The aim of this proposal is the acquisition of the key information necessary for sound and scientifically based clinical use of dental Cone Beam Computed Tomography (CBCT). In order that safety and efficacy are assured and enhanced in the ‘real world’, the parallel aim is to use the information to develop evidence-based guidelines dealing with justification, optimisation and referral criteria and to provide a means of dissemination and training for users of CBCT. The objectives and methodology of the proposed collaborative project are: 1. To develop evidence-based guidelines on use of CBCT in dentistry, including referral criteria, quality assurance guidelines and optimisation strategies. Guideline development will use systematic review and established methodology, involving stakeholder input. 2. To determine the level of patient dose in dental CBCT, paying special attention to paediatric dosimetry, and personnel dose. 3. To perform diagnostic accuracy studies for CBCT for key clinical applications in dentistry by use of in vitro and clinical studies. 4. To develop a quality assurance programme, including a tool/tools for quality assurance work (including a marketable quality assurance phantom) and to define exposure protocols for specific clinical applications. 5. To measure cost-effectiveness of important clinical uses of CBCT compared with traditional methods. 6. To conduct valorisation, including dissemination and training, activities via an ‘open access’ website. At all points, stakeholder involvement will be intrinsic to study design.