Method and apparatus for real-time tumor tracking by detecting annihilation gamma rays from low activity position isotope fiducial markers
First Claim
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1. A method for real-time tracking of a target in a human body, the method comprising the acts of:
- implanting into the target a plurality of physical positron emission fiducial markers having a low activity positron-emitting isotope source;
detecting two annihilation gamma rays resulting from positron annihilation associated with each of a plurality of position-emitting nuclear decay events of the low activity positron-emitting isotope source using a plurality of position-sensitive detectors, wherein the plurality of position-sensitive detectors comprises two pairs of position-sensitive detector modules mounted external to the human body in an orthogonal orientation such that the angle between the two pairs of position-sensitive detector modules is between 65 degrees and 90 degrees;
forming a coincident line from only the two detected annihilation gamma rays for each of the plurality of position-emitting nuclear decay events;
sorting the coincident lines into clusters based on an iterative Expectation-Maximization clustering algorithm;
determining the locations of the plurality of physical position emission fiducial markers using only said clusters; and
tracking, during radiation therapy delivery, movement and change of orientation of the target in real-time based on a change in position and orientation of plurality of physical positron emission fiducial markers, wherein said tracking provides target movement information for use in performing said radiation therapy delivery.
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Abstract
Method and apparatus for real-time tracking of a target in a human body. In one embodiment of the invention, positron emission marker may be implanted into a target, the positron emission marker having a low activity positron isotope. In one embodiment, annihilation gamma rays associated with the low activity positron isotope may be detected using a plurality of position-sensitive detectors. In another embodiment, the target may be tracked in real-time based on a position of the positron emission marker.
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Citations
21 Claims
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1. A method for real-time tracking of a target in a human body, the method comprising the acts of:
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implanting into the target a plurality of physical positron emission fiducial markers having a low activity positron-emitting isotope source; detecting two annihilation gamma rays resulting from positron annihilation associated with each of a plurality of position-emitting nuclear decay events of the low activity positron-emitting isotope source using a plurality of position-sensitive detectors, wherein the plurality of position-sensitive detectors comprises two pairs of position-sensitive detector modules mounted external to the human body in an orthogonal orientation such that the angle between the two pairs of position-sensitive detector modules is between 65 degrees and 90 degrees; forming a coincident line from only the two detected annihilation gamma rays for each of the plurality of position-emitting nuclear decay events; sorting the coincident lines into clusters based on an iterative Expectation-Maximization clustering algorithm; determining the locations of the plurality of physical position emission fiducial markers using only said clusters; and tracking, during radiation therapy delivery, movement and change of orientation of the target in real-time based on a change in position and orientation of plurality of physical positron emission fiducial markers, wherein said tracking provides target movement information for use in performing said radiation therapy delivery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for radiation therapy based on real-time three-dimensional position and orientation of a target in a human body, comprising:
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a plurality of physical positron emission fiducial markers implanted into the target, the plurality of physical positron emission fiducial markers having a low activity positron-emitting isotope source; a plurality of detectors arranged near a radiation isocenter configured to detect two annihilation gamma rays resulting from position annihilation associated with each of a plurality if positron-emitting nuclear decay events of the low activity positron-emitting isotope source of the plurality of physical positron emission fiducial markers, wherein the plurality of position-sensitive detectors comprises two pairs of position-sensitive detector modules mounted external to the human body in an orthogonal orientation such that the angle between the two pairs of position-sensitive detector modules is between 65 degrees and 90 degrees; and a module configured to; form a coincident line from only the two detected annihilation gamma rays for each of the plurality of position-emitting nuclear decay events, sort the coincident lines into clusters based on an iterative Expectation-Maximization clustering algorithm, determine the location of one of the plurality of physical position emission fiducial markers using only said clusters, and track, during radiation therapy delivery, movement and change of orientation of the target in real-time based on a change in position and orientation of the plurality of physical positron emission fiducial markers, wherein said module provides target movement information for use in performing said radiation therapy delivery. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification