Intrafraction Volumetric Imaging for Partial ITV Motion Management
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Solution Overview
Problem
Traditional radiation delivery systems treat the entire range of motion of a treatment target with a margin of expansion, leading to excessive exposure of normal tissue, especially when tumors undergo large excursions during breathing.
Innovation Solution
The use of intrafraction volumetric imaging to reduce motion management uncertainties by determining a partial Internal Target Volume (ITV) based on the target's motion amplitude, allowing for more precise treatment delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire range of motion (ITV) is treated with a margin of expansion, then setup inaccuracy and gross patient movement are compensated, but large volumes of normal tissue are exposed to the prescription dose
Solution Approach 1:
The patent segments the internal target volume (ITV) into multiple sub-volumes based on respiratory phase (e.g., inhale phase ITV and exhale phase ITV). Treatment is then delivered in segments corresponding to these sub-volumes at different respiratory phases, rather than treating the entire ITV continuously. This segmentation allows normal tissue to be spared during portions of the respiratory cycle when the tumor is not in the treatment zone.
Solution Approach 2:
The patent implements periodic gating of the treatment beam based on the patient's respiratory cycle. The radiation beam is activated only during specific phases of respiration (e.g., during exhale or inhale phases) when the tumor is within the planned treatment window. This periodic on/off action synchronizes treatment delivery with the periodic nature of respiratory motion, reducing exposure to normal tissues that would otherwise be irradiated continuously.
2Object-affected harmful factors
If the ITV is reduced to a partial-ITV, then normal tissue exposure is reduced, but target coverage may be insufficient
Solution Approach 1:
The patent dynamically adapts the treatment target volume and beam gating based on real-time or planned respiratory motion. The partial-ITV is not a fixed reduction but a dynamic volume that changes with respiratory phase. During inhale phase, the target volume corresponds to the inhale position; during exhale phase, it corresponds to the exhale position. This dynamic adjustment ensures adequate target coverage at each phase while minimizing normal tissue exposure overall.
Solution Approach 2:
The patent changes the spatial parameters of the target volume definition based on respiratory phase. Instead of using a single static ITV encompassing the full range of motion, the system defines different target volumes (partial-ITVs) for different phases of respiration. These parameter changes in target volume definition, combined with temporal gating, ensure that the tumor receives adequate dose while normal tissues receive reduced exposure.
Data Source
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AI summary
A method of the present disclosure includes identifying, based on a reference image, a full motion range of a target, wherein the full motion range of the target defines a full internal target volume (ITV). The method further includes identifying a non-target object in a motion image or the reference image. The method further includes performing a volumetric alignment of the ITV and the non-target object. The method further includes modifying a non-target to target displacement vector based on the volumetric alignment. The method further includes tracking the target based on the modified non-target to target displacement vector.