COMPARATIVE ASSESSMENT OF OCCUPATIONAL EXPOSURE DOSES OF PERSONNEL INVOLVED IN THE PRODUCTION OF RADIOPHARMACEUTICALS

SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 69 COMPARATIVE ASSESSMENT OF OCCUPATIONAL EXPOSURE DOSES OF PERSONNEL INVOLVED IN THE PRODUCTION OF RADIOPHARMACEUTICALS D.A. Zaredinov1, S.O. Goziyev2, M.V. Lee3, M.J. Uzakbaeva4 Center for the Development of Professional Qualifications of Medical Workers, Ministry of Health of the Republic of Uzbekistan, Tashkent, Republic of Uzbekistan1,2,3,4 https://doi.org/10.5281/zenodo.17451612 Abstract. This article presents a comparative assessment of occupational exposure levels among workers involved in the production of medical radiopharmaceuticals in Uzbekistan, categorized by specific job roles: process engineers, production laboratory technicians, incoming quality control laboratory technicians, dosimetry technicians, senior engineers, and laboratory technicians. The analysis is based on data from the Research and Testing Radiological Laboratory at the Center for the Development of Professional Qualifications of Medical Workers. The study discusses the effectiveness of radiation protection measures at the facility and the causes of higher exposure levels among Category A personnel. Keywords: radiopharmaceutical, category A personal, individual dose, occupational exposure, dose rate. Introduction The global advancement and utilization of nuclear technologies, along with the expanding use of radioactive sources in industry and medicine, have led to an increase in occupational exposure [1,2]. One of the modern branches of clinical medicine is nuclear medicine, which is divided into diagnostic and therapeutic applications. The development of nuclear medicine involves the implementation of new radiopharmaceutical drugs, the introduction of novel technologies, and changes in research structures, all of which may increase radiation risks [3]. In Uzbekistan, nuclear medicine is a priority area in oncology, and the successful development of this field largely depends on the production of radionuclides and radiopharmaceuticals by the Institute of Nuclear Physics of the Academy of Sciences of the Republic of Uzbekistan. The key advantage of radiopharmaceutical-based treatment lies in its localized and selective action, in contrast to chemotherapy [4]. Knowledge regarding the formation of individual radiation doses and their patterns is essential for creating scientifically grounded, safe working conditions and for continuous optimization of the radiation protection system at radiation-hazardous facilities [5]. To ensure radiation safety for individuals working with sources of ionizing radiation, Uzbekistan adopted Resolution No. 613 of the Cabinet of Ministers of the Republic of Uzbekistan "On the Unified State System for Monitoring and Accounting of Individual Radiation Doses" dated September 29, 2021 [6]. The system of Individual Dosimetric Control (IDC) enables the collection and analysis of radiation exposure data by gender, age, profession, and temporal dynamics, at both site and regional levels [7]. The primary objectives of the Unified System include: monitoring and recording individual radiation doses; implementing systematic measures to reduce radiation exposure; analyzing individual and collective radiation doses received by various population groups from all types of SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 70 ionizing radiation sources; and identifying individuals whose doses exceed established limits. According to the Resolution, individual dose assessment within the system may be conducted through: direct measurements using personal dosimeters; dose estimations for the population; or evaluation based on biological, biochemical, or biophysical indicators of radiation effects. However, the reliability of the collected data can only be verified through comparative analysis [8]. Monitoring of occupational exposure is a fundamental aspect of radiation safety for personnel. From a radiological protection standpoint, monitoring aims to ensure that working conditions comply with safety standards and that radiation sources remain under control. Such monitoring helps identify exposure trends among professional groups involved in radiopharmaceutical production, facilitates strategic planning for radiation protection, and provides data essential for epidemiological research and radiation risk assessments. To ensure radiological protection, it is necessary to assess both the individual effective dose (E) of external exposure and the equivalent doses to specific organs and tissues. As the regulated quantities are not directly measurable, operational quantities derived from physical characteristics of the radiation field are used instead. Measurements of operational quantities serve as conservative estimates for regulatory purposes [9]. The operational quantity for IDC of external exposure is the personal dose equivalent, Hp(d). The parameter d (in mm), which determines the dosimeter's depth and placement on the worker's body, depends on the targeted regulatory quantity. The aim of the study is to perform a differentiated assessment of exposure levels among various personnel groups involved in the production of radiopharmaceuticals. Materials and methods. The research was conducted at the Research and Testing Radiological Laboratory of the Center for the Development of Professional Qualifications of Medical Workers. This study analyzes individual dose equivalent measurements Hp(10), obtained using the DKG-RM1610 personal dosimeter for X-ray and gamma radiation across different personnel groups involved in radiopharmaceutical production. Measurements of dose equivalent rate and photon equivalent dose were taken using a built-in energy-compensated detector based on a Geiger–Müller counter, which converts photon quanta into electrical impulses. The baseline data for this study consisted of quarterly individual radiation dose monitoring results for staff at the Institute of Nuclear Physics of the Academy of Sciences of Uzbekistan. Personnel were grouped based on working conditions into the following six categories: 1. process engineers; 2. production laboratory technicians; 3. incoming quality control laboratory technicians; 4. dosimetry technicians; 5. senior engineers; 6. laboratory technicians. To