Medical Imaging ROI Tracking via Position Map Calibration
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Solution Overview
Problem
Existing medical imaging technologies face challenges in accurately tracking a region of interest during medical imaging procedures, especially when the patient is moved through the imaging device, as the shape of the region of interest changes due to perspective changes.
Innovation Solution
An apparatus and method that utilize monitoring images, support position data, and a position map to accurately determine the position and shape of a region of interest in subsequent monitoring images, even as the patient is moved, by mapping calibration support positions to calibration monitoring positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If purely image based tracking is used to monitor a region of interest when the patient is moved through the imaging device, then the monitoring can be performed without additional sensors, but the tracking accuracy deteriorates due to perspective changes causing shape distortion of the region of interest
Solution Approach 1:
The patent introduces a position map as an intermediary data structure that maps support positions to region of interest positions in monitoring images. This position map serves as a mediator between the support movement and the region of interest tracking, allowing accurate tracking without complex real-time image analysis. The position map is created during calibration and stores the relationship between support positions and corresponding ROI positions, enabling efficient querying during actual monitoring.
Solution Approach 2:
The patent performs calibration in advance to create the position map before actual monitoring begins. During calibration, the system captures monitoring images at various support positions and stores the mapping between support positions and region of interest positions. This preliminary action eliminates the need for complex real-time tracking calculations during actual monitoring, improving both accuracy and efficiency.
2Measurement precision
If calibration data is collected at multiple support positions to create an accurate position map, then the tracking precision improves, but the calibration time and complexity increase
Solution Approach 1:
The patent collects calibration data at more support positions than the minimum required, creating a comprehensive position map that covers the entire range of motion. This excessive calibration action ensures that the position map remains accurate even when the support moves to positions not exactly matching calibration points, as the system can interpolate between calibration positions. The additional calibration overhead is minimal compared to the benefit of having a robust, accurate position map for the full motion range.
3Measurement precision
If the region of interest position is determined using complex image analysis algorithms, then the tracking accuracy improves, but the computational cost and processing time increase
Solution Approach 1:
The patent creates a simplified representation (position map) that copies the essential spatial relationship information from complex calibration images. Instead of performing complex image analysis during monitoring, the system queries the pre-computed position map, which contains the mapped positions. This copying approach replaces computationally intensive real-time image processing with simple lookups, dramatically reducing computational requirements while maintaining accuracy.
Data Source
AI summary
The invention refers to an apparatus for monitoring a subject (121) during an imaging procedure, e.g. CT-imaging. The apparatus (110) comprises a monitoring image providing unit (111) providing a first monitoring image and a second monitoring image acquired at different support positions, a monitoring position providing unit (112) providing a first monitoring position of a region of interest in the first monitoring image, a support position providing unit (113) providing support position data of the support positions, a position map providing unit (114) providing a position map mapping calibration support positions to calibration monitoring positions, and a region of interest position determination unit (115) determining a position of the region of interest in the second monitoring image based on the first monitoring position, the support position data, and the position map. This allows to determine the position of the region of interest accurately and with low computational effort.