Seeds (ca. 1940s - 1960s)
"seeds" contained a radioactive material and were intended to be
permanently implanted into a tumor or other diseased tissue. The seeds
shown in the photo are of two kinds. The single gold seed, immediately below the
penny, would have been filled with radon. The rest of
the seeds are made of titanium. They were probably used to hold
Today, the two radionuclides most commonly used in implantable seeds are iodine-125 and palladium-103. They are primarily used to treat prostate cancer. Gold-198, and to a far lesser extent, cobalt-60, have also been used
Radon seeds were usually 0.75 - 1.0 mm in diameter and 4 to 7.5 mm long.
They were made by filling a hollow gold tube (ca. 0.3 mm wall thickness)
with radon and using pliers to pinch the tube off into the
appropriate lengths. The activities might range from 0.05 to 5
millicuries per seed. Since radon has a 3.8 day half-life, it was common to
leave the gold seeds in the patient permanently. Nevertheless, they would
contain some residual activity due to the long lived radon decay product
The idea of using gold originated with Gino Failla (ca. 1920) at Memorial Hospital in New York. Until then, radon had been sealed in glass, but the betas emitted by the radon decay products caused necrosis of the tissue in the immediate vicinity of the seeds. Gold, on the other hand, filtered out the betas while still allowing the gamma rays (which did the real work of killing off the diseased tissue) to escape.
|Radon seeds were
implanted in a wide range of tissues: cervix, mouth, tongue, tonsils,
rectum, bladder, etc. In the 1960s, radon seeds fell out of favor
and were replaced with gold-198 grains.
Radium Chemical Company catalog. Radium Radon. No date. ca. 1940s, 1950s.
E.R.N. Grigg. The Trail of the Invisible Light. Charles C Thomas. Springfield. 1965.
Richard Mould. A Century of X-rays and Radioactivity in Medicine. Institute of Physics Publishing. Bristol. 1993.
Walter Murphy. Radiation Therapy. W.B. Saunders Company. Philadelphia. 1959.
Copyright 1999, Oak Ridge Associated Universities