One challenge, Durkee says, will be keeping the equipment running. “Our goal is 99% uptime. If it goes down, treatments would be delayed, and that’s costly and disruptive to patients.” For those awaiting proton therapy, even a brief interruption matters. To prevent that, UW has tasked two on-site engineers with keeping the beam precisely tuned and the system running smoothly.

Maintenance is reshaping how centers design proton therapy systems, Loo says. He argues that modular setups like Stanford’s offer a practical edge over massive, centralized builds.


“Every machine eventually needs upgrades or replacement,” he explains. In traditional facilities, downtime can halt everything. Modular systems allow centers to upgrade or replace one treatment machine at a time, instead of shutting down an entire multiroom facility. Loo says it keeps patient care moving in a way that feels “much more organic,” calling it “the new paradigm.”

Scaling up: The next frontier
The goal, Loo says, is not only to make proton therapy accessible, scalable, and integrated, but also to advance its clinical benefits. “From the start, we wanted to push the envelope and advance the field at Stanford,” he adds.

Removing the gantry and rotating patients more flexibly opens new possibilities, Loo explains. It allows more beam angles and greater control over dose distribution. “Think of a helix, not just an arc,” he says. Treatments can cover a longer area, giving clinicians more ways to sculpt the dose; something conventional therapy couldn’t achieve.

“Stanford is doing something really cool, and we’re also doing something really cool too: bringing the footprint down,” Durkee says. “That saves money for payers and makes protons more accessible nationally and internationally.”

MacDonald cautions that globally, the proton therapy sector still has a long way to go. Many countries — including Canada and Australia, both known for strong healthcare systems — still lack an operating proton center.

The U.S., however, shows no signs of slowing down. More than 100 proton therapy centers are expected to be under construction or under contract by 2030, Durkee projects — a sign of growing confidence in the technology. Hospitals increasingly view proton therapy not as a distant, high-cost outlier, but as part of a broader cancer strategy.

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