Pencil Beam Scanning Nozzle

Treatment fields are delivered using a technique known as pencil beam scanning (PBS) utilizing layer scanning, where the target volume is subdivided into water equivalent depth planes and all spots required to cover the target at that range are delivered consecutively. Once complete, the accelerator produces protons of the next required energy and the subsequent layer is delivered, continuing until the entire volume is irradiated to the prescribed dose.

As the system can vary energy (depth in patient), intensity (number of protons per spot) and spot position, complex treatment strategies are possible, such as the simultaneous integrated boost technique, where high risk tumor regions may receive higher dose that lower risk regions during the same treatment. The PPTS allows for high precision treatment required for pediatric and CNS therapy.

In-Room CT (P-ARTIS CT)

Incorporated into the treatment workflow the CT scanner allows for both treatment planning CT simulation studies and daily treatment position verification using 3D/3D registration to the planning CT.

With respect to daily treatment verification, CT scanner provides information regarding daily patient position as well as proton beam range verification. In this latter role it becomes ideal for a proton adaptive radiotherapy platform, where range variation due to patient change is directly addressed with the capability of acquiring daily diagnostic quality CT images.

Robotic Patient Positioning System

The PPTS provides a six-degree of freedom, chair-based patient positioning system with a sub-millimeter localization accuracy. Positioning instructions created by the treatment plan are automatically sent to the PPS along with daily positioning correction provided by P-ARTIS CT.

Utilizing these angular degrees of freedom, treatment locations from the head to the lower pelvis are sites indicated for use by the PPTS system. This highly versatile positioning system allows for the removal of the traditional gantry from the proton radiotherapy environment, dramatically reducing system size and related costs of deployment and maintenance without sacrificing clinical utility.

Orthogonal X-Ray Positioning Verification

Centered on isocenter, the PPTS provides a motorized, orthogonal X-Ray imaging system that may be retracted when not in use to provide greater clearance for the PPS. The system is engaged during the treatment workflow as clinically indicated to verify the patient position at isocenter, providing a 20x20 cm image size in the isocentric plane. Positional adjustments, determined using a 2D/3D registration algorithm based on the referenced planning CT, are applied to the PPS on demand.

Safety Systems

The PPTS is a fully integrated proton radiotherapy solution, where both software and hardware implementations are tied by a common safety system.

PPTS implements a guided treatment workflow interface, where unsafe clinical operations are excluded by design.

A parallel software architecture culminating with the Machine Parameter Verification System (MPVS) verifies all instructions regarding the delivery and positioning of the PPTS prior to treatment.