A new device now maps the body’s internal organs with sound waves.… Shaped like an oversized fountain pen, the transducer is held over the body above the internal organ to be studied. Short pulses of ultrasonic energy radiate out, and harmlessly bounce back from the internal surfaces. The time they take to return is analyzed, and results are recorded immediately on the instrument’s screen. A “map” of the organ inside the body can thus be studied. The principle is the same as that of sonar systems using sound waves to locate objects under water…. Formerly doctors have relied upon X-rays or other means to obtain information about the interior of the body. But radiation dosages make these procedures dangerous.