Objectives

1. To ensure surveys within this area are conducted to standards appropriate to the present legislation.
2. To ensure that the standards defined for the performance of equipment based on new technologies is consistent (a) with justification and optimisation, and (b) between end users, regulators and industry.
3. To define standards for equipment performance appropriate to the new technology and to the European user needs and have those standards adopted by standards bodies.
4. To establish an information base for European industry.

Description of work

1. Consensus on image quality toolkits and their application.
2. Trial employing toolkits and their theoretical formulation.
3. Establishment of consensus positions among end users and standards bodies.

Deliverables

1. Standardization requirements of new imaging techniques and input to IEC.
2. Inventory and assessment methodologies.

 

Workpackage description

A radical alteration of the technology employed and its clinical application in this way produces major new challenges in the:

• Performance Assessment of the Technology,
• Standardisation issues for the new Technology,
• Extent to which exposure selection and image processing are in practice taken over by software functions much of the time.

The promise of dose reduction tends not to be developed in practice, images produced by direct digital imaging devices are subject to software processing. Image quality is affected by image processing, which is often performed by software provided by manufacturers without the user having the option to switch this programme on or off. This is compounded by a lack of detailed information on the actual impact of the image processing on clinical outcome. For example, most direct digital detectors will have some of the individual detectors which are faulty. There are clinical issues about how corrections for dead pixel detectors occur and financial as well as clinical issues about when the number of faulty pixels is too large and the active detector requires replacement.

Image processing is often performed to enhance diagnostic images so that clinical details are clearer and functional information may be extracted. The impact of these programs must be audited.

Clinical practice has undergone significant change and expansion as a result of the new and emerging digital imaging technology and it is imperative that end users be intimately involved with the industry in meeting the challenges of the new technology. This is particularly important in the optimisation and user training processes given the increasing array of adjustable system parameters. Furthermore, user sensitive safe performance standards are an important part of the knowledge base required by the European Industry to sustain a competitive position.

In the SENTINEL project developments in the assessment of Image Quality and the associated equipment performance of the new technology will be linked with user assessment and industry standards. These objectives will be achieved by a consensus number of basic physical studies intimately linked with existing trials undertaken by a broad sweep of end users throughout the EU. The SENTINEL group has access to a wide range of new detector systems for general radiology, interventional radiology and cardiology. The trials will be based on previously published models. Simple physical measures of image quality and equipment performance will be evaluated side by side with clinician's judgement on related questions. If left alone manufacturers will set up their equipment with high dose/image quality. What is needed is the image quality/dose to enable the diagnosis to be made. These are not necessarily the same. What is needed are physics tests which can direct the clinician to the image quality required. It remains to extend this to more sophisticated physical measures, where required, and to associate this with a widely based trial of clinicians assessments of equipment performance. It is expected that it will be possible to model this association so that a less contentious basis for commissioning or rejecting equipment will emerge. For example acceptance/QA/write-off protocols traditionally based solely on the assessment of subjective, semi-subjective and other physical measures will have an association with the clinical judgement. There is also a cost-benefit aspect to this process. This will ensure that individuals participating in SENTINEL, faced with these decisions as a matter of routine, can base their opinion on a substantive scientific foundation. This will inform other centres faced with a similar process. Each partner will undertake a small scale survey to establish the numbers of each type of cardiological equipment and their ages.

In addition, equipment manufacturers are at present uncertain about the design specification of new digital technologies in terms of measurable analytical parameters such as noise power spectrum detective quantum efficiency and modulation transfer function etc. The association of such parameters with end user clinical assessments will help to address this imbalance such that physical parameters can in turn be used to derive equipment specifications. Such associations will also provide key input into the development of acceptance / constancy check protocols for the new technology and in the development and assessment of equipment self-testing protocols.

Side by side with the above, enormous development is required in the standards used by manufacturers to guide the design and performance of radiological equipment, dose monitoring, recording and display equipment and equipment software. Attempts to produce updated standards dealing with the issues involved have been seriously hampered by the absence of suitable end user information, particularly on basic physical quantities such as image quality and dose. Likewise the approaches adopted by standards bodies have been inadequately assessed or tested by end users, either on an individual basis or in trials of the type mentioned above. The linkage between end users and standards organisations needs to be strengthened as representatives from the SENTINEL project will be able to have an input into IEC meetings.

Furthermore the modus operandi of standards bodies makes it difficult for end users to participate. Within SENTINEL existing work performed by partners to define the functional performance of a range of equipment employing new technologies will provide an input into the standards process. This includes adapting the approaches already developed for:

• General interventional radiology / fluoroscopy
• and Computed Radiography

to the challenges of digital flat panel detectors. In addition we propose to undertake a similar range of work in respect of the increasing range of digital technology, which is finding application in:

• Dental radiology,
• Bone Mineral determination,
• Mammography,
• Fluoroscopy examinations

These approaches will include assessment of functional imaging performance and provision of the user information base for standardisation. This will be achieved by building upon activities already undertaken by consortium partners. For example, a number of consortium partners have recently taken delivery of new flat panel direct digital detectors. These will be subject to acceptance and quality assurance activities. The experience of different groups faced with the task of acceptance testing this equipment in the absence of accepted protocols will be shared as part of the coordination action. At an early stage in the project a consensus meeting will be arranged. It is anticipated that an experience based consensus will be achieved. They will also include approaches to the industry/standards bodies to use the information already available within systems to best achieve the objectives of Optimisation and Justification. A survey of inventory and standards within the partners' organisations will be collated. This for example could be achieved by release of information presently contained in DICOM image headers for the provision of key dose related parameters to the end user. It is essential that practice keeps pace with developments in digital imaging technology if Quality Assurance efforts are to be properly guided and sufficiently comprehensive, and if equipment related standards are to remain relevant in this rapidly changing environment. The ethical issues of equipment replacement will be assessed.