X-ray CT Diffraction Body for High Count Rate Photon Detection
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Solution Overview
Problem
Photon counting X-ray computed tomography apparatuses face challenges in achieving high count rates due to count losses from pileup in indirect conversion methods and dead time in direct conversion methods, limiting the maximum count rate to around 10^6 photons/mm^2/sec.
Innovation Solution
An X-ray computed tomography apparatus utilizing an X-ray diffraction phenomenon with a diffraction body and X-ray detection elements arranged to diffract polychromatic X-rays into Debye-Scherrer rings, allowing for the separation and counting of X-ray photons by energy, enabling the reconstruction of medical images across multiple energy bins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single photon detection is performed at high count rates (10^9 photons/mm^2/sec), then medical image reconstruction becomes feasible, but count losses occur due to pileup in indirect conversion methods or dead time in direct conversion methods
Solution Approach 1:
The invention segments the detection process by spatially separating photons of different energies through diffraction. The diffraction body divides the incident polychromatic X-ray beam into multiple Debye-Scherrer rings, each corresponding to a specific energy range. Detection elements are arranged to detect photons from different rings independently, enabling energy-resolved photon counting without pileup or dead time losses that plague conventional single-photon detectors.
Solution Approach 2:
The diffraction body acts as an intermediary between the incident X-ray beam and the detection elements. It mediates the energy separation process by diffracting photons according to their energy, converting the temporal overlap problem (pileup/dead time) into a spatial separation problem that can be resolved by the detection element array.
2Reliability
If the size of semiconductor detector is decreased to reduce count loss, then the maximum count rate remains limited to about 10^6 photons/mm^2/sec
Solution Approach 1:
The invention transitions from a one-dimensional temporal detection problem to a two-dimensional spatial-energy detection problem. By arranging detection elements in a two-dimensional array and using the diffraction body to map photon energy to spatial position (Debye-Scherrer ring radius), the system can process multiple photons simultaneously across different spatial locations, thereby increasing the maximum count rate beyond the limitations of single-pixel detectors.
3Productivity
If polychromatic X-rays are used for imaging, then imaging speed and productivity improve, but energy spectrum information is lost
Solution Approach 1:
The invention applies local quality by assigning different detection elements to detect photons of different energies. Each detection element or group of elements is specialized for detecting photons from a specific Debye-Scherrer ring, which corresponds to a specific energy range. This enables the system to maintain high imaging speed with polychromatic beams while preserving energy spectrum information through spatially-resolved detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the generation of an energy spectrum and reconstruction of medical images corresponding to each energy bin, enhancing the ability to handle high photon count rates and reducing count losses, thereby improving the efficiency of photon counting X-ray CT systems.
Implementation Method 1
utilizing an X-ray diffraction phenomenon with a diffraction body and X-ray detection elements arranged to diffract polychromatic X-rays into Debye-Scherrer rings
Implementation Method 2
diffract polychromatic X-rays into Debye-Scherrer rings, allowing for the separation and counting of X-ray photons by energy
Data Source
AI summary
According to one embodiment, an X-ray computed tomography apparatus includes an X-ray tube, collimators including through holes respectively collimating an X-ray and diffraction bodies provided in the holes respectively, diffracting the X-ray at an angle to an X-ray energy, X-ray detection elements provided at predetermined distances from the bodies, counting circuitry counting the number of photons originating from the X-ray, storage circuitry storing statistical information, corresponding to energy bins in the X-ray, concerning a count distribution of count values with positions of the elements, classification circuitry classifying the numbers of counted photons for the bins by using the information, reconstruction circuitry reconstructing a medical image to the bins based on the number of photons classified for the bins.