Using Shaped Beam Surgery to Sculpt for Hard-to-Reach Brain Tumors
The new technology, called shaped beam surgery, can mold radiation beams to fit the exact size and shape of a tumor. Jefferson is the only medical center in the Delaware Valley that offers it, and one of only a few centers in the nation.
“Shaped beam surgery is a huge advance in treating both benign and malignant tumors in the brain and the spinal cord regions,” says neurosurgeon David Andrews MD, Professor and Director of the Division of Neurooncologic Neurosurgery and Stereotactic Radiosurgery. So far, the new technology has mostly been used against benign tumors in the brain. “We are curing benign tumors we couldn’t treat before,” he says, and as a result, “often restoring vision and hearing if tumors involve these functions.
“Shaped beam surgery gives us infinite flexibility to deal with lesions from the top of
the head to the bottom of the spine. We can wrap doses around structures such as the spinal cord, and can create a very high dose of radiation while leaving the cord untouched. There’s no other technology out there that can do this.”
The new technology enables specialists to focus radiation more precisely on specific targets while leaving healthy tissue virtually untouched, holding great therapeutic promise for hard-to-reach and difficult-to-treat tumors, including meningiomas, pituitary tumors, recurrent brain tumors, spine tumors, and acoustic tumors. Shaped
beam surgery relies on computers to develop and carry out a treatment plan that includes tailoring the shape and intensity of the radiation beams to fit the exact size of the tumor, while sparing healthy tissue.
A recurrent challenge in radiosurgery is to position the patient properly for radiation treatment. The new technology overcomes this in part by rotating around the patient, constantly editing the beams of radiation and adapting the shape of the beam to the shape of the tumor, in order to supply exactly what is needed at any angle.
The preparation begins with x-rays that are taken to locate the tumor. Then, along with results from a CT scan, a computer program calculates to the millimeter the best position for treating the patient’s tumor. A computer-guided treatment couch then positions the patient—and repositions him or her as necessary—moving the individual’s tumor into exactly the position needed to receive radiation. Treatment planning that might take hours, if not days, can be reduced to minutes. “This is important because many tumors are irregularly shaped, and we want to spare
healthy tissue,” notes Maria Werner-Wasik MD, Associate Professor and Director of Radiation Oncology within the radiosurgery program.
While it’s still early in its use, Dr. Andrews notes that there is evidence that the technology is already helping improve survival for individuals with the usually deadly brain tumor, glioblastoma multiforme. Preliminary data show that patients’ median survival time has improved from 12 to 19 months.
The new technology will not replace Jefferson’s on-site Gamma Knife, which is used in many similar ways for treating difficult-to-reach areas of the brain. The Gamma Knife is more likely to be used when the individual patient’s tumor requires targeting a very high dose of radiation at a very specific point in the brain. The Gamma Knife is static, whereas shaped beam surgery is dynamic.
“Shaped beam surgery does everything the Gamma Knife can do and more,” Andrews says, including treatments for various types of tumors, epilepsy, trigeminal neuralgia, and even, in some cases, obsessive compulsive disorder and movement disorders.