Intensity Modulated Radiation Therapy (IMRT)
Intensity modulated radiation therapy (IMRT) is a sophisticated radiation therapy delivery method that allows sparing of normal tissues and increased doses of radiation which are delivered to the primary target (tumor). Very few physicians have experience with IMRT that is as long as the experience of the radiation oncologists at St. Luke’s Episcopal Hospital. They are among the most experienced physicians in the world in using IMRT.
Normal tissues and treatment areas are outlined on each CT slice. Additional imaging such as CAT scans, MRI and PET scans are often incorporated (fused) with the planning CAT scan. The treatment team along with the physician creates the optimal 3D treatment plan that highly conforms to the target shape with maximal sparing of radiation dose to the adjacent normal body structures. Targets and avoidance structures are evaluated with graphic analysis and dose to normal structures are limited to established safety guidelines. The custom treatment plan uses multiple unique beam angles and each beam has a three dimensional shape due to temporal beam modulation.
IMRT is recommended for head and neck cancers, prostate cancer, brain tumors, anal cancer, gyencologic tumors, lung cancers, recurrent cancers as well as other unique indications.
All of our IMRT utilizes modern treatment position verification which is termed image guidance radiation (IGRT) on a daily basis.
IMRT is equivalent to proton beam therapy as far as conforming the high dose portion of the radiation to the shape of the target. Class I evidence does not exist which shows superiority of protons over IMRT for any tumor type. The most common tumor that is treated with protons is prostate cancer and proton facilities have been reluctant to initiate randomized trials to determine if protons have any value for prostate cancer. Interestingly, in April of 2012, an article in the Journal of the American Medical Association suggests that proton radiation causes significantly greater gastrointestinal side effects when compared to IMRT for prostate cancer.