American Shared Hospital Services Shares News Regarding Proton Therapy System under Development by Mevion Medical Systems, Formerly Still River Systems

SAN FRANCISCO--()--AMERICAN SHARED HOSPITAL SERVICES (AMEX:AMS), a leading provider of turnkey technology solutions for advanced radiosurgical and radiation therapy services, today shared a recent announcement from Mevion Medical Systems, Inc., formerly Still River Systems, Inc., regarding progress in the development of Mevion's compact proton therapy system. AMS owns preferred stock in Mevion and is developing proton therapy centers in Boston (Tufts Medical Center), Orlando (Orlando Regional Healthcare) and Long Beach, California (Long Beach Memorial Medical Center) which are expected to employ the MEVION S250 proton therapy device:

Mevion Medical Systems Delivers the World's First Superconducting
Synchrocyclotron for Proton Therapy to Barnes Jewish Hospital

Delivery Marks a Technical Triumph and the First Step
in Providing Accessible Proton Therapy Solutions

Littleton, MA - October 31st 2011 - Mevion Medical Systems announced today it has delivered the world's first superconducting synchrocyclotron to the S. Lee Kling Center for Proton Therapy at the Siteman Cancer Center at Barnes Jewish Hospital and Washington University School of Medicine in St. Louis MO. This inaugural shipment marks the last phase of the manufacturing of the first MEVION S250 proton accelerator module and the first of many to come deliveries of this revolutionary cancer therapy device.

The synchrocyclotron was delivered after a 1,200 mile, 4-day trip from Mevion's Headquarters in Littleton MA to St. Louis MO. "It was a very rewarding day to see our first system leave our factory knowing that what we have achieved may affect and improve the lives of cancer patients," stated Joseph K. Jachinowski, chief executive officer of Mevion Medical Systems. "The innovative design of the MEVION S250 makes adding proton therapy remarkably easier for our hospital partners than what was previously available."

Powered by a TriNiobium CoreTM, the high-energy proton source of the MEVION S250 will preserve all of the treatment benefits of conventional proton treatment systems while removing the obstacles of size, cost and complexity that have limited the wide adoption of this promising cancer treatment modality. The MEVION S250 Proton Therapy System combines a patented, gantry-mounted proton source with a highly integrated, image-based workflow and robotic patient positioning, making proton therapy a practical clinical reality.

Similar to traditional radiation therapy systems in terms of footprint, workflow, and throughput, the MEVION S250 will easily integrate within existing radiation therapy departments to deliver innovative cancer care in a very conventional way. "Barnes Jewish Hospital prides itself in providing the most advanced technologies to its patients. We are delighted to add this latest development in radiation therapy to our cancer-fighting arsenal", says Jeff Bradley, MD, director of the S. Lee Kling Center for Proton Therapy at Siteman Cancer Center.

This installation of the MEVION S250 at Barnes Jewish Hospital is to be completed early next year. Two additional facilities are also in the midst of installation; Robert Wood Johnson University Hospital in New Brunswick, NJ and Oklahoma University in Oklahoma City, OK. Both of these installations are also to be completed in 2012.

ABOUT MEVION MEDICAL SYSTEMS

Mevion Medical Systems, Inc. (formerly Still River Systems, Inc.) is a radiation therapy company dedicated to advancing the treatment of cancer. As the pioneering developer of modern proton therapy systems, Mevion provides innovative, safe, and effective solutions by transforming advances in medical technology and science into practical clinical reality.

Mevion's flagship product, the MEVION S250 Proton Therapy System, is designed to preserve all of the treatment benefits of traditional proton therapy systems while removing the obstacles of size, cost, and complexity. Realizing this vision, Mevion has forever changed the economics and accessibility of proton therapy worldwide.

Founded in 2004, Mevion is a privately held company headquartered in the Boston metropolitan area with international offices in the United Kingdom and Japan.

The United States Food and Drug Administration has not cleared the MEVION S250 Proton Therapy System for clinical use.

Visit us at: www.mevion.com

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Contact:
Melanie M. Miller
Marketing & Communications Coordinator
Mevion Medical Systems
E: melanie@mevion.com
P: 978.540.1551

About AMS

American Shared Hospital Services provides turnkey technology solutions for advanced radiosurgical and radiation therapy services. AMS is the world leader in providing Gamma Knife radiosurgery equipment, a non-invasive treatment for malignant and benign brain tumors, vascular malformations and trigeminal neuralgia (facial pain). The Company also offers the latest IGRT and IMRT systems, as well as its proprietary Operating Room for the 21st Century® concept. Through its preferred stock investment in Mevion Medical Systems, Inc., formerly Still River Systems, AMS also plans to complement these services with the MEVION S250 proton beam radiation therapy (PBRT) system, which has not yet been approved by the FDA.

Safe Harbor Statement

This press release may be deemed to contain certain forward-looking statements with respect to the financial condition, results of operations and future plans of American Shared Hospital Services, which involve risks and uncertainties including, but not limited to, the risks of the Gamma Knife and radiation therapy businesses, the risks of developing The Operating Room for the 21st Century program, and the risks of investing in a development-stage company, Mevion Medical Systems, Inc., without a proven product. Further information on potential factors that could affect the financial condition, results of operations and future plans of American Shared Hospital Services is included in the filings of the Company with the Securities and Exchange Commission, including the Company's Annual Report on Form 10-K for the year ended December 31, 2010, the Quarterly Report on Form 10-Q for the quarters ended March 31, 2011 and June 30, 2011, and the definitive Proxy Statement for the Annual Meeting of Shareholders held on June 9, 2011.

Contacts

American Shared Hospital Services
Ernest A. Bates, M.D., (415) 788-5300
Chairman and Chief Executive Officer
e.bates@ashs.com
or
Berkman Associates
Neil Berkman, (310) 826-5051
President
info@berkmanassociates.com

Release Summary

American Shared, a leading provider of turnkey technology solutions for advanced radiosurgical and radiation therapy services, today shared a recent announcement from Mevion Medical Systems, Inc.

Contacts

American Shared Hospital Services
Ernest A. Bates, M.D., (415) 788-5300
Chairman and Chief Executive Officer
e.bates@ashs.com
or
Berkman Associates
Neil Berkman, (310) 826-5051
President
info@berkmanassociates.com