Compact Radiation System Delivers Conformal RT Treatments

Novel pencil beam scanning (PBS) technology uses hyperscanning to deliver faster, sharper, and more robust radiation therapy (RT) treatments.

The Mevion Medical Systems (Mevion; Littleton, MA, USA) S250i Proton Therapy System with Hyperscan PBS technology is designed to shape the delivered radiation dose by “painting” tumors spot-by-spot and layer-by-layer with the sub-atomic proton particles. Hyperscan technology helps overcome clinical challenges faced by first generation PBS systems by reducing delivery times to less than five seconds, thus reducing errors resulting that can undermine the high precision of PBS due to the target tumor shifting under normal organ motion, such as breathing.


In addition to Hyperscan, the system utilizes an adaptive, robotically controlled aperture proton multi-leaf collimator (pMLC), which is capable of trimming the edges of the beam at every layer of delivery. This capability can deliver up to a three times sharper drop off in radiation at the delivery field edge, sparing healthy tissue and limiting unnecessary radiation to sensitive locations. As other members of the S250 Series platform, the S250i includes a gantry mounted superconducting synchrocyclotron, a six degree-of-freedom treatment couch, and advanced in-room image guidance.

“Delivering sharp field edges has been a real challenge for PBS, especially in shallow fields. In intracranial procedures, where critical structures are in close proximity to tumors at shallow depths, having the sharpest lateral penumbra is essential,” said Skip Rosenthal, VP of clinical education at Mevion. “The sharp penumbras of the adaptive aperture system have substantial benefits for these patients. In addition, the enhanced speed of Hyperscan PBS could enable greater confidence in treating thoracic tumors.”

Proton therapy is a precise form of RT that uses charged particles instead of x-rays. It can be a more effective form of treatment than conventional radiotherapy as it directs the RT more precisely, with minimal damage to surrounding tissue. Evidence is growing that protons can be effective in treating a number of cancers, in particular in children and young people with brain tumors, for whom it appears to produce fewer side effects such as secondary cancers, growth deformity, hearing loss, and learning difficulties.