A special computer program which uses each patient’s own CT scan data assists the physicians and staff to map the three-dimensional location of the cancer in the body. This allows radiation beams to be accurately directed to the shape of the cancer from multiple directions and allows the physicians to increase the doses utilized without increasing the risk of side effects.
IMRT allows very precise external beam radiotherapy treatments rather than having a single large radiation beam pass through the body. With IMRT, the radiation is effectively broken up into thousands of tiny radiation beams, providing accuracy so that all beams intersect on the cancer, minimizing harm to surrounding tissues.
VMAT is a new approach to intensity-modulated radiation therapy (IMRT) that delivers precise treatments in shorter times than conventional IMRT. VMAT rotates 360 degrees around the patient, enabling the very small beams with varying intensity to be aimed at the tumor from multiple angles. Unlike helical IMRT treatments or other forms of radiation therapy, with VMAT the radiation treatment delivered to the patient can be modulated continuously throughout treatment. This means that higher doses of radiation are delivered to hit the tumor harder, and less radiation is delivered to surrounding healthy tissue. VMAT represents a major medical advance and is more comfortable for patients because they spend less time in their daily treatments. A fast, precise VMAT treatment takes 80 percent less time than conventional IMRT. Patients can be in and out of treatment quickly and return to their daily routine.
IGRT allows the imaging and targeting of the tumor directly to improve the accuracy of radiation therapy. Cone-beam computed tomography technology allows physicians the ability to see a three-dimensional image of the tumor and adapt the treatment in real time to maximize accuracy and effectiveness.
A specialized type of external beam radiation therapy is called stereotactic radiation therapy. SRT uses focused radiation beams targeting a well-defined tumor, relying on detailed imaging, computerized three-dimensional treatment planning and precise treatment set-up to deliver the radiation dose with extreme accuracy. Robotic technology is implemented to achieve the required precision. Both the X-ray delivery system (accelerator) and the patient positioner (couch) can be controlled using robots to achieve optimal target positioning with minimal patient discomfort.
There are two types of stereotactic radiation therapy:
Stereotactic radiosurgery (SRS) refers to a single or several stereotactic radiation treatments of the brain or spine. SRS is delivered by a team involving a radiation oncologist and a neurosurgeon.
Stereotactic body radiation therapy (SBRT) refers to one or several stereotactic radiation treatments within the body, excluding the brain or spine.
SRS/SBRT is best for very small tumors. Doctors use specialized scans to pinpoint exactly where within the body the tumor target is located. A customized holder may be used to keep the body perfectly still during treatment, or the treatment machine may have the ability to adjust for patient motion such as during breathing. These techniques allow doctors to give a high dose of radiation to the tumor in a short amount of time. SRS/SBRT is a type of external beam radiation therapy that can be completed in one to five days rather than over several weeks.
TBI is the delivery radiation to the entire body. It is often done before chemotherapy and a stem cell or bone marrow transplant to eliminate any diseased cells. Radiation therapy may be used alone or in combination with chemotherapy or biologic therapy.