Yang Yun, Shoniyozov Khayrullo, Li Taoran, Lockamy Virginia, Bieda Michael, Teo Boon-Keng Kevin, Nagda Suneel, Alonso-Basanta Michelle, Gu Wenbo
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Varian, a Siemens Healthineers Company, Palo Alto, California, USA.
J Appl Clin Med Phys. 2025 Jul;26(7):e70143. doi: 10.1002/acm2.70143.
For LINAC-based stereotactic radiosurgery (SRS) treatments, the binary MLC models utilizing single dosimetric leaf gap (DLG) parameters in Eclipse versions prior to v18 can result in imperfect agreement between measured and calculated doses, increased commissioning complexity, and user-dependent variability. This study aims to evaluate the efficiency and accuracy of the enhanced leaf model (ELM) in Eclipse version 18.0, which incorporates the actual rounded-end MLC design in dose calculations.
ELM parameters were determined from measurements and configuration in a test Eclipse v18.0 system for an Edge LINAC with High Definition MLC (HDMLC) and a TrueBeam LINAC with the Millennium 120-leaf MLC (M120). The anisotropic analytical algorithm (AAA) was used to calculate doses for both 10FFF and 6FFF energies. The v18 ELM model was compared to the current version 16.1 (v16) model, which utilized single DLG parameter. Dose calculations were performed and compared for (1) static small on-axis fields, (2) static small off-axis fields, (3) single-isocenter single-target (SIST) HyperArc plans, and (4) single-isocenter multiple-target (SIMT) HyperArc plans. Gafchromic EBT4 film and myQA SRS device were used for dose verification.
The measurement required for ELM was similar to that of the original DLG, but ELM configuration provided significant time savings. The measurements showed comparable or improved accuracy with the ELM model for both static fields and patient-specific plans. A significant improvement in dose calculation accuracy was observed with the ELM particularly for SIMT patients with a large number of small targets.
The new ELM introduced in Eclipse v18 substantially improves efficiency and consistency of the modeling process in the Eclipse dose calculation algorithm while maintaining comparable or superior accuracy for Linac-based SRS.
对于基于直线加速器的立体定向放射外科（SRS）治疗，在Eclipse v18之前的版本中使用单一剂量学叶片间隙（DLG）参数的二元多叶准直器（MLC）模型可能导致测量剂量与计算剂量之间的一致性不佳、调试复杂性增加以及用户依赖的变异性。本研究旨在评估Eclipse 18.0版本中增强叶片模型（ELM）的效率和准确性，该模型在剂量计算中纳入了实际的圆头MLC设计。
在一个测试的Eclipse v18.0系统中，针对配备高清MLC（HDMLC）的Edge直线加速器和配备千禧120叶MLC（M120）的TrueBeam直线加速器，通过测量和配置来确定ELM参数。使用各向异性分析算法（AAA）计算10FFF和6FFF能量下的剂量。将v18 ELM模型与当前的16.1版本（v16）模型进行比较，后者使用单一DLG参数。对以下情况进行剂量计算并比较：（1）静态小轴上野，（2）静态小离轴野，（3）单等中心单靶区（SIST）HyperArc计划，以及（4）单等中心多靶区（SIMT）HyperArc计划。使用Gafchromic EBT4胶片和myQA SRS设备进行剂量验证。
ELM所需的测量与原始DLG相似，但ELM配置节省了大量时间。测量结果表明，对于静态野和特定患者计划，ELM模型的准确性相当或有所提高。特别是对于有大量小靶区的SIMT患者，ELM在剂量计算准确性方面有显著提高。
Eclipse v18中引入的新ELM在保持基于直线加速器的SRS具有相当或更高准确性的同时，显著提高了Eclipse剂量计算算法中建模过程的效率和一致性。
