Radiation 101: How Radiation Therapy Works

Organization: Author:
Alam Nisar M. Syed, M.D., medical director, radiation oncology and endocurietherapy, MemorialCare Todd Cancer Institute, Long Beach Memorial
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Radiation therapy is one of the most commonly used treatments for cancer. Radiation may be the primary treatment of early stage cancers, such as cancers of the head and neck, cervix, prostate, lung and Hodgkin’s disease. However, radiation therapy is more commonly used in combination with surgery and chemotherapy to treat many cancers.

All cells, whether cancerous or healthy, grow and divide to form new cells. But cancer cells grow and divide more quickly than normal cells.

Radiation therapy uses special equipment to deliver high doses of radiation to cancerous cells, killing or damaging them so they cannot repair or spread. Radiation works by breaking a strand of the DNA molecule inside the cancer cell. Unlike chemotherapy which exposes the entire body to the cancer-fighting chemicals, radiation therapy is a local treatment and does not affect the whole body.

With careful planning, radiation can be directed to the cancer and away from most normal tissues. Technology has advanced so that highly targeted radiation beams ensure precision, often down to the millimeter, minimizing exposure to healthy tissue and minimizing the side effects.

It takes time for the body to get rid of dead cancer cells. After treatment is completed, it can take several months before the tumor is completely gone.

Types of Radiation Therapy

Depending on the type of cancer, the extent of the cancer and its location, patients may receive treatment on more than one site of the body or from different angles. In addition, some people may need more than one type of radiation, which may require the use of more than one machine and technique.

There are two main types of radiation therapy, external beam radiation therapy and interstitial (internal) radiation therapy, commonly referred to as brachytherapy.

External beam radiation therapy is most often delivered in the form of photon beams (either x-rays or gamma rays). Patients usually receive external beam radiation therapy in daily treatment sessions over the course of several weeks.

Brachytherapy is a form of advanced internal radiation, where a high radiation dose is given using radioactive seeds or sources placed in or near the tumor site using applicators or plastic catheters. The radiation travels a short distance in the body to preserve healthy tissues. The procedure has a low risk for complications, minimal side effects and results in shorter treatment times.

What to Expect

Once the type of radiation therapy or therapies have been prescribed, an appointment will be made for a planning session (simulation).

During the simulation, a radiation therapist will determine the position that will be used during actual treatments. During the simulation, the radiation therapist will use computerized treatment planning systems to create 3-D tumor images allowing the dosimetrist and medical physicist to design individualized computer treatment plans.

Long Beach Memorial also specializes in providing hyperthermia, i.e. heating the tumor to 40°-44°C, along with radiation and chemotherapy to accentuate the effects of radiation.

Accredited by the American College of Radiology, the Thomas and Dorothy Leavey Radiation Oncology Center at the MemorialCare Todd Cancer Institute at Long Beach Memorial offers a comprehensive program providing a range of radiation therapy options for patients.

Alam Nisar M. Syed, MD
Featured physician:

Alam Nisar M. Syed, MD

Medical Director Radiation Oncology & Endocurietherapy, MemorialCare Cancer Institute at Long Beach Medical Center
Specialties:
  • Radiation Oncology, Radiology