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TWINNING FINAL REPORT
EUROPEAN COMMISSION
TWINNING PROJECT FINAL REPORT Project Title: Strengthening of administrative structures for
radiation protection and safety use of ionizing radiation in diagnostics and radiotherapy
Partners: National Centre of Radiobiology and Radiation Protection of Bulgaria (NCRRP)
STUK – Radiation and Nuclear Safety Authority of Finland (MS partner)
Date: August 12, 2009 Twinning Contract No: BG 06 IB/SO/01
Twinning Contract No: BG 06 IB/SO/01 1 (49)
Section 1: Project data
Twinning Contract Number BG 06 / IB / SO / 01
Project Title:
Strengthening of administrative structures for radiation protection and safety use of ionizing radiation in diagnostics and radiotherapy
Twinning Partners (MS and BC) • STUK Radiation and Nuclear Safety Authority (MS)
• National Centre of Radiobiology and Radiation Protection (NCRRP) (BC)
Duration of the project: 12 +3 months
Authors: • Ritva Bly, STUK
• Ivanka Rupova, NCRRP
Twinning Contract No: BG 06 IB/SO/01 2 (49)
Section 2: Content 2A – EXECUTIVE SUMMARY
2B – BACKGROUND
2C – IMPLEMENTATION PROCESS
2D – ACHIEVEMENT OF MANDATORY RESULTS
2E – IMPACT
2F – FOLLOW-UP AND SUSTAINABILITY
2G –CONCLUSIONS
2H – FINAL RECOMMENDATIONS
2I – ANNEXES
Twinning Contract No: BG 06 IB/SO/01 3 (49)
2A - EXECUTIVE SUMMARY The aim of the project was increasing the safe use of ionizing radiation for medical purposes especially 1) to increase effectiveness of early cancer diagnostics and treatment, 2) to apply comprehensive QA policy to radiotherapy and related diagnostic radiology and 3) to innovate and to enhance the activity of the Secondary Standard Dosimetry Laboratory (SSDL) in accordance to the EC requirements. Extent of coverage: The project covered >90% of the radiotherapy facilities in the country, >60% nuclear medicine facilities, nearly 30% of computed tomography (CT) facilities, one third of mammography and about 75% of interventional facilities. Also all calibration procedures of the SSDL for the above mentioned practices were included. Implementation Process: Training: The mechanisms utilized were training courses conducted in Bulgaria, visits to institutions (STUK and hospitals) in Finland and onsite training at work places in Bulgaria by experts from Finland. In addition a significant part of the training accrued in the process of data collection, analysis and interpretation. Guidance documents were prepared with the help of Finnish experts including manuals that were translated into the Bulgarian language. A six-step model developed by MS was utilized that lays importance on stakeholder involvement. Interaction with professional societies was an important component in the project as the dominant approach in the project was to use promotional means rather than regulatory enforcement and that was in line with the 6-step model. Data collection in hospitals on patient doses and quality control activities formed a major part of the work in this project. Results:
1. Good practice requires accuracy in dose to within 3%. Assessment of accuracy in radiotherapy indicated that doses at reference points in non-reference conditions were >3% in 27% of situations against 0,7% under similar conditions in Finland. This is a significant observation requiring actions to avoid over and under dosage to patients. Doses in references conditions were within an acceptable range.
2. 300 staff members were trained through various mechanisms. 3. For the first time in Bulgaria, diagnostic reference levels (DRLs) for computed tomography
(CT) were established and they were found to be lower than values provided by the EC. This indicates a higher level of patient safety in Bulgarian hospitals.
4. For the first time, reference levels for a number of interventional procedures were established.
5. For the first time, reference levels for a number of fluoroscopic examinations were established.
6. The first full scale national survey on the number of procedures in nuclear medicine, level of QC and activity administered was carried out and reference levels were established.
7. For the first time, written dosimetric protocols and QA procedures in radiotherapy were prepared.
8. For the first time, the concepts of quality audit and clinical audit were introduced and criteria for auditing were prepared.
9. For the first time, a workshop on accident prevention in radiotherapy was organized in Bulgaria. This raised awareness among professionals and they are now taking the lead in actions, thus the project acted as a catalyst.
Twinning Contract No: BG 06 IB/SO/01 4 (49)
10. The project resulted in collaboration and cooperation with professional societies of radiotherapy and nuclear medicine.
11. European methodology was applied for collective dose estimation. 12. Verification of calibration methods for the accreditation and QA system according to ISO
system was developed. Impact: Major impacts accrued in cooperation with professional societies, such as:
• The Bulgarian Guild of Radiotherapists is drafting protocols for incident and accident prevention in radiotherapy and agreed to publish the document prepared in this project on most probable incidents and accidents. Further, the Guild took responsibility for distribution of achievements of this project at their annual conference.
• The Bulgarian Society of Nuclear Medicine acknowledged that the information generated through surveys conducted under this project was very helpful to them. They discussed the data and results in their annual conference.
Recommendations: It is recommended that:
• The NCCRP website should have a page on this twinning project that should contain as much information as possible about the project and achievements. This will increase visibility of the excellent performance and results of this project.
• Simple and short pamphlets on radiation safety for use in hospitals for different areas are prepared.
• A commission or a body for quality audit through Ordinance is created. • Requirements for treatment planning systems in radiotherapy, patient positioning lasers
and other safety aids as identified in this project are introduced through ordinance • The results are published in scientific journals as per list that has been prepared • Clinical dosimetry protocols are published
Follow up and sustainability
• There is a need to continue with national surveys as required in the EU Directive and in national ordinance.
• Continuous actions on competence building of inspectors are required. • There is a need to develop unified guidelines on how to register patient doses in diagnostic
radiological examinations. • There is need to have a pilot project on quality audit covering all areas namely
radiotherapy, diagnostic radiology and nuclear medicine. Special focus should be given on the quality of screening procedures.
• Actions are needed on developing guidelines on patient protection in newer imaging technologies.
• Medical physicist’s involvement in diagnostic radiology is in the Ordinance but needs to be implemented.
• There is a possibility of cooperation between the radiographers associations of Bulgaria and Finland.
• There is a need to maintain training workshops on radiation protection in medical specialties for sustainability.
The above areas that require follow up and actions for sustainability need to be explored through projects. Some options would be “Twinning Light” and bilateral projects.
Twinning Contract No: BG 06 IB/SO/01 5 (49)
2B - BACKGROUND Starting Point General Bulgaria is a country with a good regulatory framework and a well organised system of safety of radiation sources and radiation protection of radiation workers and the general public. The Act of the Safe Use of Nuclear Energy (Promulgated in the State Gazette No. 63 of June 28, 2002) charges the Nuclear Regulatory Agency (NRA), under the Council of State, with the licensing and governmental control of all sources of ionising radiation. The Ministry of Health is charged by the Act on Health (Promulgated in the State Gazette No. 70 of August 10, 2004) with the organization, coordination and control over all activities directed towards protection of human health and assurance of healthy working conditions for the population. The Council Directive 97/43/EURATOM for health protection of individuals against the hazards of ionizing radiation in relation to medical exposures was transposed into Bulgarian legislation by the Ordinance of the Ministry of Health No30 from 31 October 2005 for Protection of Individuals at Medical Exposure, promulgated in State Gazette № 91 of November 15, 2005. The National Centre of Radiobiology and Radiation Protection (NCRRP) is a research institution and a specialized advisory body within the Ministry of Health responsible for all the issues of radiobiology and radiation protection. NCRRP, together with five Radiation Protection Inspectorates (in Plovdiv, Varna, Burgas, Vratsa, Rousse) are charged by the Act on Health with ensuring the state control of the parameters of working and living environments, assessment of public exposure and risk assessments. Implementing the requirements of the Ordinance for Protection of Individuals at Medical Exposure needed a number of new activities. This Ordinance stated new demands to radiological practices and detailed requirements for the use of radiological equipment, which have not been previously included in the Bulgarian legislation. Implementing these new requirements needed increased capacity of the existing administrative structures, and improved competence of the NCRRP staff and professionals using radiation in hospitals The Project was designed to support the process of practical implementation of the requirements of the Council Directive 97/43/EURATOM. Component 1: Modernized and effectively operating National Secondary Standard Dosimetry Laboratory (SSDL) in process of preparation Before the project, a crucial remaining task in implementing the EU requirements in radiation protection was improving the accuracy of measurements in clinical dosimetry and quality control in radiotherapy, nuclear medicine, diagnostic radiology and radiation protection, as well as the traceability of the measurements to national and international standards. These responsibilities are assigned to the National Secondary Standard Dosimetry Laboratory (SSDL) – a department of the NCRRP, established in the late 1970s. This Laboratory performs acceptance testing and calibrates radiotherapy systems in the country and provides metrological control of the clinical dosimeters and radiation protection monitors, including individual dose monitors. Since 1980, the SSDL regularly takes part in IAEA/WHO TLD Postal Dose Quality Audit for high energy photon beams using Co-60 and (for protection level measurements), Cs-137. The implementation of the requirements of EC Directive 97/43 EURATOM puts new demands concerning Quality Control of radiological equipment and patient dosimetry, requiring a new generation of control and measuring instruments and introduction of more advanced dosimetric and calibration methods. All this necessitated further development of the SSDL. Accreditation is the way to prove the quality of calibrations done in the laboratory. This is also a prerequisite for the laboratory to be a part of IAEA SSDLs network. According to the Law of
Twinning Contract No: BG 06 IB/SO/01 6 (49)
Measurements (Promulgated in the State Gazette No. 46 of May 7, 2002) only calibrations done in accredited laboratories are valid in the country and so can be used by the customers. Presently the SSDL works with more than 30 year old equipment and that has been one of the reasons not to seek accreditation. Nowadays the hospitals use only manufacturers’ calibrations; therefore they are forced to send their dosimetry equipment abroad for recalibration, which costs a lot of time and money. Accreditation of the national SSDL would develop their methods and this would increase the accuracy and quality, as well as reduce uncertainty in calibration and verification processes. In order to apply for an accreditation, the SSDL urgently needed supply of modern calibration equipment and know-how transfer for updating the calibration methodology. Component 2: Developed system for quality audit in radiotherapy Thirteen radiotherapy departments operate in Bulgaria situated in National Oncological Hospital in Sofia, University Hospital “Queen Joanna” in Sofia, University Hospital in Plovdiv and Oncological Clinics in Stara Zagora, Burgas, Varna, Shumen, Vratsa, Ruse, Veliko Tarnovo, Pleven, Blagoevgrad and Haskovo. At the beginning of the project, the radiotherapy equipment comprised 2 multi-mode accelerators (LINACs); 11 teletherapy (Cobalt 60) units; 15 orthovoltage and 14 superficial X-ray therapy machines; brachytherapy with 1 HDR remote afterloading unit (192Ir) and 9 centres with manual afterloading (137Cs for gynaecological applicators and 192Ir wires for interstitial applications). The biggest problem in radiation therapy in Bulgaria is the old fashioned treatment equipment. In order to meet international good radiotherapy practice, there is an urgent need for new treatment facilities with verification systems and computerized treatment planning systems. The national strategy for modernization of radiotherapy envisages supply of linear accelerators, high dose rate brachytherapy equipment, computed tomography (CT) scanners and X-ray simulators. With the Ordinance of the Ministry of Health No30 from 31 October 2005 for Protection of Individuals at Medical Exposure new Quality control programs for the radiotherapy equipment were introduced. Their implementation needed both nationally accepted protocols and trained staff. Radiotherapy departments using both new and old radiotherapy equipment need to implement quality assurance programs, including standards of good practice and system for preventing and reporting incidents and accidents. The national discussion and awareness of preventing incidents and accidents in RT can be improved. Quality audit required by EC Directive 97/43 EURATOM and by the Ordinance of the Ministry of Health No30 from 31 October 2005 should be introduced in the country. Component 3: Optimised Patient Radiation Protection in Diagnostic Radiology and Nuclear Medicine by means of the Diagnostic Reference Levels (DRL) In order to facilitate implementation of the Ordinance of the Ministry of Health No30 from 31 October 2005 for Protection of Individuals at Medical Exposure, a new department for Radiation Protection at Medical Exposure was established in 2003 at the NCRRP. The staff of this department develop quality control and dosimetry methodologies, perform training of medical physicists and other staff and are responsible for performing national patient dose surveys and elaboration of national Diagnostic Reference Levels (DRLs). The first large scale national patient dose survey in conventional Diagnostic Radiology was conducted in 2003-2004 within the PHARE Project BG/2000/IB/EN 01-05 “Radiation Protection and Safety at the Medical Use of Ionizing Radiation”. As a result, national reference patient dose
Twinning Contract No: BG 06 IB/SO/01 7 (49)
levels were elaborated and included in the Ordinance of the Ministry of Health No30 from 31 October 2005. These reference levels needed to be updated with enlargement of a national survey in conventional diagnostic radiography and fluoroscopy, interventional radiology, computed tomography and nuclear medicine. The purpose was to implement internationally accepted methodologies for dosimetry and data analysis. The NCRRP performs population dose estimation from different sources of exposure. The methodology of collective dose estimate due to medical exposure needed to be updated according to the European guidance. Objectives Overall objectives Strengthening of the administrative and institutional health care structures in Bulgaria with regard to radiation protection, reduction of radiation exposure of the population during medical use of ionizing radiation as required in the EC Basic Safety Standards 96/29 EUROTOM and the Medical Exposures Directive 97/43/EUROATOM, raising the level of the medical services and so approaching a better quality of life. Project purposes Increasing the safe use of ionizing radiation for medical purposes and effectiveness of early cancer diagnostics and treatment, applying comprehensive QA policy radiotherapy and diagnostic radiology, nuclear medicine and innovation and enhancing the activity of the Secondary Standard Dosimetry Laboratory in accordance to the EC requirements. Mandatory Results – A Modernized and effective National Secondary Standard Dosimetry Laboratory (SSDL) in
process of preparation – A developed system for quality audit in radiotherapy – Optimised Patient Radiation Protection in Diagnostic Radiology and Nuclear Medicine by
means of Diagnostic Reference Levels (DRL)
Twinning Contract No: BG 06 IB/SO/01 8 (49)
2C - IMPLEMENTATION PROCESS Developments outside the project The results of the project have been supporting material for the regulatory work of the Nuclear Regulatory Agency (NRA). Some changes in the Act of the Safe Use of Nuclear Energy (Promulgated in the State Gazette No. 63 of June 28, 2002), are still proceeding in Parliament. These are expected to improve and simplify the licensing process for sources of ionising radiation used in medicine. Good collaboration exists between NRA and the Ministry of Health and all outstanding issues regarding radiation protection during medical exposure have been duly settled. In connection with the dosimetry workshop, a management level workshop was arranged with the contribution of Finnish Embassy. A meeting with high level representatives of the Ministry of Health, NRA and NCRRP was held in the Finnish Embassy invited by Ambassador Jämsén. Director Eero Kettunen from STUK gave a presentation on the organization and functions of STUK. It was agreed that to strengthen radiation protection and safe use of ionizing radiation a discussion of the administrative infrastructure of the radiation protection authority will be continued and Ambassador Jämsén made the suggestion to invite the meeting again after few months. An inspection workshop was also arranged in NCRRP for BC and MS inspectors. Some differences in working methods came up. MS inspectors also participate in research that supports the supervision of radiation practices and the licensees respect inspectors as experts. Project developments General According to the EC Medical Exposure Directive (MED), member states shall ensure that appropriate quality assurance (QA) programmes, including quality control measures and assessments of patient dose or administered activity, are implemented by the holder of the radiological installation. This requires good co-operation between authorities and radiation users. The project Implementation process included effective stakeholder involvement in all components. There were three training workshops to organize discussions and to meet professionals from hospitals and to get their societies involved. Also training was given in these workshops especially for trainers and feedback was collected for improving the developed QA procedures. The quality of the workshops was evaluated by the participants to be very good (Figure 1).
