Evolution of radiation protection for medical workers

Determination of relative dose of ionizing radiation in the thyroid gland using a panoramic device with different protocols

BACKGROUND

The use of panoramic radiography (PR) is a complementary examination to aid in the diagnosis of cases in paediatric dentistry. The lack of specific protocols for these devices, however, can result in high doses of radiation, affecting critical organs such as the thyroid.

AIM

To evaluate the discrepancies in ionizing radiation received by the thyroid during PR examinations using anthropomorphic paediatric simulators built from computed tomography images.

DESIGN

Two anthropomorphic paediatric phantoms were printed and used, representing children aged 6 and 11 years, with an opening in the thyroid region for the insertion of dosimetric radiographic films. The simulators were subjected to different pre-existing protocols in the PR devices. The radiographic films were processed and analysed using a luxmeter.

RESULTS

The radiation dose to the thyroid was higher in the 6-year-old phantom than in the 11-year-old phantom, for given exposure factors. In addition, there was an increase in dose in children's protocols compared with small adult protocols.

CONCLUSION

Therefore, companies that develop PR equipment must develop child protocols for separate age groups that will consequently reduce the radiation dose in children, especially in their critical organs.

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

PURPOSE

To 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 METHODS

A 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.

RESULTS

Median 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).

CONCLUSIONS

Occupational 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.

Five historical innovations that have shaped modern orthopaedic surgery

Throughout history, many innovations have contributed to the development of modern orthopaedic surgery, improving patient outcomes and expanding the range of treatment options available to patients. This article explores five key historical innovations that have shaped modern orthopaedic surgery: X-ray imaging, bone cement, the Thomas splint, the Pneumatic tourniquet and robotic-assisted surgery. We will review the development, impact and significance of each innovation, highlighting their contributions to the field of orthopaedic surgery and their ongoing relevance in contemporary and perioperative practice.

Development of DynamicMC for PHITS Monte Carlo package

Previously, we have developed DynamicMC for modeling relative movement of Oak Ridge National Laboratory phantom in a radiation field for the Monte Carlo N-Particle package (Health Physics. 2023,124(4):301-309). Using this software, three-dimensional dose distributions in a phantom irradiated by a certain mono-energetic (Mono E) source can be deduced through its graphical user interface. In this study, we extended DynamicMC to be used in combination with the Particle and Heavy Ion Transport code System (PHITS) by providing it with a higher flexibility for dynamic movement for an anthropomorphic phantom. For this purpose, we implemented four new functions into the software, which are (1) to generate not only Mono E sources but also those having an energy spectrum of an arbitrary radioisotope (2) to calculate the absorbed doses for several radiologically important organs (3) to automatically average the calculated absorbed doses along the path of the phantom and (4) to generate user-defined slab shielding materials. The first and third items utilize the PHITS-specific modalities named radioisotope-source and sumtally functions, respectively. The computational cost and complexity can be dramatically reduced with these features. We anticipate that the present work and the developed open-source tools will be in the interest of nuclear radiation physics community for research and teaching purposes.

Fucoxanthin Abrogates Ionizing Radiation-Induced Inflammatory Responses by Modulating Sirtuin 1 in Macrophages

Ionizing radiation (IR) triggers an overproduction of reactive oxygen species (ROS), disrupting the normal function of both immune and metabolic systems, leading to inflammation and metabolic disturbances. To address the pressing requirement for protection against IR, fucoxanthin (FX), a naturally occurring compound extracted from algae, was utilized as an efficient radioprotective agent in macrophages. In this study, we cultured murine RAW 264.7 macrophages and treated them with FX, along with agents influencing the activity of sirtuin 1 (SIRT1) and estrogen receptor α (ERα), to investigate their impact on IR-induced cellular responses. FX significantly attenuated IR-induced upregulation of pro-inflammatory genes (Il1b, Tnf, and Ccl2) and inhibited macrophage polarization toward the pro-inflammatory M1 phenotype. Additionally, FX regulated IR-induced metabolic genes mediating glycolysis and mitochondrial biogenesis. The ability of FX to mitigate IR-induced inflammation and glycolysis was ascribed to the expression and activity of SIRT1 and ERα in macrophages. This study not only uncovers the underlying mechanisms of FX's radioprotective properties but also highlights its potential as a protective agent against the detrimental effects of IR, thus offering new opportunities for enhancing radiation protection in the future.

