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Fission and radiation protection

Safety and Efficacy of Computed Tomography (CT): A Broad Perspective

Computed tomography (CT), sometimes called a CAT scan, can provide highly detailed medical diagnostic information and can show bone, soft tissue and blood vessels in the same images. However, it is associated with a relatively high exposure of patients to radiation. This project will undertake research that will produce new guidelines for the use of CT which will improve radiation safety in Europe and optimise the use of CT in health care.

Balancing safety, clinical need and cost

A Computed Tomography (CT) scanner installation © Courtesy: Leiden University, Medical Centre
A Computed Tomography (CT) scanner installation
© Courtesy: Leiden University, Medical Centre
CT uses special X-ray equipment to obtain multiple images of the body from different angles, which are then synthesized to show cross-sections of body, tissue and organs. However, the technique is associated with relatively high radiation exposure for patients, accounting for 30-40% of the collective dose due to diagnostic radiology in Europe whilst representing only 3-6% of all X-ray examinations undertaken. New developments in CT, in particular the introduction of sub-second multi-slice scanning, have had a great impact on medical care and radiation protection. CT now enables large volumes to be scanned and the same body part to be scanned several times within a much reduced time span.

The project consortium will perform original research from which practical guidelines for safety and efficacy of CT will result. The main focus of the research will be on improving radiation safety standards in Europe in relation to the justification and optimisation of use of CT, thereby contributing also to the cost-effectiveness of health care. Justification of CT will analyse specific clinical problems, taking into account the efficacy, (radiation) safety and costs of CT and alternative methods. The clinical implementation of CT will be optimised to achieve good diagnostic sensitivity with an associated radiation exposure to the patient that is as low as is reasonably achievable. This can be achieved by optimisation of CT acquisition parameters and automatic exposure control for certain CT procedures.

Optimising use, minimising dose

The main focus of the research will be on improving radiation safety standards for a comprehensive range of clinical applications of CT, including cardiac, interventional and paediatric CT. Existing practices for the clinical indication of CT use in six participating hospitals will be assessed, evaluated and identified. The best practices that appropriately balance benefit and risk will be identified and used to generate decision algorithms. Diagnostic algorithms will also be generated and evidence-based decision algorithms derived for the application of CT. Optimising CT is difficult due to the large number of control and patient parameters encountered. The project will attempt to relieve of the burden of selecting technical scan parameters using the concept of an automatic exposure control (AEC) for CT involving relevant CT manufacturers. There is also a need to optimize use of CT in paediatric medicine, where opportunities for such have not yet been fully studied.

Dosimetry is an essential element in the management of patient dose from CT, and modelling has an important role here. New computational tools will be further developed to provide a validated dosimetry system that accurately models the exposure conditions used. This tool will be combined with results from other parts of the project to assess effective doses for the diagnostic algorithms and optimised techniques developed. The software will also be used to provide estimates of foetal doses from CT examinations on pregnant patients.

Guidelines for best practice

The project aims to provide professional groups with essential information on the justification and optimisation of computed tomography in a broad context. The general public will be informed, e.g. through the project website (see below).

The consortium will establish national and international standards in the field of dosimetry and decision-making. The research on optimisation is expected to lead to standards and recommendations regarding tube current modulation of modern CT scanners, automatic exposure control, choice of X-ray spectra and optimised protocols for paediatric CT that are derived from pan-European research but will have an international impact. Innovative research will be provided by the consortium which includes researchers in radiology, medical physics and radiation protection who are regarded as scientific key players, not only in Europe, but also worldwide. Enhanced safety and efficacy of computed tomography contributes not only to the quality of medical practice but also to cost-effectiveness in medicine. Radiologists and other medical doctors will benefit from a clear and thorough justification for specific applications of computed tomography that will enhance their decisionmaking.

Reducing public exposure, maximizing healthcare benefits

Radiological imaging in general, and CT in particular, play an increasingly important role in medical diagnosis, treatment and follow-up of patients. Several healthy populations participate in programmes for X-ray screening of diseases. Each year, European citizens will be involved, either directly or indirectly, in radiological imaging. The benefit of enhancing the safety and efficacy of radiology in general, and of CT in particular, for those who are directly involved, either as patients or as participants in a screening programme, lies in achieving excellent medical care at the highest standards in radiation protection. Unborn children and parents may get involved in radiological imaging indirectly, e.g. when the mother of an unborn child is examined or when young children require an examination using X-rays. On some occasions, unjustified anxiety about the radiation exposure of (unborn) children by parents, general practitioners and radiologists makes mothers and children concerned about the radiation risks of X-ray imaging. This may affect the effectiveness of their diagnosis and treatment and may have considerable societal impact. Enhancing the safety and efficacy of CT and providing proper information about patient dose and radiation risk are effective measures for reducing unjust anxiety about medical exposure to X-rays.

Project website: