Intensity Modulated Radiation Therapy (IMRT)
See also: IMRT video
When cancer is diagnosed in a patient, Carolinas Hospital System offers a range of services to treat the disease. In addition to chemotherapy and surgery, radiation oncology services have been available at the hospital for the past seven years. Used to treat cancers including lung, breast, and prostate cancer, radiation therapy (also known as external beam radiotherapy) is delivered on an outpatient basis using a piece of equipment called a linear accelerator. Directed at specified areas of the body, the high-energy x-rays interfere with cancer cells’ ability to multiply and make new tumor cells and kills existing cancer cells.
Carolinas has the capability to deliver radiation therapy treatment with Intensity Modulated Radiation Therapy (IMRT). Using the linear accelerator and the Radiation Oncology Department’s sophisticated system of treatment planning technology; IMRT allows radiation to be focused even closer to the treatment site than was possible with conventional radiation therapy.
"This is the cutting edge in radiation therapy," said Dr. Rhett Spencer, a radiation oncologist on staff at Carolinas Hospital System. Because IMRT provides oncologists increased control in shaping the radiation beams, it is an excellent tool for cancers that are located in close proximity to vital organs and structures. "It allows us to make the radiation dose much more uniform and to contour or shape it more accurately to the shape of the tumor," said Dr. Spencer. "The shaping allows us to spare more normal tissue while treating the desired cancerous tissue," he explained.
The hospital is currently using IMRT primarily for prostate and breast cancers. Dr. Larry Grubb finds the technique to be particularly useful when treating prostate cancer because of the proximity of the prostate to the bladder and rectum. "Since you can define your beam better, with the same dose or a lower dose, with less exposure to normal tissue, you can increase the amount of radiation to the prostate," the radiation oncologist said "Using I-Beam ultrasound technology together with IMRT helps to further enhance targeting accuracy on a daily basis". Because less normal tissue is affected by the radiation, the use of IMRT helps minimize complications and side effects. Cure rates can also be improved through the higher doses that can be delivered closer to tumors.
While IMRT functions with an upgrade to the hospital’s linear accelerator, Dr. Spencer emphasizes that the technique encompasses far more than the accelerator itself. "It’s an overall interdepartmental system," he said, referring to the complex process involved in planning a patient’s radiation oncology treatments. This process becomes even more extensive with IMRT. Dr. Grubb added, "The entire treatment planning process is improved. A lot of things had to take place to allow us to do IMRT; a lot of technology had to improve."
Dr. Spencer notes that all tumors do not require the use of IMRT, explaining, "In many instances this would not be the optimal form of treatment, and we still retain the ability to treat with conventional radiation therapy." In the future, radiation oncologists plan to utilize IMRT at Carolinas to treat head and neck cancers, as well as other types of cancers. "It’s probably the biggest advance we’ve seen since the linear accelerators came out," Dr. Grubb said. "It’s as state of the art as there is," added Dr. Spencer, noting, "It’s the speed and power of the treatment planning computer that allowed this jump in technology. The computer technology to drive this is huge."
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