The technological explosion in medicine has given birth to imaging devices that allow doctors to look inside the body without surgery.

Currently on display in the Hall of Medical Sciences at the National Museum of American History is a new exhibit, "Body Imaging," which features three devices: the first magnetic resonance imaging machine, used to scan the entire body; the first CAT scan, which uses X-rays to create cross-section images of internal organs; and an ultrasound machine, which uses sound waves to see inside the body.

"These machines are an important part of diagnostic testing, and the public should know what they look like," said Dr. Ramunas Kondratas, curator and supervisor of the museum's medical sciences division.

Also included in the exhibit are the patents granted for the machines, information on the history of their development and photos of the images they produce.

These advanced body imaging devices have been developed over the last 20 years; they have their roots in X-ray technology invented at the turn of the century by William Konrad Roentgen.

The museum is at 14th Street and Constitution Avenue NW. Hours are daily from 10 a.m. to 5:30 p.m. Admission is free. -- Wendy Melillo