Mean Annual Dose Research Articles

Assessment of occupational external radiation exposure of workers in the Southwest of Libya using portable NaI detector

In this study, gamma dose rates generated from the naturally occurring radioactive materials (NORM) were measured in the waste streams of a large scale and sludge onshore petroleum operations. Measurements conducted in this work involved: sludge recovery from separation tanks, sludge forming, NORM storage, scaling in oil tubulars, scaling in gas production and sedimentation in produced water evaporation ponds. Field work was carried out in many places of different terrain of an operation oil exploration and production in Murzuq basin in the Southwest of Libya. The radiation dose rates were measured using portable InSpector-1000. A total of 400 dose rates were acquired. The highest dose rate was 70 μSv/h acquired in sludge stored in barrels. The estimated mean annual equivalent doses in this field were in the range of 0.2–2.8 mSv/y in the first scenario, while in the second scenario the calculated mean annual equivalent doses were in the range of 0.04–0.68 mSv/y. It is assumed that workers may face various exposures in the field where measurements took place, considering the total annual effective dose to be 1.53 mSv/y. The main radioisotopes detected in these samples indicated by the display of the measuring device were 226Ra and 228Ra but detecting both radioisotopes in the same run is not achievable by using the display of the screen.

Risk Assessment of Drinkable Water from Hand-dug Reservoirs Using Gross Alpha and Beta Radioactivity Levels in Ogwashi-Uku, Delta State

Over the past decade, radioactivity in drinking water has become a matter of urgent concern following reports from various scientific researches. The rapid urbanization and increase in population of Ogwashi-Uku has culminated in the increase for demand of safe and potable water hence the need for this study. A total of 10 samples were collected from the study location. Standard methods for determination of gross alpha and gross beta activity concentrations in the water samples were deployed. The measured gross alpha activity concentrations for all water samples are below 0.1 Bq/L while the measured gross beta activity concentrations in all water samples collected are lower than 1.0 Bq/L permissible limit. The mean annual dose equivalent in all the water samples for gross alpha and gross beta activity is lower than 0.1 mSv recommended dose for radionuclides in water, hence the life cancer risk assessment showed lower values, indicating the water is safe for drinking. The purpose of this study is to assess the concentration of gross alpha and beta activity levels of drinking water from hand-dug reservoirs in Ogwashi-Uku, Delta State in order to offer a scientific basis for making decisions regarding mitigating radioactive pollution and also to ensure the safety of drinking water and public health.

Evaluation of outdoor radon levels and its dependence on the radium content in soil in the environs of Belagavi India

The paper presents the seasonal variation of outdoor radon levels and the measured lung dose to the population of the Belagavi region of India. The outdoor radon levels were measured in different seasons using LR-115 (type II) films fixed in a pin-hole cup detector. The outdoor radon levels in this work were found to be high in summer with values ranging from 11.8 to 27.3 Bq m−3 with a mean value of 20.0 Bq m−3. Lower radon levels were observed in monsoon season and the values range from 3.8 to 15.8 Bq m−3, with a mean value of 10.0 Bq m−3. The potential alpha energy concentration was maximum in summer with a mean value of 3.3 mWLM. The mean annual exposure was found to be 1.4 mWLM and the mean annual inhalation dose was 0.2 mSv y−1. The activity of 226Ra in soils was measured using a NaI (Tl) detector based on gamma ray spectrometer. The 226Ra activity of the study area was in the range of 16.5 to 70.4 Bq kg−1 with a mean value of 32.4 Bq kg−1. The correlation coefficient between the radium content in soil and outdoor radon levels was studied. The present study shows a significant correlation of 0.7, between outdoor radon levels and the radium content in the soil.

Cost and operational context for national human papillomavirus (HPV) vaccine delivery in six low- and middle-income countries

IntroductionThere are concerns from immunization program planners about high delivery costs for human papillomavirus (HPV) vaccine. Most prior research evaluated costs of HPV vaccine delivery during demonstration projects or at introduction, showing relatively high costs, which may not reflect the costs beyond the pilot or introduction years. This study sought to understand the operational context and estimate delivery costs for HPV vaccine in six national programs, beyond their introduction years. MethodsOperational research and microcosting methods were used to retrospectively collect primary data on HPV vaccination program activities in Ethiopia, Guyana, Rwanda, Senegal, Sri Lanka, and Uganda. Data were collected from the national level and a sample of subnational administrative offices and health facilities. Operational data collected were tabulated as percentages and frequencies. Financial costs (monetary outlays) and economic costs (financial plus opportunity costs) were estimated, as was the cost per HPV vaccine dose delivered. Costing was done from the health system perspective and reported in 2019 United States dollars (US$). ResultsAcross the study countries, between 53 % and 99 % of HPV vaccination sessions were conducted in schools. Differences were observed in intensity and frequency with which program activities were conducted and resources used. Mean annual economic costs at health facilities in each country ranged from $1,207 to $3,190, while at the national level these ranged from $7,657 to $304,278. Mean annual HPV vaccine doses delivered per health facility in each country ranged from 162 to 761. Mean financial costs per dose per study country ranged from $0.27 to $3.32, while the economic cost per dose ranged from $3.09 to $17.20. ConclusionHPV vaccine delivery costs were lower than at introduction in some study countries. There were differences in the activities carried out for HPV vaccine delivery and the number of doses delivered, impacting the cost estimates.

Impact of climate change on non-communicable diseases caused by altered UV radiation.

UV radiation can cause serious skin and eye diseases, especially cancers. UV-related skin cancer incidences have been increasing for decades. The determining factor for this development is the individual UV exposure. Climate change-induced changes in atmospheric factors can influence individual UV exposure. On the basis of a topic-specific literature research, a review paper was prepared and supplemented by as yet unpublished results of the authors' own studies. The need for scientific research and development is formulated as well as primary prevention recommendations. Climate change alters the factors influencing UV irradiance and annual UV dose in Germany. First evaluations of satellite data for Germany show an increase in mean peak UV irradiance and annual UV dose for the last decade compared to the last three decades. The climate change-related influences on individual UV exposure and the associated individual disease incidence cannot yet be reliably predicted due to considerable uncertainties. However, the current UV-related burden of disease already requires primary preventive measures to prevent UV-related diseases.

Evaluation of outdoor background ionizing radiation level around radiological sections in Federal Teaching Hospital Gombe, Gombe State Nigeria

This study presents the results of ambient radioactive radiation, radiation health hazard indices and excess lifetime cancer risk estimation around radiological sections in Federal Teaching Hospital Gombe, Gombe State, Nigeria using a well calibrated Rados-200 meters and a Global Positioning System (Garmin 765). The mean annual outdoor equivalent dose of 0.078 mSv/y. was measured. Mean annual outdoor effective doses of 0.1358 mSv/y. and 0.0950 mSv/y. were computed respectively, that were less than 1 mSv/y. maximum recommended limit for general public. The mean outdoor ELCR values of 0.3330 x10-3 was also estimated. The results though below the world’s average, are comparable with those of some other locations similar to the study area.

Assessment and evaluation of residents’ excess lifetime cancer risk of federal university of Kashere, Gombe State, Nigeria

A Study of indoor and outdoor radiation dose rate level measurements for male and female hostels at the Federal University of Kashere Hostels, Gombe State, Nigeria, has been carried out with the radiation alert smart 4 to ascertain the radiation level. The measured radiation dose rates were used to calculate the excess lifetime cancer risk and assess radiological health risks. The mean annual outdoor and indoor equivalent doses were 0.025 mSv/y. and 0.370 mSv/y. were recorded, with less than 1 mSv/y. maximum recommended limit for the general public. The mean annual outdoor and indoor effective doses were 0.017 mSv/y. and 0.086 mSv/y. respectively with a total of 0.103 mSv/yr. respectively. were computed. Mean outdoor and indoor ELCR values of 0.061X10-3and 0.302X10-3 respectively, with a mean total of 0.363X10-3 were also computed.

