Occupational Radiation Dose Research Articles

Thyroid scintigraphy of healthy cats using small-field-of-view gamma cameras

IntroductionSmall-field-of-view (SFOV) gamma cameras can offer higher sensitivities than conventional gamma cameras. However, there are currently no reports on the efficacy and safety of thyroid scintigraphy using SFOV gamma cameras in veterinary medicine. Therefore, we aimed to evaluate the efficacy and radiation safety of an SFOV gamma camera for feline thyroid scintigraphy.Materials and methodsThree veterinary staff members (operator, staff 1, and staff 2) performed thyroid scintigraphy on 10 healthy cats in this study. The operator administered either 2 or 4 mCi of technetium-99m pertechnetate (99mTcO−4) through the cephalic vein. At 20, 40, and 60 min after injection, thyroid images were obtained using a SFOV gamma camera under various acquisition conditions (100,000, 150,000, and 200,000 counts and 30 and 60 s). Thyroid scintigraphy images were analyzed by calculating the thyroid-to-salivary ratios (TSR) and thyroid-to-background ratios (TBR). Surface and ambient radiation were measured hourly from immediately after injection to 6 h. The cumulative occupational radiation doses were measured during the procedure.ResultsThe TSR and TBR median values aligned with the previously reported normal range obtained using a large-field-of-view gamma camera. There were no notable differences in TSR and TBR between the two doses of 99mTcO−4, nor across acquisition conditions and timelines. The 4-mCi group consistently emitted more ambient (p < 0.05) and surface (p < 0.05) radiation than did the 2-mCi group. Staff 1 consistently received higher cumulative radiation doses than did staff 2 and the operator (p < 0.05).ConclusionThe SFOV gamma camera demonstrated adequate image quality for thyroid scintigraphy in healthy cats even with relatively low doses and short acquisition conditions. Radiation exposure during the procedure posed minimal safety concerns. Therefore, the SFOV gamma camera could be a valuable tool for evaluating thyroid glands in cats.

Radiation dose to health care workers measured by thermoluminescent dosimetry

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. 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. 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. 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 doses to eye lens during interventional radiology procedures

Assessment of occupational radiation doses to eye lens during interventional radiology procedures

The estimation of the occupational radiation dose for medical staff in Thailand by using retrospective annual dosimetry data

The estimation of the occupational radiation dose for medical staff in Thailand by using retrospective annual dosimetry data

Comprehensive analysis of occupational radiation exposure and radiation safety practices in cardiac catheterization laboratories: A five-year experience

AimThe objective is to analyze the occupational radiation dose experienced by medical workers in the Cardiac catheterization Lab in Bahrain and evaluate their adherence to established radiation safety protocols. Material and methodsRetrospective analysis for the Hp(10) and Hp(0.07) doses over a five-year (2017–2021). Descriptive analyses conducted for both annual dose and cumulative data across all years for all healthcare workers. A questionnaire was administered to evaluate their adherence to radiation safety protocols. Descriptive statistics were conducted for all responses and ANOVA was conducted to discern differences in best practices across various demographics groups. ResultsNo single dose exceeded the dose limits and 89.4% of the workers received Hp(10) and Hp(0.07) radiation doses of less than 2 mSv. The overall mean and range of the annual Hp(10) and Hp(0.07) radiation dose over the 5-year study period for all workers were 1.07 (9.50-0.01) and 0.64 (11.30-0.02), respectively. The overall mean and range of the annual Hp(10) and Hp(0.07) (mSv) for cardiologists were 1.79 (9.50-0.04) and 1.42 (11.30-0.07), respectively. The survey showed inconsistent practices and gaps. In best practice scoring, physicians had highest score and cardiovascular technologists scored the lowest. ConclusionIt is important to emphasize proper radiation safety practices for healthcare professionals to reduce the risk of long-term repeated exposure. Commitment to radiation safety is shows the dedication to providing high-quality care and adhering to radiation safety practices is an ethical obligation towards patient. There is a need for tailored training on radiation safety and enforcement of safety measures.

