Computed Tomography

How does it work? CT scans involve a more sophisticated and intense use of X-rays, along with special sensors. The patient lies on a table that slides into a tunnel in the machine. Images are produced by numerous narrow beams of radiation and detectors that rotate 360 degrees around the patient. The process has been compared to examining a loaf of bread by photographically cutting it into very thin slices. A computer reassembles the “slices,” providing a detailed cross-sectional view of the body’s interior. The latest machines scan the body in a helical, or spiral, fashion, thereby speeding up the process. Because CT scans provide much detail, they are often used for examining the chest, the abdomen, and the skeleton, and for diagnosing various cancers and other disorders.

Risks: CT scans usually involve higher doses of radiation than regular X-rays. The additional exposure carries a small but significant increased risk of cancer, and this should be carefully weighed against the benefits. Some patients have an allergic reaction to contrast agents, which commonly include iodine; and in certain patients, there may also be an element of risk to the kidneys. If a contrast fluid is used, nursing mothers may have to wait 24 hours or more before resuming breast-feeding.

Benefits: Painless and noninvasive, CT scans provide finely detailed data that can be digitally converted into three-dimensional images. Scans are relatively fast and simple, and they can save lives by revealing internal injuries. CT scanners do not affect implanted medical devices.

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CT

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