Method and Apparatus for Ion Beam Bragg Peak Measurement

Abstract

A system and method for recording in real-time the duration, position, and energy of ion beams as delivered by a proton or heavy ion cancer treatment system for the purpose of calibrating the radiological system and verifying the treatment plans for various lesions. The energy of the ion beam is calculated from the beam ion depth penetration through a phantom as recorded on a two-dimensional scintillator surface which is viewed by a sensitive visible-light camera mounted in a darkened enclosure. The energy of the beam is degraded by a novel multi-step dual-slope chevron wedge phantom which creates, at a minimum, two bright spots in the camera's field of view. The distance between the centers of these two spots along with the dimensions and density of the multi-step dual-slope chevron wedge are used to calculate the Bragg Peak penetration depth of the ion beam. A computer connected to the camera measures the location and intensity of these spots during treatment delivery and archives the original beam image, spot parameters, timing, and computed beam energies to memory. Software algorithms reconstruct a mathematical description of each treatment beam. The operator can then determine discrepancies between the measured dosimetric pattern and the intended treatment or calibration pattern.

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