ОЦЕНКА РАДИАЦИОННОГО РИСКА СМЕРТИ ОТ СЕРДЕЧНО-СОСУДИСТЫХ ЗАБОЛЕВАНИЙ ЛИКВИДАТОРОВ ПОСЛЕДСТВИЙ АВАРИИ НА ЧАЭС – РАБОТНИКОВ ПРЕДПРИЯТИЙ АТОМНОЙ ПРОМЫШЛЕННОСТИ ПО ДАННЫМ О ДОЗАХ РАЗЛИЧНЫХ ВИДОВ ОБЛУЧЕНИЯ

Background: Assessment of the risk of death from circulatory system diseases due to radiation exposure in liquidators of the Chernobyl accident consequences (hereinafter referred to as liquidators) using data on doses of various types of exposure. Material and methods: The work used the information base of the Industry Register of persons exposed to radiation as a result of the accident at the Chernobyl nuclear power plant (hereinafter referred to as the register), nuclear industry workers. The radiation risk assessment study included men - 12,706 liquidators who had data on external emergency radiation doses when working in the 30 km Chernobyl NPP zone, 1,327 of them had data on occupational radiation doses. Poisson regression was chosen as the statistical model of risk. The study covers the period from 1987 to 2021. During the observation period, the register accumulated 304,023 person/years. The majority of the register in 1986 was made up of men – 84.7 %, women – 15.3 %. Results: When data on doses of different types of radiation are used to calculate doses, different results of excess relative risk are obtained. Only the total radiation dose (occupational, emergency, medical, natural) can provide correct results for calculating the radiation risk of death from radiation-induced diseases. Conclusion: The prospect of research should be considered to be filling the information base of the Industry Register with data on doses of all types of radiation.

Potential risk assessment: a model for quality evaluation in fluoroscopy-guided interventional procedures.

This study presented a model applied for potential risk assessment in an interventional radiology setting. The model of potential risk assessment (MARP) consisted of the creation of a scale of indicators ranging from 0 to 5. The radiation levels were categorized according to gender, kind of procedure, value of kerma air product (Pka), and accumulated radiation dose (mGy). The MARP model was applied in 121 institutions over 8 y. A total of 201656 patient radiation doses (Dose-area product and accumulated kerma) data were launched into the system over time, with an average of 22406 doses per year. In the context of the workers (cardiologists, radiographers, and nurses) monitored during the MARP application, 8007 cases (with an average of 890 per year) of occupational radiation doses were recorded. This study showed a strategy for quality evaluation in fluoroscopy using a model with a compulsory information system for monitoring safety.

Shape of radiation dose response relationship for ischaemic heart disease mortality and its interpretation: analysis of the national registry for radiation workers (NRRW) cohort

Statistically significant increases in ischemic heart disease (IHD) mortality with cumulative occupational external radiation dose were observed in the National Registry for Radiation Workers (NRRW) cohort. There were 174 541 subjects in the NRRW cohort. The start of follow up was 1955, and the end of the follow-up for each worker was chosen as the earliest date of death or emigration, their 85th birthday or 31 December 2011. The dose-response relationship showed a downward curvature at a higher dose level >0.4 Sv with the overall shape of the dose-response relationship best described by a linear-quadratic model. The smaller risk at dose >0.4 Sv appears to be primarily associated with workers who started employment at a younger age (<30 years old) and those who were employed for more than 30 years. We modelled the dose response by age-at-first exposure. For the age-at-first exposure of 30+ years old, a linear dose-response was the best fit. For age-at-first exposure <30 years old, there was no evidence of excess risk of IHD mortality for radiation doses below 0.1 Sv or above 0.4 Sv, excess risk was only observed for doses between 0.1–0.4 Sv. For this age-at-first exposure group, it was also found that the doses they received when they were less than 35 years old or greater than 50 years old did not contribute to any increased IHD risk.

