X-ray vision.

If you broke your wrist Rollerblading more than a century ago, you'd be: a) ahead of your time, and b) in serious trouble. Why? Back then, doctors couldn't see inside you to fix your broken bones. But 100 years ago, X-rays were discovered. Since then, scientists have developed all kinds of ways to turn the human body inside out. See for yourself.

A FACE A MUMMY COULD LOVE

How can you learn about a 3,000-year-old mummy without cutting it open? Scientists recently used Computed Axial Tomography (CT or CAT) scans. To get the scans, doctors slid the mummy--case and all--into the large hole of a CAT scan machine (inset). Inside, an X-ray beam passes through a cross section (or "slice") of the mummy's head. The beam rotates around the head, taking many X-ray pictures of the same slice from different angles. A computer converts the X-rays into an image on-screen. The image can show a cross section or a 3-D structure, like this mummy's face. The scientists learned this mummy was a 35-year-old woman who died from a tooth infection. Doctors also use CT on living patients to help diagnose diseases like cancer.

X-RAY VISIONARY

German scientist Wilhelm Roentgen created the first "inner-body" photo--this X-rays image of his wife's hand--in 18959. Roentgen had accidentally discovered the invisible, high-energy rays while conducting an experiment. He later found that these "X" (for unknown) rays could pass right through soft body parts like muscles and blood vessels to expose (or blacken) photographic paper. But hard tissues like bones absorb X-rays, so the rays don't reach the paper. That's why the bones of Mrs. Roentgen's hand (and her metal rings) show up as white shadows.

A FACE A MUMMY COULD LOVE

How can you learn about a 3,000-year-old mummy without cutting it open? Scientists recently used Computed Axial Tomography (CT or CAT) scans. To get the scans, doctors slid the mummy--case and all--into the large hole of a CAT scan machine (inset). Inside, an X-ray beam passes through a cross section (or "slice") of the mummy's head. The beam rotates around the head, taking many X-ray pictures of the same slice from different angles. A computer converts the X-rays into an image on-screen. The image can show a cross section or a 3-D structure, like this mummy's face. The scientist learned this mummy was a 35-year-old woman who died from a tooth infection. Doctors also use CT on living patients to help diagnose diseases like cancer.

HEAD STRONG

Scientist snapped a picture of this normal brain using a Magnetic Resonance Imaging (MRI) scanner. A giant magnet lines up protons (positively charged subatomic particles) in some of your body's hydrogen (H) atoms. Then the scanner transmits radio waves, a type of energy,, into the body. Some of the protons absorb this energy and emit a signal back. The more hydrogen in the tissue (i.e., the more water, or [H.sub.2]O) the stronger the return signal. A computer transforms the signals it receives into front, side, or cross-section "snap shots" of the body part. Doctors use MRI to diagnose diseases like cancer in the brain and liver and injuries in joints.

HI, MOM!

This image shows of fetus's hand "waving" from inside its mother's uterus. Doctors captured the hand on film by sending ultrasound high-frequency sound waves) through the mother's abdomen. The sound waves bounce off tissues (including the developing baby) inside the expectant mom, and bounce back as echoes. The farther away the tissue, the longer it takes the echo to return. A computer links all the echoes together, creating a live-action image of the baby on a computer monitor. Result: The doctor can see that the baby is developing normally.

UN-HAND-SOME SMOKER

Doctors used this thermogram, or "heat map," to record this smoker's blood circulation. To make the map, they scanned the hand with a device that senses infrared radiation (heat) coming from the surface of the skin. A sensor converts each temperature reading to a color. Blues and greens indicate cool temperatures; yellows and oranges pinpoint warmer regions. Doctors use thermograms to look for abnormal patterns of body-heat distribution, which may indicate abnormal blood circulation. The thermogram at right shows that little body heat (blood) is reaching the tips of this smoker's three lower fingers. The message: Smoking can damage arteries, which carry blood to body parts.

BOY AND GIRL BRAINS

Do boys and girls use their brains differently when they read? To find out, scientists used Functional Magnetic Resonance Imaging--(fMRI)--a technique that can detect functioning parts of the brain. Picture this: A study subject lies on a table and reads while doctors slide the patient headfirst into the scanning machine. A giant magnet aligns the protons (positively charged subatomic particles) of certain elements (like carbon) that are used by active cells. When the machine transmits radio waves into the patient, some of the protons absorb the energy and emit a signal back. More active areas send back stronger signals. A computer transforms the signals into a color-coded map of the brain. The scans above show the most active brain regions of a boy (left) and a girl (right) who were reading while being scanned.

Dr. Kathleen Herd checks out your insides

As a kid in elementary school, Kathleen Herd realized how much she loved science. So when Herd got to college, she took a lot of biology classes. She went to medical school and became a radiologist (a doctor who uses X-rays and other body-imaging technologies to see inside patients). "I love radiology because there's never a dull moment," Herd says. "The fun part is making a diagnosis. Not a day goes by that I don't enjoy finding out how to help my patients."

To find out more about careers in radiology, write: American College of Radiology Department of Communications 1891 Preston White Drive Reston, VA 22091