Radiation Therapy: 3 Official Forms Used In Therapy


Radiation therapy

Radiation therapy

Radiation therapy utilizes energy in the form of ionizing radiation to treat or cure diseases such as cancer, thyroid disease, and non-cancerous or benign tumors.

Ionizing radiation is energy that can disrupt atoms and molecules within the human body. During radiation therapy, waves of energy are aimed at abnormal cells.

The radiation breaks apart the DNA of cells, causing them to die.

During radiation therapy, both normal and abnormal cells die. The goal of treatment is to kill as many cancer cells as possible while limiting the damage to normal cells.

Radiation therapy is predominately used to treat cancer. It can be an effective treatment to shrink tumors, reduce symptoms of cancer that has spread to other organs, and help prevent recurring cancer.


Radiation is a form of energy. During radiation therapy, various forms of radiation are used, such as X-rays and parts of atoms called protons to kill cells.

There are three main forms of radiation therapy:

External beam radiation therapy, internal beam radiation therapy, and systemic radiation therapy.

External beam radiation therapy

This is the most prevailing form of radiation therapy and involves aiming beams of radiation at specific cancerous tumors and areas of the body with abnormal growths.

During external beam radiation therapy and under the direction and care of a medical team, a machine called a linear accelerator aims at highly focused beams of radiation at cancer cells and tumors.

External beam radiation therapy happens inside a hospital or treatment center. Your doctor will carefully mark where the radiation will be aimed.

You gonna lie down on a table, and then the linear accelerator will move into a position around you so that the radiation can be precisely focused.

There several different types of external beam therapy:

  • Photon beam radiation therapy—Traditional external beam therapy uses photons to kill cancer cells; however, these photons also damage other healthy cells they pass through.
  • Proton beam radiation therapy—Another more common form of radiation therapy, this type of external beam therapy can pass through healthy cells and tissue without harm and aimed inside tumors to kill cancer cells.
  • Three-dimensional conformal radiation therapy (3D-CRT)—This type of radiation therapy focuses on the radiation from several different angles to mold the radiation to the exact shape of the cancerous growth and protect as many healthy cells and tissues as possible.
  • Image-guided radiation therapy (IGRT)—A type of 3D-CRT. This treatment involves diagnostic scans like X-rays and CT scans before each treatment to preserve as many healthy cells as possible. These treatments are very specifically targeted.
  • Intensity-modulated radiation therapy (IMRT)—Another form of 3D-CRT, this type of external beam therapy uses varying strengths of radiation beams or waves to target different areas within a cancerous growth with stronger radiation in an attempt to save as many healthy cells as possible.
  • Helical-tomotherapy—An adaptive type of radiation therapy, helical-tomotherapy combines a type of CT scan machine with a linear accelerator to provide radiation therapy that can be adapted in real-time to the shape and size of a tumor.
  • Stereotactic radiosurgery—Though not technically a surgery, this type of radiation therapy is used for tumors in sensitive areas such as the brain, lung, or spine. It uses highly targeted linear accelerators X-Knife, CyberKnife, Clinic, and Gamma Knife. These tools allow high radiation levels to be delivered to particular areas with limited damage to surrounding tissue.
  • Intraoperative radiation therapy (IORT)—This type of radiation therapy is administered during surgery to help shrink tumors or prevent them from returning. This therapy is performed in a special operating room built to contain radiation. During this process, your doctor will open your body, protect surrounding tissue, and allow radiation to access tumors without passing through other tissues directly.

Internal beam radiation therapy

Internal beam radiation therapy, called brachytherapy, is a type of radiation therapy in which radiation is placed inside or near a tumor or group of cancerous cells.

This type of therapy allows higher levels of radiation than external beam therapy.

The radioactive material is enclosed in a small container and placed inside the body during surgery. This type of radiation therapy occurs in a hospital setting.

There are several ways the radioactive material may be contained for implantation including, capsules of various sizes, wires, needles, balloons, or tubes.

These containers may be placed inside a body cavity such as your abdomen(intracavitary radiation) or near a tumor but not inside a cavity (interstitial radiation).

Depending on your treatment plan, the capsules may be inside your body for only a few minutes, several days, or they may remain permanently if the radioactive material will eventually stop giving off radiation.

If you have internal beam radiation therapy, you may need to avoid contact with other people until the radiation capsule has been removed because you may expose others to unhealthy radiation from the material inside the capsule.

Systemic radiation therapy

During this type of radiation therapy, radiation travels throughout your body. You will take the radiation by mouth, or it will be injected into a vein.

It is often used to treat thyroid cancer, cancers of the head, eye, neck, breast, cervical, and prostate cancer.

You may check in the hospital for a couple of days during systemic radiation therapy.

Because your bodily fluids, such as sweat, urine, blood, and spit, may be radioactive, you may need to avoid touching other people or your pets during systemic radiation therapy.

If you are at home, you may need to sleep in a separate bedroom and take special precautions when bathing, using the restroom, or washing your clothes to protect your family members and those you live with.

You may as well need to avoid having sex, kissing, or getting too close to other people. You may not be allowed to touch infants, children, or pets for a while.

Your doctor will give you detailed instructions and let you know when it is safe for you to resume normal activity and contact.


Depending on which type of radiation therapy you have, you may be admitted to a hospital for treatment and for a period of time afterward.

Your radiation therapy may be administered during one session, or you may need weeks of treatments.

External radiation therapy sessions generally last between 10 to 30 minutes, while internal or systemic radiation therapy may require one or more hospital admissions and procedures.

You may receive treatment in a special room to protect others from radiation exposure.

During therapy sessions, a medical team will remain in contact with you via radio and or video, and someone will always be close by to assist you if necessary.

Your radiation therapy will be directed and managed by a team of health care professionals. In addition to doctors, called oncologists, and nurses, your radiation therapy team may include:

  • radiation oncologists
  • therapeutic medical physicist
  • radiation therapist
  • dosimetrist (medical specialists in the planning and operation of radiation therapy equipment)
  • radiation oncology nurses
  • social workers
  • dieticians
  • other health care professionals


Radiation exposure generally has side effects. Your side effects will depend on the amount of radiation needed for your treatment, the duration of each treatment, and the length of time you undergo radiation therapy.

Side effects of radiation therapy may include:

  • hair loss (temporary or permanent)
  • skin irritation
  • dry mouth
  • mouth sores
  • tooth decay
  • difficulty swallowing
  • nausea
  • vomiting
  • diarrhea
  • bladder difficulties
  • frequent urination
  • sexual function problems

The aftermath of radiation therapy varies from person to person.

Certain people may not have side effects at all. If you experience side effects or if your symptoms worsen, notify your health care team immediately.

They can help develop a plan to address any discomfort you may experience. There are options for managing side effects like hair loss, nausea and vomiting, and others.



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“Radiation therapy.” American Cancer Society. https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/radiation.html (accessed on December 20, 2018).

“Radiation therapy.” Mayo Clinic. March 28, 2018. https://www.mayoclinic.org/tests-procedures/radiation-therapy/about/pac-20385162 (accessed December 20, 2018).

“Radiation therapy.” MedlinePlus. December 27, 2018. https://medlineplus.gov/radiationtherapy.html (accessed December 28, 2018).


American Cancer Society, 250 Williams Street NW, Atlanta, GA, 30303, (800) 227-2345, contactus@cancer.org, https://www.cancer.org.

American College of Radiology, 1891 Preston White Drive, Reston, VA, 20191, (800) 227-5463, info@acr.org, https://www.acr.org/.