Department of Neurological Surgery

Computerized Photon Knife

Computer-interactive stereotactic technology has been an integral component of Vanderbilt University Medical Center's neurosurgical services since its introduction in 1987. Today, a revolutionary advance in this high technology field has provided a remarkably safe and effective means of eradicating brain tumors and other intracranial lesions, even those previously considered inoperable or those recurring after previous therapy.

The technique uses a computerized photon knife for performing stereotactic radiosurgery. It combines the extreme precision of computer-interactive stereotactic guidance, the lightning speed of enormous image processing computers for surgical treatment planning, and the harnessed energy of tightly focused photons through linear acceleration.

This unique procedure offers a new treatment option, free from many risks of conventional neurosurgery, to patients with new or recurrent tumors formerly left untreated due to the difficulty or dangers of surgical intervention.

How Stereotactic Radiosurgery is Performed
A stereotactic frame is temporarily affixed to the patient's head for the treatment, using only local anesthesia. The patient then undergoes the appropriate imaging studies necessary to define the exact location and shape of the lesion. Depending on the type of lesion, these studies may include digital angiography, CT, MRI, or PET (positron emission tomography) scanning.

The digital databases from these scanned images are entered into an intraoperative high-speed image processing computer, and a comprehensive three-dimensional map is created which defines the contours of the patient's head and pinpoints the location of the abnormality.

Once the target lesion has been defined and localized, computer-processed calculations assist the photon knife radiosurgery team in planning the precise dosimetry prescription of accelerated photons necessary to ablate the lesion. A high-precision coupling device confers an accuracy of 0.2 mm (0.005 inch) to the photon beam treatment.

X-ray photons, provided by the linear accelerator, are focused directly on the lesion, while being spread widely in broad arcs over the superficial tissues of the head. The radiation dose to the tumor is lethal, although the radiation dose to immediately surrounding normal brain tissue is minimal.

The actual photon treatment time is only 15 to 20 minutes, although the entire treatment process takes 3 to 6 hours. After the initial local anesthetic for the stereotactic frame application is administered, neither anesthesia nor analgesia is required. The patient remains awake throughout the entire process and experiences no sensation during treatment or discomfort at any time. At the conclusion of treatment, the stereotactic frame is removed, and the patient is free to return to his or her room. Typically, no side effects are noted. After a brief observation period, the patient is discharged with no restrictions on activity. Several weeks later, the patient may return for routine follow-up outpatient consultation.

A Multidisciplinary Team Effort Essential to Success
An interdependent team of highly trained and experienced subspecialists is fundamental to the successful application of the computerized photon knife. This broad foundation of exceptional multidisciplinary expertise is firmly established at Vanderbilt University Medical Center and is the reason Vanderbilt is one of only a few medical referral centers in North America at which stereotactic radiosurgery with the computerized photon knife is available.

Every patient is initially evaluated by a team of neurosurgeons subspecializing in the care of patients with arteriovenous malformations, adult and pediatric brain tumors, and seizures. The interdisciplinary surgical team includes a stereotactic neurosurgeon, radiation oncologist, radiation physicist, computer scientists and software engineers, biomedical engineers, radiation therapy technicians, radiology technicians and stereotactic neurosurgical nurses. Significantly, every member of this team participates in all phases of the procedure in order to ensure successful photon treatment delivery. Only through the concerted and cooperative effort of each specialist during every patient treatment can safe and effective results be achieved.

Computerized photon knife stereotactic radiosurgery represents a significant resource of cutting-edge technology and comprehensive multidisciplinary care. In order to guarantee optimal ongoing medical care for each patient before, during, and after treatment, the photon knife team members are committed to forging a strong professional partnership between themselves and the referring physician.

Unique Benefits of Stereotactic Radiosurgery with the Computerized Photon Knife
The advantages of treatment with the computerized photon knife are numerous:

  • It provides a treatment option for patients whose tumors or abnormalities are unsuitable for conventional neurosurgical craniotomy.
  • It provides a treatment option for those patients who are not normally candidates for conventional neurosurgical craniotomy because of age, medical condition, or patient preference.
  • Tumors traditionally considered resistant to, or recurring after, conventional radiation therapy can be successfully treated.
  • Because of its potential for limiting the risks inherent in the typical craniotomy, photon knife radiosurgery may be offered as an alternative treatment for lesions that would normally be considered operable.
  • The procedure is bloodless and painless without incision or suturing.
  • No general anesthesia is required.
  • The pinpoint accuracy of photon treatment delivery is to within 0.2 mm, or 0.005 inch.
  • There is no significant radiation exposure for the normal brain tissue, even that immediately surrounding the tumor.
  • It is essentially an outpatient procedure, without a lengthy hospitalization or intensive care unit stay.
  • Actual treatment cost is much less that for traditional craniotomies due to the short procedure and minimal recovery times.

To schedule an appointment, please have your primary care physician or referring doctor contact our clinic at (615) 322-7417.

Our mailing address:

Department of Neurological Surgery
Vanderbilt University Medical Center
1161 21st Avenue South 
T-4224 Medical Center North
Nashville, TN 37232-2380

At this time, please do not send any medical records, and provide only a brief medical history.

Our success is based on a multidisciplinary team approach to diagnosis and treatment that provides excellent continuity of care within the Vanderbilt Medical Center system. We offer state-of-the-art treatment options.

This page was last updated March 10, 2016 and is maintained by