Fuss M, Salter B J, Caron J-L, Vollmer D G, Herman T S
Department of Radiation Oncology, The University of Texas Health Science Center at San Antonio, 78229, USA.
Acta Neurochir (Wien). 2005 Nov;147(11):1141-9; discussion 1149-50. doi: 10.1007/s00701-005-0572-9.
Presentation of intensity-modulated radiosurgery (IMRS) for the treatment of inoperable, complex shaped pediatric arterio-venous malformations AVM.
Between 03/99 and 11/04, IMRS was delivered to seven children aged six to 18 years. Prescribed minimum doses ranged from 17.5 to 20 Gy (median 18 Gy). Radiosurgery planning and delivery used a serial tomotherapeutic IMRT technique (Peacock IMRT, North American Scientific/Nomos, Cranberry Township, PA) over two to four couch angles. A linear accelerator attached binary multi-leaf collimator was used to generate pencil beams of 10 mm by either 8.5 or 4.0 mm. Treatment planning employed an inverse treatment planning optimization algorithm. Parameters submitted to the treatment planning system were: prescription dose (PD), volume of target allowed to receive less dose (standard 3%), minimum dose (0.5 Gy less than PD), and maximum dose (200% of PD). Planning system specific IMRS target and tissue types were selected to prioritize dose conformality over dose homogeneity. The prescription isodose encompassed at least 95% of the target volume. We calculated conformality (CI) and homogeneity indices (HI) to characterize the quality of IMRS plans, and summarized preliminary clinical outcomes.
Target volumes ranged from 0.71 to 63.02 cm(3) (median 13.8 cm(3), 6/7 AVM larger than 10 cm(3)). Median CI was 1.07 (range 1.05 to 1.7) according to RTOG criteria. Median HI was 1.12 (range 1.09 to 1.23). During limited follow-up (median 32 months, range 5 to 53 months), two AVM completely obliterated at 19 and 22 months, and partial obliteration (>75%) was observed in three cases. No treatment-related side effects, other than acute nausea and temporary headaches interpreted as being associated with changes in cerebral blood distribution, were observed.
IMRS can allow for highly conformal planning and delivery of radiosurgery radiation doses even if pediatric AVM target volumes are large and/or highly complex in shape. This technique has been seen to result in favorable preliminary outcomes, thus supporting future exploration of this technique in pediatric and adult patients.
介绍调强放射外科（IMRS）用于治疗无法手术的复杂形状小儿动静脉畸形（AVM）。
在1999年3月至2004年11月期间，对7名6至18岁的儿童进行了IMRS治疗。规定的最小剂量范围为17.5至20 Gy（中位数为18 Gy）。放射外科计划和治疗采用串行断层放射治疗IMRT技术（孔雀IMRT，北美科学公司/诺莫斯公司，宾夕法尼亚州克兰伯里镇），在两到四个治疗床角度进行。使用配备二元多叶准直器的直线加速器产生10毫米×8.5毫米或4.0毫米的笔形束。治疗计划采用逆向治疗计划优化算法。提交给治疗计划系统的参数包括：处方剂量（PD）、允许接受较低剂量的靶区体积（标准为3%）、最小剂量（比PD低0.5 Gy）和最大剂量（PD的200%）。选择计划系统特定的IMRS靶区和组织类型，以优先考虑剂量适形性而非剂量均匀性。处方等剂量线包绕至少95%的靶区体积。我们计算了适形性指数（CI）和均匀性指数（HI）以表征IMRS计划的质量，并总结了初步临床结果。
靶区体积范围为0.71至63.02 cm³（中位数为13.8 cm³，7例中有6例AVM大于10 cm³）。根据RTOG标准，CI中位数为1.07（范围为1.05至1.7）。HI中位数为1.12（范围为1.09至1.23）。在有限的随访期间（中位数为32个月，范围为5至53个月），2例AVM在19个月和22个月时完全闭塞，3例观察到部分闭塞（>75%）。除了被解释为与脑血流分布变化相关的急性恶心和短暂头痛外，未观察到与治疗相关的副作用。
即使小儿AVM靶区体积大且/或形状高度复杂，IMRS也能实现高度适形的放射外科放射剂量计划和治疗。已观察到该技术产生了良好的初步结果，从而支持在小儿和成人患者中对该技术进行进一步探索。
