Radiotherapy Support Surface Rotation for Healthy Tissue Dose Reduction
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Solution Overview
Problem
Existing radiotherapy devices face challenges in minimizing radiation dose to healthy tissue surrounding the target region due to patient movement, table top flexing, and the need for accurate target positioning during treatments like spiral therapies, which often require additional imaging, leading to longer treatment times and increased exposure.
Innovation Solution
A radiotherapy apparatus with a subject support surface that can rotate about an isocenter and includes sensors to measure table top deflection, allowing precise positioning and minimizing radiation exposure to healthy tissue by rotating the patient support surface outside the radiation plane, and using a system to compensate for table top flexing without the need for repeated imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the radiation source rotates around the patient by use of a rotating gantry to deliver radiation from a plurality of different angles, then the cumulative radiation dose at the target region is built up while reducing the dose to healthy tissue, but after the radiation source has been rotated 180°, subsequent radiation beams begin to pass through regions of healthy tissue which have already been irradiated, increasing the radiation dose applied to healthy tissue
Solution Approach 1:
The patent transitions from coplanar radiation delivery (2D rotation in the radiation plane) to non-coplanar radiation delivery by rotating the patient support surface about a vertical axis perpendicular to the radiation plane. This adds a third dimension to the treatment geometry, allowing radiation beams to approach the target from angles that do not re-expose previously irradiated healthy tissue regions.
2Object-affected harmful factors
If the patient support surface is rotated to change the angle of the patient relative to the plane of radiation to further reduce the radiation dose to healthy tissue, then the radiation dose to healthy tissue is reduced, but accurate positioning of the target region at the isocenter becomes more difficult due to patient movement and table top flexing
Solution Approach 1:
The patent incorporates sensors that detect the position of the target region and provide feedback to the control system. This feedback mechanism allows the system to monitor and compensate for patient movement and table top flexing during rotation, maintaining accurate positioning of the target region at the isocenter while enabling non-coplanar radiation delivery.
Solution Approach 2:
The patent replaces manual positioning methods with an automated control system that uses sensors to detect target region position and automatically adjusts the patient support surface orientation. This substitution of mechanical/manual positioning with sensor-based automated control improves positioning accuracy during complex rotational movements.
3Measurement precision
If additional imaging is performed to ensure accurate target positioning during spiral therapies, then the positioning accuracy is improved, but the treatment time increases and the patient receives increased exposure to imaging radiation
Solution Approach 1:
The patent enables continuous non-coplanar radiation delivery without interrupting the treatment beam for repeated imaging. The sensor-based feedback system maintains continuous monitoring of target region position during the entire treatment arc, allowing the radiation delivery to proceed continuously while accurately tracking and compensating for any position changes.
Data Source
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AI summary
The present application relates to a radiotherapy apparatus for delivering radiation to a subject. The apparatus comprises a source of radiation configured to rotate about an isocenter and emit radiation in a radiation plane containing said isocentre. The apparatus also comprises a subject support surface configured such that a portion of the subject support surface can be located substantially at the isocenter. The apparatus also comprises a subject support surface rotation mechanism configured to rotate the subject support surface about an axis of rotation that passes through the isocenter, wherein the subject support surface rotation mechanism is located outside the radiation plane.