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  2. 2. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 2 of 103
  3. 3. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 3 of 103 CONTENTS CONTENTS_________________________________________________________________ 3 1. INTRODUCTION _________________________________________________________ 5 1.1. Purpose and Background____________________________________________________ 5 1.2. Basis for Criteria of Acceptability in European Directives __________________________ 7 1.2.1. Requirements of the Medical Exposure Directive_____________________________________7 1.2.2. Wider context, the MDD Directive and Equipment Standards___________________________9 1.3. To whom this document is addressed ________________________________________ 11 1.4. Criteria of Acceptability____________________________________________________ 12 1.4.1. Approaches to Criteria_________________________________________________________12 1.4.2. Suspension Levels ____________________________________________________________13 1.4.3. Identifying and Selecting Criteria ________________________________________________15 1.5. Special Considerations, Exceptions and Exclusions ______________________________ 17 1.5.1. Special Considerations_________________________________________________________17 1.5.2. Exceptions __________________________________________________________________18 1.5.3. rapidly evolving technologies ___________________________________________________18 1.5.4. Exclusions___________________________________________________________________19 1.6. Establishing criteria of acceptability have been met _____________________________ 19 2. DIAGNOSTIC RADIOLOGY ________________________________________________ 22 2.1. Introduction _____________________________________________________________ 22 2.2. X-Ray Generators and equipment for General Radiography_______________________ 23 2.2.1. Introduction _________________________________________________________________23 2.2.2. Criteria for X-Ray Generators, and General Radiography ______________________________26 2.3. Radiographic Image Receptors and Viewing Facilities____________________________ 29 2.3.1. Introduction _________________________________________________________________29 2.3.2. Criteria for Image Receptors and Viewing Facilities __________________________________31 2.4. Mammography___________________________________________________________ 37 2.4.1. Introduction _________________________________________________________________37 2.4.2. Measurements_______________________________________________________________38 2.5. Dental Radiography _______________________________________________________ 41 2.5.1. Introduction _________________________________________________________________41 2.5.2. Intra-Oral Systems ____________________________________________________________41 2.5.3. Criteria for Dental Radiography__________________________________________________42 2.5.4. Panoramic radiography ________________________________________________________43 2.5.5. Cephalometry _______________________________________________________________43 2.6. Fluoroscopic Systems______________________________________________________ 44 2.6.1. Introduction _________________________________________________________________44 2.6.2. Criteria for Acceptability of Fluoroscopy Equipment _________________________________45 2.7. Computed Tomography____________________________________________________ 46 2.7.1. Introduction _________________________________________________________________46 2.7.2. Criteria for Acceptability of CT Systems ___________________________________________48 2.8. Dual Energy X-ray Absorptiometry ___________________________________________ 49 2.8.1. Introduction _________________________________________________________________49 2.8.2. Acceptability Criteria for DXA Systems ____________________________________________49
  4. 4. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 4 of 103 3. NUCLEAR MEDICINE EQUIPMENT__________________________________________ 50 3.1. Introduction _____________________________________________________________ 50 3.2. Nuclear Medicine Therapeutic Procedures ____________________________________ 52 3.2.1. Introduction _________________________________________________________________52 3.2.2. Activity Measurement Instruments_______________________________________________53 3.2.3. Contamination Monitors _______________________________________________________53 3.2.4. Patient Dose Rate Measuring Instruments _________________________________________54 3.2.5. Radiopharmacy Quality Assurance Programme _____________________________________55 3.3. Radiopharmacy for Gamma Camera based Diagnostic Procedures _________________ 56 3.3.1. Introduction _________________________________________________________________56 3.3.2. Activity Measurement Instruments_______________________________________________57 3.3.3. Gamma Counters_____________________________________________________________57 3.3.4. Thin Layer Chromatography Scanners_____________________________________________58 3.3.5. Contamination monitors _______________________________________________________58 3.4. Radiopharmacy for Positron Emission Based Diagnostic Procedures________________ 59 3.3 Gamma Camera based Diagnostic Procedures__________________________________ 59 3.3.1 Introduction ___________________________________________________________________59 3.4.1. Planar Gamma Camera ________________________________________________________60 3.4.2. Whole Body IMAGING System___________________________________________________61 3.4.3. SPECT System________________________________________________________________62 3.4.4. Gamma Cameras used for Coincidence Imaging_____________________________________63 3.5. Positron Emission Diagnostic Procedures______________________________________ 64 3.5.1. Introduction _________________________________________________________________64 3.5.2. Positron Emission Tomography System ___________________________________________65 3.5.3. Hybrid Diagnostic Systems______________________________________________________66 3.4 Intra-Operative Probes ____________________________________________________ 67 4 RADIOTHERAPY ________________________________________________________ 69 3.6. Introduction _____________________________________________________________ 69 3.3 Linear accelerators________________________________________________________ 70 3.7. Simulators_______________________________________________________________ 73 3.8. CT Simulators ____________________________________________________________ 76 3.9. Cobalt-60 units___________________________________________________________ 79 3.10. Kilovoltage Units _______________________________________________________ 81 3.11. Brachytherapy _________________________________________________________ 82 3.12. Treatment Planning Systems______________________________________________ 83 3.13. Dosimetry Equipment ___________________________________________________ 84 3.14. Radiotherapy Networks__________________________________________________ 85 APPENDIX 1 INFORMATIVE NOTE ON IMAGING PERFORMANCE_____________________ 88 APPENDIX 2 AUTOMATIC EXPOSURE CONTROL __________________________________ 89 APPENDIX 3 EQUIPMENT ____________________________________________________ 90 REFERENCES & SELECTED BIBLIOGRAPHY _______________________________________ 92 ACKNOWLEDGEMENTS_____________________________________________________103
  5. 5. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 5 of 103 1. INTRODUCTION1 1.1. PURPOSE AND BACKGROUND2 The purpose of this publication is to specify minimum performance standards for3 radiological, nuclear medicine and radiotherapy equipment. The criteria of4 acceptability presented here are based on levels of performance that prompt5 intervention and will result in the use of the equipment being curtailed or terminated,6 if not corrected. The criteria are produced in response to Directive 97/43/Euratom,7 which requires that medical exposures be justified and carried out in an optimized8 fashion. To give effect to this Directive, Article 8.3 stipulates that Member States9 shall adopt criteria of acceptability for radiological equipment in order to indicate10 when action is necessary, including, if appropriate, taking the equipment out of11 service. In 1997, the Commission published Radiation Protection 91: Criteria for12 acceptability of radiological (including radiotherapy) and nuclear medicine13 installations (EC, 1997), in pursuit of this objective. This specified minimum criteria14 for acceptability and has been used to this effect in legislation, codes of practice and15 by individual professionals throughout the member states and elsewhere in the world.16 RP 91 considered diagnostic radiological installations including conventional and17 computed tomography, dental radiography, and mammography, radiotherapy18 installations and nuclear medicine installations. However, development of new19 radiological systems and technologies, improvements in traditional technologies and20 changing clinical/social needs have created circumstances where the criteria of21 acceptability need to be reviewed to ensure the principles of justification and22 optimization are upheld. To give effect to this, the Commission, on the advice of the23 Article 31 Group of Experts, initiated a study aimed at reviewing and updating RP 9124 (EC, 1997), which in due course has led to this publication.25 This revised publication is, among other features, intended to:26 1. Update existing acceptability criteria.27 2. Update and extend acceptability criteria to new types of installations. In diagnostic28 radiology, the range and scope of the systems available has been greatly29
  6. 6. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 6 of 103 extended (e.g. computed radiography, digital radiography, digital fluoroscopy,1 multislice computed tomography (CT) and dual energy x-ray absorptiometry2 (DXA)). In nuclear medicine, there are Positron Emission Tomography (PET)3 systems and hybrid scanners. In radiotherapy, there are linear accelerators with4 multileaf collimators capable of intensity modulated radiotherapy (IMRT).5 3. Identify an updated and more explicit range of techniques employed to assess6 criteria of acceptability,7 4. Provide criteria that have a reasonable opportunity of being accepted, and that8 are achievable throughout the member states.9 5. Deal, where practical, with the implications for screening techniques, paediatrics,10 high dose techniques and other special issues noted in the 1997 Directive.11 6. Promote approaches based on an understanding of and that attempt to achieve12 consistency with those employed by the Medical Devices Directive (MDD)13 (Council Directive 93/42/EEC), industry, standards organizations and professional14 bodies.15 7. Make practical suggestions on implementation and verification.16 To achieve this, the development and review process has involved a wide range of17 individuals and organizations, including experts from relevant professions,18 professional bodies, industry, standards organizations and relevant international19 organizations. It was easier to achieve the last objective with radiotherapy than with20 diagnostic radiology. This is because of a long tradition of close working relationships21 between the medical physics and international standards communities, which has22 facilitated the development and adoption of common standards in radiotherapy. An23 attempt has been made, with the cooperation of the International Electrotechnical24 Commission (IEC), to import this approach to the deliberations on diagnostic25 radiology and to extend it, where it already exists, in nuclear medicine.26 The intent has been to define parameters essential to the assessment of the27 performance of radiological medical installations and set up tolerances within which28 the technical quality and equipment safety standards for medical procedures are29
