In May, the Verkhovna Rada of Ukraine passed bill No. 5550-d “On Amending Some Laws of Ukraine on Nuclear Energy Use” in the first reading. The bill envisages bringing the Ukrainian legislation in compliance with European and international safety standards in the sphere of nuclear energy use. The bill of the State Nuclear Regulatory Inspectorate of Ukraine (SNRIU) was submitted to the parliament one year ago and it aims to strengthen human protection against the effects of radiation. The adoption of bill No. 5550-d will allow Ukraine to implement important measures on radiation protection of the public and personnel and will allow the national radiation protection system to be brought to European practice and legislation.
We talked to Ruslana Tripailo, SNRIU Deputy Chairperson and encourager of the bill on amendments, about the importance of movement towards an appropriate legislation for the control and regulation of equipment used in X-ray diagnostics and radiotherapy, arrangement of perfect monitoring of dose loads on patients for its optimization and regulation of nuclear and radiation safety issues regarding the reduction of risks from long-term exposure by radon products.
SNRIU Deputy Chairperson
– Currently, according to the Basic Health and Radiation Safety Rules of Ukraine, individual dosimetric monitoring (IDM) is obligatory for workers whose radiation dose may exceed half the annual dose limit or for women under the age of 45 years. According to the approved amendments, the dose limit is introduced for trainees and students who work with radiation sources during internship and training. Will the dose monitoring be obligatory for them?
– Yes, this is the objective of the bill that is to ensure radiation protection of trainees and students on the same level as personnel through mandatory dosimetric monitoring of their exposure doses during training, internship or other educational processes involving radiation sources. The assignment of trainees and students to persons subject to occupational exposure in no way applies to them main exposure dose limits specified by the Law of Ukraine “On Human Protection against Impact of Radiation” (20 mSv of effective exposure dose per year).
The bill assumes that the main exposure dose limits of trainees and students should not exceed two millisieverts of effective exposure dose per year. The adoption of the bill will force educational institutions to control the individual exposure doses received by trainees and students and to optimize their protection to reduce risks of negative impact of radiation on their health. On the other hand, the bill will ensure the revision of outdated health and safety rules and standards that do not meet current international system of protection and European legislation regarding radiation protection of this category of people.
– In the amendments to the Law, the function of developing and approving an action plan on reducing exposure of the public by radon and its fission products was added to the duties of the Cabinet of Ministers of Ukraine, ministers and other central executive bodies on human protection against radiation. In your opinion, which issues should such a plan include? What should be done first?
– The action plan on reducing exposure of the public by radon and its fission products should include the following priority measures:
- Mapping of each administrative and territorial unit of Ukraine and creation of a map of radon concentrations by types of buildings, soils, landscapes, etc. The results of mapping should be the basis for the planning of targeted preventive anti-radon measures;
- Measurements of radon concentrations in rooms (residential, public, office);
- Establishment of common methodologies and requirements for measuring equipment, criteria for the recognition of laboratories and radon experts, keeping their register. The local authorities, the public, construction organizations will be able to involve these laboratories in determining activity concentration of radon in rooms, workplaces, soils, water;
- Revision of construction standards and rules, technical and design documents;
- Increasing awareness of the public, construction experts, designers, etc. on the health risks from radon in residential, public rooms, workplaces and on effective anti-radon measures;
- Implementation of educational programs for educational institutions of different accreditation levels about radon and counteraction of its impact;
- Optimization of radon exposure at the workplaces of workers, for whom such an exposure is not occupational (coal, iron ore and uranium mines, other underground workplaces).
– Let us proceed to medicine. One of the amendments to the Law “On Human Protection against Impact of Radiation” is the obligatory recording of the dose to the patient, but only for new devices, meaning those devices manufactured, imported and commissioned in Ukraine. What should be done the old devices? Do they also need to be equipped with exposure dose measuring instruments?
