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Session: Multi-Disciplinary General ePoster Viewing [Return to Session]

Range Modulated Proton Radiography Using High Energy Therapeutic Proton Scanning Pencil Beams

C Pelas1*, N Alsbou2, S Ahmad1, I Ali1, (1) University of Oklahoma Health Sciences, Oklahoma City, OK, (2) Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK,


PO-GePV-M-61 (Sunday, 7/25/2021)   [Eastern Time (GMT-4)]

Purpose: To investigate visibility of range modulated proton radiography using scanning pencil beam proton from high energy MEVION proton therapy machine. The image quality including uniformity, linearity, contrast and spatial resolutions of the proton radiographs obtained were evaluated quantitatively.

Methods: High energy proton beams from the scanning pencil beam MEVION proton therapy machines were used to obtain radiographs of different phantoms. These phantoms include LEEDS which is used for quality assurance of diagnostic KV photon beams. The proton radiographs of pelvis and head phantoms were acquired to evaluate visibility of proton radiography on the scale of patients. A phosphorus scintillation detector was used to acquire the proton radiographs. The effects of different beam parameters such as dose, depth, modulation, and separation between the detector and the object being imaged on the image quality of proton radiographs were evaluated quantitatively.

Results: The contrast and spatial resolutions of the proton radiographs were decreasing with increasing depth of the testing objects in phantom, increasing spot size, increasing separation between the spot sizes and increasing range modulation. Both resolutions of the proton radiographs were affected by the proton beam scattering in the medium where it was degraded with increasing depth in phantom and increasing range modulation. Proton radiographic images showed high contrast of the soft tissue features in the beam view, while the intensity of photon radiographic images showed mainly high contrast of bone anatomy. The proton radiographs were affected by head and pelvis phantom thickness irregularities where the water equivalent depths across the image were largely variable.

Conclusion: Proton radiography has a potential for image guided proton therapy as an alternative to photon radiography using attachable diagnostic kV photon beam systems. The use of range modulation of pencil beam scanning proton therapy system provides an approach to account for variations in patient thickness.



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