Cohort profile: ORICAMs, a French cohort of medical workers exposed to low-dose ionizing radiation

Medical personnel represent the largest group of workers occupationally exposed to ionizing radiation. Although the health risks associated with occupational exposure to low doses of ionizing radiation in the medical field have been investigated in several national cohorts, no study has been conducted in France to date. The ORICAMs (Occupational Radiation Induced Cancer in Medical staff) cohort is a nationwide French longitudinal cohort of medical workers exposed to ionizing radiation aiming to investigate the risk of radiation-associated cancer and non-cancer mortality. The ORICAMs cohort was set up in 2011 and includes all medical personnel monitored for ionizing radiation exposure with at least one dosimetric record in the SISERI database (the national registry for monitoring ionizing radiation exposure in workers) over the period 2002-2012. Causes of death were abstracted from death certificates and coded according to ICD-10. The follow-up ended on 31/12/2013. Standardized mortality ratios (SMRs) were calculated by cause of death to compare the mortality in the cohort to that in the French population, by gender, age group and calendar period. Among the 164,015 workers included in the cohort (60% women) a total of 1,358 deaths (892 in male and 466 in female) were reported. The observed number of all-cause deaths was significantly lower than expected based on national rates in both male (SMR = 0.35; 95% CI: 0.33, 0.38; ndeaths = 892) and female (SMR = 0.41; 95% CI: 0.38, 0.45; ndeaths = 466). This analysis leads to the conclusion that mortality in French workers exposed to medical radiation is significantly lower than the national reference rates. However, these results based on a comparative analysis with national rates may be impacted by the healthy worker effect towards low SMRs, and do not enable to establish a potential relationship between occupational exposure and mortality risk, even if we may suspect an impact of high SES of these professionals on the observed decreased mortality. Thus, further dose-response analyses based on individual ionizing radiation exposure and job's type will be conducted to characterize correlation between risk of cancer mortality and occupational exposure.

DynamicMC: An Open-source GUI Program Coupled with MCNP for Modeling Relative Dynamic Movement of Radioactive Source and ORNL Phantom in a 3-dimensional Radiation Field

ABSTRACT

The present work introduces an open-source graphical user interface (GUI) computer program called DynamicMC. The present program has the ability to generate ORNL phantom input script for the Monte Carlo N-Particle (MCNP) package. The relative dynamic movement of the radiation source with respect to the ORNL phantom can be modeled, which essentially resembles the dynamic movement of source-to-target (i.e., human phantom) distance in a 3-dimensional radiation field. The present program makes the organ-based dosimetry of the human body much easier, as users are not required to write lengthy scripts or deal with any programming that many may find tedious, time consuming, and error prone. In this paper, we have demonstrated that the present program can successfully model simple and complex relative dynamic movements (i.e., those involving rotation of source and human phantom in a 3-dimensional field). The present program would be useful for organ-based dosimetry and could also be used as a tool for teaching nuclear radiation physics and its interaction with the human body.

Mortality among medical radiation workers in the United States, 1965-2016

BACKGROUND

Estimates of radiation risks following prolonged exposures at low doses and low-dose rates are uncertain. Medical radiation workers are a major component of the Million Person Study (MPS) of low-dose health effects. Annual personal dose equivalents, H_P(10), for individual workers are available to facilitate dose-response analyses for lung cancer, leukemia, ischemic heart disease (IHD) and other causes of death.

MATERIALS AND METHODS

The Landauer, Inc. dosimetry database identified 109,019 medical and associated radiation workers first monitored 1965-1994. Vital status and cause of death were determined through 2016. Mean absorbed doses to red bone marrow (RBM), lung, heart, and other organs were estimated by adjusting the recorded H_P(10) for each worker by scaling factors, accounting for exposure geometry, the energy of the incident photon radiation, sex of the worker and whether an apron was worn. There were 4 exposure scenarios: general radiology characterized by low-energy x-ray exposure with no lead apron use, interventional radiologists/cardiologists who wore aprons, nuclear medicine personnel and radiation oncologists exposed to high-energy photon radiation, and other workers. Standardized mortality ratio (SMR) analyses were performed. Cox proportional hazards models were used to estimate organ-specific radiation risks.

RESULTS

Overall, 11,433 deaths occurred (SMR 0.60; 95%CI 0.59,0.61), 126 from leukemia other than chronic lymphocytic leukemia (CLL), 850 from lung cancer, and 1654 from IHD. The mean duration of monitoring was 23.7 y. The excess relative rate (ERR) per 100 mGy was estimated as 0.10 (95% CI -0.34, 0.54) for leukemia other than CLL, 0.15 (0.02, 0.27) for lung cancer, and -0.10 (-0.27, 0.06) for IHD. The ERR for lung cancer was 0.16 (0.01, 0.32) among the 55,218 male workers and 0.09 (-0.19, 0.36) among the 53,801 female workers; a difference that was not statistically significant (p-value = 0.23).