Monitoring Occupational Radiation Dose in Radiography Students: Implications for Safety and Training

Background: This study aimed to investigate the occupational exposure of undergraduate radiography students to ionising radiation and evaluate the effectiveness of safety protocols and training in reducing radiation exposure. Methods: This study tracked undergraduate radiography students from the University of Sharjah, UAE, using thermoluminescent dosimeters (TLDs) from 2015 to 2023. TLD readings were conducted every 15 weeks during 384 h of clinical placement. This study encompassed various radiographic procedures, and the TLDs were used to measure shallow (HP (0.07)) and deep doses (HP (10)). Results: A data analysis from 599 dosimeters revealed an average of 74 students annually. The average effective doses for HP (10) and HP (0.07) were 0.227 mSv and 0.222 mSv, respectively. These doses were well-below the recommended annual limits. Conclusion: This study’s results indicated that radiography students’ occupational radiation exposure during clinical training was within the safe limits, demonstrating the effectiveness of training and safety protocols. A comparison with international data corroborated the low exposure levels. Clinical training is essential for radiography students, and this study highlights the success of safety protocols in minimising occupational radiation exposure. Continuous monitoring and education are crucial to sustaining these positive outcomes.

Occupational Radiation Dose Trends in U.S. Radiologic Technologists Assisting with Fluoroscopically Guided Interventional Procedures, 1980–2020

PurposeTo summarize dose trends from 1980 to 2020 for 19,651 U.S. Radiologic Technologists who reported assisting with fluoroscopically guided interventional procedures (FGIPs), overall and by work history characteristics. Materials and MethodsA total of 762,310 annual personal dose equivalents at a 10-mm reference depth (doses) during 1980–2020 for 43,823 participants of the U.S. Radiologic Technologists (USRT) cohort who responded to work history questionnaires administered during 2012–2014 were summarized. This population included 19,651 technologists who reported assisting with FGIP (≥1 time per month for ≥12 consecutive months) at any time during the study period. Doses corresponding to assistance with FGIP were estimated in terms of proximity to patients, monthly procedure frequency, and procedure type. Box plots and summary statistics (eg, medians and percentiles) were used to describe annual doses and dose trends. ResultsMedian annual dose corresponding to assistance with FGIP was 0.65 mSv (interquartile range [IQR], 0.60–1.40 mSv; 95th percentile, 6.80). Higher occupational doses with wider variability were associated with close proximity to patients during assistance with FGIP (median, 1.20 mSv [IQR, 0.60–4.18 mSv]; 95th percentile, 12.66), performing ≥20 FGIPs per month (median, 0.75 mSv [IQR, 0.60–2.40 mSv]; 95th percentile, 9.44), and assisting with high-dose FGIP (median, 0.70 mSv [IQR, 0.60–1.90 mSv]; 95th percentile, 8.30). ConclusionsOccupational doses corresponding to assistance with FGIP were generally low but varied with exposure frequency, procedure type, and proximity to patients. These results highlight the need for vigilant dose monitoring, radiation safety training, and proper protective equipment.

Assessment of the Occupational Radiation Exposure of Anesthesia Staff in Interventional Cardiology.

