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36 I I research _ CBCT movement artefacts, low contrast resolution, limited capability to visualise internal soft tissues and, owing to distortion of Hounsfield Units, CBCT cannot be used for the estimation of bone density. It is crucial that the ALARA principle (As Low As Reasonably Achievable) is respected during treatment, as far as the radiation dose of CBCT imagingisconcerned.CBCTimagingwillimprove patient care, but users have to be trained to be able to interpret the scanned data thoroughly. Dentists should ask themselves whether these imaging modalities actually add to their diag- nostic knowledge and raise the standard of den- tal care or whether they only place the patient at a higher risk. Continuous training, education and thorough research are thus absolutely essential. One of the most clinically useful aspects of CBCT imaging is the highly sophisticated soft- ware that allows the huge volume of data collected to be broken down, processed or recon- structed.131 This makes data interpretation much more user friendly, if the appropriate technical and educational knowledge is available. The increasing popularity of CBCT resulted in numerous CBCT-unit manufacturers, frequent presentations at conferences and an increase in published papers. This resulted in an uncon- trolled and non-evidence based exchange of ra- diation dose values and attributed to the limited technical knowledge about medical imaging de- vices for new-user groups. As a result, the Euro- pean Academy of DentoMaxilloFacial Radiology has developed the following basic principles on the use of CBCT in dentistry:132 1. CBCT examinations must not be carried out unlessahistoryandclinicalexaminationhave been performed. 2. CBCT examinations must be justified for each patient to demonstrate that the benefits outweigh the risks. 3. CBCTexaminationsshouldpotentiallyaddnew informationtoaidthepatient’smanagement. 4. CBCT should not be repeated on a patient ‘routinely’ without a new risk/benefit assess- ment having been performed. 5. When accepting referrals from other dentists for CBCT examinations, the referring dentist must supply sufficient clinical information (resultsofahistoryandexamination)toallow the CBCT practitioner to perform the justifi- cation process. 6. CBCT should only be used when the question for which imaging is required cannot be answered adequately by lower dose conven- tional (traditional) radiography. 7. CBCT images must undergo a thorough clin- ical evaluation (radiological report) of the entire image dataset. 8. Where it is likely that evaluation of soft tis- sues will be required as part of the patient’s radiological assessment, the appropriate im- aging should be conventional medical CT or MR, rather than CBCT. 9. CBCT equipment should offer a choice of vol- ume sizes, and examinations must use the smallest that is compatible with the clinical situation, if this provides a lower radiation dose to the patient. 10. Where CBCT equipment offers a choice of resolution, the resolution compatible with an adequate diagnosis and the lowest achiev- able dose should be used. 11. A quality assurance programme must be established and implemented for each CBCT facility, including equipment, techniques and quality-control procedures. 12. Aids to accurate positioning (light-beam markers) must always be used. 13. All new installations of CBCT equipment shouldundergoacriticalexaminationandde- tailed acceptance tests before use to ensure that radiation protection for staff, members of the public and patient are optimal. 14. CBCTequipmentshouldundergoregularrou- tine tests to ensure that radiation protection, roots4_2010 Fig. 7a_Multiple endodontically treated teeth with a history of peri-apical surgery. Fig. 7b_Peri-apical image showing a compromised crown-to-root ratio. Fig. 7c_CBCT image showing the absence of the buccal plate and a compromised palatal plate, indicating that the teeth need to be extracted and site grafting performed before implant placement. Fig. 7a Fig. 7b Fig. 7c