Twinning Contract No: BG 06 IB/SO/01 9 (49)
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Figure 1. Results from the feedback questionnaire on the Workshop on dosimetry in radiotherapy and related diagnostic radiology, Workshop on preventing accidents and incidents in radiotherapy and the Workshop on quality auditing (96 respondents). Figure 2 describes a six-step model (Parkkinen 2006) that was followed in the project. At step 1 there was introduction of new international recommendations and new national dosimetry procedures that were developed in the project. At step 2, the biggest effort was taken in up-dating DRLs. Steps 3 and 5 were taken in the training workshops and a good example of step 4 is that radiation therapy physicists were actively involved in drafting QA protocols. Step 6 was taken in the follow-up questionnaires and continuous improvement of the process will be achieved through clinical auditing that was also introduced in the project.
Figure 2. Improving quality in medical radiological practices using stakeholder involvement effectively. (Parkkinen R, Järvinen H. Implementation of QA in medical radiologica practices: A national cooperation mode. Book of extended synopses. IAEA-CN-146. International Conference on Quality Assurance and New Techniques in Radiation Medicine. 13-15 November 2006, Vienna, Austria. p. 114-115)
6. Making verifications of the present situation and improving the process
3. Organizing discussions and meeting on QA with different specialists and organizations
5. Educating and training a number of advisors who can distribute information among other specialists
4. Preparing guidelines for radiation users together with specialists
2. Undertaking research to support the regulations
1. Introducing regulations for the use of radiations
Twinning Contract No: BG 06 IB/SO/01 10 (49)
Stakeholder involvement of hospitals was most strongly needed in the activities related to radiation therapy. All except one radiotherapy clinic out of 13 in the country participated in the project (Figure 3a). The clinic that did not participate has only one orthovoltage treatment equipment and the workload is minor compared to the others. Ten out of 18 hospitals having nuclear medicine department had a direct contact with the project (Figure 3b) in order to improve the quality by establishing clinical auditing. All NM departments participated to the survey for up-dating DRLs.
a) Participation of radiotherapy departments
8%
15%
77%
Site visits or 2-3 Workshops 1 Workshop No contact
b) Participation of nuclear medicine departments
39%
44%
17%
Two or more contacts One contact No contact
Figure 3a and 3b. Participation of hospitals in the implementation process of the project concerning radiation therapy and related nuclear medicine.
Component 1: Modernized and effectively operating National Secondary Standard Dosimetry Laboratory (SSDL) in process of preparation Several activities were implemented:
Preparatory activities for SSDL modernization were started with long term training of about 6 man months of BC staff. During the training all main activities of the modern SSDL were covered. The main focus was on calibrations that are related to radiotherapy, x-ray diagnostics and survey meters.
Technical specifications for the supply of the necessary measurement and control equipment were defined and prepared by the BC staff. The time limit from the BC’s The Central Finance and Contracts Unit at the Ministry of Finance (CFCU) was only one day after the CFCU’s notification of the beginning of the project. MS were not able to fully give expertise in the preparation of technical specifications. Since CFCU announced a call for tender only four months later, it should have been quite possible to complete the support according to the contracted work plan.
The methodology for calibrations was updated according to the internationally accepted codes of practice. Three procedures for calibration were drafted: one procedure for calibration of dosimeters used in Radiotherapy; one procedure for calibration of dosimeters used in Radiation Protection and one – for calibration of dosimeters used in Diagnostic Radiology.
Twinning Contract No: BG 06 IB/SO/01 11 (49)
Inter-calibrations between BC and MS SSDLs were carried out using six BC ionization chambers. Results showed good agreement between BC and MS SSDLs.
Methods for traceability of measurements and inter-laboratory comparisons between radiotherapy treatment systems were introduced and implemented. The emphasis in the training was given to practical performance of calibrations and analysis of the results. There were 11 site visits to MS hospitals for the field dosimetry.
Several activities were fulfilled in order to prepare the SSDL for certification in accordance with national institutional requirements: a quality manual was drafted and evaluated in several steps including stakeholder involvement in the dosimetry workshop; the methodology for uncertainty estimations was introduced. In practice estimations can only be finalized after commissioning of the new calibration equipment.
Activities related to drafting of documentation for the accreditation of the SSDL will be wasted if the Investment Project for the supply of equipment is not funded. Component 2: Developed system for quality audit in radiotherapy Technical specifications for the supply of the necessary quality control equipment were defined and prepared by the BC staff. The time limit from the BC’s CFCU was only one day after the CFCU’s notification of the beginning of the project. MS were not able to fully give expertise in the preparation of technical specifications. Since CFCU announced a call for tender only four months later, it should have been quite possible to complete the support according to the contracted work plan. Key elements of QC in radiotherapy of different modalities were recognized in practical sessions during site visits to eight radiotherapy clinics. The main types of facilities were included – linear accelerators, HDR brachytherapy, CT, Cobalt unist and orthovoltage units. Photon and electron dosimetry protocols were drafted in an intensive interaction with the medical physicist in radiation therapy. Pilot measurements for cobalt and X-ray were conducted in eight radiotherapy centres and for LINACs – in two centres. On site visits to the National Oncological Hospital the QC of a CT-simulator was introduced in practice. A QC program for CT-simulators was drafted. QC program for SPECT-CT was drafted combining the existing programs for SPECT and for diagnostic CT with additional tests for hybrid imaging. NEMA-standards were in use for the QC of SPECT. This program was implemented by BC staff on the first SPECT-CT in the country. There is no PET yet in the country but recommendations for QC were discussed.
A QA programme was implemented in the leading radiotherapy department at the National Oncological Hospital in Sofia. This will allow the knowledge to be further shared with other clinics because this hospital is a teaching hospital for medical physicists, radiotherapists and technologists. A preliminary QA protocol was developed in intensive interactions with the medical physicists in radiation therapy. Eight of thirteen RT departments were visited by MS and dosimetry verification was carried out. Each RT department was given practical guidance on QA in site visits.
A national auditing group of 15 experts was established and trained. In the training IAEA auditing recommendations were used and preliminary national auditing criteria were established. Drafted QA protocol and auditing criteria were presented during the annual meeting of the Guild of Radiotherapists at the end of May. A formal proposal to the Minister of Health was prepared and submitted to recognize the auditing team and the main principles of the audit. They will be
Twinning Contract No: BG 06 IB/SO/01 12 (49)
included in the Ordinance of the Ministry of Health No30 from 31 October 2005 for Protection of Individuals at Medical Exposure.
The main reason for poor quality is a lack of computerized treatment planning systems. The main part of the QA and QC protocols is for verification of the patient dose. Eight of thirteen RT departments were visited by MS and dosimetry verification was carried out. The results were communicated with staff from hospitals and additional measurements were performed by the SSDL staff and hospital medical physicists A workshop on incidents and accidents in radiation therapy was carried out and a preliminary risk analysis of incidents and accidents was completed. The Guild of Radiotherapists Feedback took the responsibility for further drafting of risks and categorizing of incidents and preparing guidelines for reporting them. A questionnaire following the workshop was sent to all participants for evaluation of the degree of awareness and changes in practice after the workshop. 70% of participants from hospitals answered the questionnaire. Emergency action protocols to be included in the QA program were drafted and discussed on several meetings of the auditing group and the group responsible for QC protocols. Future actions within the Guild of Radiotherapy were agreed to increase the awareness in the radiotherapy clinics: lectures and discussions for accidental and incidental exposures will be included in the program for postgraduate training of radiotherapists, medical physicists and technologists, as well as in programs for obligatory radiation protection training. A voluntary reporting system will be organized under the coordination of the NCRRP. Component 3: Optimised Patient Radiation Protection in Diagnostic Radiology and Nuclear Medicine by means of Diagnostic Reference Levels (DRL)
The main purpose of this component was to achieve optimised patient radiation protection in Diagnostic Radiology and Nuclear Medicine by means of Diagnostic Reference Levels (DRL). Within the investment part a supply of measuring equipment was planned for further implementation of the project tasks, particularly dosimetry equipment for radiation control inspections. The technical specification was prepared and discussed but the tender failed and this stopped the plans for near future activities for increasing capacity and effectiveness of governmental control of medical exposure. The work designed in seven activities was conducted mainly by the staff of the Department for Radiation Protection at Medical Exposure at NCRRP. The task implementation required performing national patient dose surveys. This is easily achievable in countries with sufficient numbers of medical physicists in diagnostic departments. However, this is not the case in Bulgaria, and so particularly good organization and planning of the activities was critical for the success of the project. The NCRRP staff and staff of Radiation Control Inspectorate at NCRRP and Inspections in Plovdiv, Burgas, Varna, Ruse and Vratsa were included in the implementation of the project tasks. During the first expert missions of MS the methodology of the surveys was agreed, including the measured quantities, measurement methods, number of hospitals to be included, number of patients for each modality or type of the phantom used. Inter-comparisons were performed of the NCRRP and STUK measuring procedures as well as the accuracy of the results. For conventional radiography, a standard protocol and measuring instructions were developed by the NCRRP for data collection by the hospital staff and for the measurements of the tube output by the medical physicists. Five regional centres in Plovdiv, Burgas, Varna, Vratsa and Ruse were visited by NCRRP experts to train the local staff and to verify the results from the measurements of the tube output. The examinations included were radiography of the chest (PA),
Twinning Contract No: BG 06 IB/SO/01 13 (49)
pelvis (AP), lumbar spine (AP and Lat), skull (AP/PA and Lat) and urography (before and after contrasting). All data were collected by NCRRP, entered into a data base and calculations of the individual patient doses were performed. Data analyses were made by the NCRRP medical physicists and discussed several times with STUK experts. For mammography a separate protocol was developed for measurements with a standard mammography phantom of 45 mm PMMA For fluoroscopy, surveys were conducted separately in conventional fluoroscopy (Barium enema and Barium meal examinations) and in interventional radiology, including cardiology. Standard protocols were elaborated by the NCRRP and data collection was organized by medical physicists, X-ray technologists, cardiologists or other relevant staff. The measured quantity was KAP but several other parameters were also recorded, like fluoroscopy time, number of frames, number of series, complexity of the procedure, etc. Every department included in this survey was visited by NCRRP experts for DAP-meter calibrations and fluoroscopy system characterization by means of phantom measurements. During the measurements, all other observations concerning radiation protection of the staff and patients were also recorded. Results were collected and analyzed by the NCRRP expert and discussed several times with STUK experts. For computed tomography (CT) the survey was based on an internationally accepted methodology for measurements of CTDIw and DLPw values in a standard phantom. Inter-comparison of methodology and results was made between NCRRP and STUK. All the measurements were performed by NCRRP experts with the organizational support by the regional radiation control inspectorates. Updating the established DRLs in Diagnostic Radiography and determination of DRLs in fluoroscopy procedures and CT was achieved during the last quarter of the project implementation. The analyses of the results from the dosimetry surveys were presented and discussed during several meetings within the Department of Radiation Protection at Medical Exposure at NCRRP, as well as with MS experts. The overall opinion was that the survey was successfully organized and performed and new DRLs can be proposed for the official approval by the Minister of Health. For Nuclear Medicine, the STUK experience in performing the survey was introduced by the MS expert. Based on shared experience, a questionnaire was elaborated by NCRRP with consultation with the national consultant in Nuclear Medicine. All 18 NM departments in the country were asked to complete the questionnaire. All answers were collected in a database in NCRRP and analyzed. The analysis covered the equipment used, the number of in vivo diagnostic examinations for adults and children with the applied activities and radiopharmaceuticals used, as well as the number of therapeutic NM procedures. Collective dose estimation from diagnostic radiology and NM examinations was one of the final aims of project Component 3. During the MS expert mission detailed discussion was made on the recommended methodology for the collection of numbers and frequency of X-ray examinations and for effective dose calculation from different diagnostic examinations, as well as calculation of collective doses. All work on this task was performed by the NCRRP staff.
Twinning Contract No: BG 06 IB/SO/01 14 (49)
Project visibility The following steps were taken to ensure project visibility and EU visibility.
• Information materials of the project - A project poster in Bulgarian was prepared at the start of the project
introducing the project purpose, tasks and institutions involved. It was used in meetings and it was also displayed in the premises of NCRRP.
- Leaflets and folders about the project were produced and disseminated during the meetings, workshops and visits to hospitals.
• Information distributed in Bulgaria - At the start of the project letters were sent to the university hospitals and
radiotherapy clinics with information about the project and an invitation to participate and to contribute to the project implementation.
- Before the final meeting a press release about the results of the project was sent through the press-centre of the Ministry of Health (in Bulgarian).
- Information appeared in the following web-sites (in Bulgarian): http://zdrave.net/Portal/News/?evntid=TEQSCLlMroI%3D http://www.cross-bg.net/ http://www.vestnici.com/news/article/48199 http://www.bta.bg/cgi-bin/site.1/freenews/bulgariaes_news.pl?sepfilename=337837949
• Publications 1. Recently revised DRLs in nuclear medicine in Bulgaria and in Finland – H.
Korpela, R. Bly, J. Vassileva, K. Ingilizova, T. Stoyanova, I. Kostadinova and A. Slavchev – presented at the Third Malmö Conference on Medical Imaging “Optimisation in x-ray and molecular imaging” in Malmö, Sweden, 25-27 June, 2009. Will be published in Radiation Protection Dosimetry
2. A national patient dose survey and updating of DRLs for conventional radiography and mammography in Bulgaria – J. Vassileva, S. Avramova-Cholakova, D. Kostova-Lefterova, R. Borisova, K. Ingilizova, D. Taseva, J. Hristova, M. Pirinen, H.Järvinen – drafted; to be submitted to an international journal
3. A national patient dose survey and setting of reference levels for interventional radiology in Bulgaria - R. Borisova, J. Vassileva, J. Hristova, M. Pirinen, H. Järvinen - – drafted; drafted; to be submitted to an international journal
4. A national patient dose survey and setting of DRLs for fluoroscopy (barium enema and barium meal) in Bulgaria - A. Dimov, D. Dosieva, M. Pirinen, H. Järvinen – drafted; drafted; to be submitted to an international journal
5. Establishment of reference dose levels in Computed Tomography in Bulgaria – D. Stoyanov, J. Vassileva, K. Merimaa – drafted; drafted; to be submitted to an international journal
6. Estimation of population dose in the medical use of radiation in Bulgaria – J. Vassileva, K. Ingilizova, A. Dimov, R. Borisova, T. Stoyanova, J.Hristova, H. Järvinen, H. Korpela – to be drafted; to be submitted to drafted; to be submitted to an international journal
7. Аnalysis of results of the national survey of patient doses in Diagnostic Radiology - Vassileva J., Borisova R., Dimov А., Stoyanov D., Avramova-Cholakova S., Ingilizova K.,Kostova-Lefterova D., Taseva D., Hristova J., Dosieva D., Diakov I., Jarvinen H., Pirinen M. – accepted for presentation at
Twinning Contract No: BG 06 IB/SO/01 15 (49)
the Thirteen Congress of the Bulgarian Association of Radiology, Bansko 1-4 October 2009
8. Analysis of results of the national survey in Nuclear Medicine - Stoyanova T., Vassileva J., Ingilizova K.,Kostadinova I., Slavchev A., Korpela H. – accepted for presentation at the Thirteen Congress of the Bulgarian Association of Radiology, Bansko 1-4 October 2009
9. Other publications to be presented in congresses • www-pages
- A webpage was prepared on the NCRRP web-site (www.ncrrp.org) with information about the project; presentations from the meetings and workshops and materials produced during the project.
Twinning Contract No: BG 06 IB/SO/01 16 (49)
2D - ACHIEVEMENT OF MANDATORY RESULTS Component 1: Modernized and effectively operating National Secondary Standard Dosimetry Laboratory (SSDL) in process of preparation The mandatory result was to achieve a modernized and effective National Secondary Standard Dosimetry Laboratory (SSDL) in process of preparation. The main purpose of this component of the project was to prepare the SSDL for accreditation with elaboration of a quality manual based on ISO/IEC 17025 requirements. Updating methodologies for calibration and metrological control of dosimeters used in radiotherapy, radiation protection, and diagnostic radiology were an essential part of the process. One of the main tasks in the beginning of the project was to elaborate a technical specification for new equipment for the SSDL. The supply of this equipment was crucial for the success of the project task implementation. However, the tender exercise for supply of this equipment, organized by the CFCU, failed. That jeopardizes the further development of the SSDL. An aim of the project was to estimate the calibration uncertainties of the SSDL based on theoretical assumptions and practical implementation including calculation of real measurement data. Without the new equipment the parameters of dosimetry standards and calibration equipment could not be estimated. The only possible decision was to prepare the theoretical part. This included seminars and exercises on different models, discussions on influencing parameters, distribution, and environmental conditions. The uncertainty budget for the different calibrations with the present equipment exists. As an example, the model of uncertainty calculations used by STUK was discussed. About 6 man months of training of BC staff was carried out in MS. As a part of the training in the SSDL inter-comparisons of calibrations were carried out for the following ionisation chambers: DAP chamber, plane parallel chamber, CT chamber, mammography chamber and three cylindrical chambers used in radiation therapy calibrations. The agreement was good, except in DAP calibrations, where differences were about 15 %. The reason for that was investigated carefully with more measurements both in NCRRP and STUK and the conclusion was that for this chamber type (KDK – chamber in chamber) the difference is due to the strong dependence on the field size of the chamber response. The results of the inter-calibrations are in the Annex 2. The aim of the project was to draft three calibration procedures – one for calibration of dosimeters used in radiotherapy; one for calibration of dosimeters used in radiation protection and one for calibration of dosimeters used in diagnostic radiology. These procedures are based on the existing IAEA protocols and the work included not only drafting of written material but also real laboratory measurements for the testing and implementation of procedures.
Good practice during the project was the close involvement of the SSDL staff in the implementation of the other two components of the project with participation in the measurements performed in hospitals, especially in radiotherapy departments. This helped in the understanding of the real needs and in estimation of the impact of the calibrations and uncertainties provided. The calibration procedures that were developed were discussed during the visits in hospitals, workshops and meetings. A training workshop on dosimetry in radiotherapy and related diagnostic radiology was performed on 6 and 7 November 2008 in Sofia, with 56 participants (medical physicists and inspectors): 26 from hospitals, 17 from NCRRP; 8 from RP inspectorates and 4 from QC companies. Lectures were given by 6 STUK experts and 9 Bulgarian medical physicists from NCRRP and from hospitals. The workshop was highly rated by participants. All of the participants found the
Twinning Contract No: BG 06 IB/SO/01 17 (49)
workshop very useful for their practical work. Recommendations were given for organization of future of courses on practical dosimetry, radiation protection dosimetry, and on optimisation of clinical practice. All participants pointed out the need for national agreement on standard dosimetry protocols. List of documents (drafts) prepared during the project:
1. Quality Manual Contents (in English) 2. Quality Manual Structure (in English) 3. Procedure for calibration of dosemeter for therapy (Syllabus in English) 4. Procedure for calibration of dosemeter for therapy (in Bulgarian) 5. Procedure for calibration of a diagnostic dosemeter for air kerma with x-rays (Syllabus in
English) 6. Procedure for calibration of a diagnostic dosemeter for air kerma with x-rays (in Bulgarian) 7. Procedure for calibration of a ambient dose equivalent H*(10) ratemeter using 137Cs
reference radiation (Syllabus in English) 8. Procedure for calibration of a ambient dose equivalent H*(10) ratemeter using 137Cs
reference radiation (in Bulgarian) Component 2: Developed system for quality audit in radiotherapy The mandatory result was a developed system for quality audit in radiotherapy. Several steps were undertaken to achieve this result. The final aim of this project component was to develop a national system for quality assurance and quality audit in radiotherapy. A distinctive feature of this component was the close cooperation in its implementation between the NCRRP and medical physicists, radiation oncologists and radiotherapy technologists from the oncological clinics in the country. All the work was carried out voluntarily and without cost. An important level of organisational support was given also by the National consultant in Radiotherapy and the President of the Guild of Radiotherapists in Bulgaria. Creation of a national protocol for Quality Control in radiotherapy From the start of the project, the key elements in Quality control (QC) in radiotherapy of different modalities were recognized. Quality control of linear accelerators, Co-therapy units, x-ray treatment units and brachytherapy equipment was introduced in hospitals by the MS expert. Also QC of simulators and CT-simulators was included. Practical sessions on QC were conducted on site visits to 8 of 13 Bulgarian radiotherapy clinics. International methodology and MS experience was introduced. For therapy equipment, the most important issue is dose comparison in reference conditions and that was carried out in each radiotherapy centre. The BC experts drafted QC protocols for photon and electron dosimetry, based on the IAEA TRS 398. The drafting was made in five parts with different persons responsible for each part - QC protocol for gamma-therapy, QC protocol for X-ray machines, QC protocol for LINACs (inear accelerators), QC protocol for CT and X-ray simulators, QC protocol for PET-CT, SPECT-CT. The drafts were presented and discussed during the workshop on dosimetry in radiotherapy and diagnostic radiology. The drafts were discussed in detail in three other workshops with key medical physics experts from hospitals and experts from NCRRP. All the drafts were combined and reviewed by one responsible person. The final drafts were reviewed by medical physicists
Twinning Contract No: BG 06 IB/SO/01 18 (49)
from most of the therapy departments and corrections were suggested by them. Pilot measurements were carried out during the on-site visits in eight radiotherapy centres and in both centres with LINACs On site visits to the National Oncological Hospital, QC of a CT-simulator was introduced in practice. The BC staff drafted a QC program for CT-simulators based on the existing QC program for diagnostic CT and additional tests for radiotherapy applications. The international guidelines for SPET-CT and PET-CT were discussed. The BC staff drafted QC program for SPECT-CT combining the existing programs for SPECT and for diagnostic CT with additional tests for hybrid imaging. NEMA-standards were in use for the QC of SPECT. There is no PET in use yet in the country; however the first one is under commission testing. Results of dose comparison in radiotherapy Dose comparisons in reference conditions in photon beams with two accelerators and seven Co-60 units showed good agreement (Figure 4). Only one beam out of 11 measured was deviating more that 2 %. These doses have been regularly controlled by the NCRRP dosimetry laboratory.
0
1
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3
-3 -2 -1 0 1 2 3
Figure 4. The difference between measured and stated photon dose [%] in reference conditions using FS (field size) 10 cm x 10 cm. In accelerator beams reference depth was 10 cm in either fixed SSD (source to skin distance) 100 cm or isocentrically. In Co-60 beams SSD was 75 cm, reference depth was 5 cm. The difference was more than ±3 % in 1/11 (9%) of beams. Tolerance of 1,5 - 2 % deviance would be acceptable. However doses at reference points in non-reference conditions showed more deviations (Figure 5). 16 beams out of 59 (27 %) were deviating more than 3 %. This can be compared to Finnish results, where only 7 % deviate more than 2 % and 0,7 % deviate more than 3 %. There are many possible reasons for these results in Bulgarian radiation therapy centres. Front pointers inaccurately indicating distances were the main reason for dose deviations. Moreover most hospitals do not have a treatment planning system and an adequately accurate dose
Twinning Contract No: BG 06 IB/SO/01 19 (49)
calculation is therefore impossible. There were no lasers available in most centres, for patient positioning purposes.
