Mr. Peters, 35-year-old father of four and a resident of Chicago’s
northwest side, went to a Chicago hospital one winter day after
persistent headaches had made his life miserable. Routine examinations
showed nothing amiss and his doctor ordered a “brain scan” in the
hospital’s department of nuclear medicine.
Thirty minutes before “scan time”, Mr. Peters was given, by intravenous
injection, a minute amount of radioactive technetium. This radiochemical
had been structured so that, if there were a tumor in his cranium, the
radioisotopes would be attracted to it. Then he was positioned so an
instrument called a scanner could pass close to his head.
As the motor-driven scanner passed back and forth, it picked up the
gamma rays being emitted by the radioactive technetium, much as a Geiger
counter detects other radiation. These rays were recorded as black
blocks on sensitized film inside the scanner. The result was a piece of
exposed film that, when developed, bore an architectural likeness or
image of Mr. Peters’ cranium.
[Illustration: _The inset picture shows a brain scan made with a
positron scintillation camera. A tumor is indicated by light area above
ear. (Light area in facial region is caused by uptake in bone and
extracellular space.) The photograph shows a patient, completely
comfortable, receiving a brain scan on one of the three rectilinear
scanning devices in the nuclear medicine laboratory of a hospital._]
Mr. Peters, who admitted to no pain or other adverse reaction from the
scanning, was photographed by the scanner from the front and both sides.
The procedure took less than an hour. The developed film showed that the
technetium had concentrated in one spot, indicating definitely that a
tumor was present. Comparison of front and side views made it possible
to pinpoint the location exactly.
Surgery followed to remove the tumor. Today, thanks to sound and early
diagnosis, Mr. Peters is well and back on the job. His case is an
example of how radioisotopes are used in hospitals and medical centers
for diagnosis.
[Illustration: _The first whole body scanner, which was developed at the
Donner Laboratory in 1952 and is still being used. The lead collimator
contains 10 scintillation counters and moves across the subject. The bed
is moved and serial scans are made and then joined together to form a
head-to-toe picture of the subject._]
[Illustration: _The diagram shows a scan and the parts of a scanner.
(Also see page 21.)_]
In one representative hospital, 17 different kinds of radioisotope
measurements are available to aid physicians in making their diagnoses.
All the methods use tracer quantities of materials. Other hospitals may
use only a few of them, some may use even more. In any case they are
merely tools to augment the doctors’ skill. Examples of measurements
that can be made include blood volume, blood circulation rate, red blood
cell turnover, glandular activity, location of cancerous tissue, and
rates of formation of bone tissue or blood cells.
Of the more than 100 different radioisotopes that have been used by
doctors during the past 30 years, five have received by far the greatest
attention. These are iodine-131, phosphorus-32, gold-198, chromium-51,
and iron-59. Some others have important uses, too, but have been less
widely employed than these five. The use of individual radioisotopes in
making important diagnostic tests makes a fascinating story. Typical
instances will be described in the following pages.
[Illustration: _A differential multi-detector developed at Brookhaven
National Laboratory locates brain tumors with positron-emitting
isotopes. By using many pairs of detection crystals, the device shortens
the scanning time and increases accuracy. (See cover for another type of
positron scanner.)_]