  7. 7. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 7 of 103 ensured. The methods for performance assessment recommended generally rely on1 non-invasive measurements open to the end user. This publication will benefit the2 holder of radiological installations, bodies responsible for technical surveillance and3 authorities charged with verifying compliance of installations with regulations on4 grounds of technical safety. However, it is important to bear in mind that the present5 publication follows the precedent established in RP 91, is limited to the equipment6 and does not address wider issues such as those associated with, for example, the7 requirements for buildings and installations, information technology (IT) systems such8 as picture archiving and communication systems (PACS) and/or radiological9 information systems (RIS).10 1.2. BASIS FOR CRITERIA OF ACCEPTABILITY IN EUROPEAN DIRECTIVES11 1.2.1.REQUIREMENTS OF THE MEDICAL EXPOSURE DIRECTIVE12 The work of the European Commission in the field of radiation protection is governed13 by the Euratom Treaty and the Council Directives made under it. The most14 prominent is the Basic Safety Standards Directive (BSS) on the protection of15 exposed workers and the public (Council Directive 80/836/Euratom), revised in 199616 (Council Directive 96/29/Euratom). Radiation protection of persons undergoing17 medical examination was first addressed in Council Directive 84/466/Euratom. This18 was replaced in 1997 by Council Directive 97/43/EURATOM (MED) on health19 protection of patients against the dangers of ionizing radiation in relation to medical20 exposure. This prescribes a number of measures to ensure medical exposures are21 delivered under appropriate conditions. It makes necessary the establishment of22 quality assurance programmes and criteria of acceptability for equipment and23 installations. These criteria apply to all installed radiological equipment used with24 patients.25 The directive also deals with the monitoring, evaluation and maintenance of the26 required characteristics of performance of equipment that can be defined, measured27 and controlled. In particular, it requires that all doses arising from medical exposure28 of patients for medical diagnosis or health screening programmes shall be kept as29 low as reasonably achievable consistent with obtaining the required diagnostic30
  8. 8. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 8 of 103 information, taking into account economic and social factors (ALARA). Specifically,1 the requirements in respect of criteria of acceptability are stated as follows:2 “Competent authorities shall take steps to ensure that necessary measures are taken3 by the holder of the radiological installation to improve inadequate or defective4 features of the equipment. They shall also adopt specific criteria of acceptability for5 equipment in order to indicate when appropriate remedial action is necessary,6 including, if appropriate, taking the equipment out of service.”7 Additional requirements in respect of image intensification and dose monitoring8 systems are explicitly specified. These extend to all new equipment which:9 “shall have, where practicable, a device informing the practitioner of the quantity of10 radiation produced by the equipment during the radiological procedure.”11 Finally Article 9 requires that:12 “Appropriate radiological equipment ----- and ancillary equipment are used for the13 medical exposure14 • of children,15 • as part of a health screening programme,16 • involving high doses to the patient, such as interventional radiology, computed17 tomography or radiotherapy.”18 And that:19 “Special attention shall be given to the quality assurance programmes, including20 quality control measures and patient dose or administered activity assessment, as21 mentioned in Article 8, for these practices.”22 Practical consequences of these requirements are that:23
  9. 9. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 9 of 103 1. Acceptance testing must be carried out before the first use of the equipment1 for clinical purposes to ensure it complies with its performance specification2 and to provide reference values for future performance testing.3 2. Further performance testing must be undertaken on a regular basis, and after4 any major maintenance procedure.5 3. Necessary measures must be taken by the holder of the radiological6 installation to improve inadequate or defective features of the equipment.7 4. Competent authorities must adopt specific criteria of acceptability for8 equipment in order to indicate when appropriate action is necessary, including9 taking the equipment out of service.10 5. Appropriate quality assurance programmes including quality control measures11 must be implemented by the holder of the radiological installation.12 This publication deals with the first four points and will be germane to some aspects13 of the fifth. It updates and extends the advice provided in 1997 in RP 91 (EC, 1997).14 However, this document is not intended to act as a guide to quality assurance or15 quality control programmes, which are comprehensively dealt with elsewhere (CEC16 2006; APPM 2006a, b; IPEM 2005a, b; AAPM 2002; BIR 2001; Seibert 1999; IPEM,17 1997a, b, c).18 1.2.2.WIDER CONTEXT, THE MDD DIRECTIVE AND EQUIPMENT STANDARDS19 Since 1993, safety aspects of design, manufacturing and placing on the market of20 medical devices are dealt with by MDD. It is managed by the European Directorate21 General Enterprise; its main goal is to define and list the Essential Requirements,22 which must be fulfilled by Medical Devices. When such a device is in compliance23 with the Essential Requirements of the MDD, it can be “CE marked”, which opens the24 full European market to the product.25 There are a number of ways with which manufacturers can demonstrate that their26 products meet the Essential Requirements of the MDD; the one of most interest here27 involves international standards. Further, demonstration of conformity with the28
  10. 10. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 10 of 103 essential requirements must include a clinical evaluation. Any undesirable side-1 effects must constitute an acceptable risk when weighted against the performance2 intended. For the types of system that are the subject of this publication,3 demonstration of the essential requirements can be achieved by the procedures4 described in the directive annexes. Conformity of all or part of these requirements5 can be demonstrated or verified through compliance with harmonised international6 standards. These are standards that specify essential requirements for the basic7 safety and essential performance of the device, such as those issued by the IEC or8 Comité Européen de Normalisation Electrotechnique (CENELEC).9 Although the MDD includes requirements for devices emitting ionising radiation, this10 does not affect the authorisations required by the directives adopted under the11 Euratom treaty when the device is brought into use. In this regard, the Euratom12 Treaty directives have precedence over the MDD. Conformity with an IEC or13 CENELEC standard will frequently be included as part of the suppliers’ specification14 and will be confirmed during contractual acceptance (acceptance testing) of the15 equipment by the purchaser. On the other hand the acceptability criteria in this16 publication must be met during the useful life of the equipment and its compliance17 with them will generally be regularly assessed.18 The MDD was substantially amended by Directive 2007/47/EC. The amendments19 include an undertaking by the manufacturer to institute and keep up to date a20 systematic procedure to review experience gained from devices in the post-21 production phase and to implement appropriate means to apply any necessary22 corrective action. Furthermore, the clinical evaluation and its documentation must23 be actively updated with data obtained from the post-market surveillance. Where24 post-market clinical follow-up as part of the post-market surveillance plan for the25 device is not deemed necessary, this must be duly justified and documented.26 In transposing these European directives into national law, the acceptability criteria27 required by the MED may be transposed into national law using country specific28 criteria and approaches. It is clear that this may undermine the applicability essential29 performance standards as required by the MDD or through compliance with the30 international standardisation system. Such an approach conflicts with the concept of31 free circulation and suppression of barriers to trade, which is one of the goals of the32
  11. 11. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 11 of 103 EU in general and the MDD in particular. To avoid these difficulties there is an1 urgent and clear need for harmonisation between the requirements of the two2 directives (MDD and MED). Thus it is desirable that all EU countries both transpose3 the MED requirement for criteria of acceptability in a consistent fashion that will not4 harm the efforts under the MDD, the standards and CE marking systems, to ensure5 free circulation of goods and suppress trade barriers. The approach advocated in6 this publication is consistent with this objective.7 Thus, care must be exercised transposing the requirements of the MED based on8 either partial or inappropriate adoption of this publication as national legislation.9 Where this is envisaged, some caution is necessary and due discretion must be10 allowed in respect of the clinical situations envisaged in this introduction and the11 associated technology specific sections. Furthermore, adopting a regulation based12 solely on national radiation protection considerations without due regard for the13 issues arising from the MDD is likely to prove counterproductive for both suppliers14 and end users. At a national level, the solution adopted should ensure patient safety15 while fostering a cooperative framework between industry, standards, end users and16 regulators. Internationally, there is a clear need for harmonization and a level of17 uniformity between countries in recognition of the global nature of the equipment18 supply industry. It is further necessary that there be harmonization between industry19 and users, at least in terms of the methodologies employed.20 1.3. TO WHOM THIS DOCUMENT IS ADDRESSED21 Regulatory documents and standards, with respect to equipment performance, can22 be addressed to or focused primarily on the needs or obligations of a particular23 group. For example, the standards produced by IEC and CENELEC are primarily24 aimed at manufacturers and suppliers. Many of the tests they specify are type tests25 that could not be done in the field.26 However, the possible audiences for this publication include holders, end users,27 regulators, industry and standards organizations. It is recognized that each of these28 has a necessary interest in this publication and its application. It was recognized that29 the primary audience for the publication is the holders and end-users of the30 equipment (specifically, the health agencies, hospitals, other institutions,31
  12. 12. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 12 of 103 practitioners, medical physicists and other staff and agents, who deploy the1 equipment for use with patients). In addition, it was recognized that it must reflect the2 requirements of regulators when they are acting in the medical area in the interests3 of end users and/or patients. This is in keeping with the precedent implicitly4 established through the scope and format adopted for RP 91. This publication5 addresses the needs of these groups while taking due account of the reality of6 globalization of the industry, standards and the harmonization objectives viz a viz the7 MDD noted elsewhere. The technical parts of Sections 2, 3, and 4 assume those8 reading and using them are familiar with this introduction and have a good working9 knowledge of the relevant types of equipment and appropriate testing regimes.10 1.4. CRITERIA OF ACCEPTABILITY11 1.4.1.APPROACHES TO CRITERIA12 Approaches to describing the acceptability and performance of equipment have13 varied. They inevitably include requirements specifically prescribed in the directive,14 such as:15 “In the case of fluoroscopy, examinations without an image intensification or16 equivalent techniques are not justified and shall therefore be prohibited”,17 or,18 “Fluoroscopic examinations without devices to control the dose rate shall be limited19 to justified circumstances.”20 With respect to other areas, they range from provision of hard numerical values for21 performance indices to detailed specification of measurement methodologies without22 indicating the performance level to be accepted. The latter approach has come to be23 favoured in many of the standards issued by bodies like IEC or CENELEC and by24 some professional bodies.1 While this approach has the advantage that it is25 1 The IEC is the world's leading organization that prepares and publishes International Standards for all electrical, electronic and related technologies. IEC standards cover a vast range of technologies, including power generation, transmission and distribution to home appliances and office equipment, semiconductors, fibre optics, batteries, and medical devices to mention just a few. Many, if not all, of the markets involved are global. Within the EU CENELEC is the parallel standards organization and in practice adopts many IEC standards as its own aligning them within the European context.