CONCLUSIONS

Medical radiation workers were at increased risk for lung cancer that was higher among men than women, although this difference was not statistically significant. In contrast, the study of Japanese atomic bomb survivors exposed briefly to radiation in 1945 found females to be nearly 3 times the radiation risk of lung cancer compared with males on a relative scale. For medical workers, there were no statistically significant radiation associations with leukemia excluding CLL, IHD or other specific causes of death. Combining these data with other cohorts within the MPS, such as nuclear power plant workers and nuclear submariners, will enable more precise estimates of radiation risks at relatively low cumulative doses.

Radiation in Gastroenterology

The benefit of radiation is immense in the field of gastroenterology. Radiation is used daily in different gastrointestinal imaging and diagnostic and therapeutic interventional procedures. Radiotherapy is one of the primary modalities of treatment of gastrointestinal malignancies. There are various modalities of radiotherapy. Radiotherapy can injure malignant cells by directly damaging DNA, RNA, proteins, and lipids and indirectly by forming free radicals. External beam radiation, internal beam radiation and radio-isotope therapy are the major ways of delivering radiation to the malignant tissue. Radiation can also cause inflammation, fibrosis, organ dysfunction, and malignancy. Patients with repeated exposure to radiation for diagnostic imaging and therapeutic procedures are at slightly increased risk of malignancy. Gastrointestinal endoscopists performing fluoroscopy-guided procedures are also at increased risk of malignancy and cataract formation. The radiological protection society recommends certain preventive and protective measures to avoid side effects of radiation. Gastrointestinal complications related to radiation therapy for oncologic processes, and exposure risks for patients and health care providers involved in diagnostic or therapeutic imaging will be discussed in this review.

Chromosomal damage in occupationally exposed health professionals assessed by two cytogenetic methods

The study assessed occupationally induced chromosomal damage in hospital personnel at risk of exposure to antineoplastic drugs and/or low doses of ionizing radiation by two cytogenetic methods. Cultured peripheral blood lymphocytes of eighty-five hospital workers were examined twice over 2 to 3 years by classical chromosomal aberration analysis and fluorescence in situ hybridization. The comparison of the 1^st and the 2^nd sampling of hospital workers showed a significant increase in chromatid and chromosomal aberrations (all p < .05) examined by classical chromosomal aberration analysis, and in unstable aberrations (all p < .05) detected by fluorescence in situ hybridization. Both cytogenetic methods were able to detect an increase of unstable aberrations in the 2^nd sampling. The raised frequency of unstable cytogenetic parameters suggested higher recent exposure to genotoxic agents.

Designing an Indoor Radon Risk Exposure Indicator (IRREI): An Evaluation Tool for Risk Management and Communication in the IoT Age

The explosive data growth in the current information age requires consistent new methodologies harmonized with the new IoT era for data analysis in a space-time context. Moreover, intuitive data visualization is a central feature in exploring, interpreting, and extracting specific insights for subsequent numerical data representation. This integrated process is normally based on the definition of relevant metrics and specific performance indicators, both computed upon continuous real-time data, considering the specificities of a particular application case for data validation. This article presents an IoT-oriented evaluation tool for Radon Risk Management (RRM), based on the design of a simple and intuitive Indoor Radon Risk Exposure Indicator (IRREI), specifically tailored to be used as a decision-making aid tool for building owners, building designers, and buildings managers, or simply as an alert flag for the problem awareness of ordinary citizens. The proposed methodology was designed for graphic representation aligned with the requirements of the current IoT age, i.e., the methodology is robust enough for continuous data collection with specific Spatio-temporal attributes and, therefore, a set of adequate Radon risk-related metrics can be extracted and proposed. Metrics are summarized considering the application case, taken as a case study for data validation, by including relevant variables to frame the study, such as the regulatory International Commission on Radiological Protection (ICRP) dosimetric limits, building occupancy (spatial dimension), and occupants' exposure periods (temporal dimension). This work has the following main contributions: (1) providing a historical perspective regarding RRM indicator evolution along time; (2) outlining both the formulation and the validation of the proposed IRREI indicator; (3) implementing an IoT-oriented methodology for an RRM indicator; and (4) a discussion on Radon risk public perception, undertaken based on the results obtained after assessment of the IRREI indicator by applying a screening questionnaire with a total of 873 valid answers.