Use of thoracic computed tomography by general practitioners

Objective: To audit requests for computed tomography (CT) examination of the chest emanating from general practitioners and assess the appropriateness and usefulness of these requests. Methods: We reviewed 50 consecutive requests for CT examination received by two private radiology practices in Cairns between August 2004 and March 2005. Clinical details were abstracted from request forms and clarified by telephone if necessary. A subjective assessment of the appropriateness of the investigation was made by the authors. The study was performed in a large regional centre. Main outcome measures: Indications for requesting a CT scan; appropriateness of CT scan for indication specified. Results: Fifteen patients had had recent normal chest x-rays, all of whom proved to have normal CTs; eight had not had a recent chest x-ray performed. The CT scan was considered appropriate in 16 cases (32%), but 10 of these patients required referral to specialists anyway. Thirty-four CT scans (68%) were felt to be inappropriate and, of these, 10 were subsequently referred to specialists. In only six cases did the CT scan resolve the GP’s clinical problem. In six cases the wrong type of CT scan was performed (five were conventional CT scans instead of high-resolution scans; one was a high-resolution instead of low-resolution scan). Conclusions: Many CT examinations of the chest requested by GPs could be avoided or replaced by simpler, cheaper tests with lower radiation exposure. Assuming a fatal cancer risk of 1 in 3000, the radiation exposure involved in unnecessary chest CT scans could be responsible for about 40 fatal cancers a year in Australia