– Old medical diagnostic X-ray devices are not only a problem, but a big challenge for Ukraine. European countries do care about the prevention and diagnosis of oncological diseases in the early stages. In our country, old and, in some cases, poor-quality new medical radiological equipment in 75 % does not allow establishing an unambiguous diagnosis, which leads to unreasonable additional diagnostic examinations using radiation. That is why the bill offers to establish requirements for medical radiological equipment that are in compliance with European legislation and international safety standards. It should be noted that there are X-ray machines in Ukraine, which today are more than 50 years old (in comparison with European countries, where X-ray machines can be in operation not more than 8-10 years). In addition, new high-quality medical radiological equipment means lower exposure doses, higher quality of diagnostic images with wider diagnostic and treatment capabilities.
Taking this into account, the next step after approval of bill No. 5550-d should be the quality control of old X-ray diagnostic equipment operated in Ukraine in order to divide it into three categories: suitable for use, requiring maintenance, unsuitable for use. Therefore, within 5-10 years, the old equipment will be gradually decommissioned and replaced with a new one. The results of quality control of medical radiological equipment should be the criteria for the priorities in the replacement of equipment. Such an approach was proposed by the Association of Radiologists of Ukraine 10 years age and the adoption of the bill will allow it to be implemented today.
It should be noted that the first steps in this area have already been done on the initiative of the SNRIU and participants of the Interagency Working Group on Radiation Protection in Medicine. The Grigoriev Institute for Medical Radiology of the National Academy of Medical Sciences of Ukraine developed a methodological guideline “Program for Quality Control of X-Ray Equipment in Radiography”. See more information on SNRIU activities on these issues here.
– It is stated in the explanatory note to the bill on amendments that “the results of measuring the dose forming parameters of devices and the devices themselves in Ukraine according to their characteristics do not comply with national and European standards, which leads to an increase in the exposure dose of patients and deterioration of diagnostic information quality”. Please clarify, will it be sufficient to install equipment for dose monitoring on the device to improve the quality of diagnostics or whether additional control of input parameters of X-ray equipment is needed?
– The quality criterion in X-ray diagnostics is the establishment of a proper correlation between the quality of the image required for diagnosis and patient exposure dose by choosing the optimal physical and technical parameters of the medical radiological equipment.
Equipping of radiological equipment with the device for automated exposure and dose control will allow automated monitoring of radiation loads on patients. The monitoring of operational characteristics (physical and technical parameters) of X-ray diagnostic equipment is carried out to determine the compliance of these parameters with requirements of regulatory and technical documents (first of all, the operational documents on the device) and the current standards to confirm the validity of X-ray equipment (ensuring its normal performance during X-ray diagnostic examination taking into account radiation safety measures).
Monitoring of dose forming parameters should help medical institutions to ensure the quality and safety of X-ray studies. An important condition is to make sure that personnel of the medical institution understand the negative consequences in case of incompliance of the values of controlled parameters with the permissible values, as well as to implement corrective measures to change the situation.
The technical state of X-ray devices is assessed according to the input parameters, the frequency of control of which is determined by the General Radiation Safety Rules for Using Radiation Sources in Medicine approved by the joint order of the SNRIU and the Ministry of Health No. 51/151 dated 16 February 2017 (para. 2, Section II).
Therefore, periodic monitoring of radiation characteristics of X-ray equipment optimizes radiation loads on the patient with simultaneous increase in the quality of X-ray images.
– The determination of the effective dose of a patient requires not only the data on the dose, which is not a problem with new devices, but also the methodology for its calculation taking into account the age, sex, weight of the patient and the type of research conducted. Are there similar methodological recommendations in Ukraine? Who will develop them? Who will be responsible for calculating the patient doses in an ordinary hospital?
– Among all man-made radiation sources, radiological studies create the greatest exposure to the public due to their massive use for the diagnosis of various diseases. Radiation protection in medical exposure is determined by two basic principles: justification of medical procedures and optimization of radiation protection of the patient that is reducing radiation doses to the values as low as possible under conditions of preserving the required quality of the diagnostic image.
International approaches to optimizing radiation protection during medical exposure are related to the need to implement the concept of diagnostic reference levels. According to the provisions of Council Directive 2013/59/EURATOM (Art. 56), European Commission Guideline “Radiation Protection 109”: each state shall establish diagnostic reference levels in X-ray diagnostics or such activities in nuclear medicine for typical examinations for groups of standard-sized patients or standard phantoms (standard-sized patient is person weighing 70 kg + 5 kg, height 170 cm + 10 cm – ed. note).
