Variable Aperture Collimator for Radiation Dose Reduction
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Solution Overview
Problem
Current radiation therapy systems expose patients to additional radiation due to the need for high-energy x-ray imaging to track tumor motion during treatment, which can damage healthy tissues and increase overall radiation dose.
Innovation Solution
A helical delivery system with a variable aperture collimator, such as a multi-leaf or iris collimator, adjusts the field of view of the kV imaging source to a smaller region of interest around the treatment target, reducing unnecessary radiation exposure and improving image quality by minimizing the irradiated tissue area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a kV x-ray imaging system is used to obtain 2D radiographs of the radiation target, then real-time tumor position information is provided, but the radiation dose absorbed by patients increases
Solution Approach 1:
The patent applies local quality by using a variable aperture collimator to restrict the x-ray beam to a small region of interest (ROI) around the radiation target. Instead of imaging the entire treatment volume, the system focuses imaging resources locally on the tumor area, providing sufficient tumor position information while minimizing radiation exposure to surrounding healthy tissues.
Solution Approach 2:
The patent segments the imaging field into a small region of interest (ROI) containing the radiation target and the rest of the treatment volume. By using a variable aperture collimator, the system divides the x-ray beam into a focused ROI area, imaging only where necessary for tumor tracking while leaving other areas unexposed or minimally exposed to radiation.
2Object-affected harmful factors
If a variable aperture collimator is used to reduce the field of view, then radiation dose is minimized, but image quality may deteriorate due to reduced photons
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the aperture size of the variable collimator based on the treatment phase and clinical requirements. The system can vary the field of view size to optimize the balance between radiation dose reduction and image quality maintenance, changing imaging parameters adaptively rather than using a fixed aperture.
Solution Approach 2:
The patent implements periodic action by using the variable aperture collimator to periodically adjust the field of view size during treatment delivery. The system alternates between larger FOV for setup and verification and smaller FOV for routine tracking, optimizing radiation dose while maintaining sufficient image quality at different treatment stages.
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 minimizes patient exposure to additional radiation while maintaining or improving image quality by adjusting the aperture of the kV imaging source to match the size and shape of the region of interest, thereby reducing scatter and enhancing the quality of reduced field-of-view images compared to larger, uncollimated fields.
Implementation Method 1
improving image quality by minimizing the irradiated tissue area
Data Source
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AI summary
A method including imaging a first field of view (FOV) of a volume of interest (VOI) that includes a region of interest (ROI) from a first position and imaging the first FOV of the VOI from a second position. The method including receiving a first identification of a first portion of the imaged VOI designating the ROI to be imaged and a second identification of a second portion of the imaged VOI from the second position designating the ROI to be imaged. In response to the first identification, adjusting an aperture of a collimator of an imaging source to a second FOV corresponding to the ROI from the first position and imaging the ROI using the second FOV. In response to the second identification, adjusting the aperture of the collimator to a third FOV corresponding to the ROI from the second position and imaging the ROI using the third FOV.