Development of an integral system test for image-guided radiotherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Systems

Background:

• Image-guided radiotherapy (IGRT) systems enhance treatment precision.
• Accurate system calibration is crucial for effective radiotherapy.
• Integral system testing assesses overall performance without component deconstruction.

Purpose of the Study:

• To develop and validate an integral system test for an IGRT system.
• To determine the precision and accuracy of the IGRT system using x-ray volumetric imaging and micro-MLC delivery.
• To quantify positional accuracy and establish required margins for tumor coverage.

Main Methods:

• Developed an integral system test using a phantom with micromosfets.
• Utilized x-ray volumetric imaging to determine object position.
• Delivered radiation fields with a micro-multileaf collimator (micro-MLC) to verify dosimetric accuracy.
• Compared delivered dose positions with radiographic measurements.

Main Results:

• The integral system test accounted for systematic gantry flex.
• Submillimeter accuracy was achieved in imaging and dose delivery (0.2 mm axial, 1.0 mm superior-inferior).
• The IGRT system demonstrated high precision in positioning and dose delivery.

Conclusions:

• The integral system test effectively evaluated the IGRT system's precision and accuracy.
• The developed test provides a method for quality assurance in IGRT.
• Submillimeter accuracy is achievable, informing margin requirements for tumor coverage.