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Radiation Treatment Methods

Using Radiation Therapy to Treat Cancer

The goal of radiation therapy is to damage cancer cells, with as little harm as possible to nearby healthy cells. Radiation kills cancer cells chiefly by damaging their DNA (large molecules inside cells that control the cell’s function and carry genetic information from one generation to the next).

Radiation therapy uses high-energy radiation to shrink tumors and kill cancer cells. X-rays, gamma rays, and charged particles are types of radiation used for cancer treatment. The radiation may be delivered by a machine outside the body (external-beam radiation therapy), or it may come from a small x-ray machine or radioactive material placed in the body near cancer cells (internal radiation therapy, also called brachytherapy).

During Treatment

Radiation therapy is painless. You will not feel anything out of the ordinary during treatment but you will hear a buzzing sound. Our team monitors you throughout treatment, and they can pause treatment at any time to provide assistance.

For more information, contact us at 240-566-4100.

Learn more about your treatment options.

External-Beam Radiation

External-Beam Radiation therapy administers a broad beam of radiation from one or several directions for each treatment. It delivers low-dose beams of radiation from a few, up to 45 treatments - the intervals between each treatment allow healthy tissue, damaged during treatment, to recover.

  • 3-Dimensional Conformal Radiation Therapy (3D-CRT): One of the most common types of external-beam radiation therapy is called 3-dimensional conformal radiation therapy (3D-CRT). 3D-CRT uses sophisticated computer software and advanced treatment machines to deliver radiation to very precisely shaped target areas.
  • Intensity Modulated Radiation Therapy (IMRT): Some patients benefit from a more highly focused and shaped external beam therapy called Intensity Modulated Radiation Therapy (IMRT). The goal of IMRT is to increase the radiation dose to the areas that need it and reduce radiation exposure to specific sensitive areas of surrounding normal tissue. Your Radiation Oncologist will determine if IMRT is appropriate for you.
  • Image-guided radiation therapy (IGRT): In IGRT, x-ray images are taken immediately before each daily treatment is delivered and the patient position is adjusted using internal anatomy to make sure the treatment is on-target. These images are used by the therapists (the staff that delivers your treatment each day) to adjust your position so you receive precisely the treatment your doctor has ordered.


Radiosurgery uses small beams of radiation very accurately targeted to the tumor. The small size of the beams and their arrangement allow a high dose to be accurately placed on a tumor, with a sharp fall-off of dose outside the tumor. Because very little of the surrounding normal tissue is treated, very large doses can be given to the tumor, typically in one or a few sessions.


CyberKnife is a form of robotic radiosurgery designed to treat tumors anywhere in the body with pinpoint, sub-millimeter accuracy. With radiosurgery, damage to surrounding healthy tissue is minimized; therefore, the treatment can be completed in 1 to 5 days. Targets that move, such as a lung tumor that moves with breathing, can also be tracked throughout the treatment. Despite its name, there is no surgery involved.



Internal radiation therapy (brachytherapy) is radiation delivered from radiation sources (radioactive materials or tiny x-ray machines) placed inside or on the body. Permanent interstitial brachytherapy uses radiation sources about the thickness of a pencil lead placed within tumor tissue, such as within a prostate tumor. The sources are surgically sealed within the body and left there, even after all of the radiation has been given off. The remaining material (in which the radioactive isotopes were sealed) does not cause any discomfort or harm to the patient.

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