How is IMRT different than conventional radiotherapy?
The first difference is how we plan treatment. With IMRT, planning is done using sophisticated computer software that shapes the radiation dose to what the radiation oncologist specifies. Treatment is planned using 3-D computed tomography (CT) images of the patient in conjunction with computerized dose calculations to determine the dose intensity pattern that will best conform to the tumor shape. The second difference is how treatment is delivered. Instead of radiation coming out of the machine uniformly using a single beam, in IMRT there are as many as 80-120 sliding metal leaves that are used to shape the beam to fit the specific shape of the tumor or treatment site. The beam is actually composed of thousands of tiny beamlets. The metal leaves and manipulability of the beam prevents radiation from getting to nearby healthy tissue.
