Image-Guided Radiation Therapy
About 50 percent of cancer patients receive radiation therapy. When delivering radiation, it’s important to target a cancer tumor and avoid the healthy tissue around it.
Imaging is done to locate the position of the tumor before treatment. However, during a course of radiation treatment, the size and shape of a cancer tumor can change from one day to the next. The tumor location can also change as a patient breathes during treatment.
Allowing Precise Delivery of Radiation
Advanced technology called image-guided radiation therapy (IGRT) compensates for these changes. IGRT uses computerized tomography (CT) that can image a tumor just before each radiation dose is delivered. If the tumor shifts, the radiation beams or the patient’s position can be corrected, allowing the precise delivery of radiation to tumors while allowing healthy tissues to receive minimal radiation.
“Artiste allows us to observe and to correct for the actual position and potential movements of a tumor during therapy,” said Christopher Schultz, MD, Medical College of Wisconsin radiation oncologist. “With multiple built-in imaging choices, Artiste has the ability to make changes in real time. Clinicians can make critical adjustments on the spot during radiation treatment.”
Froedtert & the Medical College now have four IGRT systems, offering more flexibility to match the best treatment to each patient. In addition to Artiste, the IGRT systems are:
Types of Image-Guided Cancer Radiation
Chemoembolization — a method of delivering chemotherapy directly into a tumor. Under X-ray guidance, a catheter is placed into an artery and guided to the specific artery that supplies blood to the tumor. A potent dose of a chemotherapy drug is infused through the catheter to the tumor, and the artery section is plugged to stop further blood flow to the tumor.
Radioembolization — a method of delivering a high dose of radiation directly to a liver tumor with minimal effect to healthy surrounding tissue (using a product called TheraSphere®). A catheter is placed into an artery and guided with fluoroscopy to the artery that feeds the liver tumor. Microscopic radioactive beads are infused through the catheter into the blood that supplies the tumor. The blood carries the beads directly into the tumor, with minimal injury to surrounding tissue. Froedtert & the Medical College were the first in Wisconsin to offer Therasphere® treatment.
Radiofrequency ablation — a procedure that uses radio waves to heat and kill a tumor (in the liver, lung, kidney or bone). A special needle electrode is placed in the tumor under ultrasound or CT guidance. A radiofrequency current is passed through the electrode to heat the tumor tissue near the needle tip and ablate — or eliminate — it. The heat also closes up small blood vessels, minimizing the risk of bleeding.
Cryoablation — a procedure that kills a tumor (in the liver, lung, kidney or bone) by freezing it. This involves placing a metal tube into the tumor while watching the process with ultrasound or CT. The tube is then cooled to -190°C (-360°F), and an ice ball engulfs and kills the tumor.
In addition to interventional radiology procedures, the Froedtert & the Medical College of Wisconsin Clinical Cancer Center provides many other types of treatments for cancer.