Radiotherapy Tracking via DRR-Fluoroscopy Phase Coordination
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Solution Overview
Problem
Current radiotherapy tracking methods face challenges in accurately tracking specific regions like tumors in organs such as the liver and pancreas, which are poorly recognizable and move with breathing, leading to reduced accuracy and increased difficulty in preparing templates for markerless tracking.
Innovation Solution
A radiotherapy tracking apparatus that generates digitally reconstructed radiographic (DRR) images from four-dimensional CT data to simulate respiratory phases, allowing for markerless tracking by coordinating DRR images with X-ray fluoroscopic images using feature points and minimizing the need for pre-template preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If markerless tracking is used for poorly recognizable regions like liver and pancreas tumors, then the need for marker implantation is eliminated, but tracking accuracy deteriorates due to poor visual recognition of the specific region
Solution Approach 1:
The patent introduces DRR images as an intermediary to bridge the gap between poor visual recognition in fluoroscopic images and the need for accurate tracking. The DRR images, generated from 4D-CT data, serve as a reference that clearly shows the specific region's position and movement pattern throughout the respiratory cycle, enabling accurate tracking without requiring direct visual recognition from fluoroscopic images alone
Solution Approach 2:
The patent performs preliminary action by generating DRR images from 4D-CT data before the actual radiotherapy treatment. These pre-generated DRR images capture the specific region's appearance at different respiratory phases, allowing the system to establish a reference framework in advance that facilitates accurate tracking during treatment without requiring real-time visual recognition of poorly visible regions
2Measurement precision
If template preparation is performed in advance for markerless tracking, then tracking can be performed, but the treatment throughput deteriorates due to additional preparation time and patient discomfort from prolonged positioning
Solution Approach 1:
The patent creates copies of the specific region's appearance at different respiratory phases through DRR images generated from 4D-CT data. These copied representations capture the region's characteristics without requiring time-consuming template preparation during treatment, enabling rapid tracking by comparing current fluoroscopic images against the pre-generated DRR library
Solution Approach 2:
The patent changes the parameter representation by using DRR images derived from 4D-CT data, which encode respiratory phase information directly into the image generation process. This allows the system to track the specific region by matching against DRR images corresponding to different respiratory phases, eliminating the need for manual template preparation and adjustment during treatment
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 high-accuracy tracking of specific regions without the need for visual recognition or pre-template preparation, improving the throughput of radiotherapy and reducing patient discomfort.
Implementation Method 1
generates a plurality of DRR images including a specific region throughout an entire respiratory phase by performing a virtual fluoroscopic projection simulating a geometric fluoroscopic condition between an X-ray tube and an X-ray detector
Data Source
AI summary
A radiotherapy tracking apparatus for tracking a position of a specific region with markerless tracking even when visual recognition of the specific region of the subject is poor and for eliminating preliminary work such as preparation of a template. A control element comprises a DRR image generation element, a phase-based position calculation element, an X-ray fluoroscopic image obtaining element, a phase adjuster, a frame-based position calculation element, a gating element and a memory storage. The frame-based position calculation element calculates the position of the specific region of the subject in the X-ray fluoroscopic image having the plurality of frames frame-by-frame based on the DRR image adjusted with the X-ray fluoroscopic image in the phase adjustment element and the position of the specific region calculated by the phase-based position calculation element.