigation level (DIL; 6 mSv y-1). Personal whole-body doses (average:median:maximum) for technologists, medical physicists, nuclear medicine physicians and nurses were 1.8:1.1:7.8, 0.3:0.3:0.4, 0.1:0.1:0.2 and 0.1:0.1:0.2 mSv, respectively. Personal extremity doses for left and right hand (average and maximum doses) follow similar trends. Average annual effective whole-body and extremity doses were well below the recommended annual dose limits. The findings suggest lowering local DIL for all staff except for technologists.

Occupational radiation exposure dose and associated factors among radiology personnel in Eastern Amhara, Ethiopia

BACKGROUND

Ionizing radiation is being used more frequently in medicine, which has been linked to recognized biological effects such as cancer and mortality. Radiology services are becoming more widely available in Ethiopian health facilities but there is no compiled record of worker's radiation dose. So, assessing the magnitude and identifying the associated factors of occupational radiation exposure dose among radiology personnel help to design strategies for radiation protection.

OBJECTIVE

The study was designed to assess the occupational radiation exposure dose and associated factors among radiology personnel in eastern Amhara, northeast Ethiopia, 2021.

METHODS

Cross-sectional study was conducted from March 25 to April 30, 2021, in 57 health institutions among 198 radiology personnel. The study comprised all eligible radiology personnel. The data were collected using an electronic-based (Google form) self-administered questionnaire, and document review. The data were entered into an excel spread sheet and then, exported to Stata 14 software. Linear regression model was used to analyse the data after checking its assumptions. Variables with a p-value < 0.25 were entered into a multiple linear regression analysis, and those with a p-value < 0.05 were judged significant. VIF was used to check for multi-collinearity. Coefficient of determination was used to check the model fitness.

RESULTS

The mean (± SD) annual shallow and deep dose equivalents of radiology personnel were 1.20 (± 0.75) and 1.02 (± 0.70) mSv, respectively. Body mass index (β = 0.104, 95% CI: 0.07, 0.14), practice of timing (β = -0.43, 95% CI: -0.73, -0.13), working experience (β = -0.04, 95% CI: -0.048, -0.032), and practice of distancing (β = -0.26, 95% CI: -0.49, -0.17) were found to be statistically significant factors of annual deep dose equivalent. In addition, body mass index (β = 0.113, 95% CI: 0.08, 0.15), practice of timing (β = -0.62 95% CI: -0.93, -0.31) and, working experience (β = -0.044, 95% CI: -0.053, -0.036 had statistically significant associations with annual shallow dose equivalent.

CONCLUSION

The annual dose equivalents were two times higher than the global average of annual per caput effective dose due to medical exposure. Body mass index, practice of timing, working experience, and practice of distancing were factors of occupational radiation exposure dose. Strategies focusing on increasing the skill, experience, and lifestyle of radiology personnel would be supreme important means to reduce occupational radiation exposure dose.

Evaluation occupationally radiation exposure during diagnostic imaging examinations

Occupational radiation exposure can occur due to various human activities, including the use of radiation in medicine. Occupationally exposed personnel surpassing 7.4 millions, and respresent the biggest single group of employees who are exposed to artificial radiation sources at work. This study compares the occupational radiation dose levels for 145 workers in four different hospitals located in the Aseer region in Saudi Arabia. The occupational exposure was quantified using thermoluminescence dosimeters (TLD-100). The levels of annual occupational exposures in targeted hospitals were calculated and compared with the levels of the international atomic energy agency (IAEA) Safety Standards. An average yearly cumulative dose for the two consecutive years. The average, highest and lowest resulted occupational doses under examination in this work is 1.42, 3.9 mSv and 0.72 for workers in various diagnostic radiology procedures. The resulted annual effective dose were within the IAEA approved yearly dose limit for occupational exposure of workers over 18, which is 20 mSv. Staff should be monitored on a regular basis, according to current practice, because their annual exposure may surpass 15% of the annual effective doses.

