Radiotherapy Table Rotation With Deflection Feedback for Precise Targeting
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Solution Overview
Problem
Existing radiotherapy treatments face challenges in minimizing radiation dose to healthy tissue while accurately targeting the treatment region, particularly in devices with rotating gantries and extendable table tops, leading to increased exposure and treatment inefficiencies.
Innovation Solution
A radiotherapy apparatus with a subject support surface that rotates about the isocenter and includes sensors to measure table top deflection, allowing precise positioning and minimization of radiation dose to healthy tissue without the need for repeated imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If radiation is directed from a plurality of different angles by rotating the radiation source around the patient, then the cumulative radiation dose at the target region is increased while the dose to healthy tissue is reduced, but the volume of healthy tissue available to spread the radiation dose becomes limited after 180° rotation
Solution Approach 1:
The patent transitions from coplanar radiation delivery (2D rotation in the gantry plane) to non-coplanar radiation delivery by adding patient rotation capability. This enables radiation beams to approach the target from three-dimensional angles, utilizing healthy tissue volumes in multiple spatial dimensions to spread and dissipate radiation dose away from the target region.
2Manufacturing precision
If the patient is rotated relative to the radiation plane to further reduce the radiation dose to healthy tissue, then the dose distribution is improved, but the device complexity increases due to additional rotation mechanisms
Solution Approach 1:
The patent combines the patient rotation mechanism with the existing gantry structure, integrating multiple rotational capabilities into a unified system. The patient support surface is rotated about a vertical axis while the gantry rotates about the patient, creating a coordinated multi-axis rotation system that achieves non-coplanar radiation delivery without proportionally increasing overall device complexity.
3Measurement precision
If the table top is extended into the bore to position the target region at the isocenter, then the positioning accuracy is improved, but the table top flexes causing the target region to move relative to the isocenter
Solution Approach 1:
The patent incorporates sensors that detect table top deflection in real-time and feeds this information back to the control system. The control system then adjusts the table top position or applies compensatory forces to counteract the flexing, maintaining accurate alignment of the target region with the radiation isocenter throughout the extension and rotation processes.
4Measurement precision
If repeated imaging is performed to accurately locate the position of the target region, then the positioning accuracy is improved, but the treatment time increases and patient exposure to imaging radiation increases
Solution Approach 1:
The patent performs comprehensive patient positioning and target region localization using imaging and sensors before the actual radiation treatment begins. The table top deflection characteristics are measured and stored in advance, allowing the control system to pre-calculate compensatory adjustments. During treatment, these pre-established data and corrections are applied without requiring repeated imaging, thereby maintaining accuracy while minimizing treatment time and additional radiation exposure.
Data Source
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.