0
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4
5
6
7
8
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Figure 5. Difference between measured and stated photon dose [%] in non-reference conditions using field sizes 5 cm x 5 cm - 20 cm x 20 cm. In accelerator beams the reference point was at a depth of 10 cm, SSD 100 cm or isocentrically, in Co-60 beams at the depth of 5 cm, SSD was 75 cm. The difference was more than ±3 % in 16/59 (27%) beams and more than ±5 % in 9/59 (15 %) beams. Tolerance of 1,5 - 2 % deviance would be acceptable. Also comparisons in non-reference conditions in photon beams for 5 x-ray units were carried out (Figure 6). In 5 out of 15 beams the deviation was more that 5 %.
0
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-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18
Figure 6. Difference between measured and stated x-ray photon dose [%] in reference conditions using field sizes Ø 4 cm - 8 cm x 10 cm. Reference point was on the surface (E < 100 kV) and 2 or 5 cm (E > 100 kV). Energy range was 50 kV- 250 kV and SSD 15 cm - 50 cm. The difference was more than ±5 % in 5/15 (33%) beams.
Twinning Contract No: BG 06 IB/SO/01 20 (49)
Setting up a national auditing group for QA in radiotherapy as to EC-standards. The National consultant in Radiotherapy nominated an auditing group to be trained including 5 radiation oncologists, 5 medical physicists and 5 technologists from different clinics. This group met first in November 2008 and training was performed by the MS experts. The NCRRP (BC) and STUK (MS) jointly organized a Workshop on quality auditing (Clinical audit) in radiation therapy, x-ray diagnostics and nuclear medicine, in Plovdid 4-5 February 2009. This was the first national meeting on Clinical audit organized in Bulgaria. Besides the experts form STUK, the Workshop had 45 participants (7 persons from NCRRP, 14 persons for radiotherapy, 10 persons for NM and 14 persons for diagnostic radiology) and 1 representative from the Ministry of Health. The list of participants also included persons from the radiotherapy audit group established within this Twinning project, thereby providing additional training to that group. Specific quality indicators and organization of the audit for every specialty was discussed in groups and an action plan was prepared to facilitate the implementation process in Bulgaria. The majority of participants found the workshop very beneficial for their practical work. The third meeting of the auditing group was performed in April 2009 and final decisions were made for future actions. The QA protocol that had been drafted and auditing criteria were discussed. They were presented and widely discussed during the forthcoming annual meeting of the Guild of Radiotherapists in the end of May 2009. A formal proposal with the main principles of the audit was prepared for submission to the Ministry of Health. Proposals for changes in the Ordinance of the Ministry of Health No30 from 31 October 2005 for Protection of Individuals at Medical Exposure regarding the clinical audit were drafted. It will be submitted to the Ministry of Health together with other proposals for changes in the Ordinance until the end of 2009. Drafting scenarios for most probable accidental exposures in radiotherapy and emergency action protocols. A workshop on incidents and accidents in radiation therapy was carried out in September in Varna with 40 participants (oncologists, medical physicists, technologists, inspectors) - 22 from hospitals; 18 from NCRRP and RP inspectorates. Lectures given by the experts formed good bases for group discussions on identification of risks in Bulgaria, preventing incidents, reporting and elaborating emergency plans. The efficacy of the workshop was evaluated by a questionnaire which was sent to all participants for evaluation following the workshop. The answers indicated the degree of awareness and changes in practice after the workshop. The results are shown in Figure 7a, 7b and 7c. The questions are listed below.
Human factors
1. Do you conduct an investigation for the possible reasons in case of unusual situation or reaction of the
patient?
2. Do you have, at your opinion, enough staff for the whole workload in the department?
3. In your centre does a second physicist verify the calculations of the RT plan before the treatment of the
patient?
4. Are always a physician and a physicist participating in the first positioning of the patient for treatment?
5. Is there awareness among all the staff of the RT department with the emergency plans?
6. In how many percent of the patients do you make in-vivo dosimetry?
7. Is there a verification system (automatic or by the staff) for the positioning of the patient for treatment?
8. Do you have an operating manual translated in Bulgarian for all the therapeutical units you have in the
Twinning Contract No: BG 06 IB/SO/01 21 (49)
department?
9. Is, at your opinion, safe enough the procedure for: patient identification, the choice of the right anatomical
place to be treated, the choice of treatment time or monitor units, set on the operator’s console? Technology
10. Do you regularly execute practical training for the emergency situations of Co source sticking or electric
power cut?
11. Do you have all the necessary equipment (including duplicate) for accomplishment of your duties?
12. Does your Co unit have a second (safe) timer?
13. Do you have a system of proper handover of the equipment after servicing by the engineer?
14. Is there a system to prevent entry into treatment room when the beam is ON?
15. Do you have a camera (window) for observation of the patient during treatment? Communication
16. Do you discuss the possible incidents and accidents with the RT department staff?
17. Is there a procedure in your department for reporting of errors or problems arising during the daily work
of the radiation technologist to a physicist and radiation oncologist?
18. Do you have an elaborated procedure for action and notification of the staff in case of change of the
treatment plan of the patient?
19. Do you have practice in your department to record in written form all problems arising (technical, human
errors of the staff etc.)?
Twinning Contract No: BG 06 IB/SO/01 22 (49)
Human factors
0 %
10 %
20 %
30 %
40 %
50 %
60 %
70 %
80 %
90 %
100 %
1 2 3 4 5 7 8 9
Number of Question
Yes
answ
ers
Before
After
Technology
0 %10 %20 %30 %40 %50 %60 %70 %80 %90 %
100 %
10 11 12 13 14 15
Number of Question
Yes
answ
ers
Before
After
Communication
0 %10 %20 %30 %40 %50 %60 %70 %80 %90 %
100 %
1 2 3 4
Number of Question
Yes
answ
er
Before
After
Figures 7a, 7b and 7c. Improvement of awareness and change of practices after the workshop on preventing accidents and incidents in radiation therapy. Results of the follow-up questionnaire.
Twinning Contract No: BG 06 IB/SO/01 23 (49)
A small workgroup drafted scenarios for most probable accidental exposures in radiotherapy and guides for the content of the emergency action protocols were developed. It was decided that the President of the Guild of Radiotherapists will organize future actions within the society to increase awareness in the radiotherapy clinics. Lectures and discussions for accidental and incidental exposures will be included in the program for postgraduate training of radiotherapists, medical physicists and technologists, as well as in the programs for the obligatory radiation protection training. A voluntary reporting system will be organized under the coordination of the NCRRP. Within the investment part a supply of measuring equipment was planned for further implementation of the project tasks, particularly dosimetry and QC equipment for radiotherapy departments, as well as equipment for the auditing team. The technical specification was prepared and discussed but the tender exercise failed. Subsequently part of this chapter for the technical specification was included in other tenders for new radiotherapy equipment made by the government or by hospitals. Component 3: Optimised Patient Radiation Protection in Diagnostic Radiology and Nuclear Medicine by means of Diagnostic Reference Levels (DRL) The mandatory result was to achieve optimised patient radiation protection in Diagnostic Radiology and Nuclear Medicine by means of Diagnostic Reference Levels (DRL). This was achieved by performing large scale national patient dose surveys. The results from conventional radiography are summarized in Table 1: The data comprises a total of 1600 patient measurements and 46 X-ray rooms (about 5% of all conventional X-ray systems in the country – 29 in Sofia, 14 in regional centre and 3 in small towns).
Table 1. Summary of results from the national survey in conventional radiography and proposed DRLs Skull
PA/AP, ESK, mGy
Chest ESK, mGy
Chest KAP, Gy·cm2
Lumbar spine APESK, mGy
Lumbar spine LAT ESK, mGy
Pelvis AP ESK, mGy
Uro-graphy (1 image) ESK, mGy
Number of health care units
15 26 13 13
12 19 19
Total number of patients
91 478 341 90 103 125
148
Range 0,8-2,9 0,1-1,3 (0,08-0,70)
2,5-10,5 4,2-17,8 0,8-15,0 2,0-11,0
Average 2,1 0,4 0,37 6,2 9,5 4,1 4,7
Median 2,3 0,3 0,39 5,5 8,9 3,2 4,5
3rd quartile 2,5 0,5 0,41 8,8 12,3 4,1 5,8
Proposed DRL 2,5 0,5 0,4 9 12 4 6
Twinning Contract No: BG 06 IB/SO/01 24 (49)
In mammography, measurements were done for 32 out of about 150 mammography units. The 3rd quartile value of Incident Kerma (IK) was 11.1 mGy, the mean value 8.5 mGy and the range 1.98 - 24.3 mGy. Based on the results, consideration of the histogram and comparison with the European DRL, an IK value of 12 mGy was proposed for the Bulgarian DRL.
Interventional radiology (IR). A patient dose survey for a total of 15 IR units of about 23 IR units in Bulgaria has been completed. Data from 13 different interventional examinations performed for 1050 patient were recorded but only for 3 examinations were the statistics good enough to establish DRLs. The results together with the proposed reference levels are shown in Table 2.
Table 2. Summary of results from the national survey in interventional radiology and proposed DRLs CA PTI+CA LLA Number of patients 409 181 182 PKA (KAP) total
• mean, Gy·cm2
• 3rd quartile, Gy·cm2
• proposed RL, Gy·cm2
32 39 40
97 133 140
31 47 45
Fluoroscopy time • (min – max), min • mean, min • proposed reference interval, min
2,7 – 7,7 5,2 3,8 – 6,5
7,8 – 22,0 14,1 8,9 – 18,1
0,7 – 2,5 4,5 1,9 – 3,0
Number of images • (min – max) • mean
proposed reference interval
503-674 591 530-650
939 – 1634 1390 1290 – 1610
116 – 404 218 120 - 270
Other fluoroscopy (IR). Patient dose survey for a total of 31 fluoroscopy units and 426 patients, for barium enema and barium meal together, have been completed. The results together with a preliminary proposal for Bulgarian reference levels are shown in Table 3.
Table 3. Summary of results from the national survey in fluoroscopy (Barium examinations) and proposed DRLs Barium enema Barium meal Number of fluoroscopy units included
18 15
Total number of patients 242 228 PKA-value (КAP) Range; Gy ·cm2
3rd quartile; Gy ·cm2
Proposed RL, Gy ·cm2
6,9 – 85,5 40,3 40
4,1 – 52,3 17,5 18
Fluoroscopy time Range; min 3rd quartile, min Proposed RL, min
0,8-5,1 4,2 4,2
1,1–5,7 4,1 4,1
Number of images, average (range)
5,0 (2,0-8,2) 4,4 (1,5-6,4)
Twinning Contract No: BG 06 IB/SO/01 25 (49)
Computed tomography. Patient doses for a total of 46 CT units have been determined, including almost all multi-slice units. This is about 30 % of the total number (about 160) of CT units in Bulgaria. The measured systems consist of 33 single-slice CT, 7 of 2-10-slice, 3 units of 16-slice and 3 units of 64-slice equipment. The types of CT units consist of 1 Hitachi unit , 1 Marconi, 3 Shimadzu, 3 Philips, 4 Picker, 8 Toshiba, 12 GE and 14 Siemens. Many of the CT units were second-hand equipment. All types of hospitals have been included: 37 public and 9 private hospitals; 16 of the units are in Sofia, 28 in other big cities and 2 in small towns. Based on the results, considerations of the histograms and comparison with the European DRLs, the new Bulgarian DRLs for CT examinations are suggested as shown in Table 4.
Table 4. Summary of results from the national survey in CT and proposed DRLs CTKIw , mGy PKL, mGy·cm Examination Mean 3rd quartile Proposed
DRL Mean 3rd quartile Proposed
DRL Head 51,0 59,3 60 630 761 1000 Chest 18,4 21,0 25 423 524 550 Abdomen 18,5 21,5 30 408 468 600 Pelvis 20,2 25,0 30 389 491 550
Twinning Contract No: BG 06 IB/SO/01 26 (49)
The proposal for new DRLs prepared for submission for approval by the MH are summarized in Table 5
Table 5. Summary of updated DRLs for X-ray examinations Examination Current DRL Updated DRL Radiography Entrance surface air kerma (mGy) Chest (PA) 0.9 0.5 Skull (PA) 5 2.5 Skull (LAT) 3 2.5 Lumbar spine (AP) 10 9 Lumbar spine (LAT) 30 12 Pelvis (AP) 10 4 Urography (one image) 10 6 Incident air kerma (mGy) Mammography 13 12 Kerma area product (Gy·cm2) Chest radiography (PA) NA 0.4 Barium meal NA 18 Barium enema NA 40 Coronary angiography NA 40 PCI+CA NA 140 Lower limb arteriography NA 45 CT kerma index (mGy) CT - head 60 60 CT - thorax 30 25 CT - abdomen 35 30 CT-pelvis 35 30 Kerma length product (mGy.cm) CT - head 1050 1000 CT - thorax 650 550 CT - abdomen 780 600 CT-pelvis 570 550
A national report on the patient dose surveys is under preparation. The results will be disseminated through several lectures and presentations in national meetings, training courses etc, also in the context of optimization and other topics of radiation protection for the patient. Further, the hospitals where measurements have been carried out will receive the results for their own units together with a summary of the results (national mean or 3rd quartile values) for comparison. Nuclear medicine All 18 NM departments in the country submitted answers to the questionnaire. NCRRP analyzed the data. The summary of results is presented here. The radionuclides used in NM in Bulgaria are summarised in the Figure 8a (diagnostics) and Figure 8b (therapy).
