Author: Saad Bin Saeed Ahmed, Marcos Feijoo, Wazir Muhammad, Charles Shang, Naseem Ud Din 👨🔬
Affiliation: South Florida Proton Therapy Institute, Miami Cancer Institute, Blue Physics LLC, Florida Atlantic University 🌍
Purpose: This study introduces a novel approach for patient-specific quality assurance in proton beam therapy, utilizing new plastic scintillator detectors with high temporal resolutions to create detailed proton scanning spot dose maps.
Methods: This study utilized a BluePhysics® model-10 detector to measure proton scanning beams from the Varian ProBeam™ system. Each test plan consisted of a single energy layer at 70, 160, or 220 MeV, delivered in a 10 x 10 cm² field with 2.5mm uniformly spaced spots and 32 MUs per spot. Measurements were performed at the isocenter with a 5.0 cm solid water buildup. A custom Python script then converted the measured signal peaks into spot maps by extracting spatial coordinates from the DICOM file associated with the delivered plan.
Results: The 70 MeV plan measurements identified 33 spots within an estimated measurable area of 2.3 cm². Signal intensities or peaks were higher at the center of the field compared to the periphery. Higher-energy plans exhibited fewer identifiable spots. Measurements from redundant tests showed consistent signal intensities, with minimal interference from noise sources.
Conclusion: This research demonstrates the effectiveness of this plastic scintillation detector in scanning proton spot intensity maps. Future work will focus on enhancing detection efficiency and developing a multi-channel, multi-detector system.