Still Rivers System

One way to treat cancer with minimal damage to healthy tissue is to zap tumors with a proton beam. Proton therapy systems have been around since the 1950s. But until now, the units were as big as entire hospitals with costs over $100 million. That typically makes proton therapy unavailable to most cancer centers and patients. However, Still River Systems, Littleton, Mass., (www.stillriversystems.com) is developing a compact and cost-effective proton therapy system, the Monarch²⁵⁰.

“Our complete proton therapy system fits in a single room, making it suitable for a typical community hospital” says Engineering Services Manager Barry Mendell. “One factor that lets us scale down our system is the use of a super-conducting cyclotron to accelerate protons to the high energies needed. A large counterweighted gantry rotates the cyclotron around the patient outside the treatment room in area referred to as the ‘vault.’ The gantry repositions the cyclotron to aim protons at the tumor from any required direction with sub-millimeter accuracy. Along with the accelerator, RF electronics, cabling, cooling elements, and even an on-board vacuum system are mounted on the gantry. Three-D software from SolidWorks Corp., Concord, Mass., (SolidWorks.com) helped ensure its many components fit properly,” he says.

“The company also designed the treatment enclosure walls, ceiling, and consoles for the system in the 3D program”, says Mendell. “We eventually intend to buy the walls from a supplier of modular units. But we modeled them to ensure all components, many of which are outsourced or off-the-shelf, will fit into the design. CosmosWorks for FEA performed the necessary structural analysis. Because the cyclotron magnet produces a strong magnetic field, we exported the SolidWorks model to an outside analysis program to model the field and assist with the placement of susceptible components.”

The cyclotron includes parts almost as small as the head of a pin as well as large components, such as the 7.5-ft diameter magnet. “The accelerator has about 12 major subsystems, and we have various teams working on different portions of the design. So it is critical that we have collaboration between the groups,” says Mendell. “For this, we use PDMWorks to ensure everyone is working with the latest version of a part or subassembly.”