Nuclear Oncology

Intensity Modulated Radiotherapy (IMRT) is an advanced mode of high precision radiotherapy linear accelerators using x-ray computer-controlled for precise radiation doses to a malignant tumor or specific areas within the tumor. IMRT allows the radiation dose to conform more precisely to the three-dimensional (3-D) of the tumor by modulating (or control) the intensity of the radiation beam in several small volumes. IMRT also allows higher doses to focus on regions within the tumor while minimizing radiation exposure to surrounding normal critical structures. Treatment is carefully planned with the help of three-dimensional images of computed tomography (CT) or magnetic resonance imaging (MRI) of the patient, along with computerized dose calculations to determine the dose intensity pattern that best suits the shape of tumor. In general, combinations of multiple intensity modulated fields coming from different beam directions produce a radiation dose that maximizes individual dose to the tumor while minimizing doses to adjacent normal tissue.

Because IMRT the dose rate compared to normal tissue dose to tumor is minimized, can be given higher doses of radiation, effective and safe to tumors with fewer side effects compared to radiation therapy techniques conventional. IMRT also has the potential to reduce treatment toxicity, even at doses not increased. Because of its toxicity, IMRT compared with conventional radiotherapy, requires a slightly longer time of daily treatment, additional planning and security checks before the patient can begin treatment.

Currently, IMRT is used mostly to treat prostate cancer, head and neck, and central nervous system. IMRT has also been used in limited situations to treat breast cancer, thyroid and lung and gastrointestinal cancers, gynecological, and certain sarcomas. IMRT can also be useful to treat certain types of childhood cancers.

Radiation therapy, including IMRT, stops cancer cells from dividing and growing, which slows or stops tumor growth. In many cases, radiation therapy is capable of killing all cancer cells, thus shrinking or eliminating tumors.