According to the changes proposed by the bill, there is a requirement that “for diagnostic purposes, it is necessary to use diagnostic reference levels approved by the central executive authority, which ensures the formation of the state policy in the field of health care, and the state regulatory authority for nuclear and radiation safety”.
Currently, the General Radiation Safety Rules for Using Radiation Sources in Medicine / Order of the SNRIU and the Ministry of Health No. 51/151 dated 16 February 2017 approve the values of diagnostic reference levels for X-ray diagnostic examination of a standard-sized patient.
Methodological recommendations in Ukraine for calculating the effective dose of the patient taking into account the age, sex, weight of the patient and type of examination are in the process of development. The implementation of diagnostic reference levels in Ukraine will ensure that the medical institutions will carry out:
- annual assessment of the compliance of exposure doses of patients with diagnostic reference levels;
- monitoring of patient doses in each individual X-ray diagnostic office; corrective measures if the doses exceed the values of diagnostic reference levels or they are significantly lower than these values and the exposure does not provide useful diagnostic information.
– Given the fact that the process of patient dose calculation is rather labor-intensive, are there any plans to implement an electronic system for determining the effective dose? Is it planned to introduce a general reporting system for medical institutions regarding doses of patients during X-ray diagnostic procedures?
– Unfortunately, Order of the Ministry of Health of Ukraine No. 295 dated 18 July 2001, which in the medical sphere is called a malicious order, is still valid. This order is an illusion of actions. It actually impedes the implementation of the concept of diagnostic reference levels referred to in my answer to the previous question in medical institutions. In fact, diagnostic doses of patients are not defined, but are rewritten from this Order and do not comply with the true situation. The SNRIU has repeatedly appealed to the Ministry of Health of Ukraine on the need to abolish this order. A joint meeting of the SNRIU and the Ministry of Health was held in 2010 on this issue. In my opinion, the electronic system for accounting of diagnostic and therapeutic doses of patients should be introduced primarily in the system of the Ministry of Health, and it should be used to analyze the effectiveness of diagnostic or treatment procedures, that is, to be applied in the medical practice.
The introduction of the concept of diagnostic reference levels, which should be used for diagnostic purposes in medical practice, is one of the revolutionary amendments to the Law. Under conditions of proper arrangement of diagnostic examinations and maintenance of the relevant technical state of X-ray equipment, the doses of patients will not exceed diagnostic reference levels. Such a meaning is put into this notion according to the Provisions on Diagnostic Reference Levels developed by the Grigoriev Institute for Medical Radiology. The dose from each medical examination should be compared with the reference level, which is typical for this type of procedures. The result of this comparison will be proof that the device is dangerous and should be decommissioned. Larysa Stadnyk, Head of the Central Laboratory of Radiation Safety and Dosimetry of Medical Exposure of the Grigoriev Institute for Medical Radiology described how exactly were these levels developed and how their use can change the state of radiation safety.
Head of the Central Laboratory of Radiation Safety and Dosimetry of Medical Exposure
of the Grigoriev Institute for Medical Radiology
– Please, tell us what are the reference levels? Why do we need them?
– For most countries, the concept of diagnostic reference levels has become the main instrument for optimizing medical exposure, that is, reducing the doses of patients during medical diagnostic examinations and interventions using X-ray. Reference levels (doses – ed. note) are established in the diagnosis in order to optimize the dose load on patients. When dose limits are clearly established for personnel, dose limits for patients are not established in X-ray diagnosis and in nuclear medicine. At the same time, only two main principles of radiation safety work: the principle of justification of the appointment of any examination and the principle of optimization of medical exposure. The concept of diagnostic reference levels (levels of wellness achieved in the diagnosis) is used for the optimization.
– In what way the reference levels will work as an optimizing factor? What is the procedure for using them?
