What Is Cobalt Therapy?

A linear accelerator can be used to deliver cobalt therapy to larger tumors.
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  • Written By: Marlene Garcia
  • Edited By: Daniel Lindley
  • Last Modified Date: 29 October 2014
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A form of cancer treatment known as cobalt therapy targets malignant cells without destroying nearby healthy tissue. Also called radiosurgery, cobalt therapy aims gamma rays at cancerous cells, commonly in the brain, neck, or near vital blood vessels. These rays attack cancer from several directions as cobalt ions deteriorate. Healthy cells harmed by cobalt therapy typically regenerate and return to normal.

Cobalt-60 represents an isotope of the metal discovered in the 1930s. This discovery led to the invention of a cobalt machine to deliver gamma rays to cancer patients. One of the most common machines is known as a gamma knife, a stationary machine capable of delivering radiation to precise areas of the head. The device sends more than 200 sources of cobalt-60 to attack a brain tumor.

Surgeons using this form of cobalt therapy attach a helmet to the patient’s head to direct gamma rays through channels in the headgear. The patient remains completely still during the procedure as radiation targets a tumor. A gamma knife machine can treat reoccurring brain tumors and be used in conjunction with surgery.

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Some oncologists prefer a newer machine called a linear accelerator to deliver cobalt therapy. These movable devices typically address larger tumors by aiming higher doses of radiation than the gamma knife. A computer-controlled linear accelerator might be moved to radiate tumors from different angles over a period of weeks or months. This machine can be turned off when not in use, unlike cobalt machines, which are often kept in special rooms to prevent accidental radiation exposure.

Cobalt represents a by-product of nickel and copper mining, and the metal appears naturally in rocks and dirt. Compounds of cobalt give ceramic glass a deep blue color, and give rich tints to glazes. After the isotope cobalt-60 was identified, it became valuable as an alloy because it resists corrosion and adds strength to other metals. This form of cobalt is used in the jewelry industry, for jet aircraft parts, and in manufacturing of medical devices designed for human implantation.

Radiation therapy treats many forms of cancer, including tumors in the lungs, bladder, pancreas, and liver. It might also prove effective for leukemia and other blood cancers. This treatment might be used with chemotherapy, which delivers chemicals throughout the body, and traditional surgical procedures. Doctors commonly choose cobalt therapy when invasive surgery might harm nearby nerves or vital arteries.

Side effects of radiation treatment might include nausea and vomiting, especially if gamma rays target the abdominal area. Some patients suffer burning of the skin where the radiation enters the body, similar to a severe sunburn. Fatigue might also occur, usually appearing a couple of weeks after treatment begins.

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