Park Nicollet Cancer Center at Park Nicollet Methodist Hospital in St. Louis Park became the first facility in the state to install the Novalis shaped-beam robotic surgery system last May. The system, made by the German company BrainLab, provides a non-invasive alternative to cancer surgery, and is designed to pinpoint tumors in some of the most sensitive places in the body.
“It’s for lesions [or tumors] that are less than 10 centimeters in size. Larger treatment areas are not eligible,” says Michael Weber, medical physicist at Park Nicollet Methodist Hospital. His job is to manage the new technology and implement the doctor’s treatment plan for patients. Weber says many different cancers can be treated with the new equipment. Patients range from those with brain tumors needing a high-dose, single-treatment radiosurgery, to patients with lung lesions, liver lesions, and lesions of the spine that require higher dose treatments that may take three to five treatments. Some patients with pituitary tumors, prostate tumors, and some cancers of the head and neck may be treated with 25 to 40 lower-dose treatments.
The system comprises two main parts: software that takes images from different diagnostic scans, such as magnetic resonance imaging (MRI), and combines them into one image, helping the operator accurately direct the radioactive beams; and the Novalis machine, which has a motorized bed that precisely positions a patient for treatment. The software maps the tumor and programs coordinates for radioactive beams. Novalis beams are shaped to match the contours of a tumor so that irregularly shaped tumors get a full dose of radiation, leaving more healthy tissues untouched compared to traditional radiation therapy.
Weber says the Novalis allows him to deliver a more complex dose to patients. During treatment, the robotic arms move around the patient to deliver beams to the whole tumor from different angles. The software tracks the patient’s movements and adjusts on the fly to make sure treatment is accurate.
He describes the process for a patient with a brain tumor. “Once its determined that a patient is eligible for the treatment, we’ll take them in the CT [computed tomography, or CAT scan], and we’ll build a mask that goes on the patient’s head [to keep it in proper alignment during the treatment], and we’ll take a CT for planning purposes. At that point, the patient might get additional diagnostic scans, like an MRI.”
It takes a while to develop a treatment plan. When the patient returns, he or she gets into position with the help of the mask. “We’ll take X-rays and then line up the X-rays with images from the CT,” Weber says. “That gives us shifts in terms of a tenth of a millimeter and one-tenth of a degree [from the position the patient was in during the first CT].”
The treatment takes about 20 to 30 minutes depending on the size and location of the cancer, and patients can listen to music on earphones. Weber says a patient can be in and out of the hospital within an hour. With older treatments, a patient could spend eight hours at the hospital.
Weber adds: “Radiosurgery allows patients to decrease their steroid dependence, which means a better quality of life.”