This research seeks to evaluate the occupational radiation dose, quantified as the whole-body Annual Mean Effective Dose (AMED), received by anesthesia personnel in interventional cardiology. Thermoluminescent dosimetry data was collected over five years (2019-2023) for a total of 175 anesthesia staff. Technologists comprised approximately 72.4% of the participants (55% male and 45% female), while consultants accounted for 27.6% (70% male and 30% female). Statistical tests, including Independent Samples T-Test and One-Way ANOVA, compared AMED across genders, job titles, and years. The study's findings on AMED across all staff from 2019 to 2023 showed marked variability in AMED. There was a significant rise in AMED from 0.72 mSv in 2019 to 0.92 mSv in 2020, then a decline to 0.82 mSv in 2021, with further decreases to 0.67 mSv in 2022 and finally to 0.65 mSv in 2023 (p < 0.001). The average AMED over the five-year span (2019-2023) was 0.76 ± 0.4 mSv. In terms of gender, the overall AMED for males was 0.73 ± 0.36 mSv and for females 0.79 ± 0.45 mSv, showing no significant statistical difference (p = 0.272). Significant differences in exposure were observed between the technologists who experienced a higher overall AMED (0.8 ± 0.43 mSv) compared to consultants (0.63 ± 0.29 mSv, p = 0.008). Despite these variations, AMED values remained lower than the annual occupational dose limit of 20 mSv, indicating generally low radiation exposure for anesthesia staff. This study emphasizes the importance of ongoing monitoring and enhanced protective measures to safeguard the health of medical professionals working with radiation.

Radiation Exposure to the Interventional Echocardiographers and Sonographers: A Call to Action

Interventional echocardiography is a rapidly growing field within the disciplines of cardiology and anesthesiology, with the rise of advanced transcatheter procedures making skilled imagers more important than ever. However, these procedures also involve frequent manipulation of the transesophageal echocardiography probe, which means interventional echocardiographers (IEs) are at risk of long-term occupational radiation exposure. Studies have shown that radiation exposure is linked to various health issues, including cancer, cataracts, hypertension, hyperlipidemia, endothelial dysfunction, vascular aging, and early atherosclerosis. While there is increasing awareness of the occupational radiation dose limits and the need for better shielding methods, the importance of radiation safety for the IE is still not sufficiently prioritized in most cardiac catheterization laboratories/hybrid operating rooms. This is partly due to a paucity of studies looking at long-term radiation exposure to the IE, as this field is newer than that of interventional cardiologists.

Radiation dose to multidisciplinary staff members during complex interventional procedures

IntroductionComplex interventional radiology procedures involve extensive fluoroscopy and image acquisition while staff are in-room. Monitoring occupational radiation dose is crucial in optimization. The purpose was to determine radiation doses received by staff involved in complex interventional procedures performed in a dedicated vascular or neuro intervention room. MethodsIndividual real-time radiation dose for all staff involved in vascular and neuro-interventional procedures in adult patients was recorded over a one-year period using wireless electronic dosimeters attached to the apron thyroid shield. A reference dosimeter was attached to the C-arm near the tube housing to measure scattered, unshielded radiation. Radiology staff carried shoulder thermo-luminescent dosimeters with monthly read-out to monitor dose over time. ResultsOccupational radiation dose was measured in 99 interventional procedures. In many cases prostate artery embolization procedures exposed radiologists to high radiation doses with a median of 15.0 μSv and a very large spread, i.e. 0.2–152.5 μSv. In all procedures except uterine fibroid embolization radiographers were exposed to lower doses than those of radiologists, with endovascular aortic repair being the procedure with highest median exposure to assisting radiographers, i.e. 2.2 μSv ranging from 0.1 to 36.1 μSv. Median radiation dose for the reference dosimeter was 670 μGy while median staff dose for all procedures combined was 3.2 μGy. ConclusionRadiation doses for multiple staff were determined and the ratio between staff dose and reference dosimeter indicated proper use of shielding in general. Some high-dose procedures may need further optimization for certain staff members, especially those not primarily employed in radiology. Implications for practiceThe study provides benchmark doses that may be used widely in audits and in the ongoing effort to optimize radiation protection for staff in interventional radiology.

Assessment of dosimetric approaches in evaluating radiation exposure for interventional cardiologists in Sri Lanka.

