Program Information
Prompt Gamma Imaging with a Multi-Knife-Edge Slit Collimator: Evaluation for Use in Proton Beam Range Verification
J Ready1*, V Negut2 , L Mihailescu2 , K Vetter1,2 , (1) UC Berkeley, Berkeley, CA, (2) Lawrence Berkeley National Laboratory, Berkeley, CA
Presentations
MO-FG-CAMPUS-JeP1-1 (Monday, August 1, 2016) 4:30 PM - 5:00 PM Room: ePoster Theater
Purpose: To evaluate and characterize a multi-slit collimated imaging system for use in prompt gamma range verification of proton therapy.
Methods: Acrylic (PMMA) targets were irradiated with a 50 MeV proton beam. With the collimator placed 13 cm from the beam axis, photons of energy from 2-7 MeV were measured. Image reconstruction provided 2-dimensional distribution of gamma rays. Estimated Bragg peak location was compared with 1-dimensional profiles of photon images. Shifts in Bragg peak were simulated by physically moving the targets in 1 mm increments.
Results: The imaging system measured prompt gamma emissions resulting from a 50 MeV proton beam, at currents up to 2 nA, incident on a PMMA target. Overall system detection efficiency was approximately 2.6x10⁻⁵ gamma/proton. With delivery of 1x10¹¹ protons, shifts of 1 mm in the target location were detected in 2D prompt gamma images and 1D profiles. With delivery of 1x10⁸ protons, shifts of approximately 3 mm were detectable.
Conclusion: This work has characterized the performance of a prototype multi-slit collimated imaging system. The system can produce 2D images of prompt gamma distributions and detect shifts in Bragg peak location down to 1 mm. These results encourage further development and optimization of the system for clinical proton beam applications.
Funding Support, Disclosures, and Conflict of Interest: This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number: DE-NA0000979 through the Nuclear Science and Security Consortium.
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