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Part 1: Optimization and evaluation of dynamic trajectory radiotherapy.
Michael K Fix1, Daniel Frei1, Werner Volken1
1Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland.
Medical Physics
|July 12, 2018
Summary
Dynamic trajectory radiotherapy (DTRT) offers improved organ-at-risk sparing compared to volumetric modulated arc therapy (VMAT). This advanced technique preserves target coverage while potentially reducing radiation dose to surrounding tissues.
Area of Science:
- Radiation Oncology
- Medical Physics
- Radiotherapy Techniques
Background:
- Volumetric modulated arc therapy (VMAT) is a standard radiotherapy technique.
- VMAT utilizes a coplanar delivery approach.
- Potential improvements in VMAT may involve dynamic table and collimator rotations, leading to dynamic trajectory radiotherapy (DTRT).
Purpose of the Study:
- To develop an optimization procedure for DTRT.
- To investigate the potential benefits of DTRT across various treatment sites.
- To compare DTRT with standard VMAT.
Main Methods:
- Developed a DTRT optimization framework using the Eclipse Scripting Research Application Programming Interface (ESRAPI).
- Utilized A* pathfinding algorithms for optimizing gantry-table and gantry-collimator paths, considering OAR proximity and collision restrictions.
- Evaluated DTRT plans for head and neck, lung, esophagus, and prostate cases, comparing dose distributions with VMAT using the Swiss Monte Carlo Plan (SMCP) and gafchromic film measurements.
Main Results:
- DTRT demonstrated similar or improved target coverage and homogeneity compared to VMAT.
- DTRT achieved significant reductions in mean and maximum organ-at-risk doses, up to 16% and 38% respectively.
- Treatment delivery suitability was confirmed, with 2D gamma analysis showing >99.5% passing rate.
Conclusions:
- DTRT plans were successfully generated and compared to VMAT plans for various sites.
- DTRT shows high potential for reducing organ-at-risk doses while maintaining target coverage.
- The delivery of DTRT is suitable and offers advantages over standard VMAT.
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