Clinical Implementation of Robust Multi-isocentric Volumetric Modulated Arc Radiotherapy for Craniospinal...

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Craniospinal irradiation (CSI) is a complex radiotherapy technique.
• Volumetric Modulated Arc Therapy (VMAT) offers potential advantages in dose conformity.
• Robust optimization is crucial for managing uncertainties in radiotherapy delivery.

Purpose of the Study:

• To evaluate the safety and accuracy of multi-isocentric CSI-VMAT.
• To assess the feasibility of using robust optimization in a commercial treatment planning system for CSI-VMAT.
• To report initial clinical experience with CSI-VMAT in the first 20 patients.

Main Methods:

• Multi-isocentric CSI-VMAT was delivered to 20 patients.
• Dose constraints for organs at risk (heart, lungs) were analyzed.
• Robustness of the planning target volume (PTV) to systematic errors in isocenter position was evaluated.
• Treatment planning system (TPS) capabilities for CSI-VMAT were assessed.

Main Results:

• Median follow-up was 399 days; progression-free survival was 131 days.
• Acute toxicities (grade 3+) included neutropenia, thrombocytopenia, nausea, vomiting, and mucositis.
• Heart and lung mean doses were within acceptable ranges, varying with prescribed dose.
• PTV dose coverage remained acceptable despite simulated isocenter errors.

Conclusions:

• Multi-isocentric CSI-VMAT is a safe and accurate technique.
• Robust optimization in commercial TPS enables reliable implementation of CSI-VMAT.
• The technique demonstrates acceptable toxicity profiles and dosimetric parameters.