Diagnostic and therapeutic radioisotopes in nuclear medicine: Determination of gamma-ray transmission factors and safety competencies of high-dense and transparent glassy shields

We present the findings of an extensive examination on newly designed CdO-rich and transparent glass shields for nuclear medicine facilities in lieu of traditional and unfavorable materials, such as lead and concrete. Gamma-ray transmission factors of newly designed glass shields are determined using a variety of diagnostic, therapeutic, and research radioisotopes, including 67Ga, 57Co, 111In, 201Tl, 99mTc, 51Cr, 131I, 58Co, 137Cs, 133Ba, and 60Co. A general-purpose Monte Carlo code MCNPX (version 2.7.0) is used to determine the attenuation parameters of different material thicknesses. Next, the findings are compared using a standard concrete shielding material. The results indicate that adding more CdO to the glass composition improves the overall gamma-ray attenuation properties. As a result, among the heavy and transparent glasses developed, the C40 sample containing 40% CdO exhibited the best gamma-ray absorption properties against all radioisotopes. Furthermore, the gamma-ray absorption characteristics of this created high-density glass were shown to be better to those of a standard and heavy concrete sample. It can be concluded that the newly developed CdO-rich and transparent glass sample may be used in medical radiation fields where the radioisotopes examined are used in daily clinical and research applications.

Evaluation of annual staff doses and radiation shielding efficiencies of thyroid shield and lead apron during preparation and administration of 131I, 81Kr, and 99mTc-Labeled radiopharmaceuticals

Nuclear medicine technicians would receive unavoidable exposures during the preparation and administration of radiopharmaceuticals. Based on the staff dose monitoring, the dose reduction efficiencies of the radiation protection shields and the need to implement additional strategies to reduce the staff doses could be evaluated. In this study, medical staff doses during the preparation and administration of Tc-99 m, I-131, and Kr-81 radiopharmaceuticals were evaluated. The dose reduction efficiencies of the lead apron and thyroid shield were also investigated. GR-207 thermoluminescent dosimeter (TLD) chips were used for quantifying the medical staff doses. The occupational dose magnitudes were determined in five organs at risk including eye lens, thyroid, fingers, chest, and gonads. TLDs were located under and over the protective shields for evaluating the dose reduction efficiencies of the lead apron and thyroid shield. The occupational doses were normalized to the activities used in the working shifts. During preparation and injection of Tc-99 m radiopharmaceutical, the average annual doses were higher in the chest (4.49 mGy) and eye lenses (4 mGy). For I-131 radiopharmaceutical, the average annual doses of the point-finger (15.8 mGy) and eye lenses (1.23 mGy) were significantly higher than other organs. During the preparation and administration of Kr-81, the average annual doses of the point-finger (0.65 mGy) and chest (0.44 mGy) were higher. The significant dose reductions were achieved using the lead apron and thyroid shield. The radiation protection shields and minimum contact with the radioactive sources, including patients, are recommended to reduce the staff doses.

OCCUPATIONAL EXPOSURE IN RADIATION APPLICATIONS IN INDIA: TRENDS AND DISTRIBUTION ANALYSIS

Occupational exposure data in radiation applications provide a good insight on the radiation risks to workers from occupational hazards, the safe practices adopted and in deriving methods to prevent possible radiation exposures. The analysis of occupational exposure may be used to provide regulatory guidance and more focused attention to improve the safety systems, thus improving the personnel and environment safety. In this study, occupational exposure from radiation applications during 2004-18 amounting to a total number of 1951 486 occupational dose data are collected and analysed using the statistical software package, SPSS. As recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation, four critical parameters viz., annual collective effective dose, average annual effective dose, individual dose distribution ratio and the annual collective dose distribution ratio for each practice are estimated. Using the trend observed for these parameters, it is predicted that occupational exposure in diagnostic radiology in the year 2023 would increase by 80% in total number of monitored with 76% increase in average collective dose and no significant change in average annual effective dose. In the same manner, nuclear medicine would see 28% of increase in radiation workers with the increase of 24% in collective dose with no significant change in average annual effective dose. Further, the reasons and area of regulatory focus for the different practices are discussed.

