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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


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


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.


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.


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


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


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)


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).


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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


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%

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Site visits or 2-3 Workshops 1 Workshop No contact

b) Participation of nuclear medicine departments

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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.


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


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),


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.


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


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.


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


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


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

2

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


calculation is therefore impossible. There were no lasers available in most centres, for patient positioning purposes.

0

1

2

3

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

1

2

3

-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.


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


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.)?


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.


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


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)


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


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).


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%


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


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).


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.


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.


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.


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.


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.


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

of th

e pr

ojec

t. Th

is p

osed

ser

ious

lim

itatio

n on

MS

to u

se

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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

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