Calibration Module for Rotatable Radiation Source Alignment
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Solution Overview
Problem
Existing medical treatment arrangements with rotatable treatment radiation sources face inaccuracies in determining geometrical information due to mechanical and weight-related issues, leading to deviations in the position and alignment of radiation and imaging systems, which affect the precision of dose delivery in external beam therapy.
Innovation Solution
A method that uses a calibration module attached to the rotatable treatment radiation source unit, in addition to a phantom on the patient support, to obtain images at various rotational positions, allowing for the determination of geometrical information without assumptions about the rotation axes, using fiducial markers to evaluate positions and orientations relative to a coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rotatable treatment radiation source unit is used in medical treatment arrangements, then the versatility and effectiveness of external beam therapy is improved, but mechanical inaccuracies and weight-related issues cause deviations in the position and alignment of radiation and imaging systems
Solution Approach 1:
The patent applies preliminary action by performing geometric calibration measurements before actual treatment. A calibration module with fiducial markers is positioned in the treatment area, and multiple images are acquired at different gantry angles to pre-determine the actual rotation axis and isocenter position. This preliminary geometric characterization compensates for mechanical inaccuracies before patient treatment begins.
Solution Approach 2:
The patent replaces reliance on mechanical precision with an optical/image-based measurement system. Instead of depending on mechanically perfect rotation, the system uses fiducial markers and image acquisition to optically determine the actual rotation axis and isocenter. This substitution of mechanical assumptions with optical measurement resolves the contradiction between mechanical versatility and alignment precision.
2Manufacturing precision
If detailed inspection and quality assurance procedures are performed to improve geometrical accuracy, then the precision of dose delivery is improved, but the complexity and time required for calibration procedures increases
Solution Approach 1:
The calibration module serves multiple functions: it provides fiducial markers for geometric calibration, acts as a phantom for image quality assessment, and enables determination of rotation axis and isocenter position. This multi-functionality consolidates multiple calibration tasks into a single integrated procedure, reducing overall complexity while maintaining geometrical accuracy.
Solution Approach 2:
The system performs self-calibration by automatically detecting fiducial markers in acquired images and computing the rotation axis and isocenter position through image analysis algorithms. This automated self-service approach reduces manual intervention and procedural complexity compared to traditional manual calibration methods.
3Measurement precision
If multiple images are obtained at different rotational positions to determine geometrical information without assumptions, then the accuracy of isocenter position determination is improved, but the measurement time and number of required images increases
Solution Approach 1:
The patent uses partial action by acquiring images at a limited set of discrete gantry angles (e.g., 0°, 90°, 180°, 270°) rather than continuous imaging. This partial sampling is sufficient to determine the rotation axis and isocenter through geometric analysis, reducing measurement time while maintaining adequate precision for clinical purposes.
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 method provides accurate geometrical information about the medical treatment arrangement, enabling precise alignment and position verification of radiation and imaging systems, thereby improving the accuracy of dose delivery and stability in external beam therapy.
Implementation Method 1
the radiation source unit emits radiation in the direction of a phantom attached to the patient support and an image is obtained using the image detector, which image detector receives radiation from the radiation source unit that has passed through the phantom
Data Source
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AI summary
The invention relates to a method of determining geometrical information about a medical treatment arrangement (1) comprising a rotatable treatment radiation source unit (2), wherein the method comprises: • attaching a phantom (M1) to a patient support (10) of the medical treatment arrangement (1), • attaching a calibration module (M2) to the rotatable treatment radiation source unit (2), so that the calibration module (M2) rotates together with the rotatable treatment radiation source unit (2) when the rotatable treatment radiation source unit (2) is rotated, • obtaining for each of a plurality of rotational positions of the rotatable treatment radiation source unit (2) at least one projection image of the phantom (M1) and of the calibration module (M2) by using an image detector (6) of the medical treatment arrangement (1), while at least a part of the calibration module (M2) is positioned in a radiation propagation zone between the rotatable treatment radiation source unit (2) and the image detector (6), • evaluating images obtained for the plurality of rotational positions with respect to coordinates of the calibration module (M2) in a coordinate system of the phantom (M1), thereby obtaining an evaluation result and • determining geometrical information about the medical treatment arrangement (1) from the evaluation result.