– When this system works, it will be necessary to assess an average dose of standard-sized patient for a certain type of examination in each room during the monitoring of dose forming parameters. The received value will need to be compared with national diagnostic reference levels. The exceeding of diagnostic reference levels, as well as very low doses, should be of a great concern. This is because any dose should be compared with the image quality. It is possible to have very low doses of patient, but the diagnostic quality of images can be unacceptable. Therefore, the repeated examination can be needed, which leads to additional unreasonable radiation load on the patient. Conversely, it is possible to have a perfect image, but the dose will be significant, that is also unjustified in terms of radiation safety. After all, super quality of the image is superfluous diagnostic information.
For example, we have rooms, in which there are no inconsistencies with the established criteria revealed during the monitoring of technical parameters, but the dose of the patient is rather high and it exceeds diagnostic reference levels. Thus, it is necessary to change the procedure of conducting research and to select such modes, at which the dose can be significantly reduced while preserving diagnostic quality of the image. For example, with an increase in anode voltage by only 30 % and reducing of the exposure by two or three times, it is possible to receive an image of an appropriate quality. Moreover, such an image becomes even clearer by eliminating the blurriness caused by patient movement and scattered radiation. At the same time, the dose of the patient can be reduced by 1.5-3 times.
– There are approved national diagnostic levels and there is a clinic where X-ray diagnostic procedures are performed. How exactly will personnel compare the dose of the patient with diagnostic reference levels?
– The methodological guideline on the monitoring of dose forming parameters developed by our laboratory, which was submitted to the SNRIU for approval, includes the section of practical recommendations on how to assess the dose to a standard-sized patient using known parameters and compare it with diagnostic reference levels. It is envisaged that such activities will be carried out by radiation safety services or services responsible for the monitoring of dose forming parameters. The developed countries of the world have the Departments of Medical Physicists in large regional clinics that are responsible for monitoring the parameters of X-ray devices in their region and for assessing doses to standard-sized patient for each room. Usually, data on the doses of standard-sized patients in certain X-ray procedures shall be presented in the device control certificates, which will be checked by the regulatory authority.
For example, the certificate for determining the dose during monitoring of the room should have a separate line for diagnostic reference levels. The inspector of the regulatory authority when checking such a certificate will pay attention to the significant difference in the dose of standard-sized patient on this device and the value of diagnostic reference levels for a certain type of diagnostic examination. It would be a perfect situation if all the devices were equipped with dosimeters installed in the outlet window of the X-ray tube and which measure dose during an examination in units of “the product of absorbed dose and the area” of exposure. All results of such measurements of the clinic would be sent to the monitoring authorities, which would perform their analysis and identify X-ray devices, at which the doses significantly deviate from the established diagnostic reference levels. There are further activities on the optimization of examination modes, which should lead to a reduction in patient doses in a particular room. Such a practice of optimizing medical diagnostic exposure is very common in Europe. The national diagnostic levels are revised once every three-five years based on the national studies of patient doses using the representative sample of X-ray machines in the country.
Typically, the values of diagnostic reference levels are reduced after performing activities with all machines in which deviations were detected both by technical characteristics and by the level of doses received by the patients.
I really liked how such a work is arranged in Moldova. There, when conducting X-ray quality control that is performed by a medical physicist licensed for this type of work, simultaneously doses of a standard-sized patient are calculated for those types of examinations that are conducted on a particular device. The received dose values are compared with the national diagnostic reference levels and the conclusion is being developed for the possibility of further use of the device and recommendations for the removal of detected deviations.
– This means that the medical physicist uses special software during measurements and calculations?
– Yes, in this case, the software was developed by the physicist himself. However, doses can be calculated by any expert who monitors characteristics of the device within the quality control program using the dose calculation algorithm with known values of parameters of examinations of standard-sized patient and data on radiation of the device under control. The obtained dose values are compared with diagnostic reference levels. When the result is ready, it is considered by the regulatory authority, which makes the decision on each room separately. The only thing a medical physicist can do is give advice on the optimization of the device operating modes.
– The development of diagnostic reference levels is a long and labor-intensive process. What means were used and how long did it take?
– There are two ways to determine diagnostic reference levels.
