Photon Counting X-ray Detector K-edge Subtraction Imaging
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Solution Overview
Problem
Conventional K absorption edge subtraction methods in X-ray diagnostics require a special synchrotron radiation X-ray source, which is not practical for general hospitals, and fail to completely remove the human body structure from images due to significant movement between X-ray exposures.
Innovation Solution
An X-ray diagnostic apparatus and method that sets specific energy bands based on the K absorption edge of an X-ray absorber, using a photon counting type X-ray detector to acquire and process X-ray image data, allowing for the removal of human body structure and clear depiction of contrast agents without the need for a monochromatic X-ray source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a synchrotron radiation X-ray source is used to achieve high monochromaticity, then the K absorption edge subtraction method can be implemented, but the device cannot be used in general hospitals due to its complexity and special requirements
Solution Approach 1:
The patent changes the energy parameters of X-rays by using a continuous spectrum source with selective energy band filtering. Instead of requiring monochromatic X-rays from a synchrotron, the invention uses a conventional X-ray source that emits a continuous spectrum, then selects specific energy bands (one below and one above the K absorption edge) through the detector's energy discrimination capability. This transforms the approach from requiring a specialized monochromatic source to using a conventional source with post-emission energy selection.
Solution Approach 2:
The patent replaces the mechanical/optical monochromization system (synchrotron radiation source with its complex beam line optics) with an electronic energy discrimination system. The photon-counting detector with energy band selection replaces the need for a monochromatic source, substituting a complex source system with a simpler detection and processing system that achieves the same functional result through electronic energy windowing rather than optical monochromization.
2Measurement precision
If X-ray exposures are taken at a short time interval to consider the human body as static, then subtraction processing can remove body structure, but movement between exposures causes residual body structure to remain in the subtraction image
Solution Approach 1:
The patent segments the X-ray energy spectrum into multiple energy bands and acquires images at different energy levels. By obtaining images at two different energy bands (one below and one above the K absorption edge) and performing subtraction processing, the method enhances the contrast agent signal while suppressing the body structure signal. This energy-domain segmentation allows for better differentiation between the contrast agent and body tissues, improving the effectiveness of subtraction imaging even when temporal segmentation is limited by patient movement.
3Ease of manufacture
If a continuous X-ray energy spectrum is used instead of monochromatic X-rays, then a practical X-ray source can be used in general hospitals, but the K absorption edge subtraction method becomes more difficult to implement
Solution Approach 1:
The patent introduces an intermediary energy band selection mechanism within the photon-counting detector system. This intermediary component (the energy discrimination circuitry and processing system) acts as a mediator between the continuous spectrum X-ray source and the final image processing. It selectively filters and processes photons based on their energy levels, extracting the relevant information from the continuous spectrum without requiring the source itself to be monochromatic. This intermediary system makes the K absorption edge subtraction method implementable with conventional X-ray sources.
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
Enables clear depiction of contrast agents and reduces unnecessary radiation exposure by using a continuous X-ray energy spectrum, effectively removing human body structure from images even with movement, without the need for a specialized X-ray source.
Implementation Method 1
The K absorption edge is a discontinuous point in the energy direction of X-ray photons which exist in an X-ray absorption characteristic of a substance. The energy at the K absorption edge of iodine used as a contrast agent is about 33.169 keV.
Implementation Method 2
An X-ray tube exposes an X-ray having a continuous energy spectrum toward an object
Data Source
AI summary
According to one embodiment, an X-ray diagnostic apparatus includes an X-ray tube, an X-ray detector and processing circuitry. The X-ray tube exposes an X-ray toward an object. The X-ray detector acquires two X-ray detection data sets by counting X-ray photons, having transmitted the object, in at least two X-ray energy bands depending on a K absorption edge of an X-ray absorber taken into the object. The processing circuitry is configured to input information to specify the X-ray absorber, set the at least two X-ray energy bands based on the input information to specify the X-ray absorber and generate at least one frame of X-ray image data by data processing including subtraction processing of the two X-ray detection data sets. The X-ray absorber has been depicted in the at least one frame of the X-ray image data.