Assessment of Background Radiation in Ojota Chemical Market, Lagos, Nigeria

The monitoring of radiation levels in human-inhabited environments is imperative to avoid public exposure. The activity concentration of primordial radionuclides at Ojota Chemical Market was measured to determine the in situ activity of 238U, 232Th, and 40K in ambient air using an RS-125 Super SPEC gamma spectrometry with global positioning system. The measured absorbed dose rates ranged from 28.35 to 106.55 nGy/h, giving an average value of 70.46 nGy/h. The estimated absorbed dose rate spanned from 22.25 to 101.03 nGy/h with a mean value of 65.50 nGy/h. The average concentrations of 40K, 238U, and 232Th were 458.55, 30.26, and 54.77 Bq/kg respectively. The outdoor and indoor absorbed doses averaged 80.39 and 132.55 µSv/y, respectively, and the mean value of excess lifetime cancer risk was 0.26 × 10−6 µSv/y. The external and internal hazard index averaged 0.39 and 0.47, respectively, and the mean annual gonadal dose equivalent was 465.14 µSv/y. The radium equivalent dose averaged 143.45 Bq/kg while the gamma representative index averaged 1.05. The absorbed dose rate, mean concentration of 40K and 232Th, the average values of excess lifetime cancer risk, the annual gonadal dose equivalent, and the gamma representative index were above the permissible limit as set by the radiation regulatory agencies. The study concluded that the human activities in Ojota Chemical Market might have increased the radiation burden of the community.

Association between cumulated hydroxychloroquine in systemic lupus erythematosus and development of cardiac conduction alterations

Abstract Background/Introduction Hydroxychloroquine (HCQ) is a widely used drug in Systemic Lupus Erythematosus (SLE). It may cause cardiac alterations which includes short term arrhythmic events (via QT interval prolongation) and medium-late term dose dependent cardiomyopathy1. The few research articles published on the medium-late term effects of HCQ in cardiac conduction disorder do not show relevant alterations. Purpose To assess the effect of HCQ in cardiac conduction in a consecutive SLE population. Methods Observational, single University hospital study of all consecutive SLE patients with an electrocardiogram (EKG) at HCQ onset and at least one EKG in follow-up, with a period of at least 3 months on HCQ treatment was performed. We assessed conduction alteration by electrocardiogram (EKG), defined as any degree of atrio-ventricular block or bundle branch block. The EKGs were gathered from the clinical history and interpreted at the beginning of the treatment and during the 15.2 years (CI95% 13.24–17.16) follow-up period. We defined cumulated HCQ (cHCQ) as the multiple of the mean annual dose of the sample. Results We studied 109 (96 women/ 13 men) SLE patients with a mean (±.SD) age of 61 ±. 2.78 years. A statistically significant association was observed between the cHCQ, and the development of cardiac conduction alterations [OR 1.1 CI95% 1.02–1.19; p=0.011] (Table & Figure). A total of 8 covariates were included. Among them, those that had the greatest influence on the development of the primary event were previous conduction alterations [OR 4.15 CI95% 6.39–624.54; p<0.01]; valvular heart disease [OR 7.15 CI95% 1.31–38.91; p=0.023] and age [OR 1.07 95% CI 1.0–1.14; p=0.04] (Table). There was no statistical association between the cHCQ and atrio-ventricular block. Conclusion According to our study, it seems to be an association between the cHCQ and development of cardiac conduction alterations regardless of other variables evaluated. Wider longitudinal studies are required with a protocolized EKG performance in successive visits to further analyze this association. Funding Acknowledgement Type of funding sources: None.

Rituximab-Induced Hypogammaglobulinemia and Risk of Infection in Neuromyelitis Optica Spectrum Disorders: A 14-Year Real-Life Experience.