  13. 13. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 13 of 103 easier/possible to get consensus on it among the manufacturers, professions and1 other interests involved, it also has some disadvantages. These include an evident2 lack of transparency, associated limitations on accountability and risks of3 misapplication in the hands of inexperienced users.4 A comprehensive, consistent suite of approaches to performance and safety5 assessment of radiological equipment has been proposed by the UK Institute of6 Physics and Engineering in Medicine (IPEM, 2005a, b; IPEM, 1997a, b, c]. The7 American Association of Physics in Medicine (AAPM,, 2006a, b, 2005, 2002) and8 British Institute of Radiology (BIR, 2001) have also, among other professional9 organizations, published much useful material. The IPEM system is based on the10 assumption that deviations from the baseline performance of equipment on11 installation will provide an adequate means of detecting unsafe or inadequately12 performing equipment. This approach is questionable within the meaning of criteria13 of acceptability in the MED; if the baseline is, for one reason or another,14 unsatisfactory, there are no criteria on which it can be rejected. In light of this issue,15 the approach more recently favoured by IPEM and many standards organizations16 has not been adopted in most instances. Where possible, the emphasis has been to17 propose firm suspension levels. This is consistent with the approach adopted in18 many countries, including, for example, France, Germany, Belgium, Spain, Italy,19 Luxembourg and others which have adopted hard limits for performance values20 based on RP 91 or other sources.21 1.4.2.SUSPENSION LEVELS22 A critical reading of the directive, RP 91 and the professional literature reveals some23 shift or “creep” in the meaning of the terms remedial and suspension level since they24 came into widespread use in the mid 1990s. In the interest of clarity, we have25 redefined them in a way that is consistent with both their usage in the Directive and26 their current usage, as follows:27 Definition of Suspension Levels:28 A level of performance that requires the immediate removal of the equipment29 from use.30
  14. 14. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 14 of 103 Following a documented risk assessment involving the Medical Physics Expert1 (MPE) and the practitioner, the suspended equipment may be considered for use in2 limited circumstances. The holder and the operators must be advised in writing of the3 suspension and/or the related limitation(s) in use. 2 4 A suspension level not being met requires that the equipment is taken out of service5 immediately. Not meeting the level makes the equipment unsafe, or performance so6 poor, that it would be unacceptable to society. The level is based on minimum7 standards of safety and performance that would be acceptable in the EU and8 represent the expert judgement of the working group and reviewers based on their9 knowledge of what is acceptable among their peers and informed by the social, legal10 and political circumstances that prevail in the EU. When suspension levels are11 reached the equipment must be removed from use (or restricted in use) with patients,12 either indefinitely or until it is repaired and again satisfies the criteria.13 It is also possible that the equipment will pass an evaluation based on suspension14 levels but be unsatisfactory in some other way. This may be because we have15 mainly considered suspension levels as performance tolerances (particularly in16 radiotherapy) whereas equipment may very well fail on safety issues which are17 covered by the IEC general standards 60601-1 (IEC, 2003b) and associated18 collateral and particular standards. Many quality assurance manuals refer to the19 levels triggering such actions as remedial levels. In line with the precedent20 established in RP 91 (EC, 1997), the main thrust of this publication is concerned with21 suspension levels. Remedial levels are, on the other hand, well described in22 numerous quality assurance publications detailing them (AAPM, 2005; IPEM, 2005a,23 b; AAPM, 2002; EC, 1997, IPEM, 1997a, b, c; et al).24 Suspension levels are taken as the criteria of acceptability. They must be clearly25 distinguished from the levels set for acceptance tests. The latter are used to26 establish that the equipment meets the supplier’s specification or to verify some other27 contractual issue; they may be quite different from the criteria of acceptability28 2 Examples of how this might arise include the following: 1.In radiotherapy, a megavoltage unit with poor isocentric accuracy could be restricted to palliative treatment until the unit could be replaced. 2. In nuclear medicine, a rotational gamma camera with inferior isocentric accuracy could be restricted to static examinations. 3. In diagnostic radiology, an x-ray set with the beam limiting device locked in the maximum field of view position might be used to expose films requiring that format in specific circumstances.
  15. 15. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 15 of 103 envisaged in the directive. However, it is entirely possible that equipment meeting1 the requirements of the acceptance test will automatically pass the criteria of2 acceptability. This is because the acceptance test for modern equipment will often3 be more demanding than the criterion of acceptability. Tests based on the criteria of4 acceptability should be performed on installation and thereafter regularly or after5 major maintenance.6 In practice, acceptability testing should assure the equipment tested is serviceable7 and provides acceptable clinical image quality using acceptable patient radiation8 doses. QA testing may involve additional elements beyond the acceptability and will9 inevitably involve reporting many remedial levels. It is presumed that by the time10 acceptability is considered, acceptance tests, compliance with manufacturer’s11 specifications and commissioning tests have been successfully performed.12 Equipment may be significantly reconfigured during its useful life arising from13 updating, major maintenance or changes in its intended use. If this is done,14 appropriate new acceptability tests will be required.15 1.4.3.IDENTIFYING AND SELECTING CRITERIA16 It was not possible to devise a single acceptable approach to proposing values or17 levels for the criteria selected. Instead a number of approaches, with varying18 degrees of authority and consensus attaching to them, have been adopted and19 grouped under headings A to D as follows:20 Type A Criterion21 This type of criterion is based on a formal national/international regulation or an22 international standard.23 A reasonable case can sometimes be made for using a manufacturer’s specification24 as a criterion of acceptability. For example, all CE marked equipment, which meets25 specification, will either meet or exceed the essential safety standards with which the26 equipment complies. Thus, testing to the manufacturer’s specification could be taken27 as a means of ensuring the criteria of acceptability are met or exceeded in the area28 they address.29
  16. 16. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 16 of 103 A case can also be made that compliance with the relevant IEC, CENELEC or1 national standards might be taken as compliance with criteria that the industry has2 deemed to be essential for safety. In practice, this approach may be limited in value3 as the tests required may not be within the competence of end users or service4 engineers in the field. Thus different agreed approaches to verification will be5 required. Development in this area is essential to the harmonization referred to6 above. In particular, agreed methodology is essential in any system of equipment7 testing. Standards organizations provide a useful role model in this regard, which8 this publication has tried to emulate.3 9 Type B Criterion10 This type of criterion is based on formal recommendations of scientific, medical or11 professional bodies.12 Where industrial standards are not available or are out of date, advice is often13 available from professional bodies, notably IPEM, AAPM, NEMA, BIR, ENMS, ACR14 et al. More detailed advice on testing individual systems is available from the AAPM,15 earlier IPEM publications and a wide range of material published by many16 professional bodies and public service organizations. Much of the material is peer17 reviewed and has been a valuable source where suitable standards are not available.18 Type C Criterion19 This type of criterion is based on material published in well established scientific,20 medical or professional journals.21 Where neither standards nor material issued by professional bodies are available,22 the published scientific literature has been consulted and a recommendation from the23 drafting group has been proposed and submitted to expert review by referees.24 Where this process led to a consensus, the value has been adopted and is25 recommended below.26 3 When equipment standards are developed so that their recommendations can be addressed to and accepted by both “manufacturers and users”, the question of establishing criteria of acceptability becomes much simplified. Highly developed initiatives in this regard have been undertaken in radiotherapy (see IEC 60976 and IEC 60977). These “provide guidance to manufacturers on the needs of radiotherapists in respect of the performance of MEDICAL ELECTRON ACCELERATORS and they provide guidance to USERS wishing to check the manufacturer’s declared performance characteristics, to carry out (footnote continued)
  17. 17. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 17 of 103 Type D Criterion1 The Type D situation arises where it has not been possible to make a2 recommendation. In a small residue of areas it has not been possible to make3 recommendations for a variety of reasons. For example, where the technology4 involved is evolving rapidly, listing a value could be counterproductive. It could5 become out of date very rapidly or it could act as an inhibitor of development. In6 such situations we feel the criterion of acceptability should be determined by the7 institution holding the equipment based on the advice of the MPE or Radiation8 Protection Adviser (RPA) as appropriate.9 The criteria of acceptability proposed are identified as belonging to one or another of10 these categories. In addition, at least one reference to the primary source for the11 value and the method recommended is provided. Some expansion on the approach12 and the rationale for the choice is provided, where deemed necessary in an13 Appendix. Test methods are only fully described if they cannot be referred to in a14 high quality accessible reference.15 16 1.5. SPECIAL CONSIDERATIONS, EXCEPTIONS AND EXCLUSIONS17 1.5.1.SPECIAL CONSIDERATIONS18 The directive requires that special consideration be given to equipment in the19 following categories:20 • Equipment for screening,21 • Equipment for paediatrics and22 • High dose equipment, such as that used for CT, interventional radiology, or23 radiotherapy.24 acceptance tests and to check periodically the performance throughout the life of the equipment”. This approach has much to offer other areas.
