Emission-transmission imaging system using single energy and dual energy transmission and radionuclide emission data
First Claim
1. An emission-transmission imaging system comprisinga) a radiation source for emitting a photon spectrum,b) detector means for selectively detecting photons corresponding to said photon spectrum and photons corresponding to radionuclide emission,c) means for positioning said radiation source facing said detector means with an object positionable therebetween, said object having a radionuclide therein,d) data acquisition means connected with said detector means for receiving transmission signals from said detector means representative of the photon spectrum photons and radionuclide signals representative of detected radionuclide emission signals, said data acquisition means including pulse counting circuitry operable at low count rates and high energy resolution for radionuclide emission detection, pulse counting circuitry operable at high count rates and moderate energy resolution for simultaneous radionuclide emission and transmission detection, and current mode circuitry operable at very high count rates without energy resolution for transmission detection,e) computer means for receiving and processing said transmission signals and developing an attenuation map for photons, said computer means receiving and processing said radionuclide signals using said attenuation map for attenuation correction and producing image signals of distribution of a radionuclide in an object positioned between said radiation source and said detector means, andf) display means responsive to said image signals.
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Abstract
Radionuclide emission imaging is improved by correcting emission-transmission data for attenuation along calculated path lengths and through calculated basis material. X-ray transmission data are used to develop an attenuation map through an object which is then used in reconstructing an image based on emission data, Radiation detection circuitry is provided which has different operating modes in detecting the x-ray and emission photons passing through the object. An iterative process is used to reconstruct the radionuclide distribution using the radionuclide projection data and the attenuation map based on physical characteristics of the object being imaged. Subsets of the complete radionuclide projection data are used to reconstruct image subsets of the radionuclide distribution. The image subsets can be generated concurrently with the acquisition of the radionuclide projection data or following acquisition of all data.
161 Citations
37 Claims
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1. An emission-transmission imaging system comprising
a) a radiation source for emitting a photon spectrum, b) detector means for selectively detecting photons corresponding to said photon spectrum and photons corresponding to radionuclide emission, c) means for positioning said radiation source facing said detector means with an object positionable therebetween, said object having a radionuclide therein, d) data acquisition means connected with said detector means for receiving transmission signals from said detector means representative of the photon spectrum photons and radionuclide signals representative of detected radionuclide emission signals, said data acquisition means including pulse counting circuitry operable at low count rates and high energy resolution for radionuclide emission detection, pulse counting circuitry operable at high count rates and moderate energy resolution for simultaneous radionuclide emission and transmission detection, and current mode circuitry operable at very high count rates without energy resolution for transmission detection, e) computer means for receiving and processing said transmission signals and developing an attenuation map for photons, said computer means receiving and processing said radionuclide signals using said attenuation map for attenuation correction and producing image signals of distribution of a radionuclide in an object positioned between said radiation source and said detector means, and f) display means responsive to said image signals.
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15. An emission-transmission imaging system comprising:
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a) an x-ray source for emitting an x-ray photon spectrum, b) an x-ray detector operated in the current-mode for detecting x-ray photons from the x-ray source, c) a radionuclide detector operated in the pulse-counting more for detecting photons corresponding to radionuclide emission, d) means for positioning the x-ray source facing the x-ray detector with an object containing a radionuclide between the x-ray source and the x-ray detector, e) means for maintaining relative positions of the x-ray detector and the radionuclide detector, f) an x-ray data acquisition system connected with the x-ray detector for receiving transmission signals from the x-ray detector, g) a radionuclide data acquisition system connected with the radionuclide detector for receiving emission signals from the radionuclide detector, representative of the radionuclide emission from the object, h) means for producing signals to maintain relative positions of x-ray and radionuclide data, i) computer means for receiving and processing the transmission signals and developing an attenuation map, and receiving and processing the radionuclide signals and producing image signals of distribution of a radionuclide of the object positioned between the x-ray source and the x-ray detector and radionuclide detector, j) a display system responsive to the image signals, and k) means for maintaining relative positions of said object with said x-ray detector and said radionuclide detector. - View Dependent Claims (20, 21, 22, 23)
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16. The emission-transmission imaging system as defined by 15 wherein the radionuclide data acquisition system has multiple energy windows and counters to receive and process the radionuclide detector signals.
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17. The emission-transmission imaging system as defined in 15 wherein the radionuclide detector is scintillation camera.
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18. The emission-transmission imaging system as defined in 15 wherein the x-ray detector includes a material selected from the group consisting of at least one of cadmium tungstate, cesium iodide, bismuth germanate, gadolinium oxysulfide, germanium, cadmium telluride, zinc cadmium telluride, lead iodide, mercuric iodide, and sodium iodide.
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19. The emission-transmission imaging system as defined in 15 wherein a shaped filter is placed between the x-ray source and the object while the object is scanned to compensate for differences in x-ray absorption across the object.
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24. An emission-transmission imaging system comprising
a) a radiation source for emitting a photon spectrum, b) detector means for selectively detecting photons corresponding to said photon spectrum and photons corresponding to radionuclide emission, c) means for positioning said radiation source facing said detector means with an object positionable therebetween, said object having a radionuclide distribution therein, d) data acquisition means connected with said detector means for receiving signals from said detector means representative of the detected photon spectrum photons and radionuclide signals representative of detected radionuclide emission signals, e) computer means for receiving photon spectrum signals and for receiving said radionuclide signals, f) first processing means for developing an attenuation map from said photon spectrum signals, g) second processing means for constructing objective functions from subsets of said radionuclide signals, h) algorithm means for iteratively seeking an extremum of said objective functions to calculate image estimates of said radionuclide distribution contained in said object, and i) means for altering said subsets of said radionuclide signals and said objective functions to incorporate subsequently measured signals.
Specification