What is a CT scan?
A Computed Tomography Scan or CT scan for short is an imaging test used to visualize an acute trauma or disease that may be affecting the body. A CT scan utilizes x-rays to create intricate cross-sectional images of the body. As opposed to an x-ray where one image is taken, a CT scan will take multiple images as it rotates around your body while you remain still on a table. The computer will then combine the images to create a picture of the particular area of the body that will be studied. In some instances you may be required to drink an oral contrast, which helps to outline and differentiate the intestines from any tumors. A CT scan is also helpful in detecting if a cancer exists or has spread into the lymph nodes.
Do CT scans actually cause cancer?
CT scans expose you briefly to a small, targeted amount of ionizing radiation, which helps create an image of structures inside your body. There is no evidence that CT scans cause cancer, but the American College of Radiology does acknowledge that there is an increased risk of developing cancer because of the increased exposure to radiation. Past studies have compared the amount of radiation given off by the CT machines to the Hiroshima and Nagasaki bombings, and tried to predict the likelihood of developing cancer, but this method was unreliable as these are very different settings. CTs are performed in a controlled setting and in most cases result in limited exposure. In order to really know the risks, we need to prospectively follow patients over 20 to 30 years. What we do know is that a single CT scan subjects the human body to between 150 and 1,100 times the radiation of a conventional x-ray, or around a year's worth of exposure to radiation from both natural and artificial sources in the environment.
Do the risks of the scans outweigh the benefits?
CT scans are a great tool for clinicians to diagnose certain conditions. This said, bombarding the human body with x-ray beams, which can damage DNA and create mutations can increase the risk of cancer incidence even if just by a small percentage. If the guidelines for use of the CT machines and radiation dosage are properly followed by technicians and if clinicians order only when necessary, then the benefits outweigh the risks. If patients are comfortable with the competence of their physician and the physician feels that the test is important then the patient should get the test.
So what is the bottom line?
As physicians, we should carefully select patients for tests and consider all the benefits and risks. For patients, this should remind them that they need to ask questions about the necessity of the test and also inquire about the accreditation of the centers performing the tests to ensure that the lowest radiation dose is used.