Stereo Tube CT System for Complete Volume Reconstruction
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Solution Overview
Problem
Conventional cone beam CT systems inadequately sample and reconstruct portions of the scanned volume, leading to incomplete data acquisition and inefficient dose utilization, particularly in retrospective cardiac CT applications, where not all desired cardiac phases can be reconstructed, and only a subset of the volume can be corrected for image artifacts.
Innovation Solution
A stereo tube CT system with two x-ray sources positioned at different z-axis locations around an examination region, emitting radiation beams that alternately traverse the volume, ensuring complete data acquisition and reconstruction of the entire volume, while minimizing irradiation of regions outside the reconstructed volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cone beam source is used for axial scanning, then the system structure is simple, but the data acquisition is incomplete and only a subset of the scanned volume can be reconstructed
Solution Approach 1:
The single cone beam source is segmented into multiple separate tube assemblies, each positioned at different angular locations around the patient. Each tube assembly independently emits a cone beam, and the detectors are segmented to correspond with each tube's beam path. This segmentation allows complete data acquisition for the entire scanned volume by combining data from multiple angular positions.
Solution Approach 2:
The system transitions from a single angular position to multiple angular positions around the patient. By adding the angular dimension and positioning multiple tube assemblies at different angles, the system achieves complete 360-degree data coverage, enabling reconstruction of the entire scanned volume rather than just a subset.
2Device complexity
If a single cone beam source is used, then the device complexity is low, but the dose utilization is inefficient due to irradiation of regions outside the reconstructed volume
Solution Approach 1:
Each tube assembly is configured with its cone beam directed specifically toward a particular region of the scanned volume. The beam geometry and detector positioning are optimized for each tube's location, ensuring that radiation is concentrated on the intended target volume rather than irradiating the entire patient body. This localizes the radiation dose to the reconstructed volume.
Solution Approach 2:
By introducing multiple angular positions around the patient, the system can direct cone beams from different angles to illuminate the scanned volume from optimal directions. This angular dimension allows the beams to be confined to the volume of interest, reducing unnecessary irradiation of regions outside the reconstructed volume and improving dose utilization efficiency.
3Ease of operation
If conventional axial cone beam CT is used, then the scanning protocol is simple, but the image quality is degraded due to incomplete data and artifacts
Solution Approach 1:
The scanning system is segmented into multiple tube assemblies, each contributing to data acquisition from different angular positions. The detector array is segmented to match the multi-tube configuration, with each detector element corresponding to a specific tube's beam path. This segmentation enables complete data collection for high-quality reconstruction while maintaining a relatively simple axial scanning protocol.
Solution Approach 2:
The system incorporates feedback through iterative reconstruction techniques that use the complete data from multiple angular positions to refine and correct image artifacts. The feedback loop allows the reconstruction algorithm to iteratively improve image quality by comparing measured projections with reconstructed images, correcting for incomplete data and reducing artifacts such as cone beam and beam hardening artifacts.
4Loss of time
If only a subset of the scanned volume is reconstructed, then the reconstruction process is faster, but the clinical utility is limited for retrospective cardiac CT applications
Solution Approach 1:
The system performs preliminary complete data acquisition from multiple angular positions during the axial scan, ensuring that all necessary data is collected before reconstruction begins. This preliminary complete sampling enables retrospective analysis and flexible reconstruction of the entire scanned volume, allowing clinicians to select and reconstruct specific cardiac phases or regions of interest without time constraints.
Solution Approach 2:
By acquiring data from multiple angular dimensions around the patient, the system creates a comprehensive data set that enables complete volume reconstruction. This angular dimensionality provides the flexibility needed for retrospective cardiac CT applications, where clinicians can retrospectively select arbitrary 180 degrees of data corresponding to different cardiac phases, making the system highly adaptable to various clinical needs.
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 configuration allows for efficient dose utilization by ensuring at least 360 degrees of data is detected, enabling the reconstruction of the entire volume and reducing image artifacts, thereby improving image quality and cardiac CT applications by providing complete and accurate data for desired cardiac phases.
Implementation Method 1
two x-ray sources positioned at different z-axis locations around an examination region, emitting radiation beams that alternately traverse the volume
Implementation Method 2
A common detector detects radiation from the x-ray beams that traverses the volume and generates data indicative thereof
Data Source
AI summary
A computed tomography system (100) includes a first (1081) and a second source (108N) disposed at different z-axis locations at about a same angular position around an examination region (112) that alternately emit radiation beams (114) that traverse the examination region (112). The first source (1081) emits a first radiation beam (1141) having a first outer projection (204) and the second source (108N) emits a second radiation beam (114N) having a first outer projection (216). Both of the first outer projections (204, 216) traverse plane perpendicular to the axis of rotation, and the first outer projections (204, 216) define a width of a volume (400) within which the emitted radiation beams (114) are confined. A common detector (124) detects radiation from the x-ray beams (114) that traverses the volume (400) and generates data indicative thereof, and a reconstructor (132) reconstructs the data to generate an image of the volume (400).