  18. 18. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 18 of 103 The chapters and sections in the attached volumes dealing with the high dose group1 (CT, interventional radiology or radiotherapy), deal comprehensively with this2 requirement.3 Equipment used for paediatrics and in screening programmes is often similar or4 possibly identical to general purpose equipment. Where this is the case, additional5 guidance for the special problems of paediatrics, such as the requirement for a6 removable grid in general radiology or fluoroscopy and the special needs with regard7 to CT exposure programmes are noted in the technology specific sections. The8 special requirements for mammography are based on those appropriate to screening9 programmes.10 1.5.2.EXCEPTIONS11 Exceptions to the recommended criteria may arise in various circumstances. These12 include the cases cited in Section 1.2 above, where equipment compliant with safety13 and performance standards that predate the criteria for acceptability has to be14 assessed. In such cases, the MPE should make a recommendation to the end user15 or holder, on whether or not this level of compliance is sufficient to meet the16 intentions of the directive. These recommendations must take a balanced view of the17 overall situation, including the economic/social circumstances, older technology etc.;18 they may be nuanced in that the RPA/MPE may recommend that the equipment be19 accepted subject to restrictions on its use. Likewise it is always well to remember20 that acceptability criteria, as already outlined, may depend on the use(s) for which21 equipment is deployed.22 1.5.3.RAPIDLY EVOLVING TECHNOLOGIES23 Medical imaging is an area in which many new developments are occurring.24 Encouragement of development in such an environment is not well served by the25 imposition of rigid criteria of acceptability. Such criteria, when rigorously enforced,26 could become obstacles to development and thereby undermine the functionality and27 safety they were designed to protect. In such circumstances, the MPE should28 recommend to the end-user a set of criteria that are framed to be effective with the29 new technology and that takes account of related longer established technologies,30
  19. 19. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 19 of 103 any IEC/CEN/CENELEC standards available, the manufacturer’s recommendations,1 the related scientific and professional opinion/published literature and the maxim that2 the new technology should aspire to be at least as safe as existing technology it is3 replacing.4 1.5.4.EXCLUSIONS5 Within this publication, the term “equipment” has been interpreted to mean the main6 types of equipment used in diagnostic radiology, nuclear medicine and radiotherapy.7 This follows the precedent established in RP 91 (EC, 1997). It is important to be8 aware that the full installation is not treated. Thus, the requirements for an9 acceptable physical building and shielding that will adequately protect staff, the public10 and, on occasions, patients; power supplies and ventilation have not been11 addressed. However, this is an area of growing concern and one in which the12 requirements have changed considerably as both equipment and legislation have13 changed. In addition the acceptable solutions to the new problems, arising from both14 equipment development and legislation, in different parts of the world, are different.15 Consequently, this area is now in need of focused attention in its own right.16 Likewise, the contribution of IT networks to improving or compromising equipment17 functionality can bear on both justification and optimization. This can apply to either18 PACS or RIS networks in diagnostic radiology and imaging, planning and treatment19 networks in radiotherapy centres. The requirements for acceptability of such20 networks are generally beyond the scope of this publication, although they have been21 included occasionally, for example in radiotherapy, where they are integral to the22 treatment.23 As already mentioned elsewhere, the publication focuses on criteria of acceptability24 and it does not offer advice intended for use in routine Quality Assurance25 programmes.26 27 1.6. ESTABLISHING CRITERIA OF ACCEPTABILITY HAVE BEEN MET28 The criteria of acceptability will be applied by the competent authorities in each29 member state. The authorities for the MED are generally not the same as those for30
  20. 20. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 20 of 103 the MDD. In addition the criteria will be introduced and applied in the context of the1 unfolding requirements for clinical audit in healthcare in general and in the2 radiological world in particular. This is accompanied by a general increase in the3 requirements for individual and institutional accreditation. Thus the holder of4 radiological equipment should appoint a competent person to establish that the5 criteria of acceptability have been met. The person appointed should be an MPE or6 a person of similar standing. Who performs the tests to verify compliance is a matter7 for local arrangements. Thus the MPE may choose to perform the tests themselves,8 write them up, report on them and sign them off. Alternatively, he/she may accept9 results provided by the manufacturer’s team. These may have been acquired, for10 example, during acceptance testing or commissioning. Results for tests performed to11 agreed methodology will be satisfactory in many cases. They provide the information12 on which the MPE can make a judgement on whether or not the equipment meets13 the criteria. These two approaches represent the extremes. Most institutions will14 establish a local practice somewhere between that allows the criteria to be verified15 with confidence by a suitably qualified agent acting on behalf of the end user. In16 radiotherapy, joint acceptance testing by the manufacturer’s team and the holder’s17 MPE is commonplace. Whichever approach is taken, where a suspension level is18 not met, the outcome and any associated recommendations from the MPE and/or the19 practitioner must be communicated promptly, in writing, to both the holder and the20 operators/users of the equipment.21 In situations where the formally recommended criteria of acceptability are incomplete,22 lack precision, or where the equipment is very old, subject to exception, special23 arrangements or exemptions, the judgement and advice of the MPE becomes even24 more important. Additional, more complete, measurements may be needed to25 determine the cause of the change in performance. When equipment fails to meet26 the criteria, agreement must be established on how it will be withdrawn from use with27 patients. This must be done in association with the MPE whose advice must be28 obtained. The options, in practice, include those mentioned above and include the29 possibility of immediate withdrawal, where the failure of compliance is serious30 enough to warrant it. Alternatively a phased withdrawal or limitations on the range of31 use of the equipment may be considered. In the latter case, the specific32 circumstances under which the equipment may continue to be used must be carefully33
  21. 21. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 21 of 103 defined and documented. In addition, the advice of the MPE to the practitioner and/or1 the holder or the holder’s representative must be made available in a prompt and2 timely way, consistent with the recommendations for action.3
  22. 22. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 22 of 103 2. DIAGNOSTIC RADIOLOGY1 The technical parts of Sections 2, 3, and 4 assume those reading and using them are2 familiar with the introduction and have a good working knowledge of the relevant types of3 equipment and appropriate testing regimes.4 2.1. INTRODUCTION5 Since RP 91 (EC, 1997), there have been a number of major developments in diagnostic6 radiology. Perhaps the key new developments are the introduction of direct digital detectors7 (e.g. large area flat panel detectors) for use in radiology and fluoroscopy, as well as multiple8 slice computed tomography scanners. Both these new developments have implications for9 acceptability criteria, but suspension levels in these areas are less mature.10 Manufacturers have also incorporated information technology and other developments into11 medical imaging systems which have resulted in radiological imaging equipment being12 more stable. For instance, the stability of the applied tube potential produced by high13 frequency generators has been much improved when compared with previous x-ray14 generator designs (e.g. single phase). As equipment performance evolves, so do15 acceptability criteria.16 With the implementation of the quality culture within radiology departments and the17 evolution of quality assurance programmes, criteria have also changed. In part the18 availability of instrumentation for determination of radiation exposure in radiology linked to19 computers has also impacted on measurement approaches and quality assurance.20 However, in rapidly evolving areas of radiology, such as CT scanning, acceptability criteria21 have not kept pace with technological developments. There is a deficit in consensus based22 acceptability criteria for these areas of practice which will need to be addressed in the23 future. Acceptability criteria for all types of diagnostic radiology equipment are summarised24 in the following sections.25
  23. 23. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 23 of 103 2.2. X-RAY GENERATORS AND EQUIPMENT FOR GENERAL RADIOGRAPHY1 2.2.1.INTRODUCTION2 General radiographic systems still provide the great majority of X-Ray examinations. They3 may be subdivided in practice into a number of subsidiary specialist types of system. This4 section deals with the Suspension Levels applicable to X-Ray generators, and general5 radiographic equipment. It also includes or is applicable to mobile systems, traditional6 conventional tomography and tomosynthesis systems, system subcomponents/devices7 such as automatic exposure control (AEC), and grids. Much of what is presented here is8 also applicable to generators for fluoroscopic equipment. However, the criteria have not9 been developed with specialized X-ray equipment in mind: dental, mammographic, CT and10 DXA units are mentioned in sections 2.4, 2.5, 2.7, and 2.8.11 The criteria here refer to X-ray tube and generator, output, filtration and half value layer12 (HVL), beam alignment, collimation, the grid, AEC, leakage radiation and dosimetry.13 Suspension/tolerance levels are specified in the Tables below. Before presenting them a14 few aspects of half value layer and filtration, image quality, paediatric concerns, AEC,15 mobile devices, and spatial resolution must be mentioned to ensure that the approach and16 the Tables are interpreted correctly.17 18 HVL/filtration19 Total filtration in general radiography should not normally be less than 2.5 mm Al. The half20 value layer (HVL) is an important metric used as a surrogate measurement for filtration. It21 shall not be less than the values given in Table 2.1.22
