LINAC Isocenter Determination Using Optical Axis Tracking
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Solution Overview
Problem
Existing methods for determining the isocenter of a medical linear accelerator (LINAC) are inaccurate due to mechanical errors and non-coincidence of axes, leading to potential radiation delivery errors and adverse side effects.
Innovation Solution
A system and method that uses a signal emitter module on the collimator and a signal receiver module, typically a camera pod, to track the rotation of gantry, collimator, and couch components, determining their axes of rotation and isocenter without radiation, using stereoscopic imaging and software processing to compute the optimal isocenter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods (plumb lines, spirit levels, radiation-based techniques) are used to determine isocenter, then the process is simple and familiar, but the measurement precision is insufficient due to mechanical errors and non-coincidence of axes
Solution Approach 1:
The patent replaces traditional mechanical measurement methods (plumb lines, spirit levels, radiation-based techniques) with an optical tracking system using signal emitters, cameras, and computer vision algorithms. This substitution enables non-contact, high-precision measurement of mechanical component positions and orientations during rotation, achieving superior isocenter determination accuracy without the limitations of mechanical methods.
Solution Approach 2:
The patent creates a virtual model of the mechanical isocenter by tracking the positions and orientations of signal emitters attached to rotating components. Instead of directly measuring the isocenter point, the system captures multiple images during rotation and computationally reconstructs the axis of rotation and isocenter location, providing a precise virtual representation that can be used for alignment and verification.
2Reliability
If mechanical rotations are performed to determine isocenter, then the measurement is based on actual component behavior, but mechanical errors (non-concentric rotation, axis separation) cause harmful radiation delivery errors
Solution Approach 1:
The patent performs isocenter determination and mechanical error characterization before actual radiation treatment. By conducting the measurement process in advance using signal emitters and camera tracking during controlled rotations, the system identifies axis misalignments and mechanical imperfections beforehand, allowing for corrective adjustments to be made before patient treatment begins.
Solution Approach 2:
The patent uses real-time optical tracking feedback during mechanical rotation to precisely measure the actual positions and orientations of components. The system continuously monitors signal emitter locations through multiple camera views, compares measured positions against ideal rotational paths, and uses this feedback to calculate accurate isocenter location and characterize mechanical errors, enabling correction of radiation beam positioning.
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
Provides precise and real-time determination of the LINAC isocenter, reducing radiation steering errors and enhancing treatment accuracy by aligning the radiation beam directly to the tumor, thus minimizing adverse side effects.
Implementation Method 1
mounting a signal emitter module on a collimator; mounting a signal receiver module in a location with an unobstructed view of the signal emitter module
Implementation Method 2
The camera pod is comprised of at least 2 cameras capable of acquiring time synchronized images for computer analysis
Data Source
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AI summary
A system to determine the isocenter of a LINAC includes apparatus and processes. One embodiment does this by determining the axis of rotation for the collimator, the gantry, and may include the couch. In another embodiment only determining the axis of the rotation of the collimator is required. The system and apparatus enable the tracking of the translation-rotation of mechanical components attached to the LINAC to compute the axis of rotation of gantry, collimator and couch. Based on the data collected related to these axes the LINAC isocenter is determined. The primary apparatus utilized in the system includes a single emitter module, a signal receiver module, and a positioning module. The system also includes an isocenter target module and a gravity module to determine a gravity vector relative to the signal receiver.