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Radiotherapy and Oncology 45 (1997) 217-223 Quality assurance in conformal radiotherapy: a Departmenf of Medical Physics, University Hospital of Patras, 265 00 Patras, Greece b Department of Oncology, Haukeland Hospital, University 0f Bergen, N-5021 Bergen, Norway c Department of Medical Physics, Vrije University of Brussels, Pleinlaan 2, 1050 Brussels, Belgium d Department of Medical Physics, Institut Curie, 26 rue d 'UIm, 752 31 Paris Cedex O5, France e Department of Medical Physics, Academisch Medisch Centrum, Radiotherapy, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands f Department of Medical Physics, Karolinska Institute, University of Stockholm, Box 260, 17176 Stockholm, Sweden g Department 0f Medical Physics, Bergo Trento Hospital, Piazzale Stefani 1, 371 26 Verona, Italy Abstract Background and purpose : Conformal radiotherapy has only recently been widely implemented. Although not all aspects have yet been adequately proven, it is generally recognized that maintaining a high degree of precision throughout the process is critical to the treatment outcome while the focus for quality assurance and quality improvement will need to concentrate more on human factors, procedures, communication, organization and training. A general consensus document on quality assurance guidelines for institutions that deliver conformal radiotherapy treatments to patients bas been elaborated within the framework of the DYNARADIBIOMED concerted action on conformal radiotherapy. The present paper aims to highlight those issues that were identified as of specific importance to conformal radiotherapy. The work reported here further details this guidance by direct correlation with the issues involved in the special case of conformal radiotherapy. Methods : The DYNARAD document bas been drafted in the form of a desktop guide comprising six sets of guidelines and is based on the ESTRO advisory report on 'Quality Assurance in Radiotherapy'. Results and conclusions : The document bas been endorsed by the DYNARAD group of institutions. As such it can form the basis for further discussions and enter into the subsequent phase of expanding its consensus basis. © 1997 Elsevier Science Ireland Ltd. 1. Introduction 1.1. Rationale Increasing the probability of tumor control, without inducing severe normal tissue damage, still remains the major challenge in curative radiotherapy. Conformal radiotherapy exploits the recent advances in 3D imaging, dose planning and therapy monitoring to tailor the high dose volume as closely as possible to the target with concurrent minimization of the dose to non-target tissues. Stereotactic radiotherapy constitutes a specific form of conformal radiotherapy, aiming to deliver a large dose of radiation to a small volume of tissue in a single or multiple fractions. The present concept of conformal radiotherapy bas placed a high technological demand on the relevant processes, requiring professional support of diverse expertise. The techniques profit largely from the implementation of recent technological advances, which hold much potential for improvement of the effectiveness and efficiency of conformal procedures. At the same time, however, the increased complexity and sophistication of this technology have imposed great demands on the users, while the improved reliability of modem radiotherapy equipment is causing a shift of the focus for quality improvement to the appropriate, safe and efficient use of this technology. In consequence, the focus for quality improvement will concentrate much more on human factors, procedures, communication, organization and training. The need to effectively address quality assurance in radiotherapy has been reflected in a number of recent documents [2,7,20-24] which address the global issues for management of the service in order to promote a continuous improvement strategy for the overall process. A recent ESTRO advisory report to the Commission of the European Union for the 'Europe Against Cancer' program has considered the general requirements for quality assurance in radiotherapy [21]. This document has observed the general WHO approach, which emphasizes the need for quality assurance across areas of radiation oncology [24]. Furthermore, the document has maintained consistency with the ISO 9001 and the EN 29000 series of EC standards, which embody a rationalization of the many and various national approaches to quality systems and provide the general guidelines for their implementation and management [17]. A concerted action on conformal radiotherapy amongst 30 European institutions was launched in 1994 within the European Union BIOMED program. The project bears the acronym DYNARAD (development and standardization of new DYNAmic RADiotherapy techniques/BIOMED 1, Science Research and Development, Biomedical Health and Research, Directorate General XII, Commission of the European Communities) and is intended to provide a forum for exchange of ideas and to share experiences with the ultimate goal of improving knowledge, establishing broadly accepted practice and promoting a common understanding and concerted activity around the key issues involved. Work is performed across five main lines of action including imaging, treatment planning, special techniques, clinical evaluation and quality assurance. A document on quality assurance for conformal radiotherapy was formulated within the DYNARAD Quality Assurance Group, reflecting a general consensus on the recommended quality assurance practice for institutions that deliver conformal radiotherapy treatments as part of their radiotherapy service. The previously mentioned ESTRO advisory report on 'Quality Assurance in Radiotherapy' has been adopted as the basic reference document. The work reported here aimed at further detailing this guidance by direct correlation with the issues involved in the special case of conformal radiotherapy. The document has been endorsed by the DYNARAD group of institutions (Vrije Universiteit Brussels, BE; University Hospital of Gent, BE; University of Liege, BE; Paul Scherrer Institute, CH; Radiologische Universitatsklinik Tubingen, DE; Rigshospitaiet, DK; Arhus Kommunehospital, DK; Clinica Puerto de Hierro, ES; Universidad de Sevilia, ES; Institut Curie, FR; Hospital Tenon, FR; Centre Alexis Vautrin, FR; Centre de Protontherapie D'Orsay, FR; Institut Gustave Roussy, FR; Institut Paoli-Calmettes, FR; University College of London, GB; St. Bartholomew's Hospital, GB; University hospital of Patras, GR; Piraeus Anticancer Hospital Metaxa, GR; CRS Instituto Regina Elena, IT; Borgo Trento Hospital, IT; University of Amsterdam, NL; Academisch Medisch Centrum, NL; Haukeland Hospital, NO; Karolinska Hospital, SE; Centro de Oncologia de Coimbra, PT). As such it can form the basis for further discussions and enter into the subsequent phase of expanding its consensus basis. 