Radiotherapy, or Radiation therapy, is basically the use of ionizing radiation as a medicine to treat cancer. The radiation can control the growth of the malignant cells. When people develop cancerous tumors radiotherapy is usually applied. The Radiotherapy damages the DNA of tissue that is exposed.

The people who prescribe radiation are called radiation oncologists. Radiotherapy can also be used for the treatment of Trigeminal neuralgia, pterygium, thyroid eye disease, pigmented villonodular synovitis, scar growth, and prevention of keloid.

Radiotherapy can be used to help with many different conditions however there are some side effects. The radiation side effects are divided loosely into these two categories: 1. Acute effects and 2. Late effects.

1. Acute side effects: Acute radiation side effects occur during radiation and in the weeks and months that directly follow the treatment. Many patients that go through radiotherapy do not experience much in the way of a radiation reaction; it depends on where the body must be treated and a couple other factors. Some of the general acute side effects are: Radiation Nausea, Hair Loss (this only happens if the head receives radiation), Fatigue/Malaise, and Low Blood Count. There are a few other side effects that are organ specific

2. Late side effects: Late radiation side effects occur gradually over months and years after or during treatment. These changes may be so small that they will cause no symptoms or they are so rare that they do not cause much risk. However, these changes are important to take note of because those who do have serious late effects have results that are usually disastrous and the treatment is very difficult. Some of the late side effects include; Scarring, Carcinogenicity, and genetic effects. Though these side effects can occur, it is very rare that they do occur.

Radiotherapy side effects can be prevented a couple of ways. Two ways of preventing the side effects are one: altering how the radiation is delivered, and two: taking certain drugs to protect your normal cells from the damage that can happen during radiation.

One delivery method shortens the interval times between radiation treatments so that the cancer cells do not have time to recover. Others can provide dose control and more specified target control.

Drug therapy is not something that prevents the side effects of radiation but it can decrease them. The drugs that select and protect normal cells during the radiation process are called radiation protectors.