(AMS) World’s First MEVION S250 Proton Therapy Treatment Delivered

AMERICAN SHARED HOSPITAL SERVICES (NYSE MKT:AMS), a leading provider of turnkey technology solutions for advanced radiosurgical and radiation therapy services, today shared an announcement from Mevion Medical Systems, developer of the MEVION S250 Proton Therapy System for cancer treatment, that the world’s first MEVION S250 proton therapy treatment has been delivered to a patient at Barnes-Jewish Hospital in St. Louis.

AMS Chairman and Chief Executive Officer Ernest A. Bates, M.D., said, “Treatment of the first patient on the MEVION S250 Proton Therapy System is a major step in increasing the availability of this cutting-edge cancer fighting technology. Until now, widespread adoption of proton therapy has been limited by the high capital and operating costs of conventional systems. Because of its significantly lower capital and operating costs, we believe many leading cancer centers will now consider providing proton therapy with the MEVION S250 system. AMS’s proven financing model can help make this happen. AMS’ first MEVION S250 system is under installation at Orlando Health in Orlando, FL. We currently have commitments for two additional MEVION S250 systems and anticipate that we will place many more orders.”

AMS owns an equity interest in Mevion, and will supply a MEVION S250 for the proton center now under construction at Orlando Health, in addition to other projects under development:

World’s First MEVION S250 Proton Therapy Treatment Delivered at Barnes-Jewish Hospital

Landmark event represents a new era in radiation therapy.

ST. LOUIS, M.O., December 19, 2013 — A patient with a rare type of cancer called chondrosarcoma at the base of the skull has become the first person in the world to receive proton therapy using the revolutionary MEVION S250 Proton Therapy System from Mevion Medical Systems, Inc. of Littleton, MA. Radiation oncologists at the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis delivered the treatment. The S. Lee Kling Proton Therapy Center at Barnes-Jewish Hospital is home to the MEVION S250, a unique proton therapy device designed to deliver the same precise, non-invasive treatments delivered by conventional proton systems but with a greatly reduced physical footprint, streamlined clinical workflow, and significantly lower implementation and operational costs.

“We are extremely pleased and proud to open the Kling Proton Therapy Center for the St. Louis community and beyond,” said Rich Liekweg, President of Barnes-Jewish Hospital. The closest proton therapy center is over 230 miles away from St. Louis. “The ability to add proton therapy to our world-class cancer care program in a significantly smaller and more economical package is imperative in today’s challenging health care environment. Barnes-Jewish Hospital is the first in the world to operate a single-room proton therapy system and the addition of this advanced technology continues our tradition of providing the best care for our patients.”

Proton therapy delivers highly precise doses of radiation while limiting unnecessary radiation to healthy tissue, potentially decreasing radiation side effects and improving patient outcomes. Mevion’s ability to provide this advanced treatment in a compact form is an industry first, leading the way in providing patients and clinicians access to proton therapy without the high entry and maintenance costs plaguing conventional proton systems. “Today’s important landmark event represents the beginning of a new era in proton radiation therapy. The ability to treat with this advanced technology is no longer encumbered by astronomical costs, prohibitive space requirements, and technologically cumbersome systems that to date have defined this treatment modality,” stated Joseph K. Jachinowski, Chief Executive Officer of Mevion Medical Systems. “The MEVION S250 proves that all the benefits and more of these legacy proton therapy systems can be delivered in a fiscally responsible manner.”

The pioneering proton team at the Kling Proton Therapy Center has been working diligently for the past several months running the MEVION S250 through independent and rigorous clinical quality assurance tests to ensure that system specifications, safety, and reliability requirements are met. “The advanced clinical workflow provided by the MEVION S250 and its full integration within the clinic has made it simple and straightforward to train the radiation therapy staff and prepare their clinic for day-to-day treatments,” said Dr. Stanley Rosenthal, Vice President of Clinical Systems and Education. “The initial training experience of the therapists demonstrates that the MEVION S250 workflow and delivery times are comparable to today’s image-guided radiation therapy techniques.”

“The teams from Barnes-Jewish Hospital and Mevion have worked tirelessly and diligently to arrive at this seminal event. The opportunity to bring a revolutionary medical device into routine clinical use that will improve the lives of many people around the globe isn’t something that happens often. We have all been touched by this event and we couldn’t be prouder to be a part of this team,” added Jachinowski.

Four additional MEVION S250 proton therapy systems are under installation at Robert Wood Johnson University Hospital in New Brunswick, NJ, the Stephenson Cancer Center at Oklahoma University in Oklahoma City, OK, First Coast Oncology in Jacksonville, FL and the Proton Therapy Center at Orlando Health. In addition, the Seidman Cancer Center at University Hospitals in Cleveland, OH broke ground on their MEVION S250 center in September of this year, and has taken delivery of the first system module, thus making Mevion Medical Systems the leading supplier of proton therapy in the USA.

About Mevion Medical Systems

Mevion Medical Systems, Inc. is a radiation therapy company dedicated to advancing the treatment of cancer. As the pioneering developer of modern proton therapy, 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. Visit us at: www.mevion.com.

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^SM concept. AMS owns common stock in Mevion Medical Systems, Inc., developer of the compact MEVION S250 Proton Therapy System.

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. 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, 2012, the Quarterly Report on Form 10-Q for the quarters ended on March 31, 2013, June 30, 2013, September 30, 2013, and the definitive Proxy Statement for the Annual Meeting of Shareholders held on June 11, 2013.