Interventional cardiologists face significant radiation exposure during interventional cardiology procedures. Therefore, this study focuses on assessing radiation exposure among interventional cardiologists during their procedures. Specifically, it aims to determine the effectiveness of both single and double dosimeter methods in estimating annual occupational radiation doses. This research holds pioneering significance as it represents the very first study undertaken in Sri Lanka. Thirteen interventional cardiologists performed 486 interventional cardiology procedures over three months in three different healthcare institutes. Active Hp(10) dosimeters were placed to measure radiation exposure. Effective doses were calculated using single and double dosimetric algorithms. Annual occupational doses were assessed on an operator basis. Statistical analyses were conducted to assess algorithmic differences and dose variations using the Kruskal-Wallis test and linear regression. The highest annual occupational dose for each dosimetric algorithm received as 2.00 ± 0.24 mSv, 2.29 ± 0.48 mSv, 3.35 ± 0.71 mSv, and 2.64 ± 0.42 mSv, respectively, and remained below the recommended safety limit of 20 mSv/year. The Kruskal-Wallis test revealed no significant differences in the effective doses among double dosimetric algorithms, as well as between single and double dosimetric algorithms (p > 0.05). Linear regression showed strong correlations among various algorithms, demonstrating consistency. The findings of this study hold significant effects on interventional cardiology practice in Sri Lanka, enhancing radiation safety and monitoring.

Frequentist model averaging for analysis of dose-response in epidemiologic studies with complex exposure uncertainty.

In epidemiologic studies, association estimates of an exposure with disease outcomes are often biased when the uncertainties of exposure are ignored. Consequently, corresponding confidence intervals (CIs) will not have correct coverage. This issue is particularly problematic when exposures must be reconstructed from physical measurements, for example, for environmental or occupational radiation doses that were received by a study population for which radiation doses cannot be measured directly. To incorporate complex uncertainties in reconstructed exposures, the two-dimensional Monte Carlo (2DMC) dose estimation method has been proposed and used in various dose reconstruction efforts. The 2DMC method generates multiple exposure realizations from dosimetry models that incorporate various sources of errors to reflect the uncertainty of the dose distribution as well as the uncertainties in individual doses in the exposed population. Traditional measurement-error model approaches, typically based on using mean doses in the dose-exposure analysis, do not fully account exposure uncertainties. A recently developed statistical approach that overcomes many of these limitations by analyzing multiple exposure realizations in relation to disease risk is Bayesian model averaging (BMA). The analytic advantage of the BMA is its ability to better accommodate complex exposure uncertainty in the risk estimation, but a practical. Drawback is its significant computational complexity. In this present paper, we propose a novel frequentist model averaging (FMA) approach which has all the analytical advantages of the BMA method but is much simpler to implement and computationally faster. We show in simulations that, like BMA, FMA yields 95% confidence intervals for association parameters that close to 95% coverage rate. In simulations, the FMA has shorter length of CIs than those of another frequentist approach, the corrected information matrix (CIM) method. We illustrate the similarities in performance of BMA and FMA from a study of exposures from radioactive fallout in Kazakhstan.

Experimental and numerical investigations of sliding wear behaviour of an Fe-based alloy for PWR wear resistance applications

The excellent wear and corrosion resistance of Co-based alloys make them desirable for tribological applications in the nuclear industry. However, neutron activation of the Co-based alloys leads to significant occupational radiation doses. An alternative Fe-based alloy called RR2450 was developed by Rolls-Royce plc to replace these alloys. This paper presents the first comprehensive study evaluating the sliding wear resistance of RR2450 alloy in representative PWR conditions. The sliding counterface of RR2450 balls was a Co-based alloy, Haynes 25 discs. Four tests were performed at temperatures up to 80 °C, and 12 tests were performed up to 200 °C. Results showed wear performance of RR2450 balls degraded at higher loads and temperatures, with temperature having a significant role. Microstructural investigation revealed voids and hard silicide phases, negatively impacting wear resistance. Nonetheless, the wear performance of RR2450 was similar to a Co-based alloy, a=Stellite 20, at nuclear reactor conditions. Two wear tests with uneven wear tracks were selected for 3D finite element analysis. The wear simulation procedure is based on Archard’s wear equation and is implemented in a commercial FE package, ABAQUS. The FEA method was used to capture the wear on both surfaces, and was shown to predict nominal wear profiles. These comparisons with experiments show that the FEA results can provide representative wear profiles when wear depths and widths are asymmetrical and irregular.

