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Gamma Knife / Stereotactic Radiosurgery
The radiation oncologists of Cancer Care Consultants staff two facilities which offer stereotactic radiosurgery (SRS) for management of a variety of tumors and conditions of the brain and skull base. Both linear accelerator (LINAC) and Gamma Knife stereotactic radiosurgery are alternatives to traditional craniotomy (skull-opening) brain surgery for treating many benign and malignant tumors. SRS offers a good to excellent chance of stopping the growth of tumors and preventing the bleeding of arteriovenous malformations (AVMs) without necessarily involving traditional surgical or radiation techniques. It is generally considered a gentler approach of treatment when compared to traditional surgery. It may also be the preferred treatment choice in cases where the lesions are considered to be in inoperable locations.
Some indications for radiosurgery are:
Tumors (both benign and malignant):
- Metastatic brain tumors from various cancers
Meningiomas
- Head and neck tumors invading the skull base
- Acoustic neuromas
- Chordomas
- Chondrosarcomas
- Pituitary adenomas
- Craniopharyngiomas
- Tumors of the eye, including uveal melanoma
- Glomus tumors
- Gliomas
Vascular disorders
- Arteriovenous malformations (AVM)
Functional disorders
- Trigeminal neuralgia
- Essential tremor
- Parkinsonian tremor
SRS is suitable for patients who cannot have standard surgery due to other medical conditions or advanced age. In some patients, it may be preferable to craniotomy (skull-opening surgery) and tumor resection by offering comparable rates of tumor control without having to open the skull. In some instances, SRS may be more safely done to tumors located in areas that are too dangerous for traditional surgery to address.
The goal of SRS is to deliver highly focused radiation beams to destroy the desired target while leaving the adjacent structures relatively untouched. SRS concentrates a high dose in the abnormal tissues (usually tumors or abnormal blood vessels). Such treatment results in a halting of the growth of tumors, often shrinking them in size and in some cases causing their disappearance. AVMs can be obliterated, reducing their risk of causing harmful bleeding. Similar treatment can also be done to treat functional abnormalities such as trigeminal neuralgia or tremor.
GammaKnife® SRS
The GammaKnife® consists of 201 small radioactive sources spaced around a spherical chamber in such a way that all of the sources aim their radiation at a central point. The patient's head is placed in this chamber for immobilization during treatment to assist with targeting of the lesion. The tumor or AVM can be positioned in the exact center of all the radiation beams, where a high dose of radiation is then delivered. This treatment is usually only given in a single session and has become the most well established form of SRS available, with over 300,000 patients having been treated with this technology worldwide and over 2,000 peer reviewed journal articles written on such treatments.
After having consultations with the Radiation Oncologist and Neurosurgeon, the patient is brought to the hospital the morning of the planned procedure. The patient has a special frame attached to the head in a minimally invasive fashion. With the frame in place, the patient then undergoes an MRI or CT Scan. Once the scan has been obtained, the patient is taken to the GammaKnife® suite for treatment. While the patient rests, the physicians and medical physicist design an individualized treatment plan from the computerized MRI or CT-scan images. When the treatment plan is finished, treatment proceeds. The patient will lie on the treatment table designed to accommodate the head frame at a precise position so that the target is directly in the center of all the radiation beams. The patient will see several people in the GammaKnife® suite including the Radiation Oncologist, a Neurosurgeon, a Nurse, and Medical Physicist. Once the treatment is completed, the physicians will remove the head frame. The patient will be placed in an observation area for a short period. If there are no issues and the patient feels well enough, he or she will be discharged home. Rarely would one need to be kept in the hospital overnight. In fact, most patients are back to their usual daily activities within a few days of the treatment.
The effects of the SRS treatment, given with either Gamma Knife® or LINAC, occur over time. Radiation stops the growth of tumor cells and therefore the lesions or tumors can shrink and sometimes disappear over several weeks or months as the tumor cells die. Most treatable lesions will stop growing.
Patients usually do not experience significant side effects, since most of the high dose radiation is delivered only into the target area, with very little radiation dose in the surrounding sensitive tissues of the brain. Rarely, radiation induced edema and necrosis may occur, leading to neurological problems. Often times, these effects are easily managed by medication.
The radiation oncologists of Cancer Care Consultants perform Gamma Knife SRS at Northridge Hospital Medical Center, the only Gamma Knife facility in the San Fernando Valley. Drs. David Huang, Afshin Safa, and Michael Steinberg have special training in this modality and have extensive experience managing such cases.
For a consultation appointment with our Radiation Oncologists, please contact the Department of Radiation Oncology at Northridge Hospital at 818-885-5331. At the time of your appointment, please bring a copy of your latest MRI or CT images, along with any available medical records.
LINAC SRS
LINAC SRS is performed on a standard radiation therapy machine that is outfitted with certain modifications, capable of delivering a complex set of beams, concentrating high doses of radiation into tumors. This is generally done using sets of rotating arcs of radiation beams directed at a common central point.
One of the advantages of such machines is the ability to perform both single fraction treatments and multiple fraction treatments (which may be advantageous for larger tumors). Indications are otherwise similar to those of Gamma Knife SRS. An exception is that trigeminal neuralgia is not typically treated with this technique.
The treatment technique is slightly different. The immobilization is done again by a neurosurgeon, who places several pins into the skull. These pins are used to help immobilize the patient on the LINAC table for the treatment, assuring the patient’s head remains absolutely still for the high dose radiation treatment directed to the target. The plan is created using CT and MRI scans, with the data input into the treatment planning computer. The Radiation Oncologist, Physicist, and Neurosurgeon work together to approve the treatment plan. Subsequently the treatment is delivered in a single session or multiple sessions as indicated.
Dr. David Khan, Dr. Kenneth Wong, and Dr. David Huang are experienced Radiation Oncologists who treat patients with benign and malignant tumors with this technology. To schedule a consultation, please call the Department of Radiation Oncology at Centinela Freeman Regional Medical Center at 310-419-8353. At the time of your appointment, please bring a copy of your latest MRI or CT images, along with any available medical records. |
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