Twinning Contract No: BG 06 IB/SO/01 27 (49)
I-1317%
I-1237%
In-1113%
Cr-513%
Tc-99m80%
I-13167%
Sr-8933%
a) Diagnostics b) Therapy
Figure 8. Radionuclides used in NM The frequency of in vivo diagnostic examinations in 2007 for adults grouped by organs are presented in Figure 9.
Figure 9. Frequency of in vivo diagnostic examinations for adults by organs in 2007
Heart2%
Central nervous system
1%
Stomach1% Hematology
1%
Tumours2% Lungs
10%Kidneys
12%
Endocrine system
22%
Bones49%
Twinning Contract No: BG 06 IB/SO/01 28 (49)
On the basis of the survey of administered activities and statistical analysis, new DRLs were proposed. Those that will be submitted for approval by the MH are summarized in Table 6, together with existing DRLs.
Table 6. Summary of updated DRLs for administered activities in Nuclear Medicine
Type of examination
Radio-nuclide
Radiophar-maceutical
Number of examinations
Proposed DRL
Existing DRLs in Ordinance 30
Bone scintigraphy (planar)
99mTc MDP 6401 640
Bone scintigraphy -SPECT
99mTc MDP 3193 740 370-740
Lung perfusion 99mTc macroalbumon 1926 150 111-222
Liver/spleen scintigraphy
99mTc sulfocolloid 25 _ 111-185
Salivary gland scintigraphy
99mTc pertechnetat 109 100 37
Kidneys scintigraphy
99mTc DTPA 1569 185 74-185
Kidneys scintigraphy
99mTc MAG3 253 150 74-185
Mantle of adrenal 99mTc DMSA 452 150
MIBI tetrofosminе Stress and rest
1100 560-740 Myocardium perfusion
99mTc
stress or rest
383
560
Cerebral receptors 123I DaTScan (Ioflupane) 105 185
Thyroid scintigraphy
99mTc Рertechnetate 3952 100 74
Thyroid metastases (aftre thyroid ablation)
131I Sodium chloride 276 90 74-370
Parathyroid glands scintigraphy
99mTc MIBI (tetrophosmine) 57 700 370-740
Breast 99mTc MIBI (tetrophosmine) 237 740
Lyphatic system 99mTc Colloid 140 74
Twinning Contract No: BG 06 IB/SO/01 29 (49)
Estimation of collective dose Existing worksheets for collecting information for number and frequency of X-ray examinations were examined and compared to similar documents used in Finland and in another European countries, using the EC Publication RP154. An updated list of X-ray examinations was prepared for future data collection. The methodology for estimation of effective dose and collective dose was updated based on the international recommendations and taking into account the results from the survey. Based on the data collected for number of examinations for 2007, the total collective dose from X-ray examinations was estimated to 3191 manSv and the average annual effective dose to 0.43 mSv. The biggest contributor to the collective dose from DR is conventional radiography (Figure 10). Computed tomography has only a 4.9 % contribution in the total number of examinations but 30.1 % of the collective dose. Conventional fluoroscopy has a high contribution to the collective dose (20%).
0.0
10.020.030.0
40.050.060.070.0
80.0
Frequency, % 75.8 5.5 0.7 4.9 10.5Contribution to collective dose, % 27.3 20.0 8.7 30.1 0.1
Radiography Fluoroscopy Interventional radiology CT Dental
Figure 10. Contribution of different type of X-ray examinations to the total number of examinations and to the collective dose. The collective dose from nuclear medicine is estimated to be 55 manSv and the average annual effective dose to be 0.007 mSv. From NM examinations the biggest contribution to the collective dose is from bone examinations (Figure 9).
Twinning Contract No: BG 06 IB/SO/01 30 (49)
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
Perc
enta
ge
Frequency, % 49.7 22.1 11.7 9.9 2.2 2.0 1.0 0.7 0.7
Effective dose, % 64.6 12.9 4.4 5.8 3.0 5.7 3.2 0.3 0.0
Bones Endo-crine Kidneys Lungs Tumors Heart Central
nervous Stomach Hemato-logy
Figure 11. Contribution of different type of NM examinations to the collective dose.
Twinning Contract No: BG 06 IB/SO/01 31 (49)
2E – IMPACT Component 1: Modernized and effectively operating National Secondary Standard Dosimetry Laboratory (SSDL) in process of preparation Hospitals need to get national calibrations for their ionization chambers. So far the quality system of the NCRRP SSDL has not been documented for accreditation and the quality of the calibrations has not been comprehensively verified. In the project the NCRRP calibrations had inter-comparisons with STUK calibrations. Good agreement with the calibrations convinced of the quality of the methodology in Bulgarian national SSDL. Uncertainty of the calibrations can be improved in future by using modern calibration equipment. Clinical dosimetry was discussed for the first time with professionals (mainly with physicists from hospitals). For radiation therapy calibrations medical physicists drafted calibration protocols and a national consensus was achieved in the project. The results of the dosimetry audit showed that a lot of improvement is needed in the country. On site visits, training was given to the hospitals’ staff. Implementing the new national dosimetry procedures will help in improving clinical dosimetry.
Component 2: Developed system for quality audit in radiotherapy The project contributed to the establishment of a QA system in radiotherapy in the country. The established team for quality audits was trained in the project and practical training was also given in eight radiation therapy clinics for staff. In a significant number of radiation therapy beams, the dose comparisons showed unacceptable differences. There are many possible reasons for these results in Bulgarian radiation therapy centres. Inaccurate front pointers were the main reason for dose deviations. In addition most hospitals do not have a treatment planning system and so adequately accurate dose calculation is impossible. NCRRP sent feedback of the results to the hospitals and started to follow-up the effects of correcting actions by the hospitals. Most of the cobalt treatment units are more than 30 years old. The lack of modern equipment, treatment planning systems and all the necessary dosimetry equipment are substantial reasons for the observed deviations. In this situation, practice in the radiotherapy departments cannot be entirely compatible with the requirements of the EU. Clinical audits were discussed for the first time nationally in the country and there was a consensus that each radiation therapy centre should be audited at least after commissioning. It was also agreed that a dosimetry audit should be carried out after each change of the source. Existing regulations were found to need some changes to clearly state the organizational responsibilities for clinical audits. Awareness of preventing incidents and accidents in radiation therapy was increased and some actions had been taken during the project to improve the current situation. The Bulgarian Guild of Radiotherapists drafted a document of most probable incidents and accidents and listed actions that are needed to be taken in future. Some of them need investment. Technical specifications for quality control equipment were prepared as a part of this project but the supply of the necessary measurement and control equipment in QC in radiotherapy failed due to the tendering process conducted by CFCU.
Twinning Contract No: BG 06 IB/SO/01 32 (49)
Component 3: Optimised Patient Radiation Protection in Diagnostic Radiology and Nuclear Medicine by means of Diagnostic Reference Levels (DRL) National surveys performed in Diagnostic Radiology and in Nuclear Medicine demonstrated the real status of diagnostic practice in the country. Big variations were found between doses for similar X-ray examinations performed in different centres. The main reasons were recognized and discussed in hospitals. They are partly connected to the old diagnostic equipment, but also lack of enough standardization of clinical protocols. The new DRLs elaborated within the project will contribute to future optimization of clinical practice. The NM survey showed a reduced number of examinations in latter years because of reimbursement problems of these types of procedures, as well as an insufficient number of modern NM equipment. The estimation of collective doses demonstrated the leading role of medical exposure over other man-made radiation sources. The updated methodology for population dose estimation will allow comparison to be made with other countries. Several meetings performed with radiation control inspectors contributed to the strengthening of their capacity and knowledge. Their role in the process of patient dose reduction increased.
Twinning Contract No: BG 06 IB/SO/01 33 (49)
2 F - FOLLOW-UP AND SUSTAINABILITY Component 1: Modernized and effectively operating National Secondary Standard Dosimetry Laboratory (SSDL) in process of preparation. The results from the project are implemented in the SSDL, but the final result will be achieved after the modernization of the laboratory with new equipment. According to the quality manual, all procedures for calibration describe the premises, equipment and standards in the laboratory. Parameters of standards and stability of irradiators, x–ray machines and other basic equipment are the main points for calculating the uncertainty of calibrations. The uncertainty is the main quality indicator of the work in laboratory. The main goal of every laboratory is to reach a good level of quality sufficient to satisfy the needs of customers. The future efforts of the laboratory will be focused on this aim . To achieve good quality in calibration, participation in inter-laboratory comparisons and to be a part of SSDLs network it is necessary to fulfilled all the requirements for modern dosimetry laboratory – staff, equipment, procedures, and standards. This will take a lot of effort - including accreditation of the laboratory as a laboratory for calibration. The next step is an audit from the IAEA to continue the participation in the SSDLs network. Component 2: Developed system for quality audit in radiotherapy. In the field of radiotherapy in Bulgaria, there is a necessity for follow-up on quality. For example: Dosimetry protocols that were developed have to be published and distributed. The Quality control program in Ordinance 30/2005 should be updated based on the recommendations made within the project. A QC program for new modalities (SPECT-CT and PET-CT) should be added. When new equipment is purchased there must be permanent arrangements at national level that this equipment is used correctly, in accordance with EU requirements. This could be controlled through the independent measurements performed by NCRRP, inter-laboratory comparisons and carrying out quality audit. Clinical audits in Bulgaria should be first implemented as a pilot effort concentrating on a few basic standards of good practice, surveying the present level of quality nationwide. This effort should be coordinated as a joint effort supported by the Ministry of Health, while the existing audit groups or plans for their establishment could be exploited for the practical implementation. A special coordinating body established by the Ministry should be created. The necessary changes in Ordinance 30/2005 of the MH should be made to regulate quality audit in radiotherapy but also in diagnostic radiology and nuclear medicine. Component 3: Optimised Patient Radiation Protection in Diagnostic Radiology and Nuclear Medicine by means of Diagnostic Reference Levels (DRL) The Report from the national survey should be published and distributed in DR and NM departments. NCRRP shouldl prepare a dosimetry protocol for DR in order to standardize the measurement procedure. Medical physicists should be made available in diagnostic departments as required by EURATOM 97/43 Directive.
Twinning Contract No: BG 06 IB/SO/01 34 (49)
New DRLs shall be published and used as a reference for optimization. It is highly advisable that feedback protocols be sent to all departments participating in the survey, with recommendations for future actions for patient dose reduction. National surveys in Diagnostic radiology should be performed as a minimum with a 3 year period. The specification of the examination types and the methodology of data collection have to be reviewed and updated. In Nuclear Medicine the survey based on the questionnaire elaborated within the project should be performed annually. 2G - CONCLUSIONS Overall Assessment All mandatory results of the project were achieved successfully in the planned time frame. The work was planned in detail using a weekly time schedule and both BC and MS were committed to follow the plan. Medical professionals were coordinated by NCRRP to ensure that they could actively participate in the project. Feedback from the professionals during on-site visits as well as that raised in project meetings and workshops was that this kind of a project is very useful. A workshop on incidents and accidents in radiation therapy was conducted for the first time in Bulgaria. Calibration and quality audit procedures were drafted and clinical auditing was discussed for the first time with medical professionals. The major impact of the project is that the Bulgarian Guild of Radiotherapists and the Society of Nuclear Medicine offered to carry out further actions that are needed in the continuous development of this field in Bulgaria. This will be done in co-operation with NCRRP. It should be noted that the failure of supply of equipment may jeopardize the quality of the calibrations in the SSDL and this will therefore influence the quality of patient dosimetry in Bulgaria. 2H – RECOMMENDATIONS: lessons learned
The equipment for the RTA office (computers, fax, printer, copy machine, scanner) was not delivered throughout the project duration, because of CFCU delay in tender procedures.
The project for supply of equipment, which was expected to provide nearly 3 million euros for
the necessary equipment for calibrations, radiation protection measurements and quality control, was not fulfilled. The call for tender was postponed about four months by CFCU. The tender started but the documentation in the offers did not fully correspond to the requirements of Bulgarian regulation, and the tender was cancelled. The failure of the supply project would seriously diminish the value of the results achieved in this Twinning project.
