Gerszten Peter C, Ozhasoglu Cihat, Burton Steven A, Vogel William J, Atkins Barbara A, Kalnicki Shalom, Welch William C
Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
Neurosurgery. 2004 Jul;55(1):89-98; discussion 98-9.
The role of stereotactic radiosurgery for the treatment of intracranial lesions is well established. Its use for the treatment of spinal lesions has been limited by the availability of effective target-immobilizing devices. Conventional external beam radiotherapy lacks the precision to allow delivery of large doses of radiation near radiosensitive structures such as the spinal cord. The CyberKnife (Accuray, Inc., Sunnyvale, CA) is an image-guided frameless stereotactic radiosurgery system that allows for the radiosurgical treatment of spinal lesions. This study evaluated the feasibility and effectiveness of the treatment of spinal lesions with a single-fraction radiosurgical technique using the CyberKnife.
The CyberKnife system uses the coupling of an orthogonal pair of x-ray cameras to a dynamically manipulated robot-mounted linear accelerator with six degrees of freedom that guides the therapy beam to the intended target without the use of frame-based fixation. Real-time imaging allows the tracking of patient movement. Cervical spine lesions were located and tracked relative to cranial bony landmarks; lower spinal lesions were tracked relative to fiducial bone markers. In this prospective cohort evaluation of a spine radiosurgery technique, 125 spinal lesions in 115 consecutive patients were treated with a single-fraction radiosurgery technique (45 cervical, 30 thoracic, 36 lumbar, and 14 sacral). There were 17 benign tumors and 108 metastatic lesions. All dose plans were calculated on the basis of computed tomographic images acquired from 1.25-mm slices with an inverse treatment planning technique. Radiosurgical circular cones ranging in diameter from 5 to 40 mm were used.
Tumor volume ranged from 0.3 to 232 cm(3) (mean, 27.8 cm(3)). Seventy-eight lesions had received external beam irradiation previously. Tumor dose was maintained at 12 to 20 Gy to the 80% isodose line (mean, 14 Gy); canal volume receiving more than 8 Gy ranged from 0.0 to 1.7 cm(3) (mean, 0.2 cm(3)). No acute radiation toxicity or new neurological deficits occurred during the follow-up period (range, 9-30 mo; median, 18 mo). Axial and radicular pain improved in 74 of 79 patients who were symptomatic before treatment.
This is the first large prospective evaluation of this frameless image-guided spinal radiosurgery system. The CyberKnife system was found to be feasible, safe, and effective. The major potential benefits of radiosurgical ablation of spinal lesions are short treatment time in an outpatient setting with rapid recovery and symptomatic response. This technique offers a successful therapeutic modality for the treatment of a variety of spinal lesions as a primary treatment or for lesions not amenable to open surgical techniques, in medically inoperable patients, in lesions located in previously irradiated sites, or as an adjunct to surgery.
立体定向放射外科治疗颅内病变的作用已得到充分确立。其在脊柱病变治疗中的应用因缺乏有效的靶点固定装置而受到限制。传统的外照射放疗缺乏精准度，无法在脊髓等放射敏感结构附近给予大剂量辐射。射波刀（Accuray公司，加利福尼亚州桑尼维尔市）是一种图像引导的无框架立体定向放射外科系统，可用于脊柱病变的放射外科治疗。本研究评估了使用射波刀采用单次分割放射外科技术治疗脊柱病变的可行性和有效性。
射波刀系统将一对正交的X射线摄像机与一个可动态操控的、安装在机器人上的具有六个自由度的直线加速器相耦合，该加速器可在不使用基于框架固定的情况下将治疗束引导至预定靶点。实时成像可追踪患者的运动。颈椎病变相对于颅骨骨性标志进行定位和追踪；下脊柱病变相对于基准骨标记进行追踪。在这项对脊柱放射外科技术的前瞻性队列评估中，115例连续患者的125处脊柱病变采用单次分割放射外科技术进行治疗（45例颈椎、30例胸椎、36例腰椎和14例骶椎）。其中有17例良性肿瘤和108例转移瘤。所有剂量计划均基于从1.25毫米层厚的计算机断层扫描图像采用逆向治疗计划技术计算得出。使用直径范围为5至40毫米的放射外科圆形准直器。
肿瘤体积范围为0.3至232立方厘米（平均27.8立方厘米）。78处病变先前接受过外照射放疗。肿瘤剂量在80%等剂量线处维持在12至20 Gy（平均14 Gy）；接受超过8 Gy照射的椎管体积范围为0.0至1.7立方厘米（平均0.2立方厘米）。在随访期间（范围9至30个月；中位数18个月）未出现急性放射毒性或新的神经功能缺损。79例治疗前有症状的患者中，74例的轴向和神经根性疼痛得到改善。
这是对这种无框架图像引导脊柱放射外科系统的首次大型前瞻性评估。发现射波刀系统可行、安全且有效。脊柱病变放射外科消融的主要潜在益处是在门诊环境中治疗时间短，恢复快且有症状缓解。该技术为治疗各种脊柱病变提供了一种成功的治疗方式，可作为主要治疗方法，也可用于不适用于开放手术技术的病变、医学上无法手术的患者、位于先前照射部位的病变，或作为手术的辅助手段。