1.2. Application of recommendations From the outset it has been common strategy in radiotherapy to conform the dose distribution within the limits of a given technique as closely as possible to the internal target volume (ITV), a geometrically defined volume which contains or has a high probability of containing target tissues to be treated to a prescribed time-dose pattern in order to raise the dose to the tumor while sparing normal tissue [19]. The term 'conformal radiotherapy' is used today for radiotherapy with the high dose surface tailored to conform to the internal target volume. Individual radiation therapy centers may be utilizing very different levels of effort and technology when applying conformal radiotherapy techniques. This is often a reflection on availability of resources. For the purposes of effectively defining the framework, within which the various issues were addressed in this document, and limiting the scope of the work to the most commonly encountered level of procedures, the classification scheme proposed within DYNARAD was adopted [6]. This scheme proposes four levels of radiotherapy, each representing procedural chains of progressively increasing degrees of sophistication of equipment and practice, tools and methodology. The present document is intended to apply to conformal radiotherapy/level 2 techniques, as defined in Table 1, where the interfacing levels I and 3 are also shown. This level has been considered to reflect the most commonly encountered level of procedures applied in institutions that provide conformal radiotherapy services. Level 3, on the other hand, is considered representative of the current status and trends for research in the associated areas of conformal radiotherapy. Level I is regarded as representing the standard practice for the majority of curative treatments. A fourth level (level 0), not appearing in this table, encompasses the very simple techniques used for palliative treatments with no attempt to conform the dose to the target volume. It is understood that the list of items appearing in the columns of Table 1 may not necessarily be exhaustive nor absolute, while there is much overlap between consecutive levels. Nevertheless, this classification has proven valuable in facilitating the discussions and interaction amongst the Table I Classification of conformal therapy according to the methodology and tools associated with each step of the procedure
* 'Automatic isocenter definition at center of target volume For level 3, adjustment of the isocenter position can form part of the dose distribution optimization process. DYNARAD institutions within a commonly understood framework. As such, it has been considered as the most suitable for effectively defining the scope, by providing an appropriate reference within which the relevant issues have been treated. The DYNARAD document has maintained the overall structure of the ESTRO advisory report on "Quality Assurance in Radiotherapy"; the relevant guidance has been developed in a set of guidelines which apply to the following items: quality requirements for conformal radiotherapy; quality assurance for conformal radiotherapy; organizational structures for conformal radiotherapy; technological infrastructure for conformal radiotherapy services; process control for conformal techniques; securing knowledge and skill in conformal radiotherapy. In the following sections usage of the term conformal radiotherapy' should be taken to mean 'conformal radiotherapy/level 2' and referenced to Table 1. 2. Quality requirements in conformal radiotherapy 'Quality' as defined in the ISO standards refers to 'the totality of characteristics of an entity that bear on its ability to satisfy stated or implied needs'. The term 'entity' has a very broad scope since quality, as a concept, 15 encountered in many different contexts [18]. The concept of quality in health care services has evolved over the years and has closely followed perceptions of importance attached to the various aspects of health care at each stage. Today, quality in the health care sector 15 regarded as encompassing ail medical, technical, economic and ethical aspects of health-care delivery. Therefore, a high degree of professional excellence, efficiency in the use of resources, minimization of risk to the patient, satisfaction of the patient and the final health impact constitute the main determinants for quality in health care delivery [25]. Within this extended context, requirements for quality in conformal radiotherapy are based on the following considerations :
3. Quality assurance in conformal radiotherapy Achieving the aims of conformal radiotherapy requires a minimum level of staffing, facilities and equipment. The means by which each part of the service will be provided and the standards against which quality is to be assessed will depend on the type of radiotherapy techniques employed and they should be predefined and established prior to the implementation of any new conformal technique. These considerations have lead to the following set of basic elements for quality assurance in conformal radiotherapy. 3.1. Aims Each radiotherapy department or institution should clearly define the level of conformal radiotherapy that can be offered, taking into account available resources, manpower and expertise at a local, regional and national level; such aims should be explicitly stated and understood by ail staff involved in the process. 3.2. Criteria and standards The criteria by which the quality of both the radiotherapy process and the eventual treatment outcome will be assessed should be defined. The corresponding standards should be locally established and/or existing standards should be adopted. 3.3. Procedures Effective and efficient procedures that will lead to the intended outcome should be designed and implemented. These should allow for flexibility to accommodate specific clinical cases and/or changes for improvements. 3.4. Responsibilities All staff involved should understand the purpose and rationale of all procedures and be in a position to unambiguously identify their role in the process. 3.5. Documentation Procedures should be described in adequate detail in a departmental quality manual. Such documentation should be updated whenever changes in the procedures have been deemed necessary and have been introduced in practice. 3.6. Resources Adequate resources, both technological and human, should be allocated to the service in order to run it effectively, in compliance with the stated aims and the respective criteria and standards. 3.7. Evaluation Compliance should be systematically monitored.
