Chiropractors, like other primary care providers, sometimes employ diagnostic imaging techniques such as X-rays and CT scans that rely on ionizing radiation.[147] Although there is no clear evidence for the practice, some chiropractors may still X-ray a patient several times a year.[8] Practice guidelines aim to reduce unnecessary radiation exposure,[147] which increases cancer risk in proportion to the amount of radiation received.[148] Research suggests that radiology instruction given at chiropractic schools worldwide seem to be evidence-based.[149] Although, there seems to be a disparity between some schools and available evidence regarding the aspect of radiography for patients with acute low back pain without an indication of a serious disease, which may contribute to chiropractic overuse of radiography for low back pain.