Prad with the Mevion Beam In the Era of Shoot-through Layers and Upright Proton Therapy
Abstract
Purpose
Proton radiography (pRad) has long been proposed to reduce range uncertainties by providing patient-specific stopping power information. Recent developments in proton therapy delivery, including shoot-through beam techniques and upright patient positioning, renew interest in pRad solutions. This work investigates the feasibility and role of pRad with the Mevion beam in the context of shoot-through beams and future upright proton treatments.
Methods
pRad acquisitions were performed using a Mevion proton beam in transmission conditions compatible with shoot-through energy layers. A commercial range telescope detector (QUBEnext) was employed, and dedicated post-processing methods were applied to reconstruct water-equivalent thickness (WET) maps following established methodologies. Imaging performance was evaluated in terms of spatial resolution, WET accuracy, and sensitivity to density variations. Different spot scanning patterns were investigated to assess the impact of acquisition density on image quality. Conceptual workflows were explored for integration with shoot-through delivery and upright treatment geometries, particularly in view of the Mevion-FIT system.
Results
pRad using the Mevion beam and QUBEnext detector demonstrated robust WET reconstruction with clinically relevant accuracy and low imaging dose. The use of shoot-through energy layers enabled efficient transmission imaging without additional beam delivery overhead. The resulting pRad images showed sensitivity to anatomical heterogeneities relevant for range verification. A systematic evaluation of acquisition density identified the minimum spatial resolution and spot-to-spot distance required to preserve clinically relevant information, highlighting trade-offs between image quality, acquisition time, and dose.
Conclusion
pRad with the Mevion beam, enabled by the QUBEnext detector and shoot-through techniques, represents a promising tool for range verification in the emerging era of upright proton therapy. Integration with upright treatment systems such as Mevion-FIT could facilitate fast, patient-specific verification strategies with minimal workflow impact, supporting further development toward clinical implementation of pRad within image-guided and adaptive proton therapy.