Mechanisms for prompt identification and effective treatment of problems and implementation of corrective actions should be established. 3.9. Attitudes A culture for quality in the department should be established and sustained and a focus on continuous quality improvement should be promoted. 4. Organizational structures for conformal radiotherapy It is considered imperative that departments which aim to provide conformal radiotherapy (at level 2 or higher) should design and maintain effective quality assurance procedures by establishing and maintaining an appropriate quality system. The issues relating to the responsibility for quality, organizational relationships and staff qualifications have been discussed in detail in the ESTRO report [21]. In addition to this guidance, the following issues are specifically emphasized:
5. Technological infrastructure for conformal radiotherapy services The following guidelines focus on the equipment requirements which are necessary to ensure the establishment of effective and efficient conformal radiotherapy facilities. The minimum set of performance standards relating to the functionality and accuracy of this equipment are treated extensively in a number of relevant reports and do not fall within the scope of the present document. The guidelines are as follows:
Equipment used in conformal radiotherapy should maintain its designated performance as well as acceptable safety standards for patients, staff and the general public throughout its lifetime. Fulfillment of the above requirement should be ensured by means of systematic maintenance and quality control programs of every item of medical equipment used in conformal radiotherapy. Quality control comprises the set of operations intended to verify quality, including evaluation and monitoring of performance for maintenance of characteristics at the optimum level. The general considerations for these aspects are provided in the reference document. Further specialized technical guidance may be sought in a number of technical reports [l~5,8-l6]. The following is intended to provide a comprehensive list of equipment that should be available according to the definition of conformal radiotherapy/level 2. These items constitute the essential technological infrastructure required to appropriately implement conformal treatment procedures. 5.1. Patient data acquisition
5.2. Beam definition
5.3. Treatment planning A computerized treatment planning system should be available bearing the following features:
5.4. Treatment verification 5.4.1 Pre-treatment verification Pre-treatment verification should be performed by means of either (i) a conventional simulator and subsequently verified on the treatment machine by portal imaging or (ii) DRR and BEV functions, if both are available with the treatment planning system, verified 011 the treatment machine by portal imaging. 5.4.2. Treatment delivery verification
6. Process control for conformal techniques Conformal radiotherapy has only recently been widely implemented on a routine basis. To date, not all aspects of conformal radiotherapy have been adequately proven, as long-term follow-up of patients that have undergone such treatment is not yet complete. Consequently, the techniques which are currently implemented in institutions are based on promising but not necessarily proven clinical studies [6]. As a result, best practice guidelines are not currently available for conformal radiotherapy. In addition to the general guidelines for process control provided in the ESTRO report [21], the following considerations for conformal radiotherapy have been addressed. 6.1. Practice
6.2. Treatment planning and optimization
6.3. Records
6.4. Information flow
7. Securing knowledge and skill Departments aiming at delivery of conformal techniques should take actions to promote continuous learning and maintenance of knowledge and skills and establish effective communication with institutions with similar aims. Furthermore, commitment to research and advancement in this particular area is of particular importance.
Acknowledgements This work has been supported by the Commission of the European Communities under the BIOMED Programme. We wish to thank ail DYNARAD members for their contribution through stimulating discussions and feed-back. We particularly wish to thank the project coordinator, Professor B. Proimos for his encouragement and active support throughout the course of the work. References
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