Quality assurance for dynamic tumor tracking

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance in Radiotherapy

Background:

• Stereotactic Body Radiation Therapy (SBRT) demands high precision in dose delivery.
• Gimbal-based dynamic tumor tracking (DTT) offers advanced motion compensation for SBRT.
• Verification of treatment plans with DTT and novel gantry rotation requires robust quality assurance (QA) protocols.

Purpose of the Study:

• To develop and evaluate a treatment plan verification routine for SBRT utilizing a linear accelerator with ring gantry rotation and DTT.
• To assess the performance of three commercially available phantoms in verifying DTT-based SBRT plans.

Main Methods:

• Utilized a linear accelerator with ring gantry rotation and a gimbal system for dynamic tumor tracking (DTT).
• Measured dose distributions for DTT-planned SBRT treatments using ArcCHECK, OCTAVIUS® 4D, and MatriXX Evolution phantoms.
• Compared measured and calculated dose distributions using global Gamma Index analysis (3mm/3% criteria).

Main Results:

• All three phantoms were employed for QA of SBRT plans with ring rotations and DTT.
• Average global gamma pass rates were: ArcCHECK (93.5±7.2)%, OCTAVIUS® 4D (98.0±2.6)%, and MatriXX Evolution (98.4±4.2)%.
• Each phantom system exhibited unique limitations during the verification process.

Conclusions:

• ArcCHECK, OCTAVIUS® 4D, and MatriXX Evolution phantoms are suitable for quality assurance in SBRT with ring rotations and DTT.
• The study highlights the feasibility of using these phantoms for verifying complex treatment delivery techniques.
• Further investigation is recommended to address the identified limitations of each phantom system for comprehensive QA.