Optimizing the deliverability of binary collimation-based SRS treatment for multiple metastases with multiple...

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiosurgery/Radiotherapy Delivery

Background:

• Intra-arc binary collimation (iABC) is a novel technique for stereotactic radiosurgery/radiotherapy (SRS/SRT) planning, particularly for multiple metastases.
• Idealized iABC plans face challenges in real-world delivery due to physical limitations like multi-leaf collimation (MLC) leaf speed.
• Optimizing iABC delivery requires balancing dosimetric accuracy and treatment efficiency on clinical accelerators.

Purpose of the Study:

• To optimize the delivery of iABC-based SRS/SRT plans on a Varian TrueBeam accelerator.
• To investigate the impact of transition window (TW) width on dosimetric fidelity and treatment efficiency.
• To evaluate a variable TW approach as a compromise between accuracy and delivery time.

Main Methods:

• iABC plans were delivered on a Varian TrueBeam, varying the transition window (TW) width from 0% to 100% and using a variable TW approach.
• Dosimetric accuracy was assessed using gamma analysis (5%/2mm criteria) with a PTW Octavius detector.
• Treatment delivery efficiency was measured by recording total beam-on-time.

Main Results:

• Smaller TWs resulted in higher delivery accuracy but increased treatment times.
• The variable TW method achieved a good balance, with an average gamma pass rate of 98%.
• The variable TW approach demonstrated an average delivery time of 9 minutes.

Conclusions:

• Optimizing TW is crucial for efficient and accurate iABC delivery on Varian TrueBeam accelerators.
• A variable TW strategy effectively balances dosimetric accuracy and treatment time for iABC-based SRS/SRT.
• This optimized delivery method enhances the clinical applicability of iABC for complex radiotherapy treatments.