The building up of a modern and effectively operating national secondary standard dosimetry
laboratory (SSDL) with the capacity for metrological control of measuring devices for radiotherapy, nuclear medicine, diagnostic radiology and radiation protection could not be realized without a supply of the necessary equipment. Future efforts should be made by the BC to assure resources for modernization of the SSDL with new equipment because of the missed opportunity within this project. After technological modernization, the BC has to continue with practical implementation of the new calibration protocols developed within the project as well as to implement quality systems with the final aim being accreditation for SSDL.
Twinning Contract No: BG 06 IB/SO/01 35 (49)
While the project counterparts and CFCU have common objectives of successful
implementation of the project not only from the point of view of scientific and technical aspects but also from the point of adhering to financial rules, there are differences in perception. The financial part of the reporting procedure has caused many unforeseen and unnecessary working hours, in particular for the implementing person in STUK and for the STUK project leader.
o One reason is the lack of documentation of CFCU’s requirements beyond the Twinning Manual 2007. The Finnish partner has asked for such documentation both during the preparation of the contract and during the implementation phase. Even the contact person and contact information has been unclear (e-mail, fax and other registration requirements).
o The CFCU has rejected significant parts of the Expenditure Reports accompanying Intermediate Quarterly Reports, for procedural reasons. This has caused psychological stress for the expertise-provider (MS), since the work for which re-imbursement is rejected has undisputedly been done, and has been appreciated by the beneficiary organizations in Bulgaria
The biggest problem in radiation therapy is the old fashioned treatment technique. Linear
accelerators are urgently needed with a verification system and a computerized treatment planning system based on CT slices. With present facilities cancer cannot be treated according to international good practice.
Results from patient dose surveys in diagnostic radiology showed in average higher doses
in some procedures than in developed countries. The main reason for that is the old fashioned equipment and not optimized techniques.
A national program for quality assurance and patient protection in medical use of radiation
should be planned for the future, as required by the Medical Exposure Directive 97/43. This should include performing regular national patient dose surveys, re-examining and updating national diagnostic reference levels, performing clinical audit in diagnostic radiology, nuclear medicine and radiotherapy; and performing national training courses. An important component of this work should be the introduction of a quality assurance program for mammography screening and breast cancer treatment, based on the European guidance. A suitable budget should be provided for these activities.
2I – ANNEXES Annex 1: Overview mandatory results achieved Annex 2: Results of the inter-calibration between BC and MS SSDLs Annex 3: Final Financial Report (separately) with the Expenditure Verification Report
Ann
ex 1
. Ove
rvie
w m
anda
tory
resu
lts a
chie
ved
CO
MPO
NEN
T/
A
CTI
VITY
Exp
ecte
d M
AN
DA
TOR
Y R
ESU
LTS
(Com
pone
nts)
B
ENC
HM
AR
KS
(Act
iviti
es)
Dea
dlin
e
Del
ay
ASS
ESSM
ENT
Self-
asse
ss-
men
t rat
e
H
S hi
ghly
sat
. S
satis
fact
ory,
U
uns
at.
1. M
oder
nize
d an
d ef
fect
ivel
y op
erat
ing
Nat
iona
l Sec
onda
ry
Stan
dard
Dos
imet
ry
Labo
rato
ry (S
SDL)
MA
ND
ATO
RY
RES
ULT
A
n up
-to-d
ate
appr
oach
for t
he n
ew S
SD
L to
ach
ieve
in
tern
atio
nal l
evel
of a
nat
iona
l sta
ndar
d la
bora
tory
B
ENC
HM
AR
K
A p
relim
inar
y dr
aft o
f a S
SD
L qu
ality
man
ual
incl
udin
g ap
plic
able
cal
ibra
tion
met
hods
Mon
ths
1-12
none
All
rele
vant
cal
ibra
tion
met
hods
wer
e co
mpr
ehen
sive
ly
upda
ted
and
verif
ied
thro
ugh
inte
r-co
mpa
rison
s.
Doc
umen
tatio
n of
the
met
hods
of c
alib
ratio
ns o
f ra
diat
ion
ther
apy
ioni
zatio
n ch
ambe
rs, x
-ray
diag
nost
ics
ioni
zatio
n ch
ambe
rs a
nd s
urve
y le
vel
cham
bers
was
dra
fted.
Sus
tain
abilit
y in
clin
ical
do
sim
etry
leve
ls w
as a
chie
ved
thro
ugh
stak
ehol
der
invo
lvem
ent:
the
calib
ratio
n m
etho
ds w
ere
disc
usse
d in
the
dosi
met
ry m
eetin
g w
ith m
edic
al p
hysi
cist
s an
d S
SD
L st
aff p
artic
ipat
ed to
the
field
mea
sure
men
ts in
th
e ho
spita
ls.
The
labo
rato
ry s
till n
eeds
urg
ently
the
equi
pmen
t tha
t w
as s
uppo
sed
to b
e su
pplie
d in
con
nect
ion
with
this
pr
ojec
t. O
ther
wis
e, th
e el
abor
ated
cal
ibra
tion
proc
edur
es fo
r rad
ioth
erap
y, d
iagn
ostic
radi
olog
y an
d ra
diat
ion
prot
ectio
n ca
nnot
be
prac
tical
ly im
plem
ente
d.
HS
U
BEN
CH
MA
RK
S
1.
1 Pr
epar
ator
y ac
tiviti
es fo
r SSD
L m
oder
niza
tion
with
lo
ng te
rm tr
aini
ng
- Com
plet
ed tr
aini
ng a
ccor
ding
to s
cien
tific
vis
itors
’ pr
ogra
mm
e M
onth
s 2-
4
none
- D
urin
g th
e tra
inin
g al
l mai
n ac
tiviti
es o
f the
mod
ern
SS
DL
wer
e co
vere
d. T
he m
ain
focu
s w
as o
n ca
libra
tions
that
are
rela
ted
to ra
diot
hera
py, x
-ray
diag
nost
ics
and
surv
ey m
eter
s.
HS
1.
2 D
efin
ition
and
pr
epar
atio
n of
Te
chni
cal
Spec
ifica
tions
1.
3 Su
ppor
t in
prep
arat
ion
of th
e te
chni
cal
spec
ifica
tion
for t
he
supp
ly o
f the
ne
cess
ary
mea
sure
men
t and
co
ntro
l equ
ipm
ent
- A d
raft
for t
echn
ical
spe
cific
atio
ns b
y B
C.
Mon
ths
1-2
-1
mo
- Th
ere
was
a ti
me
limit
from
the
BC
’s C
FCU
for
tech
nica
l spe
cific
atio
ns. T
hat w
as o
nly
one
day
afte
r th
e C
FCU
’s n
otifi
catio
n of
the
begi
nnin
g of
the
proj
ect.
This
pos
ed s
erio
us li
mita
tions
on
MS
to u
se fu
lly
expe
rtise
in th
e pr
epar
atio
n of
tech
nica
l spe
cific
atio
ns.
Sin
ce C
FCU
took
four
mon
ths
to a
nnou
nce
a ca
ll fo
r te
nder
, it s
houl
d ha
ve b
een
quite
pos
sibl
e to
com
plet
e th
e su
ppor
t acc
ordi
ng to
the
cont
ract
ed w
ork
plan
.
S
1.
4. U
pdat
ing
the
met
hodo
logy
for
calib
ratio
n an
d m
etro
logi
cal c
ontr
ol
- Com
plet
ed tr
aini
ng a
ccor
ding
to s
cien
tific
vis
itors
’ pr
ogra
mm
e ea
ch ta
sk p
erfo
rman
ce c
onfir
med
by
the
head
of t
he M
S S
SD
L (s
tand
ard
dosi
met
ry) o
r the
MS
pr
ojec
t lea
der (
field
dos
imet
ry in
hos
pita
ls)
- Im
plem
enta
tion
and
cons
olid
atio
n of
dos
imet
ry th
at
is b
ased
on
inte
rnat
iona
l sta
ndar
ds.
Mon
ths
2-5
+5
mo
(enl
arge
men
t)
- The
trai
ning
in M
S S
SD
L w
as c
arrie
d ou
t acc
ordi
ng to
th
e sc
ient
ific
visi
tors
’ pro
gram
me.
- M
etho
dolo
gy fo
r cal
ibra
tions
in ra
diat
ion
ther
apy
is
base
d on
IAE
A T
RS
398
, for
cal
ibra
tions
in x
-ray
diag
nost
ics
on IA
EA
TR
S 4
57 a
nd fo
r rad
iatio
n pr
otec
tion
met
er c
alib
ratio
ns o
n IA
EA
SR
S 1
6.
- The
em
phas
is in
the
train
ing
was
suc
cess
fully
giv
en to
pr
actic
al p
erfo
rman
ce o
f cal
ibra
tions
and
ana
lysi
s of
th
e re
sults
. The
re w
ere
11 s
ite v
isits
to M
S h
ospi
tals
in
the
field
dos
imet
ry.
- Qua
lity
man
agem
ent s
yste
m o
f STU
K w
as in
trodu
ced
and
disc
usse
d w
ith th
e B
C m
anag
ers.
HS
1.
5. Im
prov
emen
t of
the
met
hods
for
trac
eabi
lity
of
mea
sure
men
ts a
nd
inte
r lab
orat
ory
com
paris
ons
betw
een
radi
othe
rapy
tr
eatm
ent s
yste
ms
- Res
ults
of t
he in
ter-
com
paris
on o
f som
e ca
libra
tions
be
twee
n ex
istin
g B
C S
SD
L an
d M
S S
SD
L M
onth
s 1-
6
-1 m
o
-Inte
r-ca
libra
tions
wer
e ca
rrie
d ou
t usi
ng fo
llow
ing
BC
io
niza
tion
cham
bers
:
Farm
er ty
pe c
ham
ber
P
lane
par
alle
l cha
mbe
r
KA
P c
ham
ber
C
T ch
ambe
r
Mam
mog
raph
y ch
ambe
r
Rad
iatio
n pr
otec
tion
cham
ber
- Res
ults
sho
wed
goo
d ag
reem
ent b
etw
een
BC
and
MS
SS
DLs
. - I
n th
e K
AP
cal
ibra
tion
a re
mar
kabl
e de
pend
ence
of
the
field
siz
e w
as fo
und
and
the
BC
met
hod
for
calib
ratio
n w
as im
prov
ed fr
om 1
5 %
dev
iatio
n to
5 %
in
the
inte
r-cal
ibra
tion.
HS
1.
6. P
repa
ratio
n an
d ap
plic
atio
n fo
r ce
rtifi
catio
n of
SSD
L in
acc
orda
nce
with
na
tiona
l ins
titut
iona
l re
quire
men
ts.
- Sta
ge o
f dev
elop
men
t of t
he q
ualit
y m
anua
l. - F
irst p
relim
inar
y un
certa
inty
bud
gets
. - F
urth
er d
evel
opm
ent g
oes
on w
hen
the
new
SS
DL
is ta
ken
into
use
.
Mon
ths
5-12
-2 m
o
- A Q
ualit
y m
anua
l was
dra
fted
and
eval
uate
d in
sev
eral
st
eps
incl
udin
g st
akeh
olde
r inv
olve
men
t in
the
dosi
met
ry w
orks
hop.
The
list
of d
rafte
d do
cum
ents
is
in th
e C
hapt
er 2
D in
this
repo
rt.
- A m
etho
dolo
gy fo
r unc
erta
inty
est
imat
ions
was
in
trodu
ced.
In p
ract
ice
estim
atio
ns c
an b
e fin
aliz
ed
only
afte
r com
mis
sion
ing
of th
e ne
w c
alib
ratio
n eq
uipm
ent.
- The
act
iviti
es re
late
d to
dra
fting
of d
ocum
enta
tion
for
the
accr
edita
tion
of th
e S
SD
L w
ill be
was
ted
if th
e In
vest
men
t Pro
ject
for t
he s
uppl
y of
equ
ipm
ent i
s no
t fu
nded
.
HS
(ove
rall)
U
: (th
e te
nder
by
the
CFC
U
for s
uppl
y of
th
e S
SD
L eq
uipm
ent
faile
d
C
OM
PON
ENT/
AC
TIVI
TY
Exp
ecte
d M
AN
DA
TOR
Y R
ESU
LTS
(Com
pone
nts)
B
ENC
HM
AR
KS
(Act
iviti
es)
Dea
dlin
e
Del
ay
ASS
ESSM
ENT
Self-
asse
ss-
men
t rat
e
HS
high
ly s
at.
S sa
tisfa
ctor
y,
U u
nsat
isfa
ctor
y 2.
Dev
elop
ed s
yste
m fo
r qu
ality
aud
it in
ra
diot
hera
py
MA
ND
ATO
RY
RES
ULT
Im
plem
enta
tion
on Q
A in
radi
atio
n th
erap
y an
d re
late
d di
agno
stic
radi
olog
y.
