Department of Radiation Oncology


Gamma Knife

Introduction to the Gamma Knife Program

The Gamma Knife is a safe, non-invasive, technologically advanced device for treating deep–seated brain tumors and Arteriovenous Malformations (AVM's). With the Gamma Knife, many conditions, including those that were once considered inoperable, can now be treated without incision and with little or no pain.

At the Center for Radiosurgery at New York Presbyterian, the University Hospital of Columbia and Cornell, one of the largest and most respected medical centers in the nation, Gamma Knife treatment is provided as part of a full spectrum of precision radiation therapy techniques.

These therapies (including stereotactic radiosurgery, fractionated radiotherapy, and intensity modulated radiation) are supported by highly trained and experienced staff, who share in the Center for Radiosurgery's long tradition of developing and employing the most effective new procedures and technologies. The Center for Radiosurgery has the broadest range of resources available to help determine the appropriate treatment.

By welcoming the involvement of both patient and referring physician in the therapeutic process and through close, personal attention to individual patient needs, the Center for Radiosurgery has created a very special environment, dedicated to providing complete supportive care and promoting optimum healing.

How the Gamma Knife works

The Gamma Knife is not a knife, but rather a highly developed treatment system, capable of directing up to 201 beams of gamma radiation to converge, with pinpoint accuracy, on a targeted abnormality within the brain. When concentrated, the rays provide enough radiation to treat the diseased area effectively, while the low intensity of each individual beam ensures the safety of the surrounding healthy brain tissue.

The Procedure

On the day of treatment, the patient is fitted into a stereotactic headframe, which allows for precise localization of the abnormality throughout the day's procedures. The patient then undergoes the appropriate imaging method (MRI, CT scan, angiogram), which determines the size and position of the tumor or AVM. With imaging studies completed, the patient has an opportunity to relax; meanwhile, the Gamma Knife team, comprising of many specialists, uses the system's computer program to help plan the course of treatment.

The target area of the brain and the appropriate radiation dosage are established in a short period of time. Now ready for the Gamma Knife, the patient lies down with his or her head still secured in the stereotactic headframe, which is positioned inside a large metal helmet, called a collimator. The collimator will direct the system's radiation to the pre-determined points in the patient's brain. Next, the patient slides into the Gamma Knife's sphere, which contains the source of radiation.

Treatment usually consists of a series of exposures, each lasting approximately 10 minutes. Patients experience little or no discomfort; most go home the same day.

Gamma Knife Benefits

With the Gamma Knife, post-treatment complications are greatly reduced and areas of the brain for which other therapies or conventional surgery are ineffective can be successfully treated. The Gamma Knife's precision and safety make it highly appropriate choice for both pediatric and adult patients.

Conditions Successfully Treated

The range of diseases effectively treated by the Gamma Knife includes:

    • Vascular lesions such as arteriovenous malformations (AVMs)
    • Acoustic neuroma
    • Meningioma
    • Pituitary Tumors
    • Pineal Tumors
    • Metastases
    • Glial and astrocytic tumors
    • Skull base tumors
    • Other benign and malignant tumors
    • Trigeminal neuralgia

The list of uses of the Gamma Knife continues to expand, as a result of ongoing research and development.

Additional Radiosurgery Choices

In addition to the Gamma Knife, the Center for Radiosurgery provides two other types of non-invasive precision radiation treatment, each appropriate for particular brain abnormalities. Both employ stereotactic methodology for highly accurate three-dimensional targeting.

Linear Accelerator-Based Stereotactic Radiosurgery is suited for larger targets. Linear Accelerator technology provides radiation in the form of a single highly focused beam applied in multiple sweeps around the brain lesion. This method also permits multiple smaller-dose, or fractionated, stereotactic radiotherapy, which offers advantages for appropriately selected patients.

The 3-D Conformal Intensity Modulated Radiation Therapy "IMRT" System uses varying beam-intensity modulation technology, enabling the shaping of radiation to correspond precisely to the target site. This technology, which can also be given with fractionation, is favored for larger, irregularly shaped lesions surrounded by healthy tissue that is especially sensitive to radiation.

A Philosophy and an Invitation

"Since our first radiosurgical treatment in 1989, we at the Center for Radiosurgery of New York Presbyterian, the University Hospital of Columbia and Cornell, have continuously expanded our technology and experience for the sole goal of improving the health of our patients and the well-being of their families.

Advancements in radiosurgery, such as Gamma Knife, while impressive and effective, are ultimately the means, and not the end, of our efforts to improve the lives of our patients. Our personal commitment and that of our colleagues at this world-renowned medical center are to be able to provide all the possibilities of modern medicine to help our patients. On their behalf, we remain dedicated to the belief that the quality of the physician-patient relationship defines the excellence of the care we wish to practice.

To the readers of this message, who are most probably interested in treatment for either themselves or those entrusted to their care, we extend a genuine invitation to become acquainted with us and our facilities, and with the kind of healing we are ready to provide."

Michael Sisti, M.D.
Co-Director, The Center for Radiosurgery
Department of Neurological Surgery

Steven Isaacson, M.D.
Co-Director, The Center for Radiosurgery
Department of Neurological Surgery

To learn more about the skilled team of medical professionals at the Center for Radiosurgery, please call (212) 305-0927 or 1 (877) PH-GAMMA (1-877-744-2662), or email the Program Director, Jerry Lesser,MS, RN at

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