Our Radiation Oncologists, Dr. Roger Good, uses image guided radiation therapy, or IGRT, to help better deliver radiation therapy to cancerous tumors. This is very useful since tumors can move between treatments due to differences in organ filling or movements while breathing. IGRT involves conformal radiation treatment guided by specialized imaging tests, such as CT scans, ultrasound or X-rays. These tests are done in the treatment room just before the patient is to receive his or her daily radiation therapy treatment. The system we are using is called "ACCULOC". Three gold seed markers are implanted into the prostate to guide the delivery of radiotherapy to the prostate. These seeds are identified using the scanning machine every time you come for your radiotherapy, allowing the radiation therapist to position the treatment table to ensure the prostate is well covered by the radiation beam.
The goal of the IGRT process is to improve the accuracy of the radiation field placement, and to reduce the exposure of healthy tissue during radiation treatments. In years past, larger planning target volume (PTV) margins were used to compensate for localization errors during treatment. This resulted in healthy human tissues receiving unnecessary doses of radiation during treatment. PTV margins are the most widely used method to correct geometric uncertainties. By improving precision and accuracy through IGRT, radiation is decreased to surrounding healthy tissues, allowing for increased radiation to the tumor for control.