Preliminary study of clinical application on IMRT three-dimensional dose verification-based EPID system

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Quality Assurance

Background:

• Intensity-modulated radiation therapy (IMRT) requires precise dose verification.
• Electronic portal imaging devices (EPIDs) offer a method for three-dimensional (3D) dose distribution verification.
• Pretreatment verification is crucial for ensuring treatment accuracy and patient safety.

Purpose of the Study:

• To evaluate the accuracy and reliability of the Edose system for 3D EPID-based IMRT dose verification.
• To compare Edose verification results with Delta4 measurements and treatment planning system (TPS) calculations.
• To analyze dose-volume histograms (DVHs) for planning target volumes (PTVs) and organs at risk (OARs) using Edose.

Main Methods:

• Thirty IMRT plans were selected for 3D dose verification using the Edose system.
• Gamma passing rates were compared between Edose, Delta4 measurements, and TPS calculations using criteria of 5%/3 mm, 3%/3 mm, and 2%/2 mm.
• DVHs for PTVs and OARs were analyzed using Edose to assess dose distributions.

Main Results:

• Average gamma passing rates for Edose were 98.58% (5%/3 mm), 95.67% (3%/3 mm), and 83.13% (2%/2 mm).
• Edose reconstructions showed dose differences within 3% for PTVs compared to TPS, with minor exceptions.
• Larger dose deviations were observed in OARs, particularly for small-volume structures like the lens.

Conclusions:

• The Edose system is suitable for 3D pretreatment dose verification of IMRT.
• Edose can effectively evaluate gamma passing rates and provide detailed dose distributions for PTVs and OARs.
• The system offers reliable data for clinical quality assurance in radiation therapy.