Ukraine has been cherishing the idea to establish a unified state register of individual doses for a long time: since the early 1990s. The need for such a database was determined by the widespread use of nuclear energy and radiation sources for peaceful purposes in Ukraine. This is not only the use of radiation in medicine (x-ray diagnostics, computed tomography, radiation therapy, interventional radiology, nuclear medicine), but also the work of personnel at nuclear power plants, enterprises in the Chornobyl exclusion zone, in uranium mining industry, radioactive waste management, etc.
Specialists receive different average doses in performing different types of activities. For example, a nuclear plant employee usually receives a dose of up to 2 mSv for a year, a radiologist receives up to 1 mSv, and a dentist who conducts dental x-ray survey receives not over 0.4 mSv.
Why is dose accounting necessary?
The state registers of occupational exposure collect all information on exposure levels of such occupational groups in many developed countries. What is the result of performance of the unified register?
Firstly, when complete information was collected on dose monitoring results in different institutions, then it can be used to analyze the doses of specialists by individual branches and professional groups and select those that receive doses at the level of the permissible occupational exposure limit for category A personnel or established reference level of annual doses. Thus, the regulatory body receives the data for certain groups of category A personnel.
Secondly, the data accumulated in the register allow the analysis of occupational doses on an international scale. It is necessary to compare the country’s doses by branches and professional groups with other countries and to provide such information in a timely manner to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) that makes an overview of radiation doses in different areas around the world every five years.
Thirdly, the register allows dose monitoring of specific individuals professionally working with radiation sources, when they change their place of work or even their field of activity or, say, work part-time in several medical institutions. These workers can order certificates of their accumulated doses, if necessary.
According to Candidate of Biological Sciences Larysa Stadnyk from the Grigoriev Institute for Medical Radiology and Oncology of the National Academy of Medical Sciences of Ukraine (GRIGORIEV IMRO NAMS), “the most important thing is that the development of the national dosimetry register and its combination with the data on health indicators of specialists based on annual dispensary examinations (in presence of dose-medical registers) will allow an epidemiological study of the prolonged effect of occupational exposure in low doses on the probability of additional cases of distant somatic-stochastic effects of radiation and determination of appropriate radiation risk factors”.
According to her, this assessment is one of the main tasks of radiation medicine and radiation safety and is especially relevant for studying the effect of low radiation doses. Indeed, the coefficients of the International Commission on Radiological Protection (ICRP) are currently used for this purpose, which were obtained mainly resulting from observations of the effects of the exposure of the Japanese cohort affected by the atomic bombings of Hiroshima and Nagasaki in 1945. However, this exposure was acute and single, which is not suitable for calculating the effect of prolonged exposure to low radiation doses. The same problem exists with risk ratios based on a medical supervision of liquidators of the Chornobyl accident.
“A striking example of implementing the results of epidemiological studies into the practice of radiation protection is the reduction of international standards such as the dose limit of the eye lens from 150 to 20 mSv per year according to the UACOS, the Ukrainian/American Chornobyl Ocular Study”, noted the head of the external radiation dosimetry laboratory of the National Scientific Center of Radiation Medicine (NSCRM) at the NAMS, Candidate of Biological Science, Honored Scientist and Engineer of Ukraine Vadym Chumak, who was responsible for dose monitoring under this epidemiological project.
“Registers are developed not only in order to record the doses of any individual employee (an employee may collect this data without a register, if necessary). The most important thing from an international viewpoint is the ability to assess these doses by type of activities dealing with radiation sources, studying the conditions of their generation, and impact on the health of specialists”, Larysa Stadnyk summarized.
The history of the oldest national registries in Canada and the United Kingdom makes up 60 years or more. Among the European countries, the national dose registers have been established in recent years in countries such as Lithuania, Turkey, Croatia, Montenegro, Northern Macedonia, Greece and Portugal.
Individual dose monitoring at the present stage
While there is no such a unified register in Ukraine, individual dose monitoring (IDM) is carried out by a number of unrelated institutions. “There were more than 70 of them prior to the Russian-Ukrainian war, but 40 of them remained in the temporarily occupied territories”, Vadym Chumak says.
