Authored by Revere Health

Understanding Types of Radiation Therapy

April 6, 2017 | Radiation Oncology

In the simplest terms, radiation refers to energy that moves from one place to another through waves or particles.

As a method of cancer treatment, radiation therapy uses X-rays, protons and other types of energy to help kill cancer cells and slow down the speed of tumor growth, without causing major damage to healthy tissues. Radiation therapy can be the primary cancer treatment, or it can be used after surgery or chemotherapy—in these cases, it’s called adjuvant therapy. If not all the cancerous cells can be killed, doctors may use palliative radiation therapy in order to shrink tumors and ease symptoms.

Over half of all cancer patients receive some kind of radiation therapy during treatment.

Types of Radiation

There are several different types of radiation therapy that can be performed:

External-beam radiation therapy:

External-beam radiation therapy is the most common type, and uses radiation delivered by a machine. This machine, called a linear accelerator, can target specific tumors and avoid healthy tissues. Types of external-beam radiation include:

  • Three-dimensional conformal radiation therapy (3D-CRT): By creating 3-D images of the cancer, usually using CT or MRI scans, this treatment allows doctors to be more precise with treatments.
  • Proton beam therapy: Rather than X-rays, this treatment uses protons, which are positively charged particles. Protons at high energy can destroy cancer cells and are especially beneficial for avoiding healthy tissue damage, as the beams do not go beyond the tumor.
  • Intensity modulated radiation therapy (IMRT): A more complex form of 3D-CRT, IMRT uses a variety of intensities with each beam, allowing your doctor to more accurately target the tumor.
  • Stereotactic radiation therapy: Using large a radiation dose to a small area, stereotactic radiation therapy is often given as a single treatment. Some patients, however, may need multiple treatments.  
  • Image-guided radiation therapy (IGRT): This treatment uses imaging to guide treatment. It allows doctors to take images throughout the treatment process and compare them with each other to track success and improve targeting.


Internal radiation therapy:

Also known as brachytherapy, this form of treatment places radiation inside the cancer itself, or the nearby tissue. Radiation can be administered through permanent implants that contain radioactive material or temporary items like needles or tubes. Radiation can remain in the body for anywhere from a few minutes to a few days.


  • Intraoperative radiation therapy (IORT): This is a surgical procedure that allows surgeons to deliver radiation therapy after healthy tissues or organs have been moved away from the affected area.
  • Systemic radiation therapy: Radioactive material can be swallowed or injected to target cancerous cells. It then leaves the body through natural fluids such as saliva, sweat or urine.
  • Radioimmunotherapy: A type of systemic treatment using antibodies to deliver radiation to the right places.
  • Radiosensitizers and radioprotectors: Radiosensitizers are substances to help treatment be more successful, and radioprotectors help make sure healthy tissue isn’t affected.


Risks and Safety Precautions

Like many types of cancer treatment, there are a few risks associated with this treatment. Some people experience major side effects, while others experience very few. Radiation can produce side effects in the area of the body treated, and some side effects may develop after radiation treatment is finished. Treatment does slightly increase the risk of future cancer, though the benefit of removing the original cancer is greater than the small risk of a new cancer.

If you undergo internal radiation therapy, your friends and family can be at risk, as this type of treatment causes the patient to emit radiation. If you are a visitor of a patient who recently had internal radiation therapy, follow these safety recommendations:

  • Don’t visit patients for longer than 30 minutes per day
  • Stay at least 6 feet away from the patient’s bed
  • People under 18 or women who are pregnant should not visit

Doctors recommend a few precautions for patients that had systemic radiation therapy:

  • Wash hands often and thoroughly, especially after using the bathroom
  • Avoid sexual contact
  • Avoid contact with young children or pregnant women if possible
  • Use separate towels and other utensils
  • Drink lots of fluids to help flush radioactive materials out of your body

Before starting treatment, your doctor will help you through a preparation plan, and these vary from case to case. For any questions or information, contact your healthcare provider to learn more about what to expect when starting chemotherapy

*Note: No two cancer cases are alike. None of the statements herein are designed to suggest a “one size fits all” approach, and each case will be evaluated individually.


We provide the latest in cancer treatment and technologies, and our staff keeps up on the latest treatment methods. Each patient has different needs and treatment goals, and there isn’t just one way to treat cancer. We will work with you to determine the best treatment options and continue to adjust and monitor your dosage or care throughout your treatment.



“Understanding Radiation Therapy.”

“Radiation therapy.” The Mayo Clinic.


The Live Better Team

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This information is not intended to replace the advice of a medical professional. You should always consult your doctor before making decisions about your health.