The first is the direct measurement of doses to patients, for example: the input surface dose is measured using the thermoluminescent dosimetry method (TLD-method). Such measurements were made in the Great Britain and Switzerland. These were the first two countries that established their first diagnostic reference levels back in the late 1950s. We measured doses for various types of examinations in the representative sample of clinic on the so-called standard-sized patient. At least ten dose measurements for each type of examination were performed for each room.
The second option is an indirect method. The radiation emission (absorbed dose rate in the primary bundle of X-ray measurement at a distance of 1 m from the focus of the tube per unit of the anode current – ed. note). After that, you can calculate the dose of a standard-sized patient taking into account the used modes that are typical for this room and the geometry of patient exposure. Our Institute conducted a national questionnaire on X-ray diagnostic rooms through the Ministry of Health of Ukraine. More than 400 rooms participated in this questionnaire. The information was collected on the modes and geometry of different types of X-ray diagnostic examinations taking into account the sex, height, weight, age of patients. As a result, information was collected in each room for each examination type not less than for 10 standard-sized patients or 20 patients with a weight of 70 ± 20 kg, which on average also corresponded to a standard-sized patient.
This approach has recently been used in different countries, which allows one to collect the required amount of information in a shorter time. Using the collected data array enabled studying the distributions of the considered parameters (examination modes, doses of patients). This made it possible to assess the values of examination parameters in each room and calculate average doses of standard-sized patients. In each room, the data set was collected only for those types of examinations, which are usually performed using this device.
A total of more than 5000 direct dose measurements and about 6000 calculations of patient doses for 10 types of X-ray examinations and fluorography were performed. According to the results of analysis of the distribution of the average values of the doses for each type of examination, diagnostic reference level was established, which corresponds to the third quartile of distribution (the dose level corresponding to the limit of 75 % of all doses in the distribution).
– Do the results obtained depend on the used equipment? Have you taken into account the data from very old X-ray machines?
– At first, we did not make a sample according to X-ray machine lifetime, but we calculated doses of each device, assessed average dose values, their distribution. Then, when calculating collective effective and equivalent doses of the public in Ukraine using the results of additional questionnaire, it was possible to define the correlation between different types of devices in the country, including their lifetime. Due to the fact that patients receive different doses from devices of different types during the same types of X-ray examinations (because of different filtration, different modes and correspondently different energy spectra of radiation), there was a task to study the distribution of equivalent doses of patients during examinations when using old and new models.
There were phantom measurements performed on devices with a lifetime of more than 15-20 years (RUM-20, TUR-D-800, etc.) and on modern digital X-ray machines. The experts took into account the coefficients of transition from the input surface doses to equivalent organ doses and to effective doses.
– Now it is clear how much work has been done by your laboratory. What means were used and how long did it take?
– The whole process of establishing national diagnostic reference levels took three years within the research and development activities under the program “Health of the Nation” and continues to the present. Typically, such studies begin the country as part of major scientific projects or within international projects, programs or at the request of the regulatory authorities of the state. Such projects can be implemented not only by experts of leading research institutions, but also by experts of industrial associations. In any case, the completion of such a large amount of work requires qualified personnel, state-of-the-art dosimetric instruments and methodological framework.
– Is it planned to continue these activities and add new examinations to the list of typical diagnostic reference levels?
– Currently, diagnostic reference levels are established for ten types of examinations. Activities will continue: it is necessary to establish diagnostic reference levels for radionuclide diagnostics, for computer tomography, dental radiography, radioscopy and mammography. It is a standard practice: each country starts from X-ray radiography in the development of diagnostic reference levels, then they proceed to the computer tomography for different age groups, then they proceed to the intervention radiology (in time and by dose rate). Each country sets its own level, because there is a completely different set of devices and many other factors that affect the average dose level.
Uatom.org editorial board
It is also envisaged to amend the Law of Ukraine “On Uranium Ore Mining and Processing”. Therefore, it is provided to extend the state regulation on one mining activities and implement licensing of this type of activity. This is primarily due to the need to ensure nuclear and radiation safety not only during the processing of uranium ore, but also during its mining taking into account peculiarities of the uranium concentrate production and exposure of workers in these industries.