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BIOLOGY AND MEDICINE
At the present cost of $14 per curie for cesium 137, the newly installed unit has a total cost
of about $29,000.
Cesium 137 is one of the most important of the relatively long-lived gamma-emitting
radioisotopes, with a half-life of approximately 35 years. In addition to its medical value,
this isotope has many applications in industry. The demand is expected to reach many millions
of curies, as the techniques for extracting cesium 137 from reactor wastes are improved and
reduced in cost.
The Michigan source consists of powder pressed at 20,000 pounds per square inch into
two pellets and placed in a stainless steel container, double sealed to produce a leak-proof
capsule. The source measures 3.2 centimeters in diameter and 3.56 centimeters in length,
and its specific activity is 24 curies per gram of cesium 137.
During the past year the Michigan group has been treating patients with conventional
X ray and with a 1,903-curie cobalt source, the largest high-specific-activity cobalt source in
this country. Acquisition of the cesium source completes the university’s planned installation
of high-energy sources for use in radiation therapy at this project. (End o
section.)
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