Occupational exposure and radiobiological risk from thyroid radioiodine therapy in Saudi Arabia

Worldwide, thyroid cancer accounts for some 10% of total cancer incidence, most markedly for females. Thyroid cancer radiotherapy, typically using 131I (T1/2 8.02 days; β- max energy 606 keV, branching ratio 89.9%), is widely adopted as an adjunct to surgery or to treat inoperable cancer and hyperthyroidism. With staff potentially receiving significant doses during source preparation and administration, radiation protection and safety assessment are required in ensuring practice complies with international guidelines. The present study, concerning a total of 206 patient radioiodine therapies carried out at King Faisal Specialist Hospital and Research Center over a 6-month period, seeks to evaluate patient and occupational exposures during hospitalization, measuring ambient doses and estimating radiation risk. Using calibrated survey meters, patient exposure dose-rate estimates were obtained at a distance of 30-, 100- and 300 cm from the neck region of each patient. Occupational and ambient doses were measured using calibrated thermoluminescent dosimeters. The mean and range of administered activity (AA, in MBq) for the thyroid cancer and hyperthyroidism treatment groups were 4244 ± 2021 (1669-8066), 1507.9 ± 324.1 (977.9-1836.9), respectively. The mean annual occupational doses were 1.2 mSv, that for ambient doses outside of the isolation room corridors were found to be 0.2 mSv, while ambient doses at the nursing station were below the lower limit of detection. Exposures to staff from patients being treated for thyroid cancer were less compared to hyperthyroidism patients. With a well-defined protocol, also complying with international safety requirements, occupational exposures were found to be relatively high, greater than most reported in previous studies.

Experimental Assessment of Workplace Radiation Exposure in Diagnostic X-ray Medical Imaging Centres in Benin from 2019 to 2020

The ease of prescribing radiological examinations has prompted an expansion in radiological procedures and, consequently, an increase of occupational dose to medical imaging workers. However, little is known about radiation exposure in the workplace of medical radiology professionals in many countries, and in Benin particularly. The purpose of this study was to assess ambient radiation doses in diagnostic X-ray medical facilities in Benin and to observe whether exposure levels are below reference levels. A total of 72 public and private medical imaging centres participated in a cross-sectional study carried out from June 2019 to February 2020 in Benin. These centres had 59 X-ray, four chest and six computed tomography (CT) scan rooms. A calibrated radiameter able to measure short, pulsed or continuous X fields and gamma/beta (50 nSv to 10 Sv) was used to measure exposure levels in these functional rooms. Scattered X-ray doses and exposure time from radiological examinations both behind the lead glass of the control area to assess the levels of exposure of professionals and outside of the examination room to evaluate the level of exposure of the public (including non-exposed workers) have been provided. Equivalent doses estimated per hour were compared with the reference levels of 7.50 and 0.05 µSv per hour for workers and the public, respectively. At the control area, the mean/median (min-max) equivalent doses were 0.09/0.07 (0.00-0.21), 2.39/0.13 (0.00-75.67), and 228.39/28.65 (0.39-869.75) µSv per hour for the chest, X-ray, and CT-scan rooms, respectively. Among 69 examination rooms, 13.04% of the equivalent dose estimated in the workplace behind the lead glass was greater than 7.50 µSv per hour; 65 out of 69 examination rooms showed that 40.00% of the equivalent dose estimated behind the doors was greater than 0.05 µSv per hour. These results demonstrated that current controls, including leaded glass separating the control panel and leaded doors between the examination room and the corridor, are inadequate to limit radiation exposures. The controls must be upgraded and a dosimetry program should be implemented to monitor exposures of employees, patients, and visitors.

