What types of radiation therapy treat prostate cancer?

There are two main types of radiation therapy used to treat prostate cancer:

• External beam: involves a computer aiming radioactive rays at your prostate from outside your body to kill cancer cells.

• 3D conformal radiation therapy (3D-CRT): 3D-CRT uses special computers to precisely map the location of the prostate. This mapping makes it possible to aim the radiation treatment directly at the prostate, avoiding other structures.

Intensity Modulated Radiation Therapy (IMRT): an advanced form of 3D-CRT with the same three-dimensional mapping capability. IMRT uses a computerized machine that moves around you to deliver radiation beams from different angels. IMRT allows physicians to adjust the strength of each radiation beam to minimize the doses that reach more sensitive tissue. The placement of three gold markers within the prostate is required to indicate the precise location of the prostate before treatment begins.

Calypso 4D System: The Calypso 4D System uses radiofrequency waves that allow for very accurate alignment of your prostate for each treatment session. It monitors the position of the prostate at all times during radiation treatment delivery. Three tiny transponders are implanted in your prostate and are required to monitor the prostate in real time throughout your treatment. Calypso allows your physicians to monitor exactly where the prostate is at all times to make quick and important decisions about your care.

CyberKnife: Surgeons are now utilizing the CyberKnife radiosurgery system, a robotic arm that can provide large and precise doses of radiation to tumors and reduces the number of treatments needed from 40 over an eight-week period to five or so over a week. Placing fiducial markers accurately identifies the prostate. Similar to surgery, radiation treatment can cause impotence, though it may not occur right away after the surgery but rather over time.

• Brachytherapy: involves implanting radioactive seeds in your prostate to kill cancer cells. This method of treatment may have fewer side effects.