Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA.
Technol Cancer Res Treat. 2019 Jan-Dec;18:1533033819883641. doi: 10.1177/1533033819883641.
The Halcyon is Varian's latest linear accelerator that offers a single 6X flattening-filter-free beam with a jawless design that features a new dual layer multileaf collimator system with faster speed and reduced transmission. Dosimetric characteristics of the dual layer multileaf collimator system including transmission, dosimetric leaf gap, and tongue and groove effects were measured. Ionization chambers, diode arrays, and an electronic portal imaging device were used to measure various multileaf collimator characteristics. Transmission through both multileaf collimator banks was found to be 0.008%, while the distal and proximal banks alone had transmission values of 0.4%. The penumbra was slightly sharper for fields using only the distal multileaf collimator bank but found to be largely independent of leaf position with values between 2.7 to 3.0 mm at d for the combined multileaf collimator banks. The dosimetric leaf gap was measured for the proximal and distal multileaf collimator banks both individually and together and found to have values of -0.216 mm, -0.225 mm, and 0.964 mm, respectively. Measurements of dosimetric leaf gap at the leaf edge and midline were also performed. Tongue and groove effects were investigated with both the electronic portal imaging device and a 2-dimensional array of diodes.
直线加速器 Halcyon 是瓦里安公司的最新产品，提供了一种无准直器设计的单一 6X 均整滤波器射线，具有全新的双层多叶准直器系统，具有更快的速度和更低的传输率。测量了双层多叶准直器系统的剂量学特性，包括传输率、剂量学叶片间隙和楔形效应。使用电离室、二极管阵列和电子射野影像装置测量了各种多叶准直器特性。发现两个多叶准直器组的传输率均为 0.008%，而单独使用远部和近部多叶准直器组的传输率分别为 0.4%。仅使用远部多叶准直器组的射野半影更锐利，但发现叶片位置的影响不大，远部和近部多叶准直器组的组合叶片的 d 处半影值在 2.7 至 3.0 毫米之间。还分别测量了远部和近部多叶准直器组的剂量学叶片间隙，并将其组合在一起，其值分别为-0.216 毫米、-0.225 毫米和 0.964 毫米。还在叶片边缘和中线处进行了剂量学叶片间隙的测量。使用电子射野影像装置和二维二极管阵列研究了楔形效应。
