Two-step intensity modulated arc therapy (2-step IMAT) with segment weight and width optimization
Author Information
Author(s): Sun Jidi, Chew Theam Yong, Meyer Juergen
Primary Institution: University of Canterbury
Hypothesis
The aim of this work was to implement the 2-step IMAT technique into a computerized treatment planning system and to develop an approach to optimize the segment weights and widths.
Conclusion
The study demonstrated that 2-step IMAT is a viable technique able to achieve highly conformal plans for concave target volumes with the optimization of the segment weights and widths.
Supporting Evidence
- The phantom study verified the correctness of the implementation and showed a considerable improvement over a non-modulated arc.
- Optimizing the segment weights and widths reduced the maximum dose from 114% of the prescribed dose to 107% and increased the minimum dose from 87% to 97%.
- This resulted in an improvement in the homogeneity index of the target dose for the clinical case from 1.31 to 1.11.
- The high dose volume V105 was reduced from 57% to 7% while the maximum dose in the organ-at-risk was decreased by 2%.
Takeaway
This study shows a new way to deliver radiation therapy that makes it easier to target tumors while protecting healthy organs.
Methodology
2-step IMAT was implemented into the Prism treatment planning system, and segment weights and widths were optimized using a dose-volume based optimization process.
Limitations
The implementation has only been tested on a phantom and a single clinical case, limiting generalizability.
Digital Object Identifier (DOI)
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