Dose reduction in CT while maintaining diagnostic confidence: A feasibility/demonstration study

In the last 30-40 years, the pace of innovation in medical imaging has increased, starting with the introduction of computed tomography (CT) in the early 1970s. During the last decade, the rate of change has accelerated further, both in terms of continuing innovation and of its global application. The great majority of patient exposure now arises from practices that barely existed two decades ago, and the technological basis for their successful dissemination only began to flourish in the last decade or so. This evolution is evident in the technology on which this publication is based, CT scanning and its widespread application throughout the world. However, this advance is often achieved at the cost of a large radiation burden to the individual patient, and to the community when the technology is widely deployed. Much effort will be required to ensure that the undoubted benefit to be gained will not be achieved at the cost of an undue level of detriment. For practitioners and regulators, it is evident that innovation has been driven by both the imaging industry and an increasing array of new applications validated in the clinical environment. It is evident that regulation, industrial standardization, safety procedures, and advice on best practice lag (inevitably) behind the industrial and clinical innovations. This TECDOC, reporting on a Coordinated Research Project (CRP), is designed to help both the medical community and equipment manufacturers/suppliers make their respective important contributions to dose reduction. In particular, it is possible that significant dose savings may be achieved in individual patients by tailoring the exposure they receive to their individual profile. It should be possible to achieve this without any loss in the level of confidence in the images produced, a possibility examined in this publication. This CRP and TECDOC were developed within the International Atomic Energy Agency's (IAEA) framework of statutory responsibility to establish standards for the protection of people against exposure to ionizing radiation and to provide for the worldwide application of these standards. The Fundamental Safety Principles and the International Basic Safety Standards for Protection against Ionizing Radiation (BSS) issued by the IAEA and co-sponsored by the Food and Agriculture Organization of the United Nations (FAO), the International Labour Organization (ILO), the World Health Organization (WHO), the Pan American Health Organization (PAHO) and the Nuclear Energy Agency (NEA), among others, require the radiation protection of patients undergoing medical exposures through justification of the procedures involved and through optimization. In keeping with its responsibility on the application of standards, the IAEA programme on Radiological Protection of Patients encourages the reduction of patient doses for radiological procedures (excluding radiotherapy). To facilitate this, it has issued specific advice on the application of the BSS in the field of radiology in Safety Report Series No. 39 and the three volumes on Radiation Protection with Newer Imaging Techniques recently produced. In addition, it has embarked on a series of CRPs, of which this is one, and which add to those already available in radiology, mammography and interventional radiology. This series of Reports is a further contribution to the resources provided by the IAEA in support of implementation of the BSS. The International Action Plan for the Radiological Protection of Patients, approved by the General Conference of the IAEA in September 2002, requires that 'The practice-specific documents under preparation should be finalized as guidance rather than regulations, and they should include input from professional bodies, from international organizations and from authorities with responsibility for radiation protection and medical care'. This TECDOC is prepared and issued in this spirit