  24. 24. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 24 of 103 Table 2.1 Minimum half-value layer (HVL) requirements1 Application Values of x-ray tube voltage. (kV) Minimum permissible (HVL) in mm Al (IEC 60601-1-3 (IEC, 2008a) and see Notes 1 and 2) General radiography x- ray equipment <50 50 60 70 80 90 100 110 120 >120 See note 3 1.8 2.2 2.5 2.9 3.2 3.6 3.9 4.3 see note 3 Note 1: These HVLs correspond to a total filtration of 2.5 mm Al for equipment operating at constant potential2 in tungsten anode.3 Note 2: Linear extrapolation to be used here.4 Note 3: Test methods differ for different modalities.5 6 Paediatric Issues7 Requirements for radiography of paediatric patients differ from those of adults, partly related8 to differences in size and immobilization during examination (see notes in Tables9 throughout Section 2). Beam alignment and collimation are particularly important in10 paediatric radiology, where the whole body, individual organs and their separation distance11 are smaller. The x-ray generator and tube must have sufficient power to make short12 exposure times possible. In addition the option to remove the grid from a radiography13 table/image receptor is essential in a system for paediatric use, as is the capacity to disable14 the AEC and use manual factors. Systems used with manual exposures (like dedicated15 mobile units for bedside examinations) should have exposure charts for paediatric patients.16 17 Image Quality and Spatial Resolution18 There are unresolved difficulties in determining objective measures of image quality that are19 both reproducible and reflect clinical performance. Measurements here are limited to high20
  25. 25. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 25 of 103 contrast bar patterns, and may be augmented by subjective or semi subjective1 assessments at the discretion of the MPE and the Practitioner. (Appendix 1)2 3 Automatic exposure control for any radiographic detector4 The AEC should provide limitation of under- and overexposure of the receptor and5 exposure time. Digital generators also require that pre-programmed exposure systems be6 assessed to ensure acceptability based on the suppliers’ specification and the MPE’s7 evaluation. It may also, at the discretion of the MPE, and subject to its being an agreed part8 of the equipment specification with the supplier, include assessment of Ka,e for a specific9 type of examination (see Table 2.2 below for radiographic detectors (method in Appendix10 2). This should be such that the Ka,e for the patient phantom is below an agreed diagnostic11 reference level (DRL). In addition, the optical density of the film should be between 1.0 and12 1.5 OD (SBHP-BVZF, 2008).13 Table 2.2 Examples of image receptor Ka,e for various examinations for some specific14 conditions see note 1 15 Examination Image receptor entrance air kerma (incl. back scatter) Ka,e (µGy) PMMA thickness (cm) Tube voltage (kVp) Abdomen radiograph adult) 5 20 80 Chest radiograph (adult) 5 11 120 Chest radiograph (child) 5 8 80 16 Note 1: For method see Appendix 2; this also includes some information on CR and DDR.17 18 19 Mobile devices20 For mobile devices the criteria for equipment for general radiography are applicable except21 the requirements for alignment, which cannot be met in practice.22 23 Conventional tomography24 The parameters for conventional tomography equipment include cut height level, cut plane25 incrementation, exposure angle, cut height uniformity and spatial resolution.26
  26. 26. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 26 of 103 2.2.2.CRITERIA FOR X-RAY GENERATORS, AND GENERAL RADIOGRAPHY1 Table 2.3: Criteria for Acceptability of General Radiography Systems2 Physical Parameter Suspension Level Reference Type Notes (Paediatrics) Mechanical and electrical safety If defects pose an immediate mechanical or obvious electrical hazard to patients or staff IEC 60601 Series A Mechanical and electrical safety failures can be the source of accidents X-RAY SYSTEM x-ray tube and generator tube voltage accuracy A Lower kVp often used in paediatrics (EC, 1996c) Dial calibration Maximum deviation: > ± 10% or ± 10 kV EC (1997) IPEM (2005a) A B Variation with tube current Maximum variation: > ± 10% EC (1997) B Precision of tube voltage Deviation > ± 5% from mean EC (1997) A x-ray tube output Magnitude of output Y(1m) > 25 µGy/mAs at 80 kV and 2.5 mm Al EC (1997) A Consistency of output Y within ± 20% of mean EC (1997 ) IPEM (2005a) B Consistency of output for range of qualities Y within ± 20% of mean IPEM (2005a) B Half-value layer (HVL ) /total filtration HVL or sufficient total filtration HVL in excess for values in Table 8.1 IEC (2008) A Additional Cu filtration 0.1 or 0.2 mm (EC, 1996c) (A) Exposure time Consistency of exposure time Actual exposure time > ± 20% of indicated value for values > 100ms EC (1997) IPEM (2005a) A B Consistency and absolute values required for shorter exposures, particularly in paediatrics (EC, 1996c) Alignment x-ray/light beam alignment Sum of misalignment in principle directions > 3% of dFID IPEM (2005a) B
  27. 27. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 27 of 103 Orthogonality of x-ray beam and image receptor (IR) The angle between central beam axis and IR ≤ 1.5º from 90º EC (1997) A Collimation Collimation of x-ray beam x-ray beam within borders of image receptor EC (1997) A Automatic collimation X-ray beam shall not differ by more than 2% of dFID at any side of image receptor Borders within IR EC (1997) A Grid A Grids preferably not to be used with children (EC, 1996c) Grid artefacts No artefacts should be visible EC (1997) A Moving grid Lamellae should not be visible on image EC (1997) A AEC verification See also Appendix 2 Focal spot (FS) size through assessment of spatial resolution A Smaller sizes may be required for various applications including paediatrics (EC, 1996c) Spatial resolution (limited by FS size and detector characteristics) Spatial resolution ≥ 1.6 lp/mm JORF (2007a) B DIN standard Limitation of overexposure Maximal focal spot charge < 600 mAs EC (1997) A Much equipment is non compliant in practice.Should this be modified. Limitation of exposure time Maximum exposure time: 6s EC (1997) A Consistency of AEC unit Ka may not differ by more than 10% from mean value SBPH-BVZ (2008) B See also Appendix 2 Verification of Ka,e at image receptor for reference examination See table 2.2. 1.0 < OD >1.5 SBPH-BVZ (2008) B See also Appendix 2 Verification of sensors of AEC Film density for each sensor may not differ by more than 0.2 OD from mean value SBPH-BVZ (2008) B For chest examinations sensors are different on purpose. See also Appendix 2 Verification of AEC at Film density for a SBPH-BVZ B See also Appendix 2
  28. 28. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 28 of 103 various phantom thicknesses phantom thickness differs by more than 0.3 OD from mean value for all thicknesses (2008) Verification of AEC at various tube voltages Film density at a tube voltage may not differ by more than 0.2 OD from mean value for all tube voltages SBPH-BVZ (2008) B See also Appendix 2 Dose to plate in CR and DDR Systems under AEC ≥ 10 µGy/plate Walsh et al (2008.) C NOTE: This is double the max normally encountered (3-5 uGy/plate). Grid in position for this measurement. AEC performance in CR and DDR Systems: > 50%* Walsh et al (2008) C * >50% variation allowed for 5 cm PMMA. Leakage radiation Leakage radiation Ka(1m) < 1mGy in one hour at maximum rating EC (1997) A Dosimetry For KAP meters see 2.6 Image quality Spatial better than 2.8 lp/mm for dose < 10 µGy. And better than 2.4 lp/mm for dose < 5 µGy. DIN 6868-58 (2001) B Use phantom described in the standard Contrast All seven steps are not visible DIN 6868-58 (2001) B Use phantom described in the standard 1 2
  29. 29. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 29 of 103 Table 2.4: Criteria for Acceptability of Conventional Tomography Systems1 Physical Parameter Suspension Level Reference Type Cut height level Difference between indicated and measured value < 5 mm EC (1997) A Cut plane incrementation Reproducibility cut height < 2 mm EC (1997) A Exposure angle Indicated and measured angle should agree within 5° for angles more than 30°. Agreement better for smaller angles EC (1997) A Cut height uniformity Image should reveal no overlaps, inconsistencies of exposures, or asymmetries in motion EC (1997) A Spatial resolution Resolution < 1.6 lp/mm EC (1997) A 2 2.3. RADIOGRAPHIC IMAGE RECEPTORS AND VIEWING FACILITIES3 2.3.1.INTRODUCTION4 The Criteria of Acceptability and the related suspension/tolerance levels for X-Ray Films,5 Screens, Cassettes, CR, DR, Automatic Film Processors, the Dark Room, Light Boxes and6 the Environment for general radiography are presented in Tables 2.5 to 2.12 below. They7 do not deal with the requirements for mammography or dental radiography.8 A wider approach to Quality Assurance of film, film processing and image receptors of all9 types is a critical part of an overall day to day quality system (IPEM, 2005a; BIR, 2001,10 IPEM, 1997a; Papp, 1998). Such a system includes commissioning. Detailed11 commissioning tests are covered in other publications (IPEM, 1997a).12 There are some fundamental differences between CR and film/screen systems. Proper13 installation and calibration of a CR system in a radiology department is extremely important.14 It is also important to note that the x-ray system needs to be properly set up so that it may15
  30. 30. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 30 of 103 be used with CR plates. In particular, the AEC needs to be appropriately set up (Section1 2.2).2 Details on desirable specifications and features of CR systems as well as their proper3 installation can be found in AAPM Report No 93 (2006a). These guidelines should be4 followed prior to the acceptability testing of CR systems. To date, unlike film systems, there5 is little guidance on the performance of CR systems, and the suspension/tolerance levels6 identified will almost inevitably need adjustment in line with future evidence and guidance7 (Section 1.4).8 Likewise, with DDR systems, the tube and generator, workstation and /or laser printer must9 be known to be working properly. When undertaking the QA of the tube and generator, it is10 advisable to keep the detector out of the beam or protected by lead. As with CR little11 guidance is available on Suspension/Tolerance levels and the advice given above for CR12 prevails. Suspension/ tolerance levels suitable for application at the present time are13 provided in Table 2.7.14 Display monitors and hardcopy images have a crucial role in the diagnostic process. IPEM15 notes that inadequacies in the imaging viewing area may serve to negate the benefits of16 other efforts made to maintain quality and consistency. Modern radiology departments17 require digital images from many modalities and from PACS systems to be viewed in many18 locations. Two classes of display are used: diagnostic (systems used for the interpretation19 of medical images) and review (viewing medical images for purposes other than for20 providing a medical interpretation). The requirements for each are different.21
  31. 31. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 31 of 103 2.3.2.CRITERIA FOR IMAGE RECEPTORS AND VIEWING FACILITIES1 Table 2.5 Criteria of Acceptability for Automatic Film Processors, Films, Screens, Darkrooms2 and Illuminators (mammography excluded)3 Physical Parameter Suspension Level Reference Type Notes Automatic Film Processor: Base plus Fog OD > 0.3 IPEM (2005a) IPEM (1997a) B See also IEC 61223- 2-1 (1993c), Papp (1988) and EC (1997) Speed Index 1.2 ± 0.3 IPEM (2005a) BIR (2001) IPEM (1997a) B See also IEC 61223- 2-1 (1993c) and Papp (1988). Contrast Index 1.0 ± 0.3 IPEM (2005a) BIR (2001) IPEM (1997a) B See also IEC 61223- 2-1 (1993c) and Papp (1988). Films, Screens, Darkroom and Illuminators: Screens and Cassettes Visible artefacts. IPEM (2005a) BIR (2001) IPEM (1997a) B See also IEC 61223- 2-2 (1993d) and EC (1997). Relative Speed of Intensifying Screens > 10% or > 0.3 OD across film. IPEM (2005a) IPEM (1997a) B See also EC (1997). Film Screen Contact Non-uniform density or loss of sharpness. IPEM (1997a) B See also IEC 61223- 2-2 (1993d) and EC (1997). Dark Room Safe Lights and Film fogging Evidence of film fogging after twice the normal Film Handling Time. IPEM (2005a) BIR (2001) AAPM (2002) B See also IEC 61223- 2-3 (1993e). Ambient Lighting > 100 Lux. IPEM (1997a) B See also Papp (1988), EC (1997). 4 5 6 7 8
