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内容記述 |
uncertainties. One possibility for monitoring is through secondary prompt gammas (PG). PG emission along the penetration path is correlated to the dose, and PG measurements can be used to infer information about the dose distribution. Methods Following promising initial investigations in phantoms presented in[1], the deconvolution approach[2], the evolutionary algorithm[3-5] and the maximum-likelihood expectationmaximization (MLEM) algorithm[6-7] were investigated in this work for dose reconstruction from PG for clinical cases. These techniques were applied first to simulations (for ideal PG emission in the patient) of a head and neck (H&N) tumour indication, considering two pencil beams delivered to regions with different heterogeneity levels. A systematic analysis depending on PG statistics is ongoing. Extension to PG from emission to detection is in progress, considering 1D PG signals acquired with a knife-edge slit camera[8] during several treatment fractions for two additional H&N patients[9-10]. Results The accuracy of the reconstructed 3D dose distributions was evaluated via γ-index and range analyses with different settings. Regarding dose reconstruction from simulated 3D PG distributions at emission, the γ(2%/2mm) passing rate was found above 97% for every algorithm used. The resulting |ΔR80| between simulated and reconstructed laterally integrated depth-dose profiles was below 1.4 mm. Results from experimental data will be presented. Conclusions The feasibility of the investigated dose reconstruction techniques applied to simulated 3D PG distributions at emission considering a H&N patient is verified. Dose reconstruction from measured PG signals will be presented. Since the emission of PG happens in a timescale below nanoseconds, the algorithms are potentially suitable for real-time adaptive particle therapy. |
