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MO‐FG‐CAMPUS‐JeP1‐01: Prompt Gamma Imaging with a Multi‐Knife‐Edge Slit Collimator: Evaluation for Use in Proton Beam Range Verification
Author(s) -
Ready J,
Negut V,
Mihailescu L,
Vetter K
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4957338
Subject(s) - collimated light , collimator , bragg peak , proton therapy , proton , beam (structure) , optics , range (aeronautics) , photon , physics , gamma camera , medical imaging , gamma ray , nuclear medicine , materials science , nuclear physics , laser , medicine , radiology , composite material
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 2.6×10 −5 gamma/proton. With delivery of 1×10 11 protons, shifts of 1 mm in the target location were detected in 2D prompt gamma images and 1D profiles. With delivery of 1×10 8 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. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number: DENA0000979 through the Nuclear Science and Security Consortium.