1940–1949
• The Betatron, a circular electron accelerator, is developed by
Dr. Donald Kerst of the University of Illinois between
1940–1943. It generates energy (20 million volts or more) by
orbiting electrons, faster and faster, through a large “doughnut,”
a circular glass tube with a heated cathode inside a
huge electromagnet.
1950–1959
• Dr. W. Goodwin introduces the concept of X-ray guided percutaneous
nephrostomy, in which a needle and then a
catheter are inserted directly into a kidney to create a
drainage tract above an obstruction (kidney stone, cancer),
allowing urine to escape from the kidneys. This procedure
allows some patients to be treated without surgery.
• Radioisotopes are introduced as sources of gamma-ray
beams for radiation therapy. The process works, for example,
by changing harmless cobalt 59 into cobalt 60, a highly unstable
nucleus that decays. As that happens, it releases two
gamma rays. The gamma-ray beams adequately reach deep
cancers without damage to the skin. Cobalt units are easy to
make and quickly become a cheaper, safer alternative to the
Betatron, though later they will become virtually unused.
• Ultrasound—images created from the echoes of sound waves
bounced off tissue—which has its roots in World War II’s
sonar (sound navigation and ranging), begins to show
promise in medical diagnostic applications.
• A Swedish physician, Dr. Sven Ivar Seldinger, refines
Dr. Moniz’s and Dr. Forssmann’s work in angiography from
the 1920s when he learns how to insert a catheter into a
blood vessel without surgery. He uses a tiny guidewire
inserted with the help of a needle into a blood vessel. The
catheter is placed over the guidewire and into the vessel,
after which the guide wire is removed. He then watches the
location of the catheter on fluoroscopy.