ASSESSMENT OF OCCUPATIONAL RADIATION DOSES OF MEDICAL RADIATION WORKERS IN TWO COMMUNITY HOSPITALS

The International Commission on Radiological Protection recommends the adoption of the linear, no-threshold model as a predictive risk model for radiation protection purposes since the relationship between low-dose radiation exposure and cancer risk is unclear. Medical radiation workers are subject to occupational exposures and differences in workload, area of work and types of exposure can lead to variations in exposures between different occupational groups. We investigated the occupational exposures of 572 workers from four departments in two community hospitals and stratified into 22 occupational groups in order to identify groups with the highest radiation exposure. The occupational doses from 2015 to 2019 were analyzed to identify the dose distribution of each occupational group, total number of monitored workers, annual and collective deep (Hp(10)), eye (Hp(3)) and shallow (Hp(0.07)) doses. We further determined the individual and occupational group lifetime doses as well as the probability that monitored workers' lifetime doses will exceed a specified lifetime dose level. The occupational groups with the highest radiation exposures were the nuclear medicine technologists, diagnostic imaging radiologists and diagnostic cardiologists. Although our data suggest that occupational doses reported are low, it is essential that exposure of occupationally exposed personnel are always kept as low as reasonably achievable with an effective radiation protection program.

ASSESSMENT OF OCCUPATIONAL EXPOSURE OF RADIATION WORKERS AT A TERTIARY HOSPITAL IN ANHUI PROVINCE, CHINA, DURING 2013-18

Data on occupational radiation exposure of radiation workers at a tertiary hospital in China during 2013-18 were analyzed to provide decision-making advice for hospitals and health administrative departments. A total of 1255 exposure records of radiation workers were collected. The average annual effective doses of radiation workers during 2013-18 was 0.4977 mSv, with 1150 (91.63%) records ranging between 0 and 1 mSv, 91 (7.25%) between 1 and 2 mSv, 10 (0.80%) between 2 and 5 mSv and 4 (0.32%) records exceeding 5 mSv. There was a significant difference in the average annual effective dose of radiation workers among different occupational categories except in 2015 indicating that hospitals and administrative authorities should pay more attention to the radiation workers in the nuclear medicine and intervention department. The average annual effective doses did not show significant differences between male and female workers except in 2017; in that year the average individual dose of female workers was higher than male workers'. There were no significant differences in the average annual effective doses among doctors, nurses and radiologic technologists except in 2016 and 2017; during that period the individual dose of nurses was higher than doctors' and radiologic technologists'.

MEASUREMENT OF OPERATIONAL DOSIMETRY QUANTITIES FOR NUCLEAR MEDICINE STAFF

According to the ALARA principle, exposure to radiation should be reduced as low as reasonably achievable. This principle is very important in nuclear medicine (NM), and different investigations have been performed by establishing protocols and standards for staff protection. This study aims to measure the operational quantities, personal dose equivalent, Hp (10), Hp (0.07) and Hp (3) for NM staff in Shiraz hospitals, and comparison with dose limits. Two types of dosimeters, TLD-100 and GR-200, were used in this study. In the first step, the calibration of dosimeters was performed using different phantoms. Then, a group of dosimeters was prepared and used for 1 month on the heads, wrists and chests of the staff for measurement of Hp (3), Hp (0.07) and Hp (10), respectively. The obtained values of Hp (10) were compared with the results of their personal dosimetry, film badge. The results of this study show good consistency in the measurements using the two dosimeters.

ESTIMATION OF OCCUPATIONAL RADIATION EXPOSURE FOR MEDICAL WORKERS IN RADIOLOGY AND CARDIOLOGY IN THE UNITED ARAB EMIRATES: NINE HOSPITALS EXPERIENCE

PURPOSE

Occupational radiation exposure for medical workers in radiology and cardiology was analyzed in nine hospitals in the UAE between 2002 and 2016. The purpose of the study was to determine the time trend and the differences in occupational radiation exposure among worker groups and hospitals in the country.

METHODS

Readings of 5700 thermoluminescence dosimeters (TLDs) were obtained from 1011 medical workers and grouped into 5 worker groups (radiographers, diagnostic radiologists, nurses, cardiologists and physicians).

RESULTS

The mean annual effective dose was from 0.38 to 0.62 mSv per worker. Even though an increase in the collective effective dose has been noticed during the study period, no significant time trend was observed in the mean effective dose. Furthermore, cardiologists received higher mean and maximum effective doses than the other worker groups.

