Photon-Counting CT Calibration Using Filter-Mounted Variable Phantoms
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Solution Overview
Problem
Existing photon counting X-ray CT systems require complex mechanisms and user-intensive tasks for acquiring calibration data using multiple phantoms, which are cumbersome and difficult to handle.
Innovation Solution
A photon counting X-ray CT apparatus that utilizes the existing filter drive mechanism to move a second phantom with varying thicknesses, minimizing additional hardware and user workload by integrating it with the bowtie filter or low-energy X-ray removal filter, allowing for efficient calibration data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate phantoms are used for calibration data acquisition, then measurement precision is improved, but device complexity and ease of operation deteriorate due to the need to replace multiple phantoms
Solution Approach 1:
The patent combines multiple separate phantoms (first phantom with first base material and second phantom with second base material) into a single integrated phantom structure. The second phantom is installed on the filter and has different thickness portions, while the first phantom is inserted into the opening portion. This merging eliminates the need to replace multiple separate phantoms while maintaining the ability to acquire calibration data for different material combinations.
2Ease of operation
If a single large phantom with multiple materials is used, then ease of operation is improved, but the phantom becomes difficult to handle and device complexity increases
Solution Approach 1:
The integrated phantom is segmented into two functional parts: the second phantom with different thickness portions installed on the filter, and the first phantom inserted into the opening portion. This segmentation allows each part to be independently positioned and adjusted using existing drive mechanisms, making the overall system easier to handle while maintaining structural complexity for achieving multiple calibration measurements.
Solution Approach 2:
The phantom structure incorporates dynamic elements where the second phantom can be moved to different positions on the filter, and the first phantom can be inserted or removed from the opening portion. This dynamic configuration allows the system to achieve multiple calibration states without requiring multiple static phantom structures.
3Productivity
If dedicated drive units are added for each phantom, then productivity is improved through automated phantom switching, but device complexity increases
Solution Approach 1:
The patent makes the existing filter drive mechanism serve multiple functions: it originally drives the filter for energy discrimination, and now also drives the second phantom with different thickness portions for calibration data acquisition. This multi-functionality eliminates the need for a dedicated drive unit for the second phantom, improving productivity while avoiding additional complexity.
Solution Approach 2:
The system uses its own existing drive mechanisms (filter drive mechanism and patient table drive mechanism) to position and move the phantoms, rather than requiring external dedicated drive units. The filter drive mechanism moves the second phantom, and the patient table drives the first phantom, allowing the apparatus to service itself without additional specialized components.
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 efficient acquisition of calibration data with reduced user tasks and minimal additional mechanisms, improving the handling and efficiency of photon counting X-ray CT systems.
Implementation Method 1
The photon counting type detector can discriminate the energy of incident radiation photons and count the number of incident radiation photons for each energy region
Implementation Method 2
an X-ray tube; a filter; a filter drive mechanism that drives the filter
Implementation Method 3
a first phantom of a first base material, which has a smaller linear attenuation coefficient than the second base material
Data Source
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AI summary
An additional mechanism to an apparatus is minimized, and a user's tasks are reduced, thereby enabling acquisition of calibration data (204). A second phantom (303) of a second base material (203), which has different thickness portions, is installed on a filter (105) of a photon counting X-ray CT apparatus (101), the filter (105) is moved using a filter drive mechanism (304) such that X-rays (104) from an X-ray tube (103) are transmitted through a desired thickness portion of the second phantom (303), and a computing device (111) radiates X-rays (104) from the X-ray tube (103) in a state in which a first phantom (301, 401) of a first base material (202), which has a smaller linear attenuation coefficient than the second base material (203), is inserted into an opening portion (109) such that X-rays (109) are transmitted through the first phantom (301, 401) of the first base material (202), and acquires projection data based on a detection value output by a detector (108).