  32. 32. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 32 of 103 Table 2.6 Criteria for Acceptability of Cassettes and Image Plates:1 Physical Parameter Suspension Level Reference Type Notes Condition of cassettes and image plates Damage to plate IPEM (2005a) B Suppliers’ recommendations for method Uniformity Gross non-uniformity Mean ± 20% IPEM (2005a) B 70kV, 1.0 mm copper at tube head, an exposure for 10µGy, read plate under linear algorithm. Table 2.7 Criteria for Acceptability of CR readers see notes 1 and 2 2 Physical Parameter Suspension Level Reference Type Notes Dark Noise Agfa SAL>130 Fuji pixel value > 280 Kodak EIGP > 80 Kodak EIHR > 380 Konica pixel value < 3975 AAPM (2006a) B Erase plates, leave plates 5 minutes, read under standard conditions. Repeat for all plate sizes. Linearity and system transfer properties Manufacturer’s specification KCARE (2005a) B KCARE CR QA. Establish system transfer properties equation (STP) Dose=f(pixel value) Erasure cycle efficiency Blocker visible in second image IPEM (2005a) B High attenuation material Exposure index consistency Indicated exposure does not agree with measured exposure within 20% KCARE (2005a) B Record detector dose indicator and calculate indicated exposure using the STP equation for all plates Detector dose indicator consistency The variation in the calculated indicated exposures differs by greater than 20% between plates for a same exposure KCARE (2005a) B Scaling errors > 2% IPEM (2005a) B Blurring Blurring present KCARE (2005a) B Use contact mesh Image quality High Contrast Resolution (Limiting Spatial Resolution) Spatial resolution better than 2.8 lp/mm for dose < 10 µGy. ≥ 2.4 lp/mm for dose < 5 µGy. DIN 6868-58 (2001) A,C Use phantom described in the standard. Also note AAPM, 2006a & Walsh et al. 2008 Contrast All seven steps visible DIN 6868-58 (2001) A,C Use phantom described in the standard
  33. 33. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 33 of 103 Low-Contrast Resolution Manufacturers specifications AAPM (2006a) B Low contrast resolution test object Laser beam function Edge not continuous the full length of the image AAPM (2006a) B Steel ruler Moiré Patterns Moiré Patterns visible KCARE (2005a) B 70kV, 1.0mm of copper at tube head, grid in place, plate in the bucky at 150cm from the focus 1 2 1. The suspension values quoted for Dark Noise were valid at the time of Publication of this document.3 However as CR is an evolving technology they are subject to change.4 2. This is a test that has to be done during the acceptance testing of the CR Reader in order to establish5 the relationship between receptor dose and pixel value. It tests whether the X-ray generator and the6 CR reader have been properly set up in order to work together correctly.7 8
  34. 34. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 34 of 103 Table 2.8 Criteria of Acceptability for DDR systems see notes 1, 2 1 Physical Parameter Suspension Level Reference Type Notes Dark Noise Excessive noise in the system IPEM (2005a ) B Image without exposure or very low exposure Linearity Manufacturers recommendation KCARE (2005b) C Establish system transfer properties equation (STP) Dose=f(pixel value) Image retention Ghosting present KCARE (2005b) C Low exposure with closed collimators and detector covered with lead apron. Exposure Index Indicated sensitivity indices differ by greater than 20% of equivalent exposure sets. KCARE (2005b) C 70kV, 1.0 mm copper at tube head, at least three times for 10 µGy. Repeat for 1 µGy and 12 µGy Uniformity Mean ± 5% IPEM (2005a) B 70kV, 1.0 mm copper at tube head, 10 µGy. Scaling errors >2% IPEM (2005a) B Grid, attenuating object of known dimensions or lead ruler Uniformity of resolution Blurring present IPEM (2005a) B Use fine wire mesh Image quality High Contrast Resolution (Limiting Spatial Resolution) Spatial resolution better than 2.8 lp/mm for dose < 10 µGy. ≥ 2.4 lp/mm for dose < 5 µGy. DIN 6868-58 (2001) A,C Use phantom described in the standard. Also note AAPM (2006a) & Walsh et al. (2008) Contrast All seven steps are visible DIN 6868-58 (2001) A,C Use phantom described in the standard 2 1. This test should be done at the acceptance testing of the DDR system in order to establish the3 relationship between receptor dose and pixel value. This is the relationship between the generator4 and the detector.5 2. It should be noted that a number of manufacturers have installed on their DDR equipment automatic6 QA software in order to carry out a number of QA tests.7 8 9
  35. 35. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 35 of 103 Table 2.9 Criteria of Acceptability for Diagnostic Monitors1 Physical Parameter Suspension Level Reference Type luminance ratio <200 IPEM (2005a) AAPM (2006a) B luminance ratio Black baseline ±35% White baseline ±30% IPEM (2005a) AAPM (2006a) B Distance and angle calibration – distortion (for CRT) 10% IPEM (2005a) RCR (2002) SEFM-SEPR (2002) B Resolution Visual inspection low and high contrast resolution different from baseline IPEM (2005a) AAPM (2006a) B DICOM greyscale (GSDF= DICOM Grayscale Standard Display Function) GSDF ±15% IPEM (2005a) AAPM (2006a) B Uniformity >40% IPEM (2005a) AAPM (2006a) B Variation between adjacent monitors >40% IPEM (2005a) AAPM (2006a) RCR (2002) B Room illumination >25 lux IPEM (2005a) AAPM (2006a) B
  36. 36. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 36 of 103 Table 2.10 Criteria of Acceptability for Printers1 Physical Parameter Suspension Level Reference Type Notes Optical density consistency Baseline ±0.30 IPEM (2005a) BIR (2001) IEC (1994a) B Note also AAPM (2006a) Image uniformity >10% IPEM (2005a) B Note also AAPM (2006a) 2 3 Table 2.11 Criteria of Acceptability for Film Scanners4 Physical Parameter Suspension Level Reference Type Grayscale >10% Halpern (1995) Lim (1996) Meeder et al (1995) Seibert (1999) Trueblood (1993) SEFM-SEPR (2002) C Image uniformity >10% Halpern (1995) Lim (1996) Meeder et al (1995) Seibert (1999) Trueblood (1993) SEFM-SEPR (2002) C Distortion >10% Halpern (1995) Lim (1996) Meeder et al (1995) Seibert (1999) Trueblood (1993) SEFM-SEPR (2002) C Spatial resolution Visual inspection low and high contrast spatial resolution different from baseline Halpern (1995) Lim (1996) Meeder et al (1995) Seibert (1999) SEFM-SEPR (2002) C 5 6 7 8 9
  37. 37. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 37 of 103 Table 2.12 Criteria of Acceptability for Viewing Boxes1 Physical Parameter Suspension Level Reference Type Notes Luminance < 1000 cd/m2 Mammography < 3,000 cd/m2 > 6,000 cd/m2 IPEM (2005a) B IEC (1993f) Uniformity >30% Mammography < 30% IPEM (2005a) B IEC (1993f) Variation between adjacent viewing boxes >30% Mammography < 15% IPEM (2005a) B IEC (1993f) Room illumination (general radiography) >150 lux IPEM (2005a) B IEC (1993f) Room illumination (mammography) >50 lux CEC (2006) A IEC (1993f) 2 2.4. MAMMOGRAPHY3 2.4.1.INTRODUCTION4 Mammography involves the radiological examination of the breast using x-rays. Mammography is5 primarily used for the detection of breast cancer at an early stage and is widely used in screening6 programmes involving healthy populations. It is also used with symptomatic patients. Early7 detection of breast cancer in a healthy population places particular demands on the radiological8 equipment as high quality images are required at a low dose. Perhaps because of the exacting9 demands of mammography, acceptability criteria are particularly well developed (IPEM, 2005b;10 CEC, 2006).11 Mammography should be performed on equipment designed and dedicated specifically for imaging12 breast tissue. Either film/screen or digital detectors may be used. The minimum features of a13 mammography unit are described in table 2.13. Table 2.14 summarises the acceptability criteria for14 conventional mammography equipment and 2.15 those for digital units.15 16 17 18 19
  38. 38. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 38 of 103 Table 2.13 Minimum Specification of an X-ray Unit Designed for mammography1 Aspect Specification X-ray Tube Nominal Focal Spot Broad focus 0.3 (IEC, 2003a) Small focus 0.15 AEC (Analogue Equipment) Adjustable or automatically adjusted position Fine control of optical density Compression Motorized Readout of compression thickness Grid Moving (dedicated mammography) Focus Film Distance ≥ 60cm 2 2.4.2.MEASUREMENTS3 Measurements to assess the performance of mammography units should be performed using a4 series of test equipment, some of which are specifically designed for the purpose.5 Specific Tests are outlined in the tables below. The purpose of the test and a recommended6 protocol are cited, together with alternative acceptable protocols. These should form part of a7 quality system (BSI, 1994).8 9
  39. 39. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 39 of 103 Table 2.14 Film Screen Mammography1 Physical Parameter Suspension Level Reference Type Notes Target Film Density OD<1.3 or >2.1 IPEM (2005a) B Not correctable by AEC fine control AEC Consistency mAs > ±5% Variation in mAs < CEC (2006) A AEC Thickness Compensation Maximum deviation in OD ≥ 0.15 from value at 4cm of PMMA or range of ODs > 0.35 CEC (2006) AFFSAPS (2007) A B Film/Screen Contact >1 cm² poor contact CEC (2006) A High Contrast Resolution < 12lp/mm CEC (2006) A Threshold Contrast > 1.5% 5-6mm CEC (2006) A X-ray/Film Alignment > 5mm CEC (2006) A Compression Maximum Force > 300N 200N not achievable by adjustment of manual control. CEC (2006) A Tube Potential > 2kV difference from set value. IPEM (2005a) B HVL See Table 2.16 CEC (2006) A Compression Force Consistency > 20N CEC (2006) A In 30S 2 3 4 5 6 7
  40. 40. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 40 of 103 Table 2.15 Digital Mammography Systems1 Physical Parameter Suspension Level Reference Type Notes AEC Consistency mAs>±5% baseline CEC (2006) A AEC Thickness Compensation CNR/PMMA Thickness, with the value at 5cm being used as reference, values at other thicknesses are 2.0cm >115% 4.5cm >103% 3.0cm >110% 5.0cm > 100% 4.0cm >105% 6.0cm > 95% 7.0cm > 90% CEC (2006) A Threshold Contrast > 0.85% 5-6mm > 2.35% 0.5mm > 5.45% 0.25mm CEC (2006) A X-ray/Film Alignment >5mm CEC (2006) A Compression Maximum Force > 300N and 200N not reachable. IPEM (2005a) CEC (2006) B A Tube Potential Accuracy > 2kV difference from set value. IPEM (2005a) B HVL See Table 2.16 CEC (2006) B Compression Force Consistency > 20N CEC (2006) A In 30S 2 3 Table 2.16 Typical HVL measurements for different tube voltage and target filter4 combinations. (Data includes the effect on measured HVL of attenuation by a PMMA5 compression plate*) (CEC, 2006)6 HVL (MM Al) for target filter combination kV Mo +30 µm Mo Mo +25 µm RH RH +25 µm RH W +50 µm RH W +0.45 µm Al 25 0.33 ± 0.2 0.40 ± .02 0.38 ± .02 0.52 ± .03 0.31 ±.03 28 0.36 ± .02 0.42 ± .02 0.43 ± .02 0.54 ± .03 0.37 ±.03 31 0.39 ± .02 0.44 ± .02 0.48 ± .02 0.56 ± .03 0.42 ± .03 34 0.47 ± .02 0.59 ± .03 0.47 ± .03 37 0.50 ± .02 0.51 ± .03 * Some compression paddles are made of Lexan, the HVL values with this type of compression7 plate are 0.01 mm Al lower compared with the values in the table.8
  41. 41. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 41 of 103 2.5. DENTAL RADIOGRAPHY1 2.5.1.INTRODUCTION2 Dental radiography, though often delivering a low dose, is the most frequently conducted type of x-3 ray examination. This section is applicable to radiographic systems for intra oral radiography using4 both film and digital detectors.5 2.5.2.INTRA-ORAL SYSTEMS6 The following are not acceptable for dental imaging:7 - Nominal or actual tube voltage < 60kVp for DC and 65-70Kvp for AC equipment8 - Mechanical timers9 - Film class lower than E10 - Focus skin distance for intra oral equipment < 20cm.11 - Non-rectangular collimators12 - Systems without audible exposure indication.13 Material and results of testing dental equipment are available in Gallagher et al. (2008), EC (1997),14 IEC standards, and the criteria for dental equipment adopted by EU member states (Belsuit van het15 FANC, 2008; IPEM, 2008; Luxembourg Annexe 7, 2008; JORF, 2007; IEC, 2000a; IPEM, 2005a;16 Directive R-08-05, 2005; SEFM-SEPR, 2002).17 Where exposure settings or pre-programmed exposure protocols are provided with the equipment,18 their appropriateness should be checked as part of the confirmation that the equipment is19 acceptable. A distinction should be made between exposure settings for adults and children.20
