1D and 3D Prompt Gamma Imaging for Dose Monitoring of Particle Therapy

Range verification and dose monitoring is important to reduce the uncertainties of particle therapy. Although prompt gamma imaging (PGI) is a promising method for online range verification, it suffers low-resolution and lack of 3D imaging capability. To address these issues, we propose a hybrid PGI system that combines one knife edge camera and eight parallel slit cameras to achieve high-sensitivity and high-resolution 1D PGI through an advanced deconvolution algorithm. A feasibility study of 3D PGI is also conducted using eight 2D parallel hole cameras for sparse sampling and compressed sensing reconstruction (expectation-maximization with total variation minimization (EM-TV)). The simulation studies show that: 1) the hybrid 1D PGI system achieves sub-mm accuracy in detection of the 50% falloff edge in a highly inhomogeneous region; and 2) EM-TV achieves root mean squared error of 0.55 compared to 3.38 of filtered backprojection reconstruction (with eight projection views and less than 20 maximum counts for each detector element) and recovers the distal falloff edge and the later spread accurately. This work lays a strong foundation for future simulation studies with more realistic settings and development of 1D and 3D PGI systems.