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Stereotactic Radiosurgery Delivers Targeted Dose To Brain While Minimizing Toxicity

Englewood Hospital uses the TrueBeam system, which delivers high-dose stereotactic radiation therapy and is capable of treating patients in one session.
Englewood Hospital uses the TrueBeam system, which delivers high-dose stereotactic radiation therapy and is capable of treating patients in one session.

Tumors in the brain no longer need to be treated with a maximum-level radiation dose, thanks to a new radiation therapy technique used by physicians at Englewood Hospital and Medical Center.

Surgeons and radiation oncologists at the medical center are working together to target tumors while sparing surrounding brain tissue from radiation exposure.

David Dubin, MD, Chief, Radiation Oncology
David Dubin, MD, Chief, Radiation Oncology

“This stereotactic radiosurgery [SRS] technique is very sophisticated, very precise and requires a lot of remarkable technology,” said David Dubin, MD, chief of radiation oncology at Englewood Hospital. “There are a lot of extra bells and whistles that lead to remarkable outcomes for our patients.”

Dr. Dubin performs SRS using a TrueBeam Radiotherapy System (Varian Medical Systems), which allows the patient to wear a thermoplastic mask. “The patient doesn’t need screws placed in their skull for rigid-fixation SRS, which is painful. With the TrueBeam linear accelerator, there’s a form-fitting mask that allows us to make adjustments for the patient and to maintain comfort,” Dr. Dubin said.

“We have six degrees of freedom in our range of motion, so we can produce a 3-D image of the tumor that accurately accounts for pitch, roll and yaw,” he explained.

The accurate 3-D image of the tumor enables physicians to target high-dose radiation solely to the tumor. “The technology is so advanced that we can isolate the tumor in space so it receives the full dose of radiation, and the exposure to the surrounding areas is negligible,” Dr. Dubin said. “The patient is often treated completely after just one dose, and experiences no nausea, no vomiting and no blurred vision, and can go home that day.”

In cases of anaplastic glioma, adjuvant therapy often accompanies radiation therapy. A recent study (J Clin Oncol 2016;34:abstr LBA2000) found that patients who received temozolomide (Temodar, Merck) after radiation therapy experienced slower disease progression and higher five-year survival rates. “We look at the research and consider it in our treatment plan, but anaplastic glioma is a very small percentage of brain cancers,” Dr. Dubin said. “The vast majority of patients we see only need localized radiation.”

Combined, Complementary Expertise

The success of localized radiation therapy and increased patient satisfaction is the result of a team effort from the physicians and staff at Englewood Hospital. “The treatment planning is the most important part,” Dr. Dubin said. “From the patient’s primary care physician to a physicist to a nurse navigator, everybody is involved in the treatment plan.”

Dr. Dubin works closely with Kevin Yao, MD, a neurosurgeon at Englewood Hospital. “Every step is done in multidisciplinary fashion,” Dr. Yao said. “We want to preserve meaningful functional longevity for the brain, so we combine our complementary expertise to formulate a plan together. Dr. Dubin’s expertise is in delivering radiation and determining what radiation dose the brain and body can tolerate. Mine is defining what is tumor versus what are normal brain structures.”

Dr. Yao champions SRS for certain brain conditions over traditional radiation therapy, which blankets the brain. “SRS treatment is done once on an outpatient basis; there’s minimal radiation to the normal brain; and it often can be repeated if the cancer returns,” Dr. Yao said. “With traditional whole-brain treatment, you can’t repeat this type of radiation even if the tumor survives or another returns.”

Drs. Dubin and Yao typically plan surgery with an on-staff physicist, who calibrates the linear accelerator so the radiation dose will only affect the tumor. “In radiosurgery, it is essential for us to define not only the boundaries of the tumor but also the surrounding brain anatomy, so the radiation dose will only affect the tumor in the brain. This process enables us to safely treat a tumor while preserving normal brain function.”

An especially important element of planning is fusing MRI and CT scans for an accurate picture. “Neuroradiology is involved in the process from pretreatment planning to follow-up evaluations to assessing tumor response,” said Marc Herman, MD, a neuroradiologist at Englewood Hospital. “The radiation treatment plans are dependent on accurate imaging assessment. Precise localization of the tumor to provide for the most effective treatment is a critical component of this process.

“The neuroradiologists at Englewood Hospital use advanced MRI applications, including spectroscopy and perfusion imaging, to more accurately assess tumors and treatment effects to help guide management.” Englewood Hospital also uses a 3-Tesla MRI scanner, which provides the highest-resolution MRI examination in clinical practices today, to thoroughly evaluate brain tumors.

These applications provide information at the molecular level, which routine MRI cannot. In addition, this technology allows for a more accurate distinction between tumor and treatment-related changes.

Regarding Englewood Hospital’s multidisciplinary team in the treatment of brain tumors, Dr. Herman said, “It’s great to be part of this team.”

Posted March 2017

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