standardize the data, background dosimeter readings were subtracted. The IDC system involves several stages: I – Registration of the organization and personnel; II – Issuance of dosimeters, safety training and instructions for workers; III – Continuous data collection from dosimeters according to a set schedule; IV – Automated data processing; V – Report generation and submission. Results and discussion. To preliminarily assess variations in radiation exposure levels among personnel performing different tasks in radiopharmaceutical production, IDC data from the SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 71 Research Laboratory were used. Average daily dose equivalent values for each of the six professional groups were compared for the fourth quarter of 2024 and the first quarter of 2025 (Fig. 1). The same employees were included in the analysis across both periods. The distribution of daily equivalent doses was approximated by log-normal distributions, confirmed via the Kolmogorov–Smirnov test (p < 0,05). The data were then log-transformed to validate the normality of the logarithmic distributions [10]. A one-way ANOVA was performed to compare mean daily dose equivalents among the six occupational groups for each period. The same personnel were observed across two consecutive quarters. Prior to analysis, dose values were log-transformed due to their log-normal distribution. Fig.1. Mean daily equivalent dose values for professional groups involved in radiopharmaceutical production. The ANOVA revealed statistically significant differences among the groups (p < 0,05). The probability of the null hypothesis—that all professional groups had identical mean doses across both quarters—was less than 1%. Therefore, the alternative hypothesis was accepted, indicating statistically significant differences in mean doses among professional groups. Repeatedmeasures ANOVA showed significant differences in daily exposure levels (p < 0,05). Average daily dose equivalents ranged from 0,008 to 0,048 mSv. Tukey’s post hoc test indicated that production laboratory technicians, laboratory technicians, senior engineers, and process engineers had significantly higher doses (0,030–0,048 mSv) compared to dosimetry technicians and incoming control laboratory staff (0,008–0,028 mSv). According to the Radiation Safety Standards and Main Sanitary Rules for Ensuring Radiation Safety, approved on January 5, 2006, №. 0193-06, the reference daily dose limit for Category A personnel is 0,036 mSv (based on a 6-hour workday and a safety factor of 2). Thus, the average daily dose equivalent exceeded this reference value on radiopharmaceutical production days for all professional groups. Maximum daily exposure values were observed among laboratory SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 72 technicians and senior engineers, reaching 0,145 mSv. However, due to the rotational work schedule, the average dose over two working weeks did not exceed permissible limits. Dose exceedances occurred primarily on active production days. No statistically significant differences in exposure levels were observed between: – production laboratory technicians and laboratory technicians; – process engineers and senior engineers; – dosimetry technicians and incoming control lab staff. This suggests that their exposure conditions were similar, despite differing job descriptions. Thus, these subgroups may be consolidated in future analyses of annual effective doses. The average monthly values of the collective equivalent dose of exposure for radiopharmaceutical production workers from October 2024 to March 2025 ranged from 5,0 to 8,0 mSv, as shown in Figure 2. Fig.2. Average monthly collective dose equivalent values for radiopharmaceutical production staff (October 2024 – March 2025) The study focused on the period from October 2024 to March 2025 due to the following factors: – this period reflects stable operation of medical institutions, with fewer staff on leave, ensuring uninterrupted data collection; – higher demand for diagnostic and therapeutic procedures, including radiopharmaceutical use, occurs in fall and winter; – summer heat can affect the reliability of radiopharmaceutical production and transportation, especially for short-lived isotopes; – the production plan allocates peak output volumes to the autumn-winter season. Figure 3 shows the maximum values of the equivalent dose rate (EDR). During the study period, the EDR for incoming inspection laboratory technicians was 14,0 µSv/h; for process engineers and senior engineers – from 7,2 µSv/h to 7,5 µSv/h; and for 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 October November December January February March Collective Dose, µSv 2024-2025 SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 73 production laboratory technicians, dosimetrists, and laboratory technicians – from 5,9 µSv/h to 6,3 µSv/h. Fig.3. Maximum equivalent dose rate values among different job roles (October 2024 – March 2025) Conclusion The study provided a detailed comparative analysis of individual radiation doses among different occupational roles involved in radiopharmaceutical production. It was established that annual effective doses for all staff remained within the regulatory limit of 20 mSv, despite increased production demand during the analysis period. The comparative assessment showed that employees directly handling open radiation sources—particularly during manual operations and synthesis of short-lived radionuclides—received the highest doses. This highlights the need to reinforce radiation protection measures at critical stages of the technological process. The findings emphasize the importance of continuous dosimetric monitoring, optimization of work practices, and the widespread implementation of automated systems and technical protective measures to enhance radiation safety and ensure compliance with established hygienic standards. REFERENCES 1. Alashrah, S., Kandaiya, S., & Ali, J. (2020). Occupational radiation dose to nuclear medicine staff at a tertiary hospital. Radiation Physics and Chemistry, 172, 108741. https://doi.org/10.1016/j.radphyschem.2020.108741 2. Bailey, D. L., Townsend, D. W., Valk, P. E., & Maisey, M. N. (2014). Nuclear medicine physics: A handbook for teachers and students. 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