The Role of Medical Imaging in Radiotheraputic Treatment Planing

The   radiation  therapy  simulator  is   a diagnostic x-ray machine Mounted on a rotating gantry, which provides geometric identical with those found on megavoltage therapy machines. Formerly the use ofconventionalradiography for treatment Planing is predominant. The first appearance of simulator was at 1970s. The procedure in which we used simulator is called simulation in the most general sense, the term simulation defines the Procedure. We are trying to “simulate” the therapy setup before Treatment actually begins. The specific of this process depends heavily on the reasons for which it is under taken. The most common Reasons are firstly, for accuracy of radiotherapy, it can be increased because of the ability to image the location and extension of the disease and/or normal tissues relative to the treatment fields. Also the ability to more easily mark the patient externally. Secondly, the Simulation process often serves as a focal point for the planning of a Patient’s and technical staff which all data pertaining to the particular patient. The last reasons that the simulator may increase the efficiency of the radiotherapy units because it allows questions of setup and planning to be
resolved without actually using the Machines. The use of ionizing radiation for cancer treatment has undergone extraordinary development during the past hundred years. The advancement of medical imaging has been critical in helping to achieve this change. The invention of computed tomography (CT) was pivotal in the development of treatment planning. Despite some disadvantages, CT remains the only three-dimensional imaging modality used for dose calculation. Newer image modalities, such as magnetic resonance (MR) imaging and positron emission tomography (PET), are also used secondarily in the treatment-planning process. MR, with its better tissue contrast and resolution than those of CT, improves tumor definition compared with CT planning alone. PET also provides metabolic information to supplement the CT and MR anatomical information. With emerging molecular imaging techniques, the ability to visualize and characterize tumors with regard to their metabolic profile, active pathways, and genetic markers, both across different tumors and within individual, heterogeneous tumors, will inform clinicians regarding the treatment options most likely to benefit a patient and to detect at the earliest time possible if and where a chosen therapy is working.