Stanford Medicine unveils world’s first ultracompact proton therapy facility

Stanford Medicine has opened a new proton therapy facility – featuring an ultracompact treatment system that’s small enough to fit in a room the size of a conventional linear accelerator vault.

Proton therapy is an advanced cancer treatment that offers precise tumour targeting while minimizing dose to healthy tissues. The technique is particularly beneficial for treating tumours located near critical structures and for treating cancers in children. Currently, however, access to proton therapy is limited by its high costs and substantial space requirements.

The new treatment facility – opened earlier this week at Stanford Medicine Cancer Center in Palo Alto, CA – incorporates the S250-FIT proton therapy system from Mevion Medical Systems, the most compact cyclotron in the industry. But even with a much small accelerator, proton therapy delivery usually requires a bulky gantry that rotates around the patient to aim the proton beams at the optimal treatment angles. As such, most proton facilities need a whole new multi-storey building to be built just to fit everything in.

To eliminate this obstacle, the Stanford facility is using a positioning system from Leo Cancer Care to deliver protons via a novel approach known as upright radiotherapy. Here, the patient is treated in an upright position (rather than lying down) and rotated in front of a static treatment beam, removing the need for a gantry and slashing space requirements and installation costs.

By combining these advanced technologies, the new equipment fits into a standard 1200 sq. ft linear accelerator vault (as used for standard X-ray-based radiotherapy) and was installed without having to construct a new building.

The advanced system also incorporates built-in CT scanning, enabling extremely precise targeting of tumours within patients with minimal collateral damage to the rest of the body.

“Developing this novel approach to proton therapy at Stanford Medicine, in collaboration with our industrial partners Mevion and Leo Cancer Care, gives us an important additional tool to treat our patients in a personalized, case-by-case way,” says Billy Loo, professor of radiation oncology and co-director of particle therapy at Stanford Medicine. “We are excited to pioneer this world’s first ultracompact and efficient technology that will benefit not only patients at Stanford but expand access to proton therapy worldwide and improve patient outcomes.”

“This milestone really marks the transition from concept and theory to clinical reality,” adds Leo Cancer Care’s CEO Stephen Towe. “Proton therapy installed inside a linac vault always felt like an impossible goal – our partnership with Stanford and Mevion has made that vision possible.”

Loo tells Physics World that patient treatments on the new proton therapy system are likely to start this summer. “As with any first-of-its-kind system in medicine, introducing this complex technology requires a rigorous process of testing and optimization to ensure it meets our high standards for patient safety and treatment quality,” he explains. “We are moving through these steps now.”

The Stanford Medicine team emphasize the particular advantages of proton therapy for children, not least that it can really decrease the radiation dose delivered to normal tissues. Minimizing irradiation of sensitive developing tissue can dramatically reduce the risk of long-term side effects. In addition, treating children while they are sitting up and actively engaged may be far less intimidating for them than having to lie down and have the treatment “happen to them”.

The first proton treatments will likely be “cranial and head-and-neck sites, for both adults and selected paediatric patients, for which we already have established patient positioning solutions,” says Loo. In parallel, the radiation oncology team will develop the workflows and immobilization solutions for all other anatomic sites.

The team also plans to investigate new ways to advance the technology and explore the clinical advantages of delivering upright radiotherapy. For example, evidence suggests that for some diseases, such as lung cancer, upright treatment puts the targeted organ in a more favourable position to irradiate safely. Upright positioning also provides greater flexibility to deliver radiation from many different angles. The team will also study the impact of upright positioning on FLASH treatments, in which radiation is delivered at ultrahigh dose rates.

Looking ahead, nine other medical centres are installing this new ultracompact proton therapy system, ultimately making proton therapy increasingly accessible to patients around the world.

“The clinical data to support the use of protons is stronger than ever before,” says Towe. “The strength of this data, combined with the cost reductions delivered by Leo’s technology, has sparked a new wave of growth for protons globally.”

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