The research in the Journal of the American Medical Association is raising concerns about costs and radiation exposure.
Sophisticated CT and pet scans typically provide more detailed images than conventional X-rays. For example, they can tell if a lymph node is swollen from infection or cancer. But they can cost thousands of dollars and what remains unclear is whether their increasing use has improved cancer patient's survival.
Radiation from imaging scans can cause cancer many years later so any excessive amount can be worrisome to doctors.