Compact 3D Stereoscopic Bore Camera Calibration for Patient Positioning
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Solution Overview
Problem
Existing patient monitoring systems in integrated bore-based medical apparatuses face challenges in accurately monitoring patient positioning and movement during scanning and treatment due to suboptimal camera configurations and calibration issues, especially when the patient is moved between imaging and treatment positions.
Innovation Solution
A 3D camera system with image sensors mounted on opposing surfaces of a circuit board and utilizing mirrors to view objects, along with a speckle projector, is designed to reduce the overall size and increase the field of view, while a calibration method using a calibration object with marked surfaces ensures accurate patient positioning models are generated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If image sensors are mounted on opposing surfaces of a circuit board with mirrors to expand field of view, then the field of view is increased and system size is reduced, but the calibration complexity increases due to lens distortions and spatial transformations
Solution Approach 1:
A calibration object with known geometric features serves as an intermediary between the camera system and the processing system. This calibration object enables automatic detection and characterization of lens distortions, mirror transformations, and spatial relationships, converting a complex manual calibration process into an automated procedure that uses the calibration object as a mediator to establish accurate mapping relationships
Solution Approach 2:
The system automatically detects and corrects for lens distortion parameters, mirror transformation parameters, and spatial transformation parameters by comparing captured images of the calibration object with its known geometry. These parameter changes are computed and stored to enable accurate 3D reconstruction without manual intervention
2Volume of moving object
If multiple image sensors and mirrors are used to reduce system size, then the physical footprint is reduced, but the measurement precision requirements increase due to the need for accurate spatial transformations
Solution Approach 1:
The system uses feedback from captured images of the calibration object to automatically compute and correct for spatial transformations, mirror transformations, and lens distortions. This feedback mechanism ensures that even with compact positioning of sensors and mirrors, the system can achieve high measurement precision by iteratively refining the transformation parameters based on actual captured data
Solution Approach 2:
The calibration process is performed preliminarily before actual patient monitoring, establishing accurate transformation parameters and distortion correction models in advance. This preliminary action ensures that the compact system configuration is pre-characterized and ready for high-precision measurements during operation
3Measurement precision
If a calibration object with marked surfaces is used to generate accurate positioning models, then patient positioning accuracy is improved, but the calibration time and process complexity increase
Solution Approach 1:
The calibration object is designed to be self-sufficient for the calibration process, with its known geometric features and marked surfaces enabling the system to automatically detect, measure, and compute transformation parameters without external intervention. The calibration object serves itself as the reference standard, eliminating the need for manual measurement and input of calibration data
Solution Approach 2:
The manual mechanical calibration process is replaced with an automated optical-digital calibration system. Instead of manually measuring and inputting calibration parameters, the system uses image capture, automatic feature detection, and computational algorithms to derive all calibration parameters, substituting mechanical measurement with optical sensing and digital processing
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
The system enables precise patient monitoring and positioning within the bore of medical apparatuses, reducing system size and maintaining high accuracy by using mirrors and a calibration method that compensates for lens distortions, allowing for real-time adjustments and warnings on patient movement.
Implementation Method 1
first mirror positioned within the housing so that the first image sensor is presented with a first view of an object to be imaged via the first mirror and second image sensor is presented with a second view of an object to be imaged via the second mirror
Data Source
AI summary
A camera monitoring system for a bore based medical apparatus is described, wherein the camera monitoring system comprises a first and a second image sensor mounted on opposing surfaces of a circuit board. The first image sensor is arranged to view an object from a first viewpoint via a first lens arrangement and a first mirror and the second image sensor is arranged to view the object from a second viewpoint via a second lens arrangement and a second mirror. By having the image sensors view an object via the mirrors, via the lens arrangements, the lens arrangements contribute to the effective separation of the first and second viewpoints enabling the size of the housing of the camera to be reduced. Furthermore, a method for calibrating a camera monitoring system in a bore based setup is described and also a configuration of arranging a camera monitoring system in connection with a bore based medical apparatus.