Indiana University

Phenix Medical LLC

Keith A Solberg

Alexander V Klyachko

John M Cameron

Dmitri Nichiporov

Mark Wolanski

Steven E Vigdor

Alan Eads

A gas scintillation detector is designed to provide in-beam absolute dose monitoring for ion beam radiotherapy treatments employing spot or raster beam scanning, especially with microsecond-scale beam pulses. Detection of prompt primary scintillation light emitted by gas molecules excited by beam passage provides electronic signals that can be processed to yield output data proportional to delivered dose up to high dose rates, and that appear quickly enough to provide feedback to influence real-time beam intensity adjustments for subsequent steps in the beam scan. When the scintillation light is collected in multiple photo-detectors, the invention is furthermore capable of measuring spot beam position with spatial resolutions of order one millimeter.

Fast, high-rate, position-sensitive absolute dosimeter for ion beam therapy

A beam profile measurement detector is a tool to efficiently verify dose distributions created with active methods of a clinical proton beam delivery. A Multi-Pad Ionization Chamber (MPIC) has 128 ionization chambers arranged in one plane and measure lateral profiles in fields up to 38 cm in diameter. The MPIC pads have a 5 mm pitch for fields up to 20 cm in diameter and a 7 mm pitch for larger fields, providing an accuracy of field size determination of about 0.5 mm. The Multi-Layer Ionization Chamber (MLIC) detector contains 122 small-volume ionization chambers stacked at a 1.82 mm step (water-equivalent) for depth-dose profile measurements. The MLIC detector can measure profiles up to 20 cm in depth, and determine the 80% distal dose fall-off with about 0.1 mm precision. Both detectors can be connected to the same set of electronics modules, which form the detectors' data acquisition system. The detectors operate in proton fields produced with active methods of beam delivery such as uniform scanning and energy stacking. The MPIC and MLIC detectors can be used for dosimetric characterization of clinical proton fields.

Dose profile measurement system for clinical proton fields

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Bloomington, IN, United States of America

Keith A Solberg