Radiotherapy Target Localization via Isodose Reference Volume
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Solution Overview
Problem
Current image-guided radiation therapy (IGRT) systems face challenges in accurately locating target volumes due to anatomical changes in soft tissues, leading to potential under-irradiation of tumors or over-irradiation of adjacent organs, especially in treatments like prostate cancer where prostate and rectum/bladder volume changes affect precision.
Innovation Solution
A method involving the use of simulated localization images and image-guided images, where a reference volume defined by isodose lines is registered to accurately determine the offset of the target volume, allowing for precise positioning and adjustment of radiation delivery, using either rigid or deformable registration techniques to account for anatomical changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional image-guided radiation therapy systems use standard localization methods, then the treatment process is simple and fast, but the accuracy of target volume localization deteriorates due to anatomical changes in soft tissues
Solution Approach 1:
The patent applies preliminary action by pre-defining a reference volume based on isodose lines from treatment planning before the actual treatment session. This reference volume is calculated in advance and stored, then used during image guidance to quickly compare with current anatomy without requiring complex real-time registration calculations
Solution Approach 2:
The patent creates a simplified copy of the target volume by using the reference volume derived from isodose lines. This reference volume serves as a surrogate that captures the essential spatial relationship between the target and surrounding structures, enabling accurate localization without requiring full anatomical reconstruction
2Productivity
If rigid registration is used to align images quickly, then processing time is reduced, but accuracy deteriorates when anatomical changes occur in soft tissues
Solution Approach 1:
The reference volume is pre-calculated from treatment planning isodose lines before patient treatment. This preliminary computation captures the spatial relationship between target and surrounding structures, allowing rapid comparison during image guidance without requiring complex real-time registration
Solution Approach 2:
The patent changes the approach from spatial parameter matching (traditional registration) to dose distribution parameter matching. By comparing the reference volume (derived from isodose lines) with current imaging, the system accounts for anatomical changes while maintaining computational efficiency
3Reliability
If the target volume is not accurately localized, then treatment delivery is fast and simple, but harmful effects occur including under-irradiation of tumors and over-irradiation of adjacent organs
Solution Approach 1:
The patent introduces a reference volume as an intermediary between treatment planning and image-guided delivery. This reference volume, derived from isodose lines, acts as a mediator that translates complex dose distribution information into a form that can be quickly compared with current anatomy to ensure accurate target localization
Solution Approach 2:
The system implements feedback by comparing the reference volume with the currently imaged anatomy and using this comparison to determine the actual target volume position. This feedback loop ensures that treatment delivery is based on current anatomical information, preventing both under- and over-irradiation
Data Source
AI summary
A method for positioning of target treatment tissue is provided, which includes: obtaining a simulated localization image from a preliminary treatment plan for a target object, the simulated localization image including a target volume and a reference volume of a target prescription dose corresponding to the target volume, and the reference volume being configured to indicate a contour volume formed by target isodose lines of the target prescription dose corresponding to the target volume on image layers in the simulated localization image; obtaining a first image-guided image of the target object; performing a rigid registration on the simulated localization image with the first image-guided image; and displaying the first image-guided image and the reference volume of the target prescription dose to determine an extent of overlap between the reference volume of the target prescription dose in the first image-guided image and the target treatment tissue.