Physics - Radiation in Treatment

X-rays and gamma rays are electromagnetic waves with similar wavelengths but they are produced in different ways.

X-rays and nuclear radiation (i.e. gamma and beta radiation) can be used in medicine.

X-rays can be used to build up a picture of the inside of a patients body. The person in a hospital who take X-rays and uses radiation is called a radiographer.

Medical radioisotopes are produced by placing materials in a nuclear reactor. They become radioactive when then absorb extra neutrons.

Gamma rays damage cells, so they can be used to treat cancer. Gamma (and sometimes beta) can pass through the skin (unlike alpha), so it can be used as medical tracers (i.e. to track the progress of a substance through a patients system). They are only used for a short time to avoid damage to healthy tissue.

Gamma rays can also be used to sterilise medical equipment because they kill germs and bacteria.

X-rays are made by firing high-speed electrons at metal targets. X-rays are easier to control than gamma rays. After alpha or beta decay, a nucleus sometimes contains surplus energy. It emits as gamma radiation, which is very high frequency electromagnetic radiation.

Treating Cancer

 Gamma rays can be used to treat cancer:

1. A wide beam of gamma rays outside the body is focused on a tumor.

2. The beam is rotated around the outside of the body with the tumor at the centre.

Gamma radiation treatment can destroy cancerous calls without the need for surgery, but it may damage healthy cells and cause sickness.    

Tracers are small amounts of radioactive materials (with a short half-life) which is swallowed or injected by the patient. The tracer spreads through the body, whilst its progress is followed using an external detector.

For example, the thyroid gland in the neck affects the bodies metabolic rate. It absorbs iodine, so a patient can be given a tracer that contains iodine-131. A detector follows the progress of a tracer. You can tell how well the gland is working by measuring the amount of iodine it absorbs.

N.B. The radioactive material must emit either gamma or beta radiation, because they both pass through the skin and can be detected outside the body.