Gamma Knife®

A revolution in advanced radiation treatment.

What is Gamma Knife?


Gamma Knife is an advanced, noninvasive treatment method that uses extremely precise beams of radiation to pinpoint tumor deposits, leaving the surrounding healthy tissue unharmed. Today, children and adults with a variety of neurological conditions and vascular malformations can take advantage of this breakthrough technology in a single session, with no overnight stay required.

Despite its name, Gamma Knife is not a blade at all; rather, a means of targeting highly precise radiation to abnormalities as small as 1/8 inch in diameter. In the experienced hands of expert Geisinger Holy Spirit physicians, this treatment can effectively help with a wide variety of disorders, including brain tumors, epilepsy and other abnormalities that can cause chronic pain. It minimizes the amount of radiation risk to the normal brain and is perfect for surgery in areas of the brain where surgery would otherwise be dangerous.

As with all advanced technologies at Geisinger Holy Spirit, the patient is assessed and supported through the procedure by a broad team of highly skilled, compassionate professionals, including oncologists, neurosurgeons and specialized nursing staff. This state-of-the-art treatment is just another way Geisinger Holy Spirit is caring for you.

Why choose Holy Spirit Gamma Knife?

Geisinger Holy Spirit is only the second health provider in Pennsylvania to utilize the Leksell Gamma Knife® Icon™ — a device that’s the gold standard for precision in radiosurgery.

Its capabilities include:

  • Adaptive Dose Control™ — ultra-precise radiation dosage throughout your entire procedure
  • Frameless workflow — a more comfortable experience, with little to no loss in treatment accuracy
  • Microradiosurgery capabilities — allowing for the lowest, most exact dosage amount possible

Advantages to patient

  • Performed by a highly skilled neurosurgery team with extensive Gamma Knife experience
  • Safe option for patients unable to undergo invasive surgery (frameless treatment available where warranted)
  • Outpatient procedure with a quick recovery time
  • Backed by Geisinger, a known leader in neurosurgery
  • Treats multiple tumor areas in one convenient session
  • Cost-effective (covered by PPOs, HMOs and Medicare)


If you’re coming from a distance and prefer to stay overnight, here is a list of hotel accommodations in the Camp Hill/Harrisburg area.

Flexible scheduling options available
880 Century Drive
Mechanicsburg, PA 17055


Holy Spirit Gamma Knife team

Jonas Sheehan, MD, FAANS, FACS
Medical school: University of Virginia School of Medicine
Residency: University of Virginia School of Medicine
Fellowship: Auckland Hospital, Auckland, New Zealand
Board certification: Neurological surgery

Dr. Sheehan has completed more than 2,000 brain tumor procedures and has maintained a 0 percent surgical infection rate over the past two years. He was on the list for Best Doctors in America, from 2007 to present, and Guide to America’s Top Surgeons, from 2008 to present.

Holy Spirit Neurosurgery
American Office Center
423 N. 21st St., Suite 300

Camp Hill, PA 17011

Ashraf Youssef, MD
Medical school: Ain Shams University, Cairo, Egypt
Residency: New York Methodist Hospital
Fellowship: New York Methodist Hospital
Board certification: Radiation oncology

Dr. Youssef is the medical director at Holy Spirit Cancer Center. He most recently worked for AtlantiCare in New Jersey, the newest member of Geisinger Health System. In addition to serving as a faculty member for several university radiation oncology programs, Dr. Youssef also served as medical director for the former Fox Chase Cancer Center.

880 Century Drive
Mechanicsburg, PA 17055


Lesly Miller-Jacobs, RN, CRNI, RNC-OB
Lesly has been a registered nurse for 28 years and holds two national certifications. She has practiced a wide variety of roles throughout her career, serving the Harrisburg community. She’s been with Geisinger Holy Spirit since 1998.

In her current role as an oncology patient navigator, Lesly assists patients in all aspects of preparation, treatment and follow-up to Gamma Knife procedures.

Holy Spirit Cancer Center
880 Century Drive
Mechanicsburg, PA 17055


Get in touch with us

If you have questions about Gamma Knife treatment options or scheduling, you can reach our patient navigator, Lesly Miller-Jacobs, at 717-691-3235 or fill out the form below to be contacted at a time that best suits you.