Radiation therapy is a treatment with high doses of energy waves, such as X-rays, gamma rays, protons, or electron beams, to destroy cancer cells or limit their ability to grow and divide. Traditionally, radiation therapy is given by directing the energy beams at the tumor from a single point above the body. The goal of radiation therapy is to deliver as much radiation to the tumor as possible and limit the damage to healthy cells. However, since the energy waves must travel through healthy tissue to reach the tumor, some normal cells are affected.

Common side effects of radiation therapy are skin changes and fatigue. Other side effects are related to the area of the body targeted for treatment. Radiation therapy to the head and neck area can lead to hair loss, dry mouth, difficulty swallowing, changes in taste, headaches, hearing problems, seizures or problems with memory. Treatment to the chest area can cause cough, shortness of breath or swallowing difficulties. In the area of the stomach or pelvis, radiation therapy can lead to nausea, vomiting, diarrhea, bladder problems, sexual dysfunction or changes in fertility.

Two other techniques are sometimes used to limit the side effects of radiation therapy. With three-dimensional conformal radiation therapy (3D-CRT), the beams of energy are aimed from different directions. A body mold is made to keep the patient still and in the same position for each treatment. That enables doctors to aim the energy beams more precisely, giving higher doses of radiation to the cancer cells and less to normal, healthy cells. Intensity-modulated radiation therapy (IMRT) is similar to 3D-CRT, but the strength of the beams can be varied to lessen the amount of energy going through normal tissues.

Lawrence Tena, M.D., Radiation Oncologist with St. Vincent's Comprehensive Cancer Center in New York City, says traditional radiation therapy requires the patient to remain absolutely still for 20 to 30 minutes or longer. If the patient moves even a tiny bit, some of the radiation beams may miss the tumor and hit healthy tissue, potentially reducing the effectiveness of the treatment and leading to more side effects. Body molds used in 3D-CRT and IMRT help keep the patient in position, but can be uncomfortable.

A new technique, called RapidArc™, uses the principles of IMRT to deliver a dose of external radiation in just a few minutes - a fraction of the time needed for standard radiation therapy. Prior to getting RapidArc, the patient is placed in a body mold. This ensures the patient stays in place and is in the same position for every treatment. Next, several imaging scans are taken of the target area of the body to map the location, size and shape of the tumor. The images are reviewed and a computer calculates the treatment plan. Finally, a radiation delivery machine, called a linear accelerator, swings 360 degrees around the patient, delivering precise, calculated doses of radiation targeting the tumor. A single treatment takes under two minutes and requires only one rotation of the linear accelerator.

Tena says with the rapid treatment time, there is less damage to normal tissues and patients have fewer side effects. Since patients are getting the same dose of radiation, treatment results should be similar to those achieved with standard radiation therapy. RapidArc can be used for most cancers that can be treated with traditional radiation. Tena says the technology is ideal for head and neck cancers because patients often have long treatment sessions and need to have a restrictive mask to keep the head still.

For information about RapidArc™, or to locate the nearest facility offering the therapy, go to http://www.varian.com/us/patient/treatments/rapidarc.html