Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
J Appl Clin Med Phys. 2011 Apr 12;12(3):3533. doi: 10.1120/jacmp.v12i3.3533.
The purpose of this study was to determine the maximum proton kinetic energy required to treat a given percentage of patients eligible for stereotactic radiosurgery (SRS) with coplanar arc-based proton therapy, contingent upon the number and location of gantry angles used. Treatment plans from 100 consecutive patients treated with SRS at the University of Wisconsin Carbone Cancer Center between June of 2007 and March of 2010 were analyzed. For each target volume within each patient, in-house software was used to place proton pencil beam spots over the distal surface of the target volume from 51 equally-spaced gantry angles of up to 360°. For each beam spot, the radiological path length from the surface of the patient to the distal boundary of the target was then calculated along a ray from the gantry location to the location of the beam spot. This data was used to generate a maximum proton energy requirement for each patient as a function of the arc length that would be spanned by the gantry angles used in a given treatment. If only a single treatment angle is required, 100% of the patients included in the study could be treated by a proton beam with a maximum kinetic energy of 118 MeV. As the length of the treatment arc is increased to 90°, 180°, 270°, and 360°, the maximum energy requirement increases to 127, 145, 156, and 179 MeV, respectively. A very high percentage of SRS patients could be treated at relatively low proton energies if the gantry angles used in the treatment plan do not span a large treatment arc. Maximum proton kinetic energy requirements increase linearly with size of the treatment arc.
本研究的目的是确定在使用共面弧形质子治疗为符合立体定向放射外科 (SRS) 条件的患者进行治疗时，所需的最大质子动能，这取决于所使用的龙门架角度的数量和位置。分析了 2007 年 6 月至 2010 年 3 月期间在威斯康星大学 Carbone 癌症中心接受 SRS 治疗的 100 名连续患者的治疗计划。对于每位患者的每个靶区，使用内部软件在多达 360°的 51 个等距龙门架角度上在靶区的远端表面放置质子铅笔束点。对于每个射束点，从患者表面到靶区远端边界的放射学路径长度通过从龙门架位置到射束点位置的射线进行计算。然后，将该数据用于为每位患者生成最大质子能量需求，该需求作为在特定治疗中使用的龙门架角度所跨越的弧形长度的函数。如果仅需要单个治疗角度，则可以用最大动能为 118 MeV 的质子束治疗研究中包含的 100％的患者。随着治疗弧的长度增加到 90°、180°、270°和 360°，最大能量需求分别增加到 127、145、156 和 179 MeV。如果治疗计划中使用的龙门架角度不跨越大的治疗弧，则可以用相对较低的质子能量治疗 SRS 患者的很大一部分。最大质子动能需求随治疗弧的大小呈线性增加。