  42. 42. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 42 of 103 2.5.3.CRITERIA FOR DENTAL RADIOGRAPHY1 Table 2.17 Criteria of Acceptability for Intra-Oral Dental Equipment2 Physical parameter Suspension level Reference (type) Type Notes Film development Developer temperature <18°C and > 40°C IPEM (2005a) Luxembourg Annexe 7 (2008) B Use Thermometer Dark room (or desktop day light processor) light proof Gross fog > 0.3 OD IPEM (2005a) B Densitometer Reproducibility of gross fog, speed and contrast Gross fog > 0.3 OD; IPEM (2005a) B Densitometer; X-ray tube and generator Tube voltage accuracy Maximum deviation ± 10% JORF (2007) A kV meter, Indication of exposure time Difference between measured exposure time and baseline > 50% IPEM (2005a) EC (1997) A, B Dosimeter Consistency of exposure time EC (1997) A Dosimeter??? Dosimetry Incident air kerma for upper molar tooth Ka > 4mGy JORF (2007) Luxembourg Annexe 7 (2008) A Measurement of incident air kerma at the tip of the collimator
  43. 43. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 43 of 103 2.5.4.PANORAMIC RADIOGRAPHY1 This section is applicable to radiographic systems for panoramic dental radiography.2 Table 2.18 Criteria for Acceptability of OPG Systems3 Physical Parameter Suspension Level Reference Type Notes Image quality Characteristics of the panoramic image Outside manufacturer’s specification D Follow manufacturer’s specifications and test object Dosimetry Kerma area product of a typical clinical exposure or calculated kerma area product from dose width product or equivalent Deviation > 35% of indicated PKA value. JORF (2007) A KAP meter or equivalent dosimeter. 4 2.5.5.CEPHALOMETRY5 This section is applicable to radiographic systems for cephalometry.6 In addition, cephalometric systems should:7 - have X-ray beams collimated to the detector and not larger than 24cmx30cm8 - have at least a distance of 150cm between focus and skin9 Table 2.19 Criteria for Acceptability of Cephalometry Systems10 Physical parameter Suspension level Reference Type Notes Dosimetry Kerma area product of a typical clinical exposure PKA > 80 mGycm2 JORF (2007) Luxembourg Annexe 7 (2008) A PKA meter or equivalent 11
  44. 44. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 44 of 103 2.6. FLUOROSCOPIC SYSTEMS1 2.6.1.INTRODUCTION2 Fluoroscopic systems can be highly flexible and are open to a wide range of applications.3 They may offer a multiplicity of modes (and sub-modes) of operation. A representative4 subset of the most probable intended uses of the equipment should be identified for5 acceptability testing. For example, the main “cardiac mode(s)” and associated sub-modes6 might be tested in a unit whose intended application will be in the area of cardiac imaging.7 If the unit is later deployed for different purposes the need for a new acceptability test will8 have to be considered by the practitioner and the MPE.9 In many cases fluoroscopic systems are supplied as dedicated units suitable for cardiac,10 vascular, gastrointestinal or other specific applications. Powerful mobile units are available11 and are generally flexible. In all cases the MPE will have to consider the intended12 application of the unit and the environment in which it will be installed and used. With13 respect to the X-Ray generator, many of the criteria of acceptability are similar to those14 prevailing for general radiographic systems.15
  45. 45. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 45 of 103 2.6.2.CRITERIA FOR ACCEPTABILITY OF FLUOROSCOPY EQUIPMENT1 Table 2.18 Criteria of Acceptability for Fluoroscopy and Fluorography Equipment2 Physical Parameter Suspension Level Reference Type Notes Mechanical – Safety If defects pose an immediate mechanical or obvious electrical-shock (hazard to patients or staff) IEC (2003b) CRCPD (2002) A 38 cm for fixed fluoro 30 cm for mobile fluoro 20 cm for special surgical fluoro Collimation Limits Irradiated area > 1.15 × imaged area IEC (2000b) A Use radiography Half-value layer Table 2.1 applies IEC (2000b) A Test methods are modality specific Patient Air Kerma Rates, and Image receptor input Air Kerma Rates The four rows BELOW are SENTINEL VALUES offered for consideration IPEM (2005a, 2002) Martin et al (1998) Dowling et al (2008) O’Connor et al (2008) C The four rows BELOW are SENTINEL VALUES offered for consideration “Patient” Entrance Dose Rate, Fluoro Mode: (Image Intensifier and FPD Systems.) > 50 mGy/min > 100 mGy/min O’Connor et al (2008) Dowling et al (2008) C Normal mode smallest field size. 20 cm water or equivalent. Normal mode, any field size. Maximum (lead) “Patient” Entrance Dose/exposure Digital Acquisition Mode (Image Intensifier and FPD Systems.) > 2mGy/exposure. Cardiac Systems: > 0.2mGy/exposure O’Connor et al (2008) Dowling et al (2008) C IPEM and Martin protocols. Largest field size. 20 cm water or equivalent. Normal from survey is 0.03 – 0.12 mGy/exposure) Detector Entrance Dose Rate, Fluoro mode :(Image Intensifier and FPD Systems). > 1 µGy/sec in continuous fluoroscopy mode. Cardiac Systems: > 1µGy/sec in continuous fluoroscopy mode. O’Connor et al (2008) Dowling et al (2008) C 2 µGy/sec quoted in IPEM but not seen in practice. IPEM protocols. Largest field size. Normal mode. Detector Entrance Dose/exposure Digital Acquisition > 5µGy/exposure. O’Connor et al (2008) Dowling et al C Normal from survey 0.06 – 0.2 µGy/exposure
  46. 46. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 46 of 103 Mode :(Image Intensifier and FPD Systems.) Cardiac Systems: >0.5µGy/exposure. (2008) IPEM protocols. Largest field size. Integrated “dose meter” calibration If absolute accuracy > ±35 % IEC (2000b) A High contrast resolution and focal- spot Spatial Resolution: < 1 lp/mm. For Cardiac Systems: < 1.2 lp/mm IPEM (2005a) B Largest Field Size. Low contrast detectability Threshold Contrast: > 4% IPEM (2005a) B Largest Field Size. Systems or modes of operation controlled by manually setting X-ray factors Radiographic generator output conditions. As above for High Contrast resolution and low-contrast detectability. See also Section 2.2 A Fluoroscopic Timer Acoustic alert is not functional or not continuous until reset. See also Section 2.2 A 1 2.7. COMPUTED TOMOGRAPHY2 2.7.1.INTRODUCTION3 CT examinations are among the highest dose procedures encountered routinely in4 diagnostic radiology and account for up to 70 percent of diagnostic medical irradiation.5 Thus it is important both in terms of individual examinations and population effects. The6 design and proper functioning, and particularly the optimal use of equipment can7 substantially influence CT dose. This can be particularly important when pregnant patients8 or children are involved. CT scanners are under continual technical development resulting9 in increasing clinical application (Nagel, 2002). In the last two decades the development of10 helical and multidetector scanning modes allowed greatly enhanced technical abilities and11 clinical application (Kalender, 2000).12 CT scanners may be replaced for reasons that, in theory, include poor equipment13 performance as demonstrated by failure to meet acceptability criteria. In practice it is also14 likely that replacement may frequently be with a view to meeting increased demands on the15 service, or to take advantage of new developments which enable improved diagnostics,16 faster throughput or other clinical benefits. In practice there are few (if any) examples of CT17
  47. 47. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 47 of 103 scanners being removed from use on the basis of their failure to meet currently accepted1 criteria of acceptability. This suggests that these criteria are ineffective or that2 obsolescence due to rapid technological development can be an overwhelming3 consideration in equipment replacement. Arising from these observations it is possible that4 the available criteria, including those which follow, should be viewed with caution. A review5 of the dose parameters or dose to patients for certain key procedures, and their comparison6 to accepted diagnostic reference levels, is a more meaningful measure of the acceptability7 of the practice using the CT scanner, but this is outside of the scope of the current8 document.9 CT scanners are increasingly utilised in radiotherapy in support of treatment planning10 (Mutic, 2003; IPEM, 1999). They are also a component of PET-CT systems and CT11 acceptability criteria can be applied to the CT component.12
  48. 48. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 48 of 103 2.7.2.CRITERIA FOR ACCEPTABILITY OF CT SYSTEMS1 Table 2.19 Criteria of acceptability for CT Equipment see notes 1-3 2 1 Protocols either programmed in lookup table or in written form.3 2 MPE should compare procedure dose levels with appropriate DRLs4 3 applicable for equipment manufactured after 20015 6 4 Protocols are programmed in lookup table or in written form 5 MPE should compare procedure dose levels with appropriate diagnostic reference levels Physical Parameter Suspension Level Reference Type Notes CTDI, DLP /CVOL, CW, PK.L,CT Dose ± 20% of manufacturer's specifications; IEC (2004a) A Accessible protocols4 should be consistent with good practice5 ESPECIALLY for paediatrics. Accuracy of indicated dose parameters Dose ± 20% indicated dose A Image noise Noise ± 25 % of baseline. IPEM (2005a) B Uniformity ±8 HU CEC (2006) B Value recommended in IEC (2004a) is ±4 HU CT number accuracy CT number ± 20 HU (water); ± 30 HU (other material) compared to baseline values IPEM (2005a) A (French standards are ±4 HU nominal or baseline) Artefact D Any artefact likely to impact on clinical diagnosis Image Display and Printing See section 2.3 Image slice width + 0.5 mm for <1 mm ; ±50% for 1 to 2 mm; ± 1mm above 2 mm. IEC (2004a) A
  49. 49. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 49 of 103 2.8. DUAL ENERGY X-RAY ABSORPTIOMETRY1 2.8.1.INTRODUCTION2 Dual-energy X-ray Absorptiometry (DXA) is primarily used in determination of bone mineral3 density; however its application has more recently been extended to include estimates of4 body fat content. It is performed on equipment specifically designed for and dedicated to5 these purposes. Similar examinations are performed on CT with much higher doses6 (Kalender, 1995).7 For comparison of scanner results and longitudinal studies the accuracy of calibration is8 critical. The effect of software updates also needs to be monitored. However there are well9 documented discrepancies between the results obtained on the scanners of major10 manufacturers (Kelly, Slovik and Neer, 1989). Further work in this area is essential.11 2.8.2.ACCEPTABILITY CRITERIA FOR DXA SYSTEMS12 Table 2.20 Criteria of Acceptability for DXA Equipment13 14 15 16 Physical Parameter Suspension Level Reference Type Notes Patient Entrance Dose Less than 500 µGv for spine examination. Outside +/- 50% deviation from manufacturers specified nominal patient dose Larkin et al (2008) Njeh et al (1999) Sheahan (2005) C Normal from survey is 20 – 200 µGv) Clinical Protocol – standard. Worst case 35% from Larkin paper and 40% from Sheahan paper. Repeatability of Exposures See Section 2.2 BMD accuracy Outside 3% of manufacturer’s specified BMD Larkin et al (2008) Sheahan (2005) BIR (2001) IAEA (2009) Sheahan et al (2005) C Standard protocol with supplier’s phantom.
