Patient Surface Tracking via Weighted ICP Registration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current medical data processing methods for tracking patient position during radiotherapy or radiosurgery face challenges in achieving real-time, accurate surface reconstruction, especially with non-coplanar treatment fields and spontaneous patient movement, as they often rely on high-speed approaches that compromise accuracy and are prone to local minima issues with iterative closest point (ICP) algorithms.
Innovation Solution
A method that uses a laser device to scan the patient's body surface, acquiring initial reflection data and subsequent scans, with positional information from later scans given lower weights to detect movement by variance comparison, allowing for continuous and efficient tracking even when parts of the body surface are outside the camera's field of view, and integrating range cameras into radiotherapy systems for stable surface registration with limited field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed surface reconstruction approaches are used to track patient position in real-time, then tracking speed is improved, but measurement accuracy deteriorates
Solution Approach 1:
The system performs preliminary surface scanning to acquire a reference surface model before treatment begins. This pre-acquired reference serves as a baseline for subsequent real-time tracking, allowing the system to compare current surface positions against the known reference geometry without requiring complex real-time reconstruction of the entire surface model.
Solution Approach 2:
The surface tracking problem is divided into two distinct phases: (1) offline reference surface acquisition using structured light scanning, and (2) online real-time tracking using range cameras. Each phase uses optimized methods appropriate to its requirements, with the reference phase prioritizing accuracy and the tracking phase prioritizing speed.
2Measurement precision
If iterative closest point (ICP) algorithm is used for surface registration, then alignment accuracy is improved, but computational complexity increases causing local minima issues
Solution Approach 1:
The system performs preliminary surface scanning to acquire a reference surface model before treatment begins. This pre-acquired reference serves as a baseline for subsequent real-time tracking, allowing the system to compare current surface positions against the known reference geometry without requiring complex real-time reconstruction of the entire surface model.
Solution Approach 2:
The reference surface model serves multiple functions: it provides the baseline for ICP registration, acts as a geometric constraint to prevent convergence to local minima, and enables tracking even when parts of the patient body move outside the camera field of view.
3Speed
If range cameras are used for real-time surface tracking, then tracking speed is improved, but measurement accuracy deteriorates due to limited field of view
Solution Approach 1:
The system creates a digital copy of the patient's surface geometry through structured light scanning before treatment. This virtual surface model can be viewed from any angle and position, compensating for the limited physical field of view of the range cameras during real-time tracking.
Solution Approach 2:
The system transitions from relying solely on direct optical observation (2D camera views) to incorporating a complete 3D surface model. This allows tracking information to be derived from the full surface geometry even when only portions are visible to the cameras at any given moment.
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 approach enables efficient, continuous, and accurate tracking of patient position, reducing the risk of local minima and improving accuracy in non-coplanar positioning, allowing for markerless setup workflows and automatic surface-based prepositioning, thereby enhancing the reliability of radiotherapy systems.
Implementation Method 1
detection of light reflections from the surface of the body by scanning the body with a laser device and receiving the laser signals reflected from the body
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
A medical data processing method for tracking the position of a body surface of a patient's body, the method comprising determining, based on initial surface reflection data and reflection pattern registration data, body surface movement data describing whether the body surface has undergone a movement.