Optimization of Radiation Protection in Pediatric Interventional Radiology in Latin America and the Caribbean: Development, Advancements, Challenges and Achievements of the OPRIPALC Program.

This article presents the development, advancements, challenges and achievements of the "Optimization of Protection in Pediatric Interventional Radiology in Latin America and the Caribbean" (OPRIPALC) program. This international initiative is led by the World Health Organization, the Pan American Health Organization and the International Atomic Energy Agency. The main objectives of OPRIPALC are to foster a culture of radiological protection in pediatric interventions, enhance these procedures' quality, and define optimization strategies such as the use of diagnostic reference levels (DRLs). Currently, 33 centers from 12 countries participate actively in the program. Significant progress has been made towards the proposed objectives, overcoming the challenges posed by the COVID-19 pandemic. Through many virtual meetings for coordination, planning, training and follow-up, a comprehensive set of DRLs for both diagnostic and therapeutic procedures, categorized by weight and age, have been established and are in use. A consensus document on good practices is in the final stage of development. The program's continuation into at least a second phase is essential to address pending issues, including the integration of automatic dose management systems, the levels of occupational radiation doses, their correlation with pediatric patient doses, and strategies to reduce them.

Assessment of extremity dose for medical staff involved in positron emission tomography/computed tomography imaging: Retrospective study.

There has been an increase in positron emission tomography (PET)/computed tomography (CT) imaging procedures, and medical workers involved in PET/CT are at increased risk of occupational exposure. Data on extremity dose exposure are limited globally. The current study aimed to evaluate the occupational radiation dose for extremities for medical workers (nurses, radiographers/radiologic technologists, and nuclear medicine physicians) working in PET/CT scanners at 5 large hospitals in Turkey. Optically stimulated luminescence (OSL) and Thermoluminescent dosimeter (TLD) ring dosimeters were used to measure equivalent dose values. Hospitals 1, 2, and 5 used OSL, and 3 and 4 used TLD. A total of 502 readings were obtained from 55 workers. In millisievert (mSv), the average annual effective dose for all workers was 14.5 ± 17.7 (0.2-157.2). A radiography technologist received a maximum dose of 157.21. Nurses received the highest average annual effective dose (15.2 ± 19.46) (0.32-65.58), followed by radiography technologists (14.7 ± 18.03) (0.4-157.2), and nuclear medicine physicians demonstrated the least dose (8.6 ± 10.5) (1.2-24.4). The results show that the extremity dose is well below the annual dose limit of 500 mSv. However, there is a wide variation in dose among the workers, underlining a need for careful assessment of working conditions to ensure safe practices for all workers.

Occupational radiation dose on the hand of assisting medical staff in diagnostic CT scans.

Chronic radiation exposure increases the risk of skin damage of medical personnel engaged in radiology. However, hand dose measurements in computed tomography (CT) for diagnostic purposes have not been evaluated. The occupational radiation dose to the hands of CT assistants was herein investigated to evaluate its compliance with the equivalent dose limit for the hand (500mSv/year). The occupational doses of nine CT assistants were measured in 89 cases (April 2017-May 2018) by installing radio-photoluminescence glass dosemeters (GD-302M) (70-μm dose-equivalent conversion coefficient=0.37) on the dorsal aspect of both hands. The occupational dose to the hand was the highest with head holding (right: 1.14mSv/CT scan, left: 1.07mSv/CT scan). Considering the results for annual work, even for head holding, the hand dose of the CT-assisting personnel was insignificant. However, CT assistants should be mindful of the possibility of locally higher doses to hands.

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 (20mSv and 500mSv y-1, respectively) and local dose investigation level (DIL; 6mSv 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 0.1:0.1:0.2mSv, 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.