CONCLUSION

The annual effective doses were below the limits set by national legislation and international standards, and for the average worker, the likelihood of high exposure is small. However, improvements in radiation protection practices could be implemented to reduce occupational radiation dose to cardiologists, who were the most exposed worker group in this study.

Radiation dose assessment for occupationally exposed workers in Malawi

Background

The objective of this study was to assess individual doses received by radiographers, and the scattered radiation dose rate reaching the control panel in X-ray departments of three hospitals in Malawi, in-order to compare them against the internationally recommended limits.

Methods

Themoluminescent Dosimeters were issued to fifteen (15) radiographers to record their dose for a month. Dose rate measurements were recorded using survey meters.

Results

Average monthly dose for workers was 0.247mSv. Average ambient dose rate values were 0.39µSv/hr for Mtengo wa Nthenga Hospital, 5.03µSv/hr for Bwaila Hospital and 4µSv/hr for Kamuzu Central Hospital.

Conclusions

Dose levels are below the limits recommended by the International Commission on Radiological Protection (ICRP).

Staff and ambient radiation dose resulting from therapeutic nuclear medicine procedures

With associated cure rates in excess of 90%, targeted ¹³¹I radioactive iodine therapy has clearly improved thyroid cancer survival. Thus said, potential radiation risks to staff represent a particular concern, current study seeking to determine the radiation exposure of staff from ¹³¹I patients during hospitalization, also estimating accumulated dose and related risk to staff during preparation of the radioactive iodine. In present study made over the three-month period 1st February to 1st May 2017, a total of 69 patient treatments were investigated (comprising a cohort of 46 females and 23 males), this being a patient treatment load typically reflective of the workload at the particular centre for such treatments. The patients were administered sodium iodide ¹³¹I, retained in capsules containing activities ranging from 370 to 5550 MBq at the time of calibration, radioiodine activity depends on many factors such as gender, clinical indication, body mass index and age. The staff radiation dose arising from each patient treatment was measured on three consecutive days subsequent to capsule administration. In units of µSv, the mean and dose-rates range at distances from the patients of 5 cm, 1 m and 2 m were 209 ± 73 (165-294), 6.8 ± 2 (5.3-9.5) and 0.9 ± 0.3 (0.7-1.2). The annual dose (also measured in units of µSv), based on annual records of doses, for medical physicists, technologists and nurses were 604, 680 and 1000 µSv respectively. In regard to current practice and workload, staff exposures were all found to be below the annual dose limit for radiation workers.

Radiation exposure among medical professionals working in the Intensive Care Unit

Background and Aims:

With the expanding use of diagnostic and therapeutic radiological modalities in critically ill patients, doctors working in Intensive Care Units (ICUs) are increasingly exposed to ionizing radiation. This risk of radiation exposure occurs not only during bedside radiologic procedures, but also when ICU physicians accompany patients to radiology suites. The aim of this study was to quantify levels of radiation exposure among medical professionals working in the ICU.

Materials and Methods:

The study was carried out prospectively over 6 months in the ICU of a tertiary-referral cancer hospital. Two teams consisting of 4 ICU resident doctors each were instructed to wear thermoluminescent dosimeters (TLDs) during their duty shifts. Standard radiation protection precautions were used throughout the study period. TLDs were also placed in selected areas of the ICU to measure the amount of scattered radiation. TLDs were analyzed at the end of every 3 months.

Results:

The readings recorded on TLDs placed in the ICU were almost immeasurable. The mean value of residents' radiation exposure was 0.059 mSv, though the highest individual reading approached 0.1 mSv. The projected maximum yearly radiation exposure was 0.4 mSv.

Conclusions:

If standard radiation safety precautions are followed, the cumulative radiation exposure to ICU resident doctors is well within permissible limits and is not a cause of concern. However, with the increasing use of radiological procedures in the management of critically ill patients, there is a need to repeat such audits periodically to monitor radiation exposure.