Development of quality control standards for radiation therapy equipment in Canada

Among the essential components of a comprehensive quality assurance program in radiotherapy are the quality control protocols to be used on the equipment and, in particular, the performance objectives and criteria. In the present work, we describe the development of a suite of quality control documents for use across Canada. Following a generic format, we are generating concise, clear standards for the most commonly used equipment in radiotherapy, with the emphasis on performance measures. The final standards of performance are confirmed following cross‐country consultation facilitated by the availability of draft documents on the Canadian Medical Physics web site. PACS number: 87.53.Xd


I. INTRODUCTION
The provision of health care services to Canadians is largely the responsibility of the ten provinces and three territories. Although the services that must be provided free to the population are specified in the federal Canada Health Act, operational and financial aspects of service provision are determined by the provinces and territories. This service delivery structure applies equally to cancer care as it does to other medical services.
The Canadian Association of Provincial Cancer Agencies (CAPCA) is a body that meets regularly to discuss issues of common interest to the organizations responsible for the delivery of cancer care in Canada. A proposal recently accepted by CAPCA was to initiate a process aimed at harmonizing quality assurance activities in radiation treatment programs across the country. This initiative has resulted in a draft document titled Standards for Quality Assurance at Canadian Radiation Treatment Centres. (hereinafter Standards). Practical and essential components of any quality assurance program for radiation therapy are the quality control tests carried out on the increasingly sophisticated equipment used in the planning and delivery of treatment. The draft document referred to appendices, which, when developed, would specify the performance standards to be required of equipment used in the preparation and delivery of radiation therapy to all Canadian cancer patients. The development of the quality control standards themselves was, appropriately, delegated to the national professional body representing Canadian radiation oncology physicists: the Canadian Organization of Medical Physicists (COMP). In turn, COMP established a Task Group, the members of which are the authors of the present work, to coordinate the generation of the standards documents.
We here describe the philosophy, format, and process adopted by the Task Group, and we refer readers to the web site on which both the approved and draft standards may be reviewed.

A. Documents
The documents upon which the standards are based originated from several sources. Some of the original documents were developed by the Medical Physics Professional Advisory Committee of Cancer Care Ontario and its predecessor, the Ontario Cancer Treatment and Research Foundation. Documents dealing with more recent technology were either specifically commissioned by CAPCA for the purpose of standards development, or, in one case, was based on a recent publication. Also vital to the present project are the many publications relating to quality control and quality assurance in radiotherapy. These include-but are not limited to-recommendations promulgated by the American Association of Physicists in Medicine, (1) The Institute of Physics and Engineering in Medicine, (2) and medical physics compendia. (3,4)

B. Philosophy and scope
The philosophy behind the development of the Standards documents was that they should focus on the standards themselves and not include descriptions of how the tests are performed. It is assumed that physicists who perform or who supervise the performance of the tests possess an appropriate level of knowledge. Otherwise, the bibliography refers the physicist to the recent literature on the subject. Furthermore, radiation safety has not been specifically included. To do so would require updating the documents each time federal or provincial regulations change, and the Task Group did not feel able to accept this responsibility. However, for completeness, some of the more straightforward tests performed on a daily basis were included.
The Standards documents are intended to be brief and unambiguous. Distribution through a web site facilitates updates as experience with new techniques is gained.
To maintain focus and unambiguity, a generic document format was adopted, with these sections: • Introduction-largely generic • Performance Objectives and Criteria-generic • System Description-custom • Acceptance Tests and Commissioning-largely generic • Quality Control of Equipment-largely generic • Documentation-generic • Table of QC Tests-custom entries in a generic format • References and Bibliography-custom

C.1 Performance Objectives and Criteria
The generic Performance Objectives and Criteria section includes six classes: • Functionality • Reproducibility • Accuracy • Characterisation and Documentation • Data Transfer and Validation • Completeness As an example of a generic portion of the documents, Appendix 1 shows the exact wording used in the Performance Objectives and Criteria section. The attempt here, and elsewhere in the generic sections, is to be unambiguous and, where appropriate, prescriptive. The six classes were considered to encompass the range of responses that adequately describe the results of testing. Frequency of testing is also clearly specified, but provides flexibility for operational considerations.

D. Document generation and review
Regardless of whether a source document was commissioned specifically for the development of the Standards or had been generated before this project was initiated, it was sent to a knowledgeable Canadian medical physicist for external review. The reviewer looked at the source document in the light of relevant international recommendations and provided detailed comments on the suggested standards.
Two of the authors of the present work were assigned to each document, one as the primary task group reviewer and one as the secondary reviewer. It was the responsibility of these two members of the group to consider the source document, the external reviewer's comments, and the international literature; to recommend the draft standards; and then to prepare the relevant documentation in the format described above. This task has been simplified for the more recent documents, because the generic format had been decided, and standards could be commissioned to be consistent with that format.
Once the primary and secondary task group reviewers had agreed on their version of the standard, that standard was circulated to whole Task Group for approval. Following this final internal step, the standard was posted on www.medphys.ca for consideration by the Canadian medical physics community at large.
During the next phase, which is ongoing, the comments from physicists "in the field" are being solicited and considered. Comments are fed back into the internal review process, and the standard is modified if required. Comments received so far have ranged from technical to language to typographical. Once the Task Group has reviewed, incorporated, and approved suggested changes, the standards undergo one final formal review by the Canadian Organization of Medical Physicists before national adoption. So far, the national review process has been completed for the first six standards.

III. RESULTS
At the time of writing, standards documents for the following equipment have been approved by COMP: The following draft standards have been posted and are currently under national review: • Remote afterloading brachytherapy equipment • Major dosimetry equipment • CT simulators • Prostate brachytherapy equipment • SRS/T equipment. Tables 1-6 show the six currently approved standards and illustrate the generic format adopted. Notes (not shown for space reasons) accompany each table to clarify the meaning of numerical tolerances and action levels, but these notes do not recommend measurement techniques.
Standards currently under development include those for • Data management systems • Treatment planning systems • Intensity-modulated radiation therapy These latter standards will be posted as they become available. The interested reader is directed to www.medphys.ca to review the complete results of the project to date.

IV. DISCUSSION AND CONCLUSIONS
This project has achieved its objectives to date. The largely generic format of the Standards has aided clarity of interpretation and expedited development of the documents-particularly the later documents, which could be composed to fit the format. At some stage in the future, if it is deemed desirable, all the available documents could easily be consolidated into one because so much of the content is generic.