Background and ObjectivesTo investigate the frequency and predictors of hypogammaglobulinemia during long-term rituximab (RTX) treatment in patients with neuromyelitis optica spectrum disorder (NMOSD) and its association with infections.MethodsWe retrospectively reviewed the data of patients with NMOSD who received RTX through the maintenance regimen based on memory B-cell detection for at least 1 year from 2006 to 2021 at an institutional referral center for NMOSD.ResultsA total of 169 patients received a median of 10 courses (range 1–27) of RTX reinfusion after induction over a median of 8 (range, 1–15) years. Their mean serum immunoglobulin (Ig)G level began to decline significantly after 2 years of treatment, steadily declined at a rate of 2%–8% per year for the following 8 years, and then plateaued after 10 years. The proportion of patients with hypo-IgG (<6 g/L) increased from 1.2% after 1 year of treatment to 41% after 14 years of treatment. While being treated with RTX, 58 (34%) patients had 114 infections, of whom 14 (8%) patients had 15 severe infections. Multivariable logistic regression analyses identified duration of RTX treatment in years (odds ratio [OR] 1.234, 95% confidence interval [CI] 1.015–1.502), mean annual RTX dose (OR 0.063, 95% CI 0.009–0.434), history of mitoxantrone (OR 3.318, 95% CI 1.109–9.93), hypo-IgG at baseline (OR 40.552, 95% CI 3.024–543.786), and body mass index >25 kg/m2 (OR 4.798, 95% CI 1.468–15.678) as independent predictors of hypo-IgG. The risk of infection during RTX treatment was independently associated with high Expanded Disability Status Scale scores (OR 1.427, 95% CI 1.2–1.697) and relapses during RTX treatment (OR 1.665, 95% CI 1.112–2.492), but not with hypogammaglobulinemia.DiscussionOver 14 years of long-term RTX treatment, IgG levels gradually decreased, and the frequency of hypo-IgG increased to 41% of the patients. Patients with prolonged memory B-cell depletion after RTX, previous mitoxantrone history, hypo-IgG at baseline, or obesity were at risk of developing RTX-induced hypogammaglobulinemia. Nevertheless, infection rates remained low during treatment, and reduced immunoglobulin levels were not associated with an increased incidence of infections.

Risk of occupational radiation exposure for radiation workers involved in interventional endourology in Saudi Arabia

In recent years, fluoroscopically-guided interventional procedures have become an essential part of endourology practices and widely performed around the world. Despite the many clinical benefits of these procedures, they expose patients and workers to a significant amount of radiation. Thus, this study aimed to estimate the mean annual occupational radiation dose for interventional endourology workers in Saudi Arabia. During the five-year period from 2017 to 2021, 262 interventional endourology workers were monitored to estimate the radiation effective dose during their work routine in 28 Saudi Ministry of Health healthcare facilities. To estimate the radiation effective doses for workers, thermoluminescent dosimeters (TLD) were used on a quarterly basis. The interventional endourology workers were asked to operate the TLD-100 device using a lead apron, a thyroid protective collar and leaded protective eyewear to protect most parts of their body. The mean annual effective dose (mSv) was used as an indicator of the overall occupational exposure for the workers. Analysis of the occupational dose data showed that the mean annual effective dose for all workers, averaged over the study period, was 0.70 mSv (0.12–3.18 mSv). The results indicate a safe environment in terms of radiation protection with no single dose exceeding the recommended occupational dose limits. However, optimisation of radiation protection practices is always advised to facilitate a reduction in the occupational exposure to the radiation dose.

Radioactive background radiation measurement in Mureş county

Abstract From the beginning, there has always been radiation in the Universe. Most people are unaware of it, even though it is around us all the time, and can have many negative effects on our bodies. In the long term, it can lead to the development of various diseases. The natural background radiation includes cosmic radiation, plus radiation from radioactive elements present in the soil, atmosphere, and living organisms. A significant, measurable fraction of this is gamma radiation. Artificial radioactive isotopes can be used in a variety of applications, such as space research, sterilization, and medical diagnostic imaging. Our objective is to measure the dose equivalent rate from the gamma fraction of background radiation in Mureş county, in open and closed spaces, and in frequently visited areas. The measurements were performed with a Gamma Scout dosimeter. The measured average dose equivalent rates are 0.104 µSv/h in Târgu Mureş, 0.111 µSv/h in Reghin, 0.112 µSv/h in Sovata, 0.091 µSv/h in Tarnaveni, 0.095 µSv/h in Ludus and 0.067 µSv/h in the Upper-Mureş Nature Park. Based on the measurements, the calculated mean annual dose is 0.884 mSv/year. According to the data based on the measurements, the dose equivalent rates measured in Mureş county do not pose a risk to our health.

