Authored by Revere Health

Understanding Radiation Therapy Options

December 26, 2017 | ImagingRadiology

Radiation therapy, a cancer treatment option performed by radiation oncologists, is used to destroy cancer cells and reduce tumor growth without harming nearby tissues. It uses high-energy X-rays or proton beams to accomplish this. There are a few different types of radiation therapy, and a few things you should be aware of if you or a loved one is preparing for radiation therapy.

Radiation Goals

Radiation describes the energy that moves from one place to another through waves or particles. High-energy radiation, like the kind found in X-rays, can change or destroy cells in the body–normally we wouldn’t want to destroy cells in our body, but when those cells are cancerous, radiation can destroy them to prevent additional growth.

Over half of people diagnosed with cancer receive some kind of radiation therapy. For some patients radiation therapy is the primary treatment, and for others, it will be a supplemental treatment in conjunction with surgery and/or chemotherapy. Some general goals and uses of radiation therapy include:

  • Killing cancer cells and slowing the growth of tumors, all without harming nearby tissues
  • Targeting remaining cancer cells left over after surgery, chemotherapy, or both
  • Improving quality of life with palliative radiation therapy that shrinks tumors and decreases symptoms like pain and pressure when it’s not possible to destroy all the cancer

External-Beam Radiation Therapy

This is the most common type of radiation therapy, delivering radiation from a machine outside the body. It can treat large or small areas, and patients usually receive a daily treatment every weekday for several weeks in a row. There are a few sub-types of external-beam radiation therapy

  • Three-dimensional conformal radiation therapy (3D-CRT): Uses detailed 3D images with more precisely aimed radiation to create better pictures.
  • Intensity-modulated radiation therapy (IMRT): A more complex form of 3D-CRT that varies radiation intensity within each beam, targeting tumors and avoiding healthy tissues more effectively.
  • Proton beam therapy: Uses protons rather than X-rays – radiation does not go beyond the tumor, and this can limit damage to other tissues.
  • Image-guided radiation therapy (IGRT): Allows the doctor to take images throughout treatment, which can then be compared to previous ones to plan treatment.
  • Stereotactic radiation therapy: Delivery of a large, precise radiation dose to a small tumor area. Often given in a single or a few treatments.


If you have a young child or infant that needs a CT scan, preparation might include a sedative to keep them calm. Too much movement during the scan can blur the images produced and lead to incorrect results, so children who can’t sit still on their own may need extra help.


Magnetic resonance imaging (MRI) is an imaging technique that uses a magnetic field and radio waves to produce images of organs and tissues inside the body. An MRI machine can produce 3D images that can be viewed from multiple angles.

Preparation for an MRI is relatively simple. You will not have to change your eating habits or any medications before the procedure unless your doctor instructs you otherwise. You’ll be asked to remove clothing and change into a medical gown, and to ensure that the test isn’t affected by them, you’ll be asked to remove the following items before the test:

  • Jewelry
  • Hairpins
  • Eyeglasses
  • Watches
  • Wigs
  • Dentures
  • Hearing aids
  • Underwire bras

PET Scan

A PET scan, or positron emission tomography scan, is a test that helps indicate the functionality of tissues and organs. It uses a radioactive tracer that’s injected, swallowed or inhaled, and can help detect disease or conditions that might take longer to show up on other imaging tests.

Before your PET scan, you may be told to avoid strenuous exercise for a couple days and stop eating a few hours beforehand. Things to tell your doctor before a PET scan include:

  • If you’ve ever had a bad allergic reaction
  • If you’ve been sick recently or have a medical condition like diabetes
  • If you’re taking any medications, vitamins or herbal supplements
  • If you’re pregnant or think you might be pregnant
  • If you’re breastfeeding
  • If you’re claustrophobic (afraid of enclosed spaces)

Your doctor may give you additional instructions depending on your individual case.

If you’re preparing for an imaging scan of any kind, your doctor can offer more specific guidelines. You can also use as a resource to help you prepare.




“CT scan (How you prepare).” The Mayo Clinic.

“Positron emission tomography scan (How you prepare).” The Mayo Clinic.

“MRI (How you prepare).” 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.