Static device for use in radiotherapy treatment and design method for such a device
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Publication Number
US-12147734-B2
Publication Date
2024-11-19
Expiration Date
Abstract
A compensating device for use in ion-based radiotherapy may comprise a disk with a number of protrusions may be placed in a radiation beam to affect the ions in the beam in different ways to create an irradiation field from a broad beam. This is particularly useful in FLASH therapy because of the limited time available or modulating the beam. A method of designing such a compensating device is proposed, comprising the steps of obtaining characteristics of an actual treatment plan comprising at least one beam, determining at least one parameter characteristic of the desired energy modulation of the actual plan by performing a dose calculation of the initial plan and, based on the at least one parameter, computing a shape for each of the plurality of elongated elements to modulate the dose of the delivery beam to mimic the dose of the initial plan per beam.
Core Innovation
A problem addressed by the invention is compensating an ion-based radiotherapy treatment delivery, including FLASH radiotherapy, by modulating an incoming beam so that a target-conforming depth/energy distribution is achieved without moving parts. The background and description relate to the limitations of modulation time in FLASH therapy and the difficulty of controlling dose and energy deposition for complex clinical objectives.
The core innovation is a static compensating device design for ion-based radiotherapy. The device includes a substantially disk-shaped structure with on one side a plurality of elongate elements, and the compensator element varies in thickness using elongate elements such as spike-shaped structures, pins, or ridges that modulate a delivery beam by creating an energy modulation that mimics an initial treatment plan per beam.
The described design method obtains a pencil beam scanning initial treatment plan optimized with respect to one or more Physical dose, Relative Biological Effective dose, and Linear Energy Transfer objectives. The method then determines parameters characteristic of desired energy modulation of an actual treatment plan by performing dose calculation on the initial treatment plan and scores per-pixel quantities on a projected upstream virtual grid, and computes a shape for each elongate element based on those parameters.
The method re-optimizes the actual treatment plan using a single energy layer while taking into account the compensating device, and iterates adjusting elongate-element shapes until the final treatment plan and compensator geometry remain stable between successive iterations.
Claims Coverage
The independent claim defines a full workflow for designing a compensating device for ion-based radiotherapy, including computing elongate-element shapes and iteratively re-optimizing until stability. It includes four inventive features.
Pencil beam scanning initial plan optimized with dose and LET/RBE objectives
Obtaining a pencil beam scanning initial treatment plan, optimized with respect to one or more of Physical dose, Relative Biological Effective dose, and Linear Energy Transfer objectives.
Dose-calculation-derived parameter for desired energy modulation
Determining at least one parameter characteristic of the desired energy modulation of the actual treatment plan by performing a dose calculation of the initial treatment plan.
Elongate element shape computation to mimic initial plan dose per beam
Based on the at least one parameter, computing a shape for each of the plurality of elongate elements to modulate the dose of the delivery beam to mimic the dose of the initial treatment plan per beam.
Single energy layer re-optimization with compensating device and stability iteration
Re-optimizing the actual treatment plan, wherein the re-optimization uses a single energy layer and takes into account the compensating device, then adjusting the shape of one or more elongate elements and iterating until the final treatment plan and the geometry of the compensating device remain stable between successive iterations.
The independent claim is grounded in a pencil beam scanning initial plan optimized with Physical dose, RBE, and LET objectives; energy-modulation parameters are derived from dose calculation of the initial plan; shapes for multiple elongate elements are computed to mimic the initial plan per beam; and the actual treatment plan is re-optimized using a single energy layer with the compensating device while iteratively adjusting element shapes until the plan and compensator geometry remain stable.
Stated Advantages
Enables complex criteria including RBE and LET objectives and robust objectives, as described.
Supports co-optimization of overlapping fields, as described.
Supports single-energy-layer delivery for faster treatment, as described.
Is suitable for FLASH due to limited modulation time, as described.
Documented Applications
Designing a compensating device for ion-based radiotherapy treatment delivery, including FLASH radiotherapy, as described.
Use in radiotherapy treatment planning contexts that include pencil beam scanning, and in the recited list of final treatment plan types such as double scattering, single scattering, or wobbling, as refinements in dependent claims, as described in the partial content.
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