He lists the institutions:
- laboratories at four operating nuclear power plants and other Energoatom enterprises;
- laboratories of the Chornobyl nuclear power plant and the Ecocenter State Enterprise in the Chornobyl exclusion zone;
- Central Laboratory for Radiation Safety and Medical Radiation Dosimetry of the Grigoriev Institute for Medical Radiology and Oncology of the National Academy of Medical Sciences of Ukraine (Kharkiv);
- laboratories at research institutions: the Institute for Nuclear Research of the NAS of Ukraine in Kyiv, the Kharkiv Institute of Physics and Technology, etc.;
- laboratories at medical institutions where radiation therapy is used: the National Cancer Institute (Kyiv), Kyiv City Clinical Oncological Center, etc.;
- external radiation dosimetry laboratory of the National Research Center for Radiation Medicine (NRCRM) of NAMS of Ukraine (Kyiv);
- Research Institute for Radiation Protection at the Academy of Technological Sciences of Ukraine (DosiMetrica Research And Production Enterprise in Kyiv since 2019);
- regional laboratory centers (former sanitary and epidemiological stations);private laboratories.
According to Mr. Chumak, who is also the main scientific consultant at the DosiMetrica Research and Production Enterprise, there are up to 10-15 reputable laboratories from this list. In his opinion, the rest of them needs to be inspected according to unbiased criteria. DosiMetrica Research and Production Enterprise provides IDM for up to 1000 people and is the only Ukrainian laboratory that monitors doses of neutron radiation to the extremities and eye lens and undergoes international intercalibration. IDM is provided in the external radiation dosimetry laboratory of the NRCRM only for personnel of the center, particularly for 20 people.
Therefore, individual dose monitoring of occupational exposure is carried out separately for each branch. Data is accumulated in local databases or, at best, in the departmental dose registers for certain periods: for a month or a quarter, which are sent to institutions subjected to dose monitoring. Annual reports are submitted to the regulatory bodies upon either request or mandatory.
For example, the Central Laboratory for Radiation Safety and Medical Radiation Dosimetry monitors doses of about 6500 medical professionals from over 700 medical institutions of Ukraine. This includes employees of the departments of radiation therapy and diagnosis of cancer centers, hospitals, X-ray rooms and computed tomography rooms in different medical institutions.
“We are not only involved in IDM of occupational exposure, we also monitor the quality of dose calibration of radiation therapy devices and study patient doses in x-ray diagnostics”, laboratory head Larysa Stadnyk noted.
According to her, their IDAIS-PC database has concentrated the data on doses to more than 18,500 people who worked earlier or are currently working with medical radiation sources. The dose register stores data on the quarterly doses of each employee for each year of observation, it also annually collects information on the annual and total doses for the observation period.
Annual reports are developed for all institutions subjected to IDM in this laboratory, according to the analysis results. In addition, summary annual reports are developed in general in Ukraine: by eight types of activities with radiation sources in medicine, and by 34 professional groups. The Central Laboratory for Radiation Safety and Medical Radiation Dosimetry submits such reports annually to the SNRIU, the Ministry of Health and the National Academy of Medical Sciences of Ukraine.
The first IDAIS database was developed in 1988. Until then, information was stored on individual employee cards of each institution. The dose register was significantly updated in 2008, and software is currently used for a complete radiation-hygienic analysis of results of the centralized IDM.
According to the SNRIU, about 50,000 people in total are subjected to individual dose monitoring in different dosimetry laboratories and IDM centers in Ukraine.
However, Vadym Chumak emphasizes that “about 20,000 dentists involved in X-ray diagnostics are not taken into account here, because dental clinics are exempt from licensing of X-ray devices. Although the current health and safety rules for dental x-ray rooms oblige their workers to undergo an individual dose monitoring during the first year after the commissioning of new equipment, in fact, their doses are not monitored”.
Therefore, if dentists will be included into the number of those who are currently subjected to monitoring, the prospective number of personnel that falls under IDM will reach 70,000. By the way, their number can be significantly higher in other countries. For example, 2.5 million people are under control in Japan, including not only dentists, but also veterinarians. “The regulatory bodies act in accordance with the following principle: it is cheaper to monitor workers in advance than to conduct a court case and pay compensation for damage to their health as a result of activities dealing with radiation sources”, Vadym Chumak stated.
