July 22, 2008 - Doctors at Melbourne Internal Medical Associates (MIMA) Cancer Center have become the first in Florida to treat cancer using RapidArc radiotherapy technology from Varian Medical Systems and to use this technology to deliver stereotactic body radiotherapy (SBRT) in the treatment of soft tissue carcinoma.
A 72-year-old man with Merkel cell carcinoma was treated for a soft tissue tumor in his thigh, which had developed close to where a similar tumor had been treated with conventional radiotherapy six months earlier.
"In this case, it was important that we avoid exposing the previously-treated area to any additional radiation," said Todd Dr. Scarbrough, M.D., radiation oncologist and director of the MIMA Cancer Center. "Using RapidArc, we completed each of his treatment sessions in just five minutes, including imaging and treatment. In the past, using conventional IMRT, this type of treatment would have required 30 minutes per session to complete."
RapidArc makes it possible to quickly deliver an advanced image-guided, intensity-modulated radiation therapy (IMRT) treatment with one 360 degree rotation of the treatment machine around the patient. In this case, however, Dr. Scarbrough and his team designed a treatment that was delivered with just half a rotation around the patient.
"The tumor was near the surface of his thigh, so a full arc would have exposed too much of his normal leg to the treatment beam," Dr. Scarbrough said.
Dr. Scarbrough's team planned the RapidArc treatment using Varian's Eclipse treatment planning software, which allowed them to visualize how the dose would be distributed within the patient's leg. "The RapidArc plan gave us a dose distribution that was superior to what we could have achieved with traditional IMRT," Dr. Scarbrough said. "Eclipse made it easy to create a plan that would avoid the previously-irradiated tissues. We just superimposed the dose distribution from his earlier treatments onto the new CT scans, created a structure out of that area, and instructed the software to avoid it as if it were a critical organ. It was very easy to do."
"Any time you have a spherical lesion that is deep within the body, and you want to deliver a high dose, RapidArc is going to be the ideal way to treat," Dr. Scarbrough said. "Our plan is to use RapidArc any time the treatment plan gives us a dose istribution that is equal to or better than what we can get with standard IMRT, because RapidArc is so much faster. And that's much better for our patients."
Dr. Scarbrough's team is now working on RapidArc treatment plans for a prostate and a lung cancer case scheduled to begin treatment later this month.
For more information: www.mima.com
