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Connecticut Welcomes State’s First Proton Therapy Technology

November 05, 2025

A major milestone in cancer treatment has arrived in Connecticut. Hartford HealthCare, Yale New Haven Health System and Proton International celebrated the arrival and installation of the S2C2 Cyclotron, the massive, state-of-the-art engine at the heart of the new Connecticut Proton Therapy Center in Wallingford.

Weighing about 55 metric tons, the machine accelerates protons to nearly 60% the speed of light — fast enough to reach the moon in just two seconds. The cyclotron’s size is just as striking: it’s large enough to hold 30,000 hardcover books or nearly 100,000 apples.

Set to open in 2026, the 25,000-square-foot facility will be the first of its kind in Connecticut, offering advanced proton therapy — a form of radiation treatment that uses proton beams instead of X-rays.

“This is an amazing precision tool to be used by world-class experts to treat patients with cancer,” said Peter Yu, MD, physician-in-chief of the Hartford HealthCare Cancer Institute. “This is something that, until now, hasn’t been available in Connecticut. Patients have had to travel to Manhattan or Boston to get this type of highly specialized treatment.”

Currently, proton therapy is available at only a handful of locations across the Northeast. Its introduction in Connecticut represents a transformative step forward in access to cutting-edge cancer care.

“It’s especially important for cancers close to very sensitive parts of the body — places like the heart or spinal cord that can be easily damaged by radiation. Proton therapy gives us the exquisite precision we need to treat those cases safely,” Dr. Yu said.

The project also marks a historic collaboration between two of Connecticut’s leading healthcare systems — Hartford HealthCare and Yale New Haven Health — working together with Proton International after nearly a decade of planning and discussion.

“This is really a landmark event,” said Dr. Yu. “The two leading health systems in the state came together after years of discussion because we knew it was the right thing to do for the citizens of Connecticut. Working together gives patients the best access and exposure to the most advanced treatments.”