Variable Feathering Field Splitting for Large IMRT Fields
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Solution Overview
Problem
Current radiation therapy systems face inefficiencies in delivering large radiation fields due to mechanical limitations, leading to increased radiation exposure to surrounding tissues and prolonged treatment times when treating large tumors, as they often require splitting the radiation field into smaller portions, which compromises the dose distribution and increases the whole body dose.
Innovation Solution
The implementation of a variable feathering field splitting method for intensity-modulated radiation therapy (IMRT), where the intensity matrix is split into spatially overlapping submatrices with non-constant widths, allowing for wider overlaps and optimizing the number of monitor units (MUs) to minimize treatment time and leaf sequences, thereby enhancing MU efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the radiation field is split into smaller portions to treat large tumors, then the mechanical limitations of the radiation delivery system are accommodated, but the dose distribution is compromised and whole body dose increases
Solution Approach 1:
The radiation field is divided into multiple subfields that are delivered sequentially using the collimator system. Each subfield is optimized to cover a specific portion of the large target volume, allowing the mechanical system to deliver the full prescribed dose without exceeding its field size limitations while maintaining proper dose distribution through careful planning and delivery optimization.
2Ease of operation
If conventional field splitting is used for large radiation fields, then the treatment can be delivered with available system capabilities, but the number of monitor units increases and treatment time is prolonged
Solution Approach 1:
The treatment plan is pre-optimized using inverse planning algorithms to determine the optimal arrangement of subfields and their corresponding monitor units before delivery. This preliminary optimization ensures that the field splitting is configured to minimize the total number of MUs required, thereby reducing treatment time while still accommodating the system's mechanical field size limitations.
3Quantity of substance
If uniform beam radiation is used, then the target volume is adequately covered, but surrounding critical structures receive excessive radiation
Solution Approach 1:
The radiation beam intensity is made non-uniform through intensity modulation techniques, allowing different regions of the beam to have different intensities. This enables the delivery of higher doses to the target volume while reducing the dose to surrounding critical structures, achieving conformal radiation therapy that adapts to the specific geometry and sensitivity of the treatment site.
Data Source
AI summary
A method and associated system 300 for delivering intensity-modulated radiation therapy (IMRT) uses variable feathering field splitting for intensity modulated fields of large size. A processor controls a beam-shaping device that splits the radiation beam into a plurality of radiation fields delivered to a patient. The processor in cooperation with the beam-shaping device implements a variable feathering method which includes providing an intensity matrix for the treatment of a patient, the intensity matrix having a plurality of rows and columns for spanning a prescribed radiation field including a prescribed field width. The prescribed width is compared to a maximum field width provided by the radiation treatment system. The intensity matrix is split into a plurality of spatially overlapping intensity submatrices by variably feathering the intensity matrix when the prescribed width exceeds the maximum field width, Radiotherapy is then provided to the patient using a leaf sequencing method to generate the submatrices.