Evaluation of Natural Radioactivity and Radiation Hazards of Soils around Petroleum Products Marketing Company using Gamma Ray Spectrometry

This study aimed at evaluating natural radioactivity and radiation hazards of soils around a petroleum product marketing company due to anthropogenic influences using gamma ray spectrometry. Top soils (5 cm deep) were collected from diverse locations inside the premises of the Company using standard analytical technique, while control samples were acquired at approximately 200 m from the study area. Mean activity concentrations of the radionuclides in the test soils were 89.36 Bq/kg for 40K, 92.1 Bq/kg for 238U and 10.95 Bq/kg for 232Th, which are more than that of control samples with statistically significant differences. Assessment of the radiological levels of the oil-contaminated soils were done using internal hazard index, external hazard index, annual gonadal dose equivalent, annual effective dose rate, radium equivalent, total absorbed dose rate and representative level index (IŸ). The results showed that mean annual equivalent dose rate of the oil-contaminated soil (0.46 mSv/yr) fell below the permissive annual dose limit (1.0 mSv/yr). Mean internal hazard index (0.55 Bq/kg) and external hazard index (0.30 Bq/kg) values were less than the minimum permissible limit (1.0). Mean annual gonadal dose equivalent value (358.46 µSvy-1) of the radionuclides was close to the world average of 300 µSvy-1, while the mean representative gamma index value (0.78) was also less than unity. Estimated mean value (114.65 Bq/kg) of the radium equivalent was also below the world average of 370 Bq/kg, the values are also more than that of the control samples. Though the soils exhibited low gamma radiation, however lengthy term exposure may pose an inherent cancerous ill-health. It is vital to repeat this investigation periodically to avert precarious effects of anthropogenic influences; also indiscriminate discarding of oils should be discouraged.&#x0D; Keywords: Gamma ray spectrometry; radionuclide; refined petroleum products; risk assessment; soil.

Evaluation of Cancer Risks Associated with Radon Concentration Measured in the Science Faculty Building Complex Basement of a Tertiary Institution in South West, Nigeria

In this study, radon concentration was measured with an active detector (RAD 7) in the Science Faculty building complex basement of a tertiary institution in South West (SW), Nigeria. The attendant risk descriptors were determined with the help of mathematical models. The range of mean detectable radon concentration in the basement is 26.5 ±12.3 – 242 ± 50.7 Bq m-3 and the mean for all the rooms examined is 61.74 ± 58.48 Bq m-3. The overall mean is less than the global mean of 100 Bq m-3. The mean annual dose rate is found to be 0.97 ± 0.92 mSv y-1. The mean annual effective doses for different subjects examined are 0.412 ± 0.391 mSv y-1 (worker), 0.0221 ± 0.0209 mSv y-1 (student in lab session), 0.515 ± 0.488 mSv y-1 (student who lives in the hostel) and 2.149 ± 2.036 mSv y-1 (home owner). Students and workers in the basement are not likely to develop serious health effects, however, if the basement is used as a living room, the radon concentration in Room I-R might lead to health effects. The range of calculated excess life cancer risks (ELCRs) are (0.64-5.82) x 10-3 and (1.16 -10.58) x 10-3 for student and homeowner respectively. The mean values for the two subjects examined fall below the maximum risk of 3.5 x 10-3.