BEN
CH
MA
RK
P
ract
ical
gui
danc
e in
QA
impl
emen
ted
in ra
diat
ion
ther
apy
and
rela
ted
diag
nost
ic ra
diol
ogy
Mon
ths
1-12
none
Impl
emen
tatio
n on
QA
in ra
diat
ion
ther
apy
and
rela
ted
diag
nost
ic ra
diol
ogy
was
car
ried
out b
y dr
aftin
g gu
idan
ce a
nd g
ivin
g pr
actic
al tr
aini
ng o
f QA
du
ring
on-s
ite v
isits
for t
he s
taff
of o
ncol
ogic
al
hosp
itals
. Tha
t inc
lude
d a
dosi
met
ry a
udit.
Mor
eove
r a
natio
nal q
ualit
y au
dit t
eam
was
est
ablis
hed
and
train
ed.
HS
BEN
CH
MA
RK
S
2.
1. C
reat
ion
of a
na
tiona
l pro
toco
l for
Q
ualit
y C
ontr
ol in
ra
diot
hera
py
- Tec
hnic
al s
peci
ficat
ions
for p
urch
asin
g ne
w
equi
pmen
t. - A
pre
limin
ary
sylla
bus
for t
he Q
C p
roto
col b
y B
C- A
pr
elim
inar
y dr
aft o
f the
pho
ton
dosi
met
ry in
the
QC
pr
otoc
ol b
y B
C
- A p
relim
inar
y dr
aft o
f the
ele
ctro
n do
sim
etry
in th
e Q
C p
roto
col b
y B
C.
- A d
raft
of th
e Q
C p
roto
col f
or a
line
ar a
ccel
erat
or, a
co
balt
ther
apy
unit,
X-r
ay th
erap
y un
its a
nd a
si
mul
ator
by
BC
. - A
pre
limin
ary
draf
t of t
he Q
C p
roto
col f
or C
T si
mul
ator
s, P
ET-
CT
and
SPE
CT-
CT
by B
C.
Mon
ths
1-9
no
ne
-The
re w
as a
tim
e lim
it fro
m th
e B
C’s
CFC
U fo
r te
chni
cal s
peci
ficat
ions
. Tha
t was
onl
y on
e da
y af
ter
the
CFC
U’s
not
ifica
tion
of th
e be
ginn
ing
of th
e pr
ojec
t. M
S d
id n
ot h
ave
full
poss
ibilit
ies
to g
ive
expe
rtise
in th
e re
view
ing
of te
chni
cal s
peci
ficat
ions
. -D
osim
etry
pro
toco
ls w
ere
draf
ted
in a
n in
tens
ive
inte
ract
ion
with
med
ical
phy
sici
sts
in ra
diat
ion
ther
apy.
-P
ract
ical
gui
danc
e w
as g
iven
in Q
C p
roto
cols
that
w
ere
draf
ted
by m
edic
al p
hysi
cist
s an
d te
sted
dur
ing
on-s
ite v
isits
in th
e on
colo
gica
l hos
pita
ls.
-The
re is
a C
T si
mul
ator
in o
nly
one
hosp
ital a
nd it
s Q
C p
roto
col w
as im
plem
ente
d. T
here
is o
nly
one
SP
EC
T-C
T at
the
mom
ent i
n th
e co
untry
and
the
QC
pr
otoc
ol fo
llow
ed in
tern
atio
nal r
ecom
men
datio
ns
(NE
MA
sta
ndar
ds).
The
first
PE
T-C
T w
as in
co
mm
issi
onin
g w
hen
the
proj
ect e
nded
. Int
erna
tiona
l re
com
men
datio
ns fo
r QC
wer
e in
trodu
ced
and
disc
usse
d.
HS
2.
2 D
evel
opm
ent o
f Q
A p
rogr
amm
es in
ra
diot
hera
py
- A p
relim
inar
y Q
A p
roto
col b
y B
C.
Mon
ths
5-9
-1
mo
- A p
relim
inar
y Q
A p
roto
col w
as d
evel
oped
in th
e in
tens
ive
inte
ract
ion
with
the
esta
blis
hed
qual
ity a
udit
grou
p (s
ee A
.2.3
.).
- Eig
ht o
f thi
rteen
radi
atio
n th
erap
y de
partm
ents
wer
e vi
site
d by
MS
and
dos
imet
ry a
udit
was
car
ried
out.
Eac
h ra
diat
ion
ther
apy
depa
rtmen
t was
giv
en
prac
tical
gui
danc
e on
site
vis
its fo
r QA
.
HS
2.
3 Se
t up
of a
na
tiona
l aud
iting
gr
oup
for Q
A in
ra
diot
hera
py a
s to
EC
-sta
ndar
ds
- Est
ablis
hing
a n
atio
nal a
uditi
ng g
roup
. - I
ntro
duci
ng in
tern
atio
nal a
uditi
ng g
uide
lines
. - P
repa
ring
prel
imin
ary
guid
elin
es fo
r nat
iona
l use
.
Mon
ths
5-8
- A n
atio
nal a
uditi
ng g
roup
of 1
5 ex
perts
(5
onco
logi
sts,
5 m
edic
al p
hysi
cist
s an
d 5
radi
ogra
pher
s) w
as e
stab
lishe
d an
d tra
ined
. In
the
train
ing
IAE
A a
uditi
ng re
com
men
datio
ns w
ere
used
an
d pr
elim
inar
y na
tiona
l aud
iting
crit
eria
est
ablis
hed.
HS
2.
4 Pi
lot
impl
emen
tatio
n of
th
e Q
A a
nd Q
C
proc
edur
es in
le
adin
g ra
diot
hera
py
cent
res
- A p
relim
inar
y Q
A p
roto
col b
y B
C.
- MS
sup
ports
BC
in in
trodu
cing
of t
he Q
C a
nd Q
A
prog
ram
mes
for p
ilotin
g ra
diat
ion
ther
apy
cent
res
for
impl
emen
tatio
n.
- W
orks
hop
on Q
A in
radi
othe
rapy
to c
onfir
m
impl
emen
tatio
n.
- Tec
hnic
al s
peci
ficat
ions
for p
urch
asin
g ne
w
equi
pmen
t.
Mon
ths
6-12
none
- The
mai
n pa
rt of
the
QA
and
QC
pro
toco
ls is
for
verif
icat
ion
of th
e pa
tient
dos
e. E
ight
of t
hirte
en R
T de
partm
ents
wer
e vi
site
d by
MS
and
dos
imet
ry
verif
icat
ion
was
car
ried
out.
It ca
me
out t
hat 9
% o
f ph
oton
bea
ms
of a
ccel
erat
ors
and
Co-
60 u
nits
wer
e ou
t of 3
% to
lera
nce
limit
in re
fere
nce
field
siz
e.
Acc
ordi
ngly
27
% a
nd 1
5 %
of t
he b
eam
s in
non
-re
fere
nce
cond
ition
s ex
ceed
ed to
lera
nce
limits
. - T
he m
ain
reas
on fo
r poo
r qua
lity
is a
lack
of
com
pute
rized
trea
tmen
t pla
nnin
g sy
stem
s. S
till s
ome
impr
ovem
ent c
an b
e m
ade
by c
alib
ratin
g di
stan
ce
met
ers
and
by m
easu
ring
mor
e da
ta fo
r man
ual
treat
men
t pla
nnin
g.
- A c
ompr
ehen
sive
pilo
t im
plem
enta
tion
of th
e Q
A a
nd
QC
pro
cedu
res
was
car
ried
out i
n th
e N
atio
nal
Onc
olog
ical
Hos
pita
l and
dur
ing
acce
ptan
ce te
stin
g in
the
Onc
olog
ical
Hos
pita
l in
Rus
e.
- A w
orks
hop
of q
ualit
y au
ditin
g in
radi
atio
n th
erap
y an
d re
late
d di
agno
stic
radi
olog
y w
as c
arrie
d ou
t. C
once
pts
of q
ualit
y au
dit a
nd c
linic
al a
udit
wer
e in
trodu
ced
for t
he fi
rst t
ime.
- T
echn
ical
spe
cific
atio
ns (s
ee 2
.1.)
wer
e re
view
ed.
HS
2.
5. D
rafti
ng
scen
ario
s fo
r mos
t pr
obab
le a
ccid
enta
l ex
posu
res
in
radi
othe
rapy
and
em
erge
ncy
actio
n pr
otoc
ols.
- Sce
nario
s fo
r mos
t pro
babl
e ac
cide
ntal
exp
osur
es
in ra
diot
hera
py a
nd e
mer
genc
y ac
tion
prot
ocol
s.
Mon
ths
7-8
-2
mo
- Firs
t int
rodu
ctio
n of
the
mos
t pro
babl
e ac
cide
ntal
ex
posu
res
in ra
diot
hera
py w
as g
iven
in th
e tra
inin
g w
orks
hop.
The
re is
evi
denc
e on
bas
is o
f the
resu
lts
of th
e qu
estio
nnai
re th
at th
e sa
fety
cul
ture
was
im
prov
ed a
fter t
he w
orks
hop.
- T
he B
ulga
rian
Gui
ld o
f Rad
ioth
erap
ists
is d
rafti
ng
prot
ocol
s fo
r inc
iden
t and
acc
iden
t pre
vent
ion
in
radi
othe
rapy
and
agr
eed
to p
ublis
h th
e do
cum
ent
prep
ared
in th
is p
roje
ct o
n m
ost p
roba
ble
inci
dent
s an
d ac
cide
nts.
The
Gui
ld is
als
o de
velo
ping
em
erge
ncy
actio
ns p
lans
.
HS
C
OM
PON
ENT
AC
TIVI
TY
Exp
ecte
d M
AN
DA
TOR
Y R
ESU
LTS
(Com
pone
nts)
B
ENC
HM
AR
KS
(Act
iviti
es)
Dea
dlin
e
Del
ay
ASS
ESSM
ENT
Self-
asse
ss-
men
t rat
e
HS
high
ly s
at.
S sa
tisfa
ctor
y,
U u
nsat
isfa
ctor
y 3.
Opt
imis
ed P
atie
nt
Rad
iatio
n Pr
otec
tion
in
Dia
gnos
tic R
adio
logy
and
N
ucle
ar M
edic
ine
by
mea
ns o
f the
Dia
gnos
tic
Ref
eren
ce L
evel
s (D
RL)
MA
ND
ATO
RY
RES
ULT
Im
prov
ed ra
diat
ion
prot
ectio
n in
dia
gnos
tic ra
diol
ogy
and
nucl
ear m
edic
ine.
B
ENC
HM
AR
K
Rev
ised
DR
Ls p
repa
red
Mon
ths
1-12
none
Pat
ient
dos
es c
an b
e co
mpa
red
to n
ew D
RLs
whi
ch
are
for t
he fi
rst t
ime
fully
bas
ed o
n na
tiona
l dat
a su
rvey
s. D
RLs
are
use
d fo
r opt
imis
ing
patie
nt d
oses
. It
was
foun
d ou
t on
basi
s of
pat
ient
dat
a co
llect
ions
th
at in
som
e pr
oced
ures
pat
ient
dos
es a
re in
ave
rage
hi
gher
than
in d
evel
oped
cou
ntrie
s. T
he m
ain
reas
on
is o
ld fa
shio
ned
equi
pmen
t and
not
opt
imis
ed
tech
niqu
es.
HS
BEN
CH
MA
RK
S
3.
1 En
larg
emen
t of
the
natio
nal s
urve
y as
to th
e ut
ilize
d m
etho
dolo
gy fo
r m
easu
rem
ent a
nd
eval
uatio
n of
pat
ient
do
ses
in
conv
entio
nal
radi
ogra
phy
- Enl
arge
men
t of t
he n
atio
nal s
urve
ys u
sing
cho
sen
met
hod.
- A
naly
sis
of c
ompa
rativ
enes
s of
the
data
to o
ther
E
urop
ean
data
.
Mon
ths
1-9
no
ne
New
nat
iona
l pat
ient
dos
e su
rvey
in c
onve
ntio
nal
radi
ogra
phy
and
mam
mog
raph
y w
as p
erfo
rmed
. A
stan
dard
pro
toco
l was
dev
elop
ed b
y N
CR
RP
and
lo
gist
ics
was
org
anis
ed to
col
lect
dat
a an
d to
ana
lyse
th
em in
NC
RR
P. T
otal
ly it
cov
ered
160
0 pa
tient
m
easu
rem
ents
in 4
6 X
-ray
room
s (a
bout
5%
of a
ll co
nven
tiona
l X-r
ay s
yste
ms
in th
e co
untry
– 2
9 in
S
ofia
, 14
in re
gion
al c
entre
and
3 in
sm
all t
owns
).In
mam
mog
raph
y, m
easu
rem
ents
wer
e do
ne fo
r 32
out
of a
bout
150
mam
mog
raph
y un
its. T
he c
ompa
rison
to
othe
r Eur
opea
n da
ta s
how
ed th
at in
som
e pr
oced
ures
pa
tient
dos
es a
re h
ighe
r in
aver
age
than
in d
evel
oped
co
untri
es.
HS
3.
