Laser Imaging  

     X-RAYS ARE A REMARKABLE DOCTOR'S TOOL SINCE THEY CAN PRODUCE
SHADOW PICTURES OF THE SKELETON, MUCH THE WAY A CHILD CAN CREATE A RABBIT
OR A BIRD BY HOLDING HIS HANDS IN FRONT OF A STRONG LIGHT.  BUT TOO MANY
X-RAYS CAN BE HARMFUL. SO RESEARCHERS WONDER WHETHER THEY CAN TAKE
THOSE SAME SHADOW PICTURES USING HARMLESS LIGHT RAYS.  LIGHT CAN ALSO
SHINE THROUGH THE SKIN, AS ANYONE WHO'S PUT HIS HAND OVER THE END OF A
FLASHLIGHT KNOWS.  BUT THE LIGHT BOUNCES AROUND SO MUCH INSIDE THAT YOU
CAN'T GET A DECENT PICTURE. BUT, PHYSICIST JACK FEINBERG AT THE UNIVERSITY OF
SOUTHERN CALIFORNIA, SAYS THAT DOESN'T MEAN LIGHT IS USELESS.

     Feinberg: "A small fraction of light does pass through the body without being scattered. We call
that ballistic light because it travels just like a bullet.  if we could. . .view that ballistic light and block the
scattered light. . . we'd be able to see structure inside the body, bones, veins, arteries, maybe even tumors." 
     THAT BALLISTIC LIGHT COMES THROUGH THE HAND JUST A FEW MILLIONTHS OF
MILLIONTHS OF A SECOND BEFORE THE SCATTERED LIGHT DOES.  SO SCIENTISTS WANT
TO TAKE A PHOTO OF THAT SINGLE INSTANT. BUT THAT'S NOT SO EASY--IF THEY TRIED
TO USE A NORMAL CAMERA THE SHUTTER WOULD HAVE TO MOVE FASTER THAN THE
SPEED OF LIGHT.  SO, INSTEAD OF CAPTURING THE PHOTO ON FILM, DR. FEINBERG HAS
RESEARCHED CAPTURING THE LIGHT ONTO A SPECIAL KIND OF HOLOGRAM.

     Feinberg: "Its a remarkable hologram, because not only does it have information about where
things are it has information about when . . .that light arrived. . .  so, the hologram records a movie and we
can then separate the early parts of the movie and the late parts of the movie."

     IN THIS WAY, FEINBERG CAN PLAY BACK JUST THE PART OF THE MOVIE HE
WANTS TO SEE--THE FIRST TRICKLE OF BALLISTIC LIGHT THAT SHOWS A DECENT
PICTURE OF THE BODY'S INSIDES.  FEINBERG'S TECHNIQUE IS ONE OF SEVERAL
METHODS BEING RESEARCHED, BUT HIS HOLOGRAM MOVIE, OR A SIMILAR HARMLESS
TECHNIQUE, MAY SOMEDAY BE GETTING RAVE REVIEWS IN A HOSPITAL NEAR YOU.