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Things to Know about the Different Types of Radiation Therapy

A person undergoing radiation therapy.


Radiation therapy is a common treatment method that is recommended to cancer patients. It uses ionizing radiation to shrink tumors or kill malignant cells. In some cases, radiation therapy or radiotherapy may be the only way to address the condition.

The cells in our bodies are continuously dividing and forming new copies. Cancer forces the cells to divide rapidly and develop tumors in the body. Radiation therapy aims to slow down or stop the progression of tumors by making small breaks in the DNA of cancer cells. Sometimes, radiation therapy can also be recommended to prevent cancer cells from developing new tumors if they have spread to other parts of your body.

Different Types of Radiation Therapy

There are two main types of radiation therapy – external beam radiation therapy and internal radiation therapy. Your doctor will recommend the right type of radiotherapy to you depending upon the type of cancer you are diagnosed with as well as the size and location of the tumors. Your general health and other treatments for the condition will also play a role in deciding which type of radiotherapy would work better for you.

In external beam radiation therapy, a large machine directs radiation beams directly over the cancer tumors from outside your body at different angles. It uses computer-aided programs to analyze the imaging scans and target radiation beams as per the shape and size of the tumor. In general, an external beam radiation therapy session can go from 30 minutes to an hour and it is usually done 5 days per week. The schedule may vary depending upon your specific condition though.

Internal radiation therapy, on the other hand, involves radiation through liquid radioactive iodine that is administered either orally or via IV injection. The radioactive iodine travels through the body to target and kill cancer cells, but it is not used for all kinds of cancers. Generally, thyroid cancer patients are recommended internal radiation therapy.

Sometimes, a different form of internal radiation therapy, known as brachytherapy, may be recommended to treat neck, breast, head, cervix, prostate, endometrial, and eye cancers. In brachytherapy, a solid form of radiation, such as a capsule or an implant, is placed inside your body through a catheter or applicator device. If high doses of radiation are used, then the implant may be taken out within 10 – 20 minutes.

If only a low dose of radiation is used in brachytherapy, then the doctor will remove the implant only after a few days. In some cases, the implant may be placed permanently in your body for long-term treatment as well. Note that when you get internal radiation therapy, your body may emit radiation for a short time. Therefore, you will be required to stay in the clinic for some time after the therapy.