Breathing Phase-Based CT Transformation for Respiratory Motion
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Solution Overview
Problem
Current methods for determining the position of treatment body parts during radiotherapy or radiosurgery, especially in the thorax or abdomen, are inadequate as they require multiple devices and expose patients to high radiation doses during CT scans, and do not effectively account for respiratory movements.
Innovation Solution
A medical data processing method that determines a transformation to predict the position of a treatment body part at a specific respiratory state by combining reference transformation data from planning CT images taken at a static respiratory state with scaling factor data from breathing CT images, allowing for the generation of four-dimensional planning tomography without the need for extensive radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CT scans with marker devices and optical tracking systems are used to determine treatment body part position, then measurement precision is improved, but device complexity increases and radiation dose increases
Solution Approach 1:
The patent extracts the essential information needed for position determination from the CT images themselves, specifically using the known geometric relationship between the imaging apparatus positions and the captured images to calculate respiratory state without requiring external marker devices or optical tracking systems. This separates the position determination function from the complex multi-device system.
Solution Approach 2:
The patent introduces a mathematical transformation model as an intermediary that bridges the planning CT (static respiratory state) and breathing CT (dynamic respiratory states). This transformation, derived from geometric relationships and scaling factors, serves as a mediator to predict treatment body part positions across different respiratory states without requiring direct real-time tracking devices.
2Measurement precision
If conventional CT scans with marker devices are used to determine treatment body part position, then measurement precision is improved, but radiation dose increases
Solution Approach 1:
The patent performs preliminary actions by acquiring CT images at specific respiratory states (planning CT at static respiratory state and breathing CT at multiple respiratory states) and pre-calculating the transformation model and scaling factors. This allows the treatment planning to be based on pre-computed geometric relationships, eliminating the need for repeated high-dose CT scans during actual treatment to determine body part positions.
Solution Approach 2:
The patent creates a mathematical copy or model of the treatment body part's geometric transformation across respiratory states using the transformation model derived from CT images. This virtual copy allows prediction of body part positions at any respiratory state without requiring additional radiation exposure, replacing the need for repeated physical CT scanning during treatment.
3Adaptability or versatility
If four-dimensional planning tomography is generated using conventional methods, then adaptability to respiratory movements is improved, but radiation dose increases
Solution Approach 1:
The patent introduces dynamic elements by modeling the treatment body part's geometric transformation across different respiratory states using the transformation model. This allows the system to adapt to respiratory movements dynamically by applying the learned transformation to predict positions at various respiratory phases, creating a dynamic understanding without requiring dynamic repeated scanning.
Solution Approach 2:
The patent changes parameters by using scaling factors and transformation models derived from geometric relationships between CT images at different respiratory states. These parameter changes allow the system to represent respiratory movement effects through mathematical transformations rather than physical repeated scanning, reducing radiation dose while maintaining adaptability to respiratory dynamics.
Data Source
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AI summary
Disclosed is a medical data processing method of determining a transformation for determining a breathing state-dependent geometry of an anatomical body part of a patient's body, the method comprising executing, on at least one processor of at least one computer, steps of: a) acquiring, at a processor, planning image data describing a set of tomographic medical planning images describing each a different part of the anatomical body part in the same respiratory state called reference planning respiratory state (y), wherein the anatomical body part is subject to respiratory movement and wherein the planning images comprise a planning image called reference planning image describing a part of the anatomical body part which is called reference planning body part; b) acquiring, at a processor, breathing image data describing a set (1) of tomographic medical breathing images of the anatomical body part, wherein the breathing images comprise a reference breathing image (A) describing the reference planning body part in a respiratory state called reference breathing respiratory state (a), which is different from the reference planning respiratory state (y), and a target breathing image (C) describing at least another part of the anatomical body part, wherein the other part of the anatomical body part is called target body part, in a respiratory state called target respiratory state (c) which is different from the reference planning respiratory state; c) determining, by a processor and based on the planning image data and the breathing image data, reference transformation data describing a transformation, called reference transformation (R), between the geometry (Factor A) of the reference planning body part in the reference planning respiratory state (y) and the geometry of the reference planning body part in the reference breathing respiratory state (a); d) acquiring, at a processor, scaling factor data describing a scaling factor (sf) which describes a relationship between the geometry (Factor A) of the reference planning body part in the reference breathing respiratory state (a) and the geometry (Factor C) of the target body part in the target respiratory state (c); e) determining, by a processor and based on the reference transformation and the scaling factor data, derived transformation data describing a transformation called derived transformation (T) between the geometry of the target body part in the reference planning respiratory state (y), and the geometry (Factor C') of the target body part in the reference breathing respiratory state (a).