What is Radiation Therapy?

Radiation Therapist at machineAll cells grow and divide to form new cells. But cancer cells grow and divide faster than the normal cells around them and invade other tissues. Radiation therapy uses high-energy radiation to shrink tumors and kill cancer cells, thus preventing the cells from growing, dividing, and spreading.

Also referred to as radiotherapy, irradiation, or x-ray therapy, radiation therapy is one of the most common treatments for cancer. Unlike chemotherapy, which exposes the whole body to cancer-fighting drugs, radiation therapy is usually applied locally, affecting only the part of the body being treated and limiting harm to nearby healthy tissue.

What Type of Radiation Therapy is Best?

Deciding which type of radiation to use depends upon the kind of cancer you have and where it is in your body. Discuss with your radiation oncologist which type of treatment plan is right for you.

Frequently Asked Questions (FAQ)

"Radiation Therapy and You" a publication by the National Cancer Institute

Types of Radiation Therapy

Radiation may be delivered by a machine outside the body (external-beam radiation therapy), or may come from radioactive material placed in the body near cancer cells (internal radiation therapy, also called brachytherapy). Oncologists may also prescribe a combination of radiation therapies to treat a patient's cancer. And radiation can be given alone or used with other treatments, such as surgery or chemotherapy. In fact, certain drugs are known to be radiosensitizers. This means they can actually make the cancer cells more sensitive to radiation, which allows the radiation to better kill cancer cells.

About half of all cancer patients receive some type of radiation therapy during the course of their treatment.     

External Beam Radiation Therapy  

External radiation (or external beam radiation) uses a machine to direct high-energy rays from outside the body into the tumor, while minimizing radiation exposure to nearby healthy tissue. Patient on TableScheduled as a series of outpatient visits, external radiation therapy is typically repeated over a period of many weeks.

icon-video Watch a video: Introduction to external radiation therapy

Valley Medical Center employs state-of-the-art treatment machines called linear accelerators that use image-guidance and x-ray technology to precisely locate tumors in real time. This is critically important since tumors can move—as a result of breathing or due to shifting caused by weight loss or other physical changes over the course of treatment. In addition, the linear accelerator is capable of mapping irregularly shaped tumors and varying the intensity and direction of beams of radiation to destroy cancerous cells and exclude healthy tissue.

There are a number of treatment plan styles available for external radiation. Selection depends upon tumor location, shape, size, proximity to organs and other factors. Discuss with your radiation oncologist which type of treatment plan is right for you.

  • Three Dimensional Conformal Radiation Therapy (3D-CRT)
    • This uses computers to precisely design a plan based on the size, shape and location of the tumor while limiting the radiation dose delivered to surrounding normal tissue.                                                                         
  • Intensity Modulated Radiation Therapy (IMRT)
    • IMRT allows for the radiation dose to conform more precisely to the three-dimensional (3-D) shape of the tumor by modulating, or controlling, the intensity of the radiation beam in short bursts. IMRT can also focus higher radiation doses within the tumor and minimize the dose to surrounding normal critical structures; which has been shown to reduce treatment related side effects.  Treatment is carefully planned by using 3-D computed tomography (CT) or magnetic resonance (MRI) images of the patient in conjunction with computerized dose calculations to determine the dose intensity pattern that will best conform to the tumor shape. 
  • Volumetric Modulated Arc Therapy (VMAT)
    • Volumetric Modulated Arc Therapy (VMAT) is a technique that establishes new standards for radiation therapy treatment speed and dose reduction to the patient. With VMAT, single or multiple radiation beams sweep in uninterrupted arc(s) around the patient, dramatically speeding treatment delivery. 
  • Image Guided Radiation Therapy (IGRT)
    • IGRT is the use of frequent imaging immediately before and during a course of radiation therapy to improve the precision and accuracy of delivery. Using specialized computer software, these images are then compared to the images taken during simulation. Any necessary adjustments are then made to the patient's position and/or radiation beams in order to more precisely target radiation at the tumor and avoid healthy surrounding tissue.  
  • Electron Treatments 
    • Electrons are used in radiation therapy for superficial malignant and benign tumors such as skin cancer, scars or tumors found just below the skin surface. They release their energy near the skin and therefore tend not to penetrate deeper normal tissues below the skin’s surface. 
  • Stereotactic Radiosurgery (SRS) or Stereotactic Body Radiation Therapy (SBRT)
    • Stereotactic treatments direct high doses of radiation in precisely focused beams (on a sub millimeter scale) to treat tumors of the brain, spine and other areas of the body. For brain and spine treatments, a neurosurgeon works with the radiation oncology team to plan and deliver treatment. Treatment is delivered in a single dose or over 5 days. 
  • The Active Breathing Coordinator (ABC) is an option used for many women with left sided breast cancer to provide maximum protection to the heart during radiation treatment. 
    • What is the ABC?  It's a procedure where a device is used to monitor you while you perform "breath holds" during your radiation treatment.  "Breath holds" expand your chest and move your chest/breast further away from your heart.  This significantly reduces, or even eliminates the amount of heart included in the radiation field. 

 Internal Radiation Therapy

Internal radiation (also called brachytherapy [brake-ee-THER-uh-pee]) uses a radioactive source in the form of a wire, seed, pellet, or balloon that’s called an implant. The implant is put inside the body in or near the tumor. The radiation from the implant travels only a short distance, so it has very little effect on normal body tissues. In some cases, patients may need to stay in the hospital while getting internal radiation.
Sometimes, after a tumor has been removed by surgery, radioactive implants are put into the area where the tumor was to kill any cancer cells that may still be there.
Implants may either be left in the patient as a permanent implant or they may be removed after a certain amount of time.

There are two types of brachytherapy, high dose and low dose. Low dose brachytherapy consists of low dose radioactive seeds permanently placed inside an organ.  This is often used for prostate cancer.  High dose brachytherapy involves the delivery of radiation through a temporarily placed applicator.  This type is often used for cervical cancer. Brachytherapy can be given alone or in conjunction with external beam radiation therapy.  Your radiation oncologist will be able to provide consultation regarding this treatment here at Valley Medical Center or refer you to appropriate specialist. 

Learn more about brachytherapy in the health library.