University of Texas Health San Antonio, Department of Radiation Oncology, 7979 Wurzbach Road, San Antonio, TX 78229, United States.
University of Texas Health San Antonio, Department of Radiation Oncology, 7979 Wurzbach Road, San Antonio, TX 78229, United States.
Phys Med. 2018 Oct;54:146-151. doi: 10.1016/j.ejmp.2018.10.003. Epub 2018 Oct 11.
With the increasingly prominent role of stereotactic radiosurgery in radiation therapy, there is a clinical need for robust, efficient, and accurate solutions for targeting multiple sites with one patient setup. The end-to-end accuracy of high definition dynamic radiosurgery with Elekta treatment planning and delivery systems was investigated in this study.
A patient-derived CT scan was used to create a radiosurgery plan to seven targets in the brain. Monaco was used for treatment planning using 5 VMAT non-coplanar arcs. Prior to delivery, 3D-printed phantoms from RTsafe were ordered including a gel phantom for 3D dosimetry, phantom with 2D film insert, and an ion chamber phantom for point dose measurement. Delivery was performed using the Elekta VersaHD, XVI cone-beam CT, and HexaPOD six degree of freedom tabletop.
Absolute dose accuracy was verified within 2%. 3D global gamma analysis in the film measurement revealed 3%/2 mm passing rates >95%. Gel dosimetry 3D global gamma analysis (3%/2 mm) were above 90% for all targets with the exception of one. Results were indicative of typical end-to-end accuracies (<1 mm spatial uncertainty, 2% dose accuracy) within 4 cm of isocenter. Beyond 4 cm, 2 mm accuracy was found.
High definition dynamic radiosurgery expands clinically acceptable stereotactic accuracy to a sphere around isocenter allowing for radiosurgery of several targets with one setup with a high degree of dosimetric precision. Gel dosimetry proved to be an essential tool for the validation of the 3D dose distributions in this technique.
随着立体定向放射外科在放射治疗中的作用日益突出，临床需要一种强大、高效、准确的解决方案，以便在一次患者摆位中对多个部位进行靶向治疗。本研究旨在调查 Elekta 治疗计划和交付系统的高清晰度动态放射外科的端到端准确性。
使用患者来源的 CT 扫描创建针对大脑中七个靶区的放射外科计划。Monaco 用于使用 5 个 VMAT 非共面弧形进行治疗计划。在交付之前，从 RTsafe 订购了 3D 打印的体模，包括用于 3D 剂量测量的凝胶体模、带有 2D 胶片插入的体模以及用于点剂量测量的离子室体模。使用 Elekta VersaHD、XVI 锥形束 CT 和 HexaPOD 六自由度桌面进行交付。
绝对剂量准确性验证在 2%以内。胶片测量中的 3D 全局伽马分析显示，3%/2mm 的通过率>95%。所有靶区的凝胶剂量学 3D 全局伽马分析（3%/2mm）均高于 90%，除一个靶区外。结果表明，在等中心 4cm 范围内具有典型的端到端精度（<1mm 空间不确定性，2%剂量准确性）。超过 4cm 时，发现精度为 2mm。
高清晰度动态放射外科将临床可接受的立体定向精度扩展到等中心周围的球体，允许一次设置对多个靶区进行放射外科治疗，并具有高度的剂量精度。凝胶剂量学已被证明是该技术中验证 3D 剂量分布的重要工具。
