Virtual EPID standard phantom audit (VESPA) for remote IMRT and VMAT credentialing

Area of Science:

• Medical Physics
• Radiation Oncology
• Clinical Trials Quality Assurance

Background:

• Facility credentialing for clinical trials using Intensity-Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) traditionally requires resource-intensive on-site audits.
• Remote auditing methods are needed to improve efficiency and accessibility, especially for international facilities.

Purpose of the Study:

• To implement and evaluate a novel virtual Electronic Portal Imaging Device (EPID) standard phantom audit (VESPA) system for remote quality assurance.
• To assess VESPA's effectiveness in supporting facility credentialing for IMRT and VMAT clinical trials.

Main Methods:

• VESPA utilizes published methods and established IMRT quality assurance (QA) procedures, extended for multi-vendor equipment.
• Facilities create treatment plans using provided CT datasets and deliver them to their EPID, along with calibration fields.
• EPID images are uploaded electronically for analysis, involving dose projection into a virtual phantom and 3D/2D gamma analysis.

Main Results:

• Pilot facilities successfully performed data acquisition and upload using VESPA across various planning and delivery systems.
• VESPA offers advantages including fast turnaround, parallel audit capability, efficient international credentialing, extensive data points, and reduced environmental impact.
• Limitations include the lack of absolute dosimetry, necessitating a Level I audit, and reliance on correctly delivered calibration fields.

Conclusions:

• The implemented EPID-based IMRT and VMAT audit system (VESPA) significantly enhances credentialing efficiency for clinical trials.
• VESPA demonstrates potential for wider applications beyond clinical trial credentialing, improving remote QA processes.