Wiggenraad Ruud G J, Petoukhova Anna L, Versluis Lia, van Santvoort Jan P C
Department of Radiotherapy, Medical Center Haaglanden, The Hague, The Netherlands.
Int J Radiat Oncol Biol Phys. 2009 Jul 15;74(4):1018-26. doi: 10.1016/j.ijrobp.2008.09.057. Epub 2009 Feb 11.
Intensity-modulated radiotherapy (IMRT) and dynamic conformal arc (DCA) are two state-of-the-art techniques for linac-based stereotactic radiotherapy (SRT) using the micromultileaf collimator. The purpose of this planning study is to examine the relative merits of these techniques in the treatment of intracranial tumors.
SRT treatment plans were made for 25 patients with a glioma or meningioma. For all patients, we made an IMRT and a DCA plan. Plans were evaluated using: target coverage, conformity index (CI), homogeneity index (HI), doses in critical structures, number of monitor units needed, and equivalent uniform dose (EUD) in planning target volume (PTV) and critical structures.
In the overall comparison of both techniques, we found adequate target coverage in all cases; a better mean CI with IMRT in concave tumors (p = 0.027); a better mean HI with DCA in meningiomas, complex tumors, and small (< 92 mL) tumors (p = 0.000, p = 0.005, and p = 0.005, respectively); and a higher EUD in the PTV with DCA in convex tumors (gliomas) and large tumors (p = 0.000 and p = 0.003, respectively). In all patients, significantly more monitor units were needed with IMRT. The results of the overall comparison did not enable us to predict the preference for one of the techniques in individual patients. The DCA plan was acceptable in 23 patients and the IMRT plan in 19 patients. DCA was preferred in 18 of 25 patients.
DCA is our preferred SRT technique for most intracranial tumors. Tumor type, size, or shape do not predict a preference for DCA or IMRT.
调强放射治疗（IMRT）和动态适形弧（DCA）是基于直线加速器的立体定向放射治疗（SRT）中使用微型多叶准直器的两种先进技术。本计划研究的目的是检验这些技术在治疗颅内肿瘤方面的相对优点。
为25例患有神经胶质瘤或脑膜瘤的患者制定SRT治疗计划。对于所有患者，我们制定了IMRT计划和DCA计划。使用以下指标对计划进行评估：靶区覆盖度、适形指数（CI）、均匀性指数（HI）、关键结构中的剂量、所需的监测单位数量以及计划靶区（PTV）和关键结构中的等效均匀剂量（EUD）。
在两种技术的总体比较中，我们发现所有病例的靶区覆盖度均足够；在凹形肿瘤中，IMRT的平均CI更好（p = 0.027）；在脑膜瘤、复杂肿瘤和小肿瘤（<92 mL）中，DCA的平均HI更好（分别为p = 0.000、p = 0.005和p = 0.005）；在凸形肿瘤（神经胶质瘤）和大肿瘤中，DCA在PTV中的EUD更高（分别为p = 0.000和p = 0.003）。在所有患者中，IMRT需要的监测单位明显更多。总体比较结果无法使我们预测个体患者对其中一种技术 的偏好。23例患者的DCA计划可接受，19例患者的IMRT计划可接受。25例患者中有18例更喜欢DCA。
对于大多数颅内肿瘤，DCA是我们首选的SRT技术。肿瘤类型、大小或形状无法预测对DCA或IMRT的偏好。
