IntroductionCT scans of the lumbar spine are indicated in the search of neural compressive lesions and in search of a cause for specific low back pain (LBP). They are associated with a high radiation exposure of 700 to 1500 mREMs per exam. The goal of the study was to investigate whether repeat spine CT scans, in patients who are symptomatic 2 years after the initial exam, contribute new clinical data.Materials and MethodsRepeated CT scans performed for LBP or radiculopathy between 2008 and 2010 were identified in our radiology department. Only patients 60 years of age and below were included. Patients with a history of trauma or surgery between exams were excluded. All scan (original and repeat) were reviewed by a senior musculoskeletal radiologist. Interval changes between scans were rated as: no change, worsening of the pathology, improvement of the pathology, or new pathology.ResultsTotal 6000 lumbar spine CT scans were performed between the years 2008 and 2010. Total 550 were repeatedly examined. Total 108 repeated CT scans met the inclusion criteria; 35 scans were ordered to investigate LBP, 46 for radiculopathy and in 27 exams the indication was not stated. The average age of the patients was 48.1 (range: 18 to 60). The average interval between the scans was 24.1 months (SD = 6 months). Spine pathology was identified in 287 levels. In 10 patients, the spine was without any pathology. Total 274 pathologies did not changed (92.3%; p < 0.05), 10 improved, and 10 worsened (disk herniation or spinal stenosis). Three new pathologies were identified (one fracture two disk herniations). In case of worsening, no substantial therapeutic change was required. In patients who were sent for a repeated CT for LBP, only two pathologies changed between exams.ConclusionCT scans cause 1% of annual cancer mortality in the USA. The repeated radiation from unnecessary exams accumulates and causes secondary malignant changes. In the time frame of 2 to 3 years, in patients suffering chronic or recurrent LBP or radiculopathy, there is a little added diagnostic value for repeated CT scans. Repeated scan should be considered only in patients with progressive neurologic deficits or signs implying serious underlying conditions.I confirm having declared any potential conflict of interest for all authors listed on this abstractYesDisclosure of InterestNone declaredAaron Sodickson, Pieter F. Baeyens, Katherine P. Andriole, et al. Recurrent CT, cumulative radiation exposure, and associated radiation-induced cancer risks from CT of adults. Radiology 2009;251:175–184