The basic health and safety rules for radiation safety in Ukraine OSPU-2005 stipulate that the results of dose accounting for each person should be recoded in a card that is stored for 50 years and until a person reaches 75 years old in the institution, where he/she worked. Even at the stage of licensing the use of radiation sources, the SNRIU should ensure that the licensing institution provides IDM for its employees. It is easier to implement it at nuclear power plants, because they have their own laboratories, as for the rest institutions, they should conclude an agreement with appropriate specialized dosimetry service.
Licensees of radiation sources annually submit annual reports to the SNRIU, where they are stored in paper and electronic form. A part of the reports on personnel doses of for a specific region or the whole enterprise is submitted to the Ministry of Health.
National system of individual dose accounting in Ukraine: what has been done?
The attempts to establish a state system for accounting of individual doses in Ukraine were started in the early 2000s. The procedure for its development was determined by two Resolutions of the Cabinet of Ministers of Ukraine No. 406 (1999) and No. 379 (2001), which entrusted the coordination of this process to the Ministry of Health.
More than ten years have passed, but neither the system nor the national registry has appeared. The concept was changed several times. “At first, it was envisaged that such a register should include information on doses of occupational exposure, medical exposure, exposure of the public from natural sources (the register for doses of residents of the territories contaminated resulting from the Chornobyl accident is already operating under the auspices of the NSCRM)”” Larysa Stadnyk noted.
Although it is understandable how to account the doses of occupational exposure, the recording all the doses of diagnostic exposure of patients turned out to be too difficult: 34 million radiation studies are annually conducted in the country.
Some countries store IDM information in the institutions where a patient was examined, but X-ray machines and computed tomography scanners are equipped there with built-in dosimeters and software with an algorithm for converting the measured doses into an effective dose for a particular patient. Nevertheless, not all radiation diagnostic rooms in Ukrainian hospitals have computers, and attempts to develop a program for collecting data from X-ray rooms and calculating doses were also unsuccessful.
Larysa Stadnyk is convinced, a significant data scope to be collected and insufficient level of computerization in X-ray rooms makes “maintaining the national register of medical doses for the public fully inadvisable”.
Since the Ministry of Health did not cope with the task, the Verkhovna Rada entrusted the State Nuclear Regulatory Inspectorate of Ukraine with responsibility to establish the State System for Monitoring and Accounting of Individual Doses of personnel and the public in 2012-2014.
The SNRIU in cooperation with the National Academy of Medical Sciences of Ukraine conducted in 2014 the national intercalibration of individual dose monitoring laboratories: blank tests under in conditions simulating actual conditions of professional exposure to different doses from radiation sources of various energies. The tests involved 18 laboratories that cover IDM of about 75% of category A specialists. The main goal of the national intercalibration was to assess the quality of dose measurements by IDM laboratories and determine those whose indicators are reliable.
“The assessment was carried out in the most reliable way according to the international criteria of ISO 14146 Standard, unfortunately, not all laboratories confirmed the high quality of activities. It is noteworthy that unsatisfactory quality of individual laboratories in no way affected their further activities in the field of IDM. The positive news was that more than half (55% of persons subjected to examination in the laboratories participating in the intercalibration) of category A personnel receives high-quality dose monitoring that meets the international requirements and quality standards”, Vadym Chumak commented.
However, two government decrees mentioned above by that time were no longer valid and have lost their practical application because a number of central executive bodies related to radiation safety regulation have changed their functions or were reorganized, and the world changed approaches to implementing the radiation protection principles. Both the arrangement and the monitoring and accounting of individual doses did not comply with the requirements and practices of the European Union.
The Inspectorate developed a draft Cabinet Resolution “On Approval of the Procedure for Establishing the Unified State System for Monitoring and Accounting of Individual Occupational Doses” in 2014.
However, the draft was submitted for review to comply with the international standards for operation of national IDM systems set forth in Council Directive 2013/59/EURATOM (5 December 2013) and the international safety standard “Radiation Protection and Safety of Radiation Sources” (2014).
