Radiotherapy Centers of Kentuckiana – Louisville - Louisville, KY

Three-dimensional conformal radiation therapy (3D-CRT) uses computers, CT scans and MRI scans to create detailed, three-dimensional representations of the tumor and surrounding organs. The treatment team uses these images to shape the radiation beams to match the size and shape of the tumor. The tools used to shape the radiation beams are multileaf collimators or custom fabricated heavy metal blocks inserted between the beam and the patient. Nearby normal tissue receives less radiation exposure because the radiation beams are targeted directly at the tumor.

Computer Tomography (CT) Scanning & Simulation allows the cancer specialists to design a treatment plan specifically for the patient based on the size, location, and shape of the tumor. The patient will have three-dimensional images (CT Scans) taken. These are used with the treatment planning software that helps determine how to best deliver the radiation beams while reducing damage to surrounding areas. In some cases, it may be necessary to mark the patient’s skin with a tiny marker so that the patient is perfectly realigned in the correct position for every session of radiation therapy. The need for a temporary or permanent marker will be discussed with the patient before the simulation.

Image-Guided Radiation Therapy (IGRT) combines three-dimensional images, such as CT scans, with the precise technology of either 3-D or intensity-modulated radiation therapy (IMRT) to pinpoint and treat cancerous tumors. The images allow the cancer specialists to precisely localize the tumor each time radiation therapy is administered. This improves both accuracy of delivery and safety by reducing radiation exposure to other areas of the body including nearby tissue and organs. IGRT is used to treat tumors in areas of the body that are prone to movement, such as the lungs, liver, and prostate gland, as well as tumors located close to critical organs and tissues.

Intensity-modulated radiation therapy (IMRT) is an advanced form of external radiation treatment that allows precise targeting of tumor cells. The CT simulator localization scan or other three-dimensional images provide the radiation oncologist with an understanding of the shape and location of the tumor. With 3D planning, the radiation oncologist specifies the dose from various beams and sums up those doses to calculate the dose to tumor and normal tissue (forward planning). With IMRT, the radiation oncologist specifies the dose desired to give the tumor and the doses acceptable to the normal tissues (as low as possible). Then the computer system provides millions of alternative beam positions and the varying intensities of each beam, comparing one plan to the next until the best plan is identified. This is called inverse planning. Since each beam is broken up into many sub-beams of varying intensity the process is called intensity-modulated radiation.