Utilising previous radiographs: the principle of dose optimisation.

Objective: In dentistry, imaging is the most frequently used diagnostic tool. As a result, a steady increase in the use of imaging modalities are leading to an increase in healthcare cost and in patients' radiation exposure.

Results: 67-year-old patient attended for a surgical removal of lower left third molar. A sectioned panoramic radiograph showed an incidental finding of a well-defined, unilocular radiolucency apical to the lower left second and third molars. This was partially superimposed over the outline of the ID canal. A Stafne's bone cavity was considered as the most likely diagnosis. Further imaging was considered due to location not being fully below the ID canal as usually described in the literature. Reviewing previous imaging on PACS revealed the patient has had a CT angiogram of the head and neck 5 years prior. This showed a lingual bone defect of the surface of the mandible in the region of interest. The extension of the submandibular gland into the defect confirmed the likely nature of Stafne's bone cavity.

Conclusion: This case highlights the essential role of reviewing (if in the same practice) or requesting (from a different practice) previous images. The international Commission for Radiological Protection regularly publishes data relating to the principles of dose reduction; Justification, Optimisation and Limitation. All examinations have to be justified to ensure the benefit to the patient outweigh the risk and radiation should be kept as low as reasonably achievable.