Evaluation of Spontaneous DNA Damage Using the Alkaline Comet Assay in Lymphocyte Cells of Humans Living in the High Level Natural Radiation Area of Mamuju, Indonesia

To evaluate the biological impacts of high background radiation exposures that are represented by spontaneous deoxyribonucleic acid (DNA) damage, an evaluation on lymphocyte cells from residents of Mamuju, West Sulawesi, Indonesia was tested. The mean annual dose received by individuals in this area is about 10.40 mSv. Of the 177 adult subjects studied, 102 were from high-level natural radiation areas of Mamuju and 75 subjects were from a nearby normal-level natural radiation area. Both areas are similar in living situations. DNA strand breaks and other parameters of study and control group were determined using a standardized comet assay. Our results showed that chronic low-level natural radiation had resulted in significantly higher (p&lt;0.001) DNA damage based on the three parameters of the assay (tail length, tail DNA, and tail moment) compared to those of control. There was a positive correlation between the level of DNA damage and age, where people aged 40 years and older had a higher level of DNA damage than those under 40 year. The level of DNA damage was also found to be higher in females compared to that of males. It was concluded that chronic exposure to natural radiation in Mamuju had induced spontaneous DNA damage in human cells after long-term exposure which was dependent on age and sex.

Assessment of extremity occupational exposure at a nuclear medicine department

There has been an increase in the use of radioactive materials in diagnostic imaging, putting nuclear medicine personnel at increased medical risks. Worldwide, there is limited data regarding extremity dose exposure with multiple studies showing wide dose variability. Therefore, in this study, extremity occupational doses for 9 nuclear medicine personnel, consisting of nurses, technologists, and nuclear medicine physicians, at a large hospital in Riyadh were monitored over a one-year period. Ring dosimeters and calibrated ThermoLuminescent Dosimeters (TLDs), specifically, a lithium fluoride-based TLD-100, were used to measure dose equivalent values. In mSv, the mean annual dose and range for three groups for extremities’ dose exposure were as follows: group one (6.24 ± 4.28) (1.1–11.7), group two (55.45 ± 7.85) (49.9–61) and group three (221.45 ± 18.03) (208.7–234.2). Within each of the three groups, the annual radiation dose was similar; however, there was large intergroup variation as would be expected due to the different roles each personnel has. However, in all cases, the extremity dose was less than the annual dose limit (500 mSv) set. Hence, this reveals a wide variation in dose among the personnel. This revealed a wide variation in dose among the personnel, highlighting the need for careful assessment of working conditions to ensure annual occupational exposures below the recommended limits.

Metrology for radiation protection: a new European network in the foundation phase

Abstract. More than 23 million workers worldwide are occupationally exposed to ionizing radiation and all people in the world are exposed to environmental radiation. The mean exposure, that is the mean annual dose of per person, is dominated by medical applications and exposure to natural sources. Due to recent developments in healthcare, e.g. the increasing application of ionising radiation in medical imaging with relative high doses like CT, and modern high dose applications (for example CT angiography), the exposure due to medical application has risen. Additionally, the changes in living conditions increase the exposure to natural radioactivity also: More living time is spent in buildings or in an urban environment, which causes higher exposure to Naturally Occurring Radioactive Materials (NORM) in building materials and higher exposure to radon. The level of radon activity concentration in buildings is far higher than in the environment (outdoor). This effect is often amplified by modern energy-efficient buildings which reduce the air exchange and thus increase the radon indoor activity concentration. In summary both medical application of ionizing radiation and natural sources are responsible for the increase of the mean annual exposure of the population. The accurate measurement of radiation dose is key to ensuring safety but there are two challenges to be faced: First, new standards and reference fields are needed due to the rapid developments in medical imaging, radiotherapy and industrial applications. Second, direct communication channels are needed to ensure that information on best practice in measurements reaches effectively and quickly the people concerned. It is therefore necessary to allow for an international exchange of information on identified problems and solutions. Consequently, a European Metrology Network (EMN) for radiation protection under the roof of EURAMET is in the foundation phase. This network EMN for Radiation Protection is being prepared by the project EMPIR 19NET03 supportBSS. The project aims to prepare this EMN by addressing this issue through the identification of stakeholder research needs and by implementing a long-term ongoing dialogue between stakeholders and the metrology community. The EMN will serve as a unique point of contact to address all metrological needs related to radiation protection and it will relate to all environmental processes where ionising radiation and radionuclides are involved. A Strategic Research Agenda and two roadmaps are in development, covering the metrology needs of both the Euratom Treaty and the EU Council Directive 2013/59/EURATOM pinning down the basic safety standards for protection against the dangers arising from exposure to ionizing radiation. Furthermore, long-term knowledge sharing, and capacity building will be supported and a proposal for a sustainable joint European metrology infrastructure is under way. This will significantly strengthen the radiation protection metrology and support radiation protection measures. The final goal of the network project is a harmonised, sustainable, coordinated and smartly specialised infrastructure to underpin the current and future needs expressed in the European regulations for radiation protection.

Space Radiation Dosimetry at the Exposure Facility of the International Space Station for the Tanpopo Mission.

Radiation dosimetry was carried out at the exposure facility (EF) and the pressurized module (PM) of the Japanese Kibo module installed in the International Space Station as one study on environmental monitoring for the Tanpopo mission. Three exposure panels and three references including biological and organic samples and luminescence dosimeters were launched to obtain data for different exposure durations during 3 years from May 2015 to July 2018. The dosimeters were equipped with additional shielding materials (0.55, 2.95, and 6.23 g/cm2 mass thickness). The relative dose variation, as a function of shielding mass thickness, was observed and compared with Monte Carlo simulations with respect to galactic cosmic rays (GCRs) and typical solar energetic particles (SEPs). The mean annual dose rates were DEF = 231 ± 5 mGy/year at the EF and DPM = 82 ± 1 mGy/year at the PM during the 3 years. The PM is well shielded, and the GCR simulation indicated that the measured mean dose reduction ratio inside the module (DPM/DEF = 0.35) required ∼26 g/cm2 additional shielding mass thickness. Observed points of the dose reduction tendency could be explained by the energy ranges of protons (10-100 MeV), where the protons passed through, or were absorbed in, the shielding materials of different mass thickness that surrounded dosimeters.

Racial Inequality in Prescription Opioid Receipt — Role of Individual Health Systems

BackgroundHistorically, the receipt of prescription opioids has differed among racial groups in the United States. Research has not sufficiently explored the contribution of individual health systems to these differences by examining within-system prescription opioid receipt according to race.MethodsWe used 2016 and 2017 Medicare claims data from a random 40% national sample of fee-for-service, Black and White beneficiaries 18 to 64 years of age who were attributed to health systems. We identified 310 racially diverse systems (defined as systems with ≥200 person-years each for Black and White patients). To test representativeness, we compared patient characteristics and opioid receipt among the patients in these 310 systems with those in the national sample. Within the 310 systems, regression models were used to explore the difference between Black and White patients in the following annual opioid measures: any prescription filled, short-term receipt of opioids, long-term receipt of opioids (one or more filled opioid prescriptions in all four calendar quarters of a year), and the opioid dose in morphine milligram equivalents (MME); models controlled for patient characteristics, state, and system.ResultsThe national sample included 2,197,153 person-years, and the sample served by 310 racially diverse systems included 896,807 person-years (representing 47.4% of all patients and 56.1% of Black patients in the national sample). The national sample and 310-systems sample differed meaningfully only in the percent of person-years contributed by Black patients (21.3% vs. 25.9%). In the 310-systems sample, the crude annual prevalence of any opioid receipt differed slightly between Black and White patients (50.2% vs. 52.2%), whereas the mean annual dose was 36% lower among Black patients than among White patients (5190 MME vs. 8082 MME). Within systems, the adjusted race differences in measures paralleled the population trends: the annual prevalence of opioid receipt differed little, but the mean annual dose was higher among White patients than among Black patients in 91% of the systems, and at least 15% higher in 75% of the systems.ConclusionsWithin individual health systems, Black and White patients received markedly different opioid doses. These system-specific findings could facilitate exploration of the causes and consequences of these differences. (Funded by the National Institute on Aging and the Agency for Healthcare Research and Quality.)

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.