Emerging technologies such as X-rays gave physicians new diagnostic tools, revealing the intervertebral disc as a source for back pain in some cases. In 1938, orthopedic surgeon Joseph S. Barr reported on cases of disc-related sciatica improved or cured with back surgery. As a result of this work, in the 1940s, the vertebral disc model of low back pain took over, dominating the literature through the 1980s, aiding further by the rise of new imaging technologies such as CT and MRI. The discussion subsided as research showed disc problems to be a relatively uncommon cause of the pain. Since then, physicians have come to realize that it is unlikely that a specific cause for low back pain can be identified in many cases and question the need to find one at all as most of the time symptoms resolve within 6 to 12 weeks regardless of treatment.