CT Data Alignment Using Isotropic Positioning Elements
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Solution Overview
Problem
Existing three-dimensional image data alignment methods for X-ray imaging face challenges in accurately combining CT data sets due to subject inclination, X-ray focus movement, and thermal expansion, leading to errors in surface shape alignment, particularly as the subject's shape increases, making it difficult to maintain precise relative positional relationships between CT data sets.
Innovation Solution
A method involving the use of at least three positioning elements with isotropic shapes, such as spherical shapes, during X-ray imaging to generate and align three-dimensional CT data sets, ensuring accurate alignment by utilizing these elements' center positions across overlapping areas, even in the presence of subject placement part inclination or X-ray focus drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the best-fit technique is used to align CT data sets, then alignment can be performed using shape data, but alignment accuracy deteriorates as the subject's shape increases due to increased path length and artifacts
Solution Approach 1:
The patent introduces positioning elements as intermediary objects that are imaged alongside the subject. These positioning elements serve as mediators for alignment by providing stable reference points (center positions) that are independent of the subject's shape. The alignment is performed based on the center positions of these positioning elements rather than directly on the subject's shape data, thereby eliminating the degradation of alignment accuracy that occurs with larger subjects.
2Area of stationary object
If CT data sets are combined from multiple imaging sessions, then coverage of the entire subject is improved, but relative positional relationships deteriorate due to subject placement inclination, X-ray focus movement, and thermal expansion
Solution Approach 1:
Positioning elements are introduced as intermediary reference objects that remain stable across multiple imaging sessions. These elements are imaged together with the subject in each session, and their center positions are used to establish accurate relative positional relationships between different CT data sets. This intermediary reference system compensates for variations caused by subject placement inclination, X-ray focus movement, and thermal expansion of the imaging apparatus.
Solution Approach 2:
The positioning elements have high contrast appearance in X-ray images (effectively a form of visual distinction similar to color changes), making their center positions easily detectable and distinguishable from the subject. This high contrast property ensures that the positioning elements can be reliably identified and measured even when the subject moves or changes position between imaging sessions.
3Quantity of substance
If the subject's shape increases, then more comprehensive imaging is achieved, but alignment errors increase due to increased path length and artifacts in shape data
Solution Approach 1:
The positioning elements serve as intermediary reference objects whose simple geometric shapes (with well-defined center positions) are independent of the subject's volume or shape. By using these positioning elements for alignment rather than relying on the subject's shape data, the patent eliminates the accumulation of alignment errors that occurs when imaging larger subjects with more complex shapes.
Data Source
AI summary
A three-dimensional image data alignment method includes a step of generating a first CT data set 23 based on a first X-ray image data set 22, and a second CT data set 25 based on a second X-ray image data set 24; and a step of aligning the first CT data set 23 with the second CT data set 25 based on positioning elements 30 included in the first CT data set 23 and the second CT data set 25.