Fast, high-rate, position-sensitive absolute dosimeter for ion beam therapy
First Claim
1. A radiation detector for absolute monitoring of radiation doses delivered by an ion beam comprising:
- a gas-tight housing with windows in the beam path;
a gaseous medium within the housing, wherein scintillation light is emitted by the gaseous medium after it is traversed by the ion beam;
one or more photo-detectors located within or around the gas-tight housing, the one or more photo-detectors configured to convert collected scintillation light into electric current;
further comprising a processor configured to generate a digitized electronic signal whose magnitude is proportional to the total amount of light collected by the one or more photo-detectors;
wherein the ion beam generates output data from the processor, the output data being indicative of a dose delivered by the ion beam to which the radiation detector was exposed, the output data being accurate to within 2% of the actual dose.
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Abstract
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.
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Citations
31 Claims
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1. A radiation detector for absolute monitoring of radiation doses delivered by an ion beam comprising:
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a gas-tight housing with windows in the beam path; a gaseous medium within the housing, wherein scintillation light is emitted by the gaseous medium after it is traversed by the ion beam; one or more photo-detectors located within or around the gas-tight housing, the one or more photo-detectors configured to convert collected scintillation light into electric current; further comprising a processor configured to generate a digitized electronic signal whose magnitude is proportional to the total amount of light collected by the one or more photo-detectors; wherein the ion beam generates output data from the processor, the output data being indicative of a dose delivered by the ion beam to which the radiation detector was exposed, the output data being accurate to within 2% of the actual dose. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A radiation detector for absolute monitoring of radiation doses delivered by an ion beam comprising:
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a gas-tight housing with windows in the beam path; a gaseous medium within the housing, wherein scintillation light is emitted by the gaseous medium after it is traversed by the ion beam; one or more photo-detectors located within or around the gas-tight housing, the one or more photo-detectors configured to convert collected scintillation light into electric current; further comprising a processor configured to generate a digitized electronic signal whose magnitude is proportional to the total amount of light collected by the one or more photo-detectors; wherein the output data of said processor are available on sub-millisecond time scales, the output data providing feedback for real-time adjustment of ion beam intensity for subsequent steps in dose delivery.
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21. A radiation detector for absolute monitoring of radiation doses delivered by an ion beam comprising:
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a gas-tight housing with windows in the beam path; a gaseous medium within the housing, wherein scintillation light is emitted by the gaseous medium after it is traversed by the ion beam; one or more photo-detectors located within or around the gas-tight housing, the one or more photo-detectors configured to convert collected scintillation light into electric current; further comprising a processor configured to generate a digitized electronic signal whose magnitude is proportional to the total amount of light collected by the one or more photo-detectors; and a plurality of photo-detectors located within or around the gas-tight housing, wherein the processor determines a difference between signals from oppositely-situated photo-detectors of the plurality of photo-detectors, divided by the sum of said signals, to provide output data sensitive to a distance of the ion beam from each of the oppositely-situated photo-detectors. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A radiation detector for absolute monitoring of radiation doses delivered by an ion beam comprising:
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a gas-tight housing with windows in the beam path; a gaseous medium within the housing, wherein scintillation light is emitted by the gaseous medium after it is traversed by the ion beam; one or more photo-detectors located within or around the gas-tight housing, the one or more photo-detectors configured to convert collected scintillation light into electric current; wherein the beam entry and exit window materials and thicknesses are configured to withstand a pressure differential of more than one atmosphere, and configured to introduce less than 2 milliradians root-mean-square angular spread in a 200 MeV proton beam.
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28. A radiation detector for absolute monitoring of radiation doses delivered by an ion beam comprising:
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a gas-tight housing with windows in the beam path; a gaseous medium within the housing, wherein scintillation light is emitted by the gaseous medium after it is traversed by the ion beam; one or more photo-detectors located within or around the gas-tight housing, the one or more photo-detectors configured to convert collected scintillation light into electric current; and one or more light-pulsers, each of which emits light at wavelengths within the spectral response region of the one or more photo-detectors, and are triggered by external electronic signals to provide periodic calibration of all photo-detector responses to reproducible amounts of light injected at known locations. - View Dependent Claims (29, 30)
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31. A radiation detector for absolute monitoring of radiation doses delivered by an ion beam comprising:
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a gas-tight housing with windows in the beam path; a gaseous medium within the housing, wherein scintillation light is emitted by the gaseous medium after it is traversed by the ion beam; one or more photo-detectors located within or around the gas-tight housing, the one or more photo-detectors configured to convert collected scintillation light into electric current; wherein the scintillation light, emitted by the gaseous medium, has a duration of less than 100 nanoseconds.
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Specification