The recommendations in these documents envisaged that the register should also include the data on IDM of employees at the enterprises dealing with the natural radionuclide content; exposure to aircraft crews; workers in coal, iron ore and uranium mines, as well as other persons who are temporarily involved in the activities in the radiation area.
The Draft “Concept for the establishment and performance of the Unified System for Monitoring and Accounting of Individual Doses and the National Dose Register” developed by specialists of the National Scientific Center for Radiation Medicine of the Academy of Medical Sciences of Ukraine headed by Vadym Chumak was presented to the SNRIU Board in 2018 and adopted as a roadmap.
The Draft envisages that the developed infrastructure will accumulate the data on exposure of the public in Ukraine in the following areas: occupational exposure of category A personnel; medical exposure of patients; exposure by natural radioactive materials at workplaces and average group estimates of dose for the public living on territories with radiation background that was increased due to anthropogenic factors.
It was proposed to collect data on individual doses in the Draft exclusively from the dosimetry services or laboratories that are officially certified and approved for data submittal to the National Dose Register.
The authors of the Draft proposed to establish a system for the transfer and storage of data in electronic form, which meant that all transactions are carried out via the Internet, and access to an individual user is provided through the authorization procedure in the user account.
However, the following amendments in the Ukrainian legislation that occurred meanwhile have corrected the regulator’s approach to the issue. In 2019, the Verkhovna Rada of Ukraine adopted in the first reading Draft Law No. 2110 “On Public Electronic Registers”. Accordingly, the IDM information database should be further developed based on the provisions of this Draft Law, when it will become the Law.
It was included into “other” state registers that are not basic ones (that is, containing among other information the data on individual special statuses of individuals and their associations, etc., that are objects of state accounting in accordance with the law). The Draft Law also defines the basis for the establishment, maintenance, cooperation, administration, update, rearrangement and closure of the public electronic register.
Nevertheless, the development of such a database is the final stage in the complex process aimed at establishing the unified system for monitoring and accounting of individual doses, at which the SNRIU directs its efforts now.
As part of this work, the SNRIU developed a Draft Resolution of the Cabinet of Ministers of Ukraine “On Some Issues of Establishing the Unified State System for Monitoring and Accounting of Individual Doses”.
The Draft determines the following:
- the Procedure for Establishing the Unified State System for Monitoring and Accounting of Individual Doses that determines the administrative measures to establish the Unified State System for Monitoring and Accounting of Individual Doses;
- the action plan for the establishment of the Unified State System for Monitoring and Accounting of Individual Doses;
- the Provisions on the State Register of Individual Doses.
- criteria for measurement laboratories.
IAEA Standard Occupational Radiation Protection, General Safety Guide No. GSG-7 (General Safety Guide for Radiation Protection in Occupational Exposure) will be implemented into the national legislation after the adoption of the Resolution of the Cabinet of Ministers of Ukraine under this Draft.
The document defines the technical activity aspects of the entities determining individual doses; it also establishes mechanisms for monitoring occupational exposure, an integrated approach to monitor external and internal occupational exposure, including exposure from materials with a natural content of radionuclides.
In addition, it establishes the requirements for ensuring data quality and reliability, measurement types, methodologies and technical requirements for quality control, the role and responsibility of the regulatory body, technical support organizations, nuclear entities, the requirements for accounting and assessment of doses, etc.
Such a position and approaches are consistent with international practice, IAEA standards and EU legislation.
The idea of creating the whole system is to have the following in it: a unified approach and requirements for monitoring and accounting of individual doses; clear criteria and requirements for the technical support of laboratories and qualification requirements for their personnel; clear requirements for quality control of measurements and calculation of doses.
Only after the implementation of these conditions is it planned to establish a special information and computer accounting system for recording doses, which will meet the international safety standards and EU legislation.
The Draft Resolution is currently under a follow-up agreement with the ministries and departments because of changes in the composition of the government. It is to be hoped that this time the question of establishing the IDM accounting system will not remain on paper, and finally it will be effectively implemented.
Uatom.org Editorial Board.