Image-Guided Radiation Therapy
Because tumors can move or shrink between or during treatments, radiation oncologists use imaging technologies to keep track of a tumor’s precise position. With image-guided radiation therapy (IGRT), radiation oncologists can use a single machine that provides both daily imaging to adjust the shape and angle of radiation beams as well as the actual radiation treatment. The integrated imaging and radiation system enables patients to benefit from precise targeting with one machine.
For patients undergoing IGRT, we use x-rays, CT scans, or MRI imaging to set initial treatment parameters. Additional scans are then taken before each treatment to guide the daily positioning of radiation beams and to ensure the highest accuracy.
The Siteman Cancer Center offers four types of image-guided radiation therapy:
The Gamma Knife is an advanced form of external beam radiation therapy that uses gamma rays to treat benign or malignant brain tumors.
It’s not actually a knife — there is no surgery involved. Instead, the Gamma Knife works by focusing 192 beams of radiation on a tumor. It’s ideal for tumors that are inoperable or near critical structures in the head, such as the brain stem or cranial nerves. It’s also an option for patients who have multiple tumors or for those whose age or medical condition rules out surgery.
At the Siteman Cancer Center, we jointly operate the St. Louis area’s only Gamma Knife in cooperation with Barnes-Jewish Hospital, Washington University School of Medicine and HealthSouth. Since Gamma Knife of St. Louis opened in 1998, thousands of patients have benefited from this type of radiation therapy technology.
Stereotactic Body Radiation Therapy (SBRT)
Stereotactic body radiation therapy is used to treat isolated cancerous lesions in the lung, liver, and spinal column. In this type of radiation therapy, the radiation dose can be shaped to curve around sensitive areas, such as the spinal cord, or matched to the shape of a tumor so that healthy surrounding tissue is spared.
The technology is used primarily for well-defined, early stage or small tumors such as those found
With the ability to use extremely high doses of radiation, SBRT can be done in fewer treatments, sometimes over the course of just a few days or a week, depending upon the type of cancer.
TrueBeam™ CT- Guided Radiation Therapy
One of the latest integrated IGRT systems is called the Varian TrueBeam™ Linear Accelerator. The system is ideal to treat cancer throughout the body, particularly the lungs, breast, and abdomen as well as tumors in the prostate and head and neck areas. The system, which can rotate around a patient, combines high-dose radiation with real-time imaging so that the precise tumor location is tracked even when the patient moves while breathing.
The TrueBeam is equipped with computerized automation that reduces the time needed to position, image, and then treat patients. Because of this automation, treatments are up to 50 percent faster than with other IGRT systems, with most procedures performed in less than 45 minutes.
ViewRay™ MRI-Guided Radiation Therapy
The ViewRay™ MRI-guided radiation therapy system is a breakthrough technology initially developed at Washington University. The integrated system combines radiation treatments with a continuous magnetic resonance imaging system.
MR imaging highlights soft tissue better than other imaging techniques. By using MRI to help guide radiation therapy treatments in real time, the radiation oncology team is able to see where the radiation dose is being delivered and determine if any subtle changes are occurring to the tumor or surrounding tissue. The ability for continuous soft-tissue imaging means that a patient’s treatment plan or radiation dose can be adjusted immediately if changes are noted.
ViewRay™ was developed by a Washington University physicist and evaluated by radiation oncologists here. The federal Food and Drug Administration (FDA) approved the technology for use in May 2012. We are the first location in the world to use this advanced cancer treatment technology. Ideal cases for ViewRay™ include cancers in the abdomen or pelvis, where current imaging doesn’t allow radiation oncologists to see clearly.