For years it has been recognized that there would be many uses for a
truly portable device for taking X-ray pictures—one that could be
carried by the doctor to the bedside or to the scene of an accident.
Conventional X-ray equipment has been in use by doctors for many years,
and highly efficient apparatus has become indispensable, especially in
treating bone conditions. There is, however, a need for a means of
examining patients who cannot be moved to a hospital X-ray room, and are
located where electric current sources are not available.
A few years ago, a unit was devised that weighed only a few pounds, and
could take “X-ray pictures” (actually gamma radiographs) using the gamma
rays from the radioisotope thulium-170. The thulium source is kept
inside a lead shield, but a photographic shutter-release cable can be
pressed to move it momentarily over an open port in the shielding. The
picture is taken with an exposure of a few seconds. A somewhat similar
device uses strontium-90 as the source of beta radiation that in turn
stimulates the emission of gamma rays from a target within the
instrument.
[Illustration: _A technician holds an inexpensive portable X-ray unit
that was developed by the Argonne National Laboratory. Compare its size
with the standard X-ray machine shown at left and above._]
Still more recently, ¹²⁵I has been used very successfully in a portable
device as a low-energy gamma source for radiography. The gamma rays from
this source are sufficiently penetrating for photographing the arms and
legs, and the necessary shielding is easily supplied to protect the
operator. By contrast with larger devices, the gamma-ray source can be
as small as one-tenth millimeter in diameter, virtually a point source;
this makes possible maximum sharpness of image. The latest device, using
up to one curie[12] of ¹²⁵I, weighs 2 pounds, yet has adequate shielding
for the operator. It is truly portable.
If this X-ray source is combined with a rapid developing photographic
film, a physician can be completely freed from dependence upon the
hospital laboratory for emergency X rays. A finished print can be ready
for inspection in 10 seconds. The doctor thus can decide quickly whether
it is safe to move an accident victim, for instance. In military
operations, similarly, it becomes a simple matter to examine wounded
soldiers in the field where conventional equipment is not available.