Patient-specific CT calibration based on ion radiography for different detector configurations in1H,4He and12C ion pencil beam scanning.

Patient-specific CT calibration based on ion radiography for different detector configurations in1H,4He and12C ion pencil beam scanning. Phys Med Biol. 2020 Jul 06;: Authors: Gianoli C, Göppel M, Meyer S, Palaniappan P, Rädler M, Kamp F, Belka C, Riboldi M, Parodi K Abstract The empirical conversion of the treatment planning X-ray Computed Tomography (CT) image to ion stopping power relative to water causes dose calculation inaccuracies in ion beam therapy. A patient-specific calibration of the CT image is enabled by the combination of an ion radiography (iRad) with the forward-projection of the empirically converted CT image along the estimated ion trajectories. This work investigated the patient-specific CT calibration for list-mode and integration-mode detector configurations, with reference to a ground truth ion CT (iCT) image. Analytical simulations of idealized carbon ion and proton trajectories in a numerical anthropomorphic phantom and realistic Monte Carlo simulations of proton, helium and carbon ion pencil beam scanning in a clinical CT image of a head-and-neck patient were considered. Controlled inaccuracy and noise levels were applied to the calibration curve and to the iRad, respectively. The impact of the selection of slices and angles of the iRads, as well as the choice of the optimization algorithm, were investigated. Accurate and robust CT calibration was obtained in analytical simulations of straight carbon ion tr...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research