  50. 50. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 50 of 103 3. NUCLEAR MEDICINE EQUIPMENT1 The technical parts of Sections 2, 3, and 4 assume those reading and using them are2 familiar with the introduction and have a good working knowledge of the relevant types of3 equipment and appropriate testing regimes.4 3.1. INTRODUCTION5 The safe, efficient and efficacious practice of nuclear medicine involves the integration of a6 number of processes. The quality of each process will have an impact on the overall quality7 of the clinical procedure and ultimately on the benefit to the patient. It is important,8 therefore, that each process be conducted within the framework of a quality assurance9 programme that, if followed, can be shown to achieve the desired objectives with the10 desired accuracy.11 The levels of activity in radiopharmaceuticals to be administered clinically are governed12 primarily by the need to balance the effectiveness and the safety of the medical procedure13 by choosing the minimum absorbed dose delivered to the patient to achieve the required14 objective i.e. diagnostic image quality or therapeutic outcome. To realize this goal, it is15 important to keep in mind that a nuclear medicine procedure consists of several16 components, all of which must be controlled in order to have an optimal outcome.17 Although the quality assurance of radiopharmaceuticals is an important process (IAEA,18 2006), it is not an objective of this section. However, the performance testing of the19 equipment needed to carry out the quality assurance of radiopharmaceuticals is an20 objective, both for therapeutic and diagnostic procedures. Devices are included for the21 determination of administered dose and radiochemical purity such as activity measurement22 instruments (activity meter or dose calibrator), gamma counter, thin layer chromatography23 scanner and high performance liquid chromatography radioactivity detector.24 More specifically the objective of this section is to specify acceptable performance tolerance25 levels (suspension levels) for the equipment used in Nuclear Medicine procedures, both for26 gamma camera and positron emission based procedures. In-vitro Nuclear Medicine27
  51. 51. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 51 of 103 diagnostic equipment and instruments are not covered since these do not contribute to the1 patient exposure.2 Some Positron Emission Tomography Installations have in-house production of the3 radiopharmaceuticals they use (e.g. FDG labelled with 18 F), utilising either self-shielded4 cyclotrons or cyclotrons placed in specially designed bunkers. This activity is regarded as a5 radiopharmaceutical manufacturing activity and therefore is outside the scope of this report.6 This section also covers the instruments needed for therapeutic procedures and intra-7 operative probes, since these are used directly on the patient to trace the administered8 radioactivity.9 When equipment no longer meets the required performance specifications (suspension10 levels), it should be withdrawn from use, may be disposed of, and replaced (Article 8 (3) of11 Council Directive 97/43/Euratom). Alternatively, following a documented risk assessment12 involving the MPE and the Physician, equipment may be used for less demanding tasks for13 which a lower specification of performance is acceptable. The operator must be advised of14 the circumstances.15 The suspension levels stated are intended to assist in the decision making process16 regarding the need for recalibration, maintenance or removal from use of the equipment17 considered.18 This section considers equipment used for:19 1 Nuclear medicine therapeutic procedures20 2 Radiopharmacy quality assurance programme21 3 Gamma camera based diagnostic procedures22 4 Positron emission diagnostic procedures23 5 Hybrid diagnostic systems24 6 Intra-operative probes25
  52. 52. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 52 of 103 Each part of this section is comprised of a brief introduction and a list of relevant equipment.1 For each piece of equipment, a brief introduction, a table with the critical performance2 parameters and the suspension levels are given. References to recommended test3 methods for each parameter are also given.4 3.2. NUCLEAR MEDICINE THERAPEUTIC PROCEDURES5 3.2.1.INTRODUCTION6 Unsealed radioactive sources are administered to patients orally, intravenously or injected7 into various parts of the body for curative or palliation purposes. The management of the8 patient depends on the activity and radionuclide used to give the prescribed absorbed dose.9 It may be necessary for the patient to be confined into a specially designed room for a few10 days before being released from the hospital to provide radiation protection to hospital staff11 and members of the public.12 When working with unsealed radioactive sources, contamination always presents a13 potential hazard. Such contamination may come from persons working with the radioactive14 sources or from patients who have been treated with these substances. Such contamination15 presents a hazard to anybody coming into contact with it and should be avoided if at all16 possible, monitored and controlled if it occurs.17 The patient undergoing treatment with unsealed radioactive sources must also be checked18 before he/she is released from hospital to determine that the dose rate from his/her body is19 down to acceptable levels for members of the public.20 Three types of equipment that are used in Nuclear Medicine therapeutic procedures are21 considered in this part. These are:22 • Activity measurement instruments23 • Contamination monitors24 • Patient dose rate measuring instruments25
  53. 53. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 53 of 103 3.2.2.ACTIVITY MEASUREMENT INSTRUMENTS1 Many different radionuclides are used for Nuclear Medicine therapeutic procedures. The2 amount of activity to be administered to the patient must be determined accurately. Activity3 measurement instruments, commonly known as Isotope Calibrators or Dose Calibrators,4 must be capable of measuring the activity of a particular radionuclide (gamma or beta5 emitting) accurately over a wide range of energies for correct determination of the patient6 dose. They must also be capable of measuring accurately over a wide range of activities.7 The performance of activity measurement instruments must be assured through a quality8 assurance programme conforming to international standards (IEC, 1994c; IEC, 2006). The9 suspension levels are given in Table 3.1 for each critical parameter together with the type of10 criterion used and a reference to a recommended test method.11 Table 3.1 Suspension Levels for Activity Measurement Instruments12 Physical Parameter Suspension Level Reference Type Background response > 1.5 X Usual Background IEC (2006) (section 4.1) IEC (1994c) (section 8) C Constancy of instrument response ± 10% IEC (2006) (section 4.2) C Instrument Accuracy ± 10% IEC (1994c) (section 3) C Instrument Linearity ± 10% IEC (2006) (section 4.3) IEC (1994c) (section 4) C System reproducibility ± 10% IEC (1994c) (section 5) C Sample volume characteristics ± 15% IEC (1994c) (section 7) C Long-term reproducibility ± 10% IEC (1994c) (section 9) C 13 The suspension levels given in the above table are for instruments used for the14 measurement of the activity of gamma emitting sources with energies above 100keV. If15 these instruments are calibrated to measure low gamma ray energies (below 100 keV),16 beta or alpha emitting sources (Siegel et al, 2004) and the instrument is suspected of17 malfunctioning then a test with a relevant source needs to be carried out to confirm the18 suspicion using the values in the above table.19 3.2.3.CONTAMINATION MONITORS20 The contamination monitor (also called area survey meter) is designed for the detection and21 measurement of radioactivity (alpha, beta and gamma) on the surface of objects, clothing,22
  54. 54. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 54 of 103 persons etc. It is used wherever contamination by radioactive substances may be1 encountered and has to be monitored routinely.2 The determination of a monitor’s (instrument’s) performance can be at different levels of3 complexity (ICRU, 1992). A more detailed level is required for the evaluation or type testing4 of a particular monitor design. Once the monitor has been type tested, less extensive5 procedures can be used to establish either that a given monitor has maintained its6 calibration or that it has the same characteristics as the original type tested monitor (IEMA,7 2004; IPSM, 1994). The complexity of the procedure depends on what information is8 required and is generally intermediate between that required by a full type test and a simple9 reproducibility check.10 The suspension levels are given in Table 3.2 for each critical parameter of contamination11 monitors together with the type of criterion used and the reference to a recommended test12 method.13 Table 3.2 Suspension Levels for Contamination Monitors14 Physical Parameter Suspension Level Reference Type Sensitivity > 1.2 X Usual Background IEC (2001a) (section 4.2) B Monitor Linearity ± 20% IPSM (1994) (section 3.3) IEC (2006) (section 4.3) IEC (1994c) (section 4) B Statistical Fluctuation of Reading ± 20% IPSM (1994) (section 3.4) B Monitor Response Time ± 10% IPSM (1994) (section 3.5) B Energy Dependence of Monitor ± 20% IPSM (1994) (section 3.6) B 15 There is a large variation between the different types of contamination monitors. The above16 suspension levels are a compromise and in some cases may be considered as too17 conservative.18 3.2.4.PATIENT DOSE RATE MEASURING INSTRUMENTS19 A patient who has been administered with a therapeutic amount of activity of a radionuclide20 becomes a radioactive source and may need to be confined in a specially designed room21 for a few days before being safe to be released from hospital. The monitoring of the patient22
  55. 55. Radiation Criteria For Acceptability Of Radiological, Nuclear Medicine And Radiotherapy Equipment Page 55 of 103 dose rate is very important when gamma radiation is being emitted that can irradiate other1 persons at a distance from the patient. Therefore, the gamma dose rate of the patient is2 measured at a standard distance and should be below the acceptable level before the3 patient is released from hospital.4 The performance of a patient dose rate measuring instrument must be assured through a5 continuous quality assurance programme conforming to international standards (IEMA,6 2004) and other commonly acceptable reports (ICRU, 1992; IPSM, 1994). The suspension7 levels are given in Table 3.3 for each critical parameter.8 Table 3.3 Suspension Levels for Patient Dose Rate Measuring Instruments9 Physical Parameter Suspension Level Reference Type Instrument Dose Rate Linearity ± 20% IPSM (1994) (section 3.3) IEC (2006) (section 4.3) IEC (1994c) (section 4) C Statistical Fluctuation of Reading ± 20% IPSM (1994) (section 3.4) C Instrument Dose Rate Response Time ± 10% IPSM (1994) (section 3.5) C Energy Dependence of Instrument ± 20% IPSM (1994) (section 3.6) C 10 There is a large variation between the different types of patient dose rate measuring11 instruments. The above suspension levels are a compromise and in some cases may be12 considered as too conservative.13 3.2.5.RADIOPHARMACY QUALITY ASSURANCE PROGRAMME14 The quality of the radiopharmaceutical administered to the patient has to be such that it will15 not cause adverse effects to the patient, expose the patient to unnecessary radiation and at16 the same time be specific for the organ of interest. As the injected radiopharmaceutical17 circulates in the blood system before it is absorbed and preferentially concentrated in the18 target organ/tissue, other organs/tissues of the body absorb some of the19 radiopharmaceutical and therefore receive an absorbed dose related to the amount of20 radiopharmaceutical. Penetrating radiation from the target organ/tissue also irradiate other21 organs/tissues. Therefore, the maximum amount administered should not exceed the22