Spine SBRT With Halcyon ™: Plan Quality, Modulation Complexity, Delivery Accuracy, and Speed

Conclusion: The Halcyon™ dual-layer MLC can generate comparable and clinically equivalent spine SBRT plans to TrueBeam plans with less rapid dose fall-off and lower conformity. MLC width leaf can impact maximum dose to organs at risk and plan quality, but does not cause limitations in achieving acceptable plans for spine SBRT treatments. Introduction Stereotactic body radiotherapy treatment (SBRT) for metastatic spinal tumors necessitates radiation treatment plans with high dose targets immediately adjacent to the spinal cord. To achieve uniform coverage while maintaining safe doses to the spinal cord, steep dose gradients must be achieved with precise dose delivery. Due to the high stakes of delivering high dose which can cause myelitis in the spinal cord, spine SBRT delivery requires dosimetric accuracy and robust patient immobilization/positioning (1, 2). Accurate plan delivery, including dose rate modulation, gantry position, collimator position, and multi-leaf collimator (MLC) position, are required to ensure sharp dose fall-off. A new dual-layer staggered 1-cm wide MLC in Halcyon™ treatment platform (Varian Medical System, Palo Alto, CA) has reduced leakage, increased speed, and improved dosimetric leaf gap (DLG), as compared to Millennium-120 MLC with 0.5 cm and High-Definition-120 (HD) MLC with 0.25 cm centrally located leaf widths associated with the TrueBeam platform (Varian Medical System, Palo Alto, CA). Despite the larger 1.0-cm leaf widt...
Source: Frontiers in Oncology - Category: Cancer & Oncology Source Type: research