2 R
evie
w o
f the
na
tiona
l sur
vey
on
the
appl
ied
activ
ities
an
d st
anda
rds
in N
M
- Eva
luat
ion
on th
e da
taba
ses
avai
labl
e fo
r upd
atin
g D
RLs
M
onth
s 2
none
Que
stio
nnai
re w
as e
labo
rate
d by
the
NC
RR
P u
sing
th
e ex
perie
nce
of S
TUK
. All
18 N
M d
epar
tmen
ts in
th
e co
untry
sub
mitt
ed a
nsw
ers
to th
e qu
estio
nnai
re.
NC
RR
P a
naly
zed
the
data
for t
he e
quip
men
t use
d,
the
num
ber o
f in
vivo
dia
gnos
tic e
xam
inat
ions
for
adul
ts a
nd c
hild
ren
with
the
appl
ied
activ
ities
and
us
ed ra
diop
harm
aceu
tical
s, a
s w
ell a
s th
e nu
mbe
r of
ther
apeu
tical
NM
pro
cedu
res.
HS
3.
3. S
ettin
g a
natio
nal s
urve
y of
C
T pr
actic
e –
defin
ing
met
hodo
logy
, pe
rfor
min
g m
easu
rem
ents
, do
se a
sses
smen
t fo
r the
sta
ndar
d C
T ex
amin
atio
ns
- Des
crip
tion
of th
e ch
osen
met
hod
for e
nlar
gem
ent
of th
e na
tiona
l sur
veys
. M
onth
s 1-
9
none
A n
atio
nal s
urve
y w
as o
rgan
ised
bas
ed o
n an
in
tern
atio
nally
acc
epte
d m
etho
dolo
gy fo
r m
easu
rem
ents
of C
TDIw
and
DLP
w v
alue
s in
a
stan
dard
pha
ntom
. Int
er-c
ompa
rison
of m
etho
dolo
gy
and
resu
lts w
as m
ade
betw
een
NC
RR
P a
nd S
TUK
. A
ll th
e m
easu
rem
ents
in B
ulga
ria w
ere
perfo
rmed
by
NC
RR
P e
xper
ts.
Pat
ient
dos
es fo
r tot
ally
46
CT
units
ha
ve b
een
dete
rmin
ed (3
0 %
of t
he to
tal n
umbe
r of
CT
units
in B
ulga
ria).
All
type
s of
hos
pita
ls w
ere
incl
uded
, 37
publ
ic a
nd 9
priv
ate
hosp
itals
; 16
of th
e un
its a
re in
Sof
ia, 2
8 in
oth
er b
ig c
ities
and
2 in
sm
all
tow
ns.
HS
3.
4 U
pdat
ing
the
esta
blis
hed
DR
Ls in
D
iagn
ostic
R
adio
grap
hy a
nd
NM
and
de
term
inat
ion
of
DR
Ls in
fluo
rosc
opy
proc
edur
es a
nd C
T
- Des
crip
tion
of th
e ch
osen
met
hod
for e
stab
lishi
ng
DR
Ls in
fluo
rosc
opy
proc
edur
es.
- Pre
limin
ary
anal
ysis
of t
he d
ata.
Mon
ths
4-12
none
-Bas
ed o
n th
e re
sults
of t
he s
urve
ys, u
pdat
ed D
RLs
w
ere
prop
osed
for r
adio
grap
hy o
f che
st (P
A),
lum
bar
spin
e (A
P a
nd L
at),
pelv
is, a
bdom
en, s
kull,
uro
grap
hy
and
mam
mog
raph
y, a
s w
ell a
s fo
r CT
exam
inat
ions
of
head
, che
st, a
bdom
en a
nd p
elvi
s.
-New
DR
Ls fo
r adm
inis
tere
d ac
tiviti
es w
ere
prop
osed
fo
r 13
NM
exa
min
atio
ns.
-Firs
t nat
iona
l pat
ient
dos
e su
rvey
was
per
form
ed in
flu
oros
copy
, inc
ludi
ng 1
5 in
terv
entio
nal r
adio
logy
uni
ts
of a
bout
23
units
in B
ulga
ria. D
ata
from
13
diffe
rent
in
terv
entio
nal e
xam
inat
ions
per
form
ed fo
r 105
0 pa
tient
wer
e re
cord
ed. P
atie
nt d
ose
surv
ey fo
r a to
tal
of 3
1 flu
oros
copy
uni
ts a
nd 4
26 p
atie
nts,
for b
ariu
m
enem
a an
d ba
rium
mea
l tog
ethe
r, ha
ve b
een
com
plet
ed.
-New
DR
Ls w
ere
prop
osed
for C
A, P
CI,
Low
er L
imb
angi
ogra
phy,
Bar
ium
mea
l and
Bar
ium
ene
ma
exam
inat
ions
.
HS
3.
5. E
nlar
gem
ent o
f th
e ex
istin
g na
tiona
l da
ta b
ase
for p
atie
nt
dose
mon
itorin
g by
el
abor
atio
n of
sp
ecia
l she
et fo
r co
llect
ion
of n
umbe
r an
d fr
eque
ncy
of X
-ra
y ex
amin
atio
ns.
- Ela
bora
ted
of d
ata
shee
t for
col
lect
ion
of n
umbe
r an
d fre
quen
cy o
f X-ra
y ex
amin
atio
ns.
Mon
ths
1 +7
mo
(spl
it in
to
two
parts
)
-Exi
stin
g w
orks
heet
s fo
r col
lect
ing
info
rmat
ion
for
num
ber a
nd fr
eque
ncy
of X
-ray
exa
min
atio
ns w
as
exam
ined
and
com
pare
d to
sim
ilar u
sed
in F
inla
nd
and
in a
noth
er E
urop
ean
coun
tries
, usi
ng th
e E
C
Pub
licat
ion
RP
154.
-U
pdat
ed li
st o
f X-r
ay e
xam
inat
ions
was
per
form
ed
for f
utur
e da
ta c
olle
ctio
n.
HS
3.
6. Im
prov
ing
the
met
hodo
logy
for
estim
atio
n of
the
radi
atio
n bu
rden
of
the
popu
latio
n du
e to
med
ical
exp
osur
e
- Sel
ecte
d m
etho
dolo
gy fo
r est
imat
ion
of th
e co
llect
ive
dose
due
to m
edic
al e
xpos
ure.
M
onth
s 8-
12
no
ne
Met
hodo
logy
for e
stim
atio
n of
effe
ctiv
e do
se a
nd
colle
ctiv
e do
se w
as u
pdat
ed b
ased
on
the
inte
rnat
iona
l rec
omm
enda
tions
and
taki
ng in
to
acco
unt t
he re
sults
from
the
surv
eys.
Bas
ed o
n th
e da
ta c
olle
cted
for n
umbe
r of e
xam
inat
ions
for 2
007,
th
e to
tal c
olle
ctiv
e do
se fr
om X
-ray
exa
min
atio
ns w
as
estim
ated
to 3
191
man
Sv
and
the
aver
age
annu
al
effe
ctiv
e do
se to
0.4
3 m
Sv.
The
col
lect
ive
dose
from
nu
clea
r med
icin
e is
est
imat
ed to
55
man
Sv a
nd th
e av
erag
e an
nual
effe
ctiv
e do
se to
0.0
07 m
Sv.
HS
3.
7. E
labo
ratio
n an
d re
view
of t
he
Tech
nica
l Sp
ecifi
catio
ns fo
r th
e eq
uipm
ent
- Tec
hnic
al s
peci
ficat
ions
for p
urch
asin
g ne
w
equi
pmen
t. M
onth
s 1-
2
none
Ther
e w
as a
tim
e lim
it fro
m th
e B
C’s
CFC
U fo
r te
chni
cal s
peci
ficat
ions
. Tha
t was
onl
y on
e da
y af
ter
the
CFC
U’s
not
ifica
tion
of th
e be
ginn
ing
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all f
or te
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S
Annex 2 Results of the inter-calibration between BC and MS SSDLs Comparison of calibration factors of DAP chamber The standard equipment of STUK and the DAP chamber from Bulgaria SSDL were used for the comparison. Type S No: Vol. Quantity Cal Factor HV DAP V34044
0099 M4KDK DAP [Gy.cm2] Ka EA [Gy]
NDFP = 1.229E+9 cGy.cm2/C Na = 7.351E+6 Gy/C
+100
0.9
1
1.1
1.2
1.3
1.4
1.5
0 2 4 6 8 10HVL (mmAl)
Na
x E
+09,
cG
y.cm
^2/C
3 mmAl incident (STUK)RQR inci (STUK)RQR trans (STUK)3mmAl trans (STUK)extra incidentextra transmittedNCRRP incidentNCRRP transmitted
Comparison of calibration factors of plane – parallel chamber The standard equipment of STUK and the plane–parallel chamber from Bulgaria SSDL were used for the comparison.
1
1.05
1.1
1.15
1.2
1.25
0 1 2 3 4 5 6
HVL (mmAl)
Na
x E+
9, G
y/C
T (PTW)
NCRRP
RQR (STUK)
DCA (STUK)
Comparison of calibration factors of CT chamber The standard equipment of STUK and the CT chamber from Bulgaria SSDL were used for the comparison. Type S No: Vol. Quantity Cal Factor HV CT 77336 W 30009
0244 4.73 cm3
Ka .l [Gy.cm] Na = 8.119E+7 Gy.cm/C (for DV Qualities) Na = 7.913E+7 Gy.cm/C (for DN Qualities)
+ 100 V
7.6
7.7
7.8
7.9
8
8.1
8.2
8.3
8.4
8.5
0 5 10 15HVL (mmAl)
Na
x E
+07,
Gy.
cm/C
DV (PTW)DN (PTW)RQT (STUK)RQR (STUK)
Comparison of calibration factors of mammography chamber The standard equipment of STUK and the mammography chamber from Bulgaria SSDL were used for the comparison. Type S No: Vol. Quantity Cal Factor HV W 77337 0058 1 cm3 Ka [Gy] Na = 2.318E+7 Gy/C (for M
Qualities) Na = 2.482E+7 Gy/C (for DV Qualities) Na = 2.358E+7 Gy/C (for DN Qualities)
+ 100 V
2
2.1
2.2
2.3
2.4
2.5
2.6
0 5 10 15 20HVL (mmAl)
Na
x E+
07, G
y/C MV (PTW)
Extra (STUK)
MH (PTW)
DV (PTW)
DN (PTW)
NCRRP
RQR (STUK)
For measurements in STUK and in NCRRP were used 2 different beam qualities. For some chambers there are also differences in the geometrical set up of the chambers in the radiation beam. For that reason the results can’t be compared directly. That’s why, on the charts are shown the curves of the calibration factors as a function of HVL. In some points, where it’s possible for the aim of comparison, in STUK were simulated the similar radiation qualities used in Bulgaria. The measurements show acceptable results in the frame of uncertainty of used equipment. For more detailed conclusions, measurements in Bulgaria must be repeated with the standard beam qualities and geometry used in STUK.
Calibrations for ionization chambers used in radiation therapy
The summary of the results from the three comparisons are shown in the table below. Calibration Coefficient x E+07,
Gy/C Chambe
r Source Unit
STUK NCRRP*/PTW**
STUK/NCRRP,
% TW3001
1
60Co Ka 4,807 4,804** 0,06
TW30013
60Co Ka 4,826 4,753* 1,50
TW30013
60Co Dw 5,281 5,257** 0,46
The result of the measurements for air kerma shows the difference 0.06%. The result of the measurements for absorbed dose to water Dw shows the difference of about 0.5 %, which is acceptable for this kind of measurements. The result of the measurements for air kerma with a chamber for absorbed dose to water shows the difference of about 1.5 %.
TW30013 was calibrated in X-ray field for the qualities similar to those that is used in Bulgaria. The results are shown in the table below.
Additional filtration,
Beam Qualities
Tube Potential,
kV
HVL
mmAl mmCu
Air KERMA, mGy/s
Calibration Coefficient x E+07, Gy/C
BIPM 100 100 4,04 mmAl 3,404 - 2,5360 4,704 BIPM 135 135 0,49
mmCu 2,203 0,232 2,5461 4,726
BIPM 180 180 0,96 mmCu
2,201 0,484 2,5512 4,743
BIPM250 250 2,44 mmCu
2,200 1,570 2,5150 4,759
Inherent filtration 0,1 mm Al For the purpose of superficial therapy in Bulgaria the chamber of NCRRP was calibrated with x–ray qualities for which the STUK have traceability to the primary standard. Some of them are similar to dose used in NCRRP so they can be compared. Results of the calibration of the plane-parallel chamber 23342 in x-ray therapy qualities.
1.1451.1501.1551.1601.1651.1701.1751.1801.1851.1901.195
0 0.5 1 1.5 2 2.5 3HVL, mmAl
Cal
ibra
tion
Coe
ffici
ent,
Na
x E+
09G
y/C
STUKPTW
Results of the calibration of W77337 in X-ray field.
Calibration Coefficient x E+07,
Gy/C
Beam Qualities
Tube Potential,
kV
HVL, mmAl
Additional filtration,
mmAl
Air KERMA, mGy/s
STUK NCRRP BIPM30 30 1,181 0,210 1,395 2,459 2,408 BIPM50b 50 1,03 1,007 1,340 2,399 2,457