A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment

Craniospinal irradiation (CSI) requires abutting fields at the cervical spine. Junction shifts are conventionally used to prevent setup error–induced overdosage/underdosage from occurring at the same location. This study compared the dosimetric differences at the cranial-spinal junction between a single-gradient junction technique and conventional multiple-junction shifts and evaluated the effect of setup errors on the dose distributions between both techniques for a treatment course and single fraction. Conventionally, 2 lateral brain fields and a posterior spine field(s) are used for CSI with weekly 1-cm junction shifts. We retrospectively replanned 4 CSI patients using a single-gradient junction between the lateral brain fields and the posterior spine field. The fields were extended to allow a minimum 3-cm field overlap. The dose gradient at the junction was achieved using dose painting and intensity-modulated radiation therapy planning. The effect of positioning setup errors on the dose distributions for both techniques was simulated by applying shifts of ± 3 and 5 mm. The resulting cervical spine doses across the field junction for both techniques were calculated and compared. Dose profiles were obtained for both a single fraction and entire treatment course to include the effects of the conventional weekly junction shifts. Compared with the conventional technique, the gradient-dose technique resulted in higher dose uniformity and conformity to the target volumes, lower organ at risk (OAR) mean and maximum doses, and diminished hot spots from systematic positioning errors over the course of treatment. Single-fraction hot and cold spots were improved for the gradient-dose technique. The single-gradient junction technique provides improved conformity, dose uniformity, diminished hot spots, lower OAR mean and maximum dose, and one plan for the entire treatment course, which reduces the potential human error associated with conventional 4-shifted plans.     

TomoDirect技术在全脑全脊髓放疗中的应用

目的 为全脑全脊髓放疗建立新的TomoDirect技术(TD)布野方案,并评价剂量学参数。方法 对本院收治的7例全脑全脊髓放疗患者进行回顾性研究,在Tomo计划系统分别设计5野TD、3野TD和螺旋断层治疗(helical tomotherapy, HT)计划,比较3种计划的靶区适形指数(CI)、均匀性指数(HI)、危及器官受量、治疗时间和机器跳数(MU)。结果 除3野TD计划外其余两者均能获得较好的靶区适形度和均匀性。其中5野TD计划靶区受量明显优于3野TD计划,但略逊于HT计划;危及器官受量则各有优势。5野TD、3野TD和HT计划的靶区平均CI分别为0.79、0.57和0.88;靶区HI分别为1.06、1.16和1.05;双肺V₂₀分别为1.99%、3.30%和2.16%;心脏平均剂量分别为6.17、12.38和10.72 Gy;肝脏平均剂量分别为5.21、5.14和4.62 Gy;左侧肾脏平均剂量分别为4.30、1.99和5.03 Gy;右侧肾脏平均剂量分别为4.42、2.09和4.91 Gy。靶区以外的正常组织V₅分别为46.80%、28.06%和55.54%。5野TD计划的治疗时间最短,5野TD、3野TD及HT计划的平均治疗时间分别为677、721和907 s,MU数分别是8 773、9 657和12 581。结论 5野的TD技术应用于全脑全脊髓放疗具有一定优势,适用于难以坚持长时间治疗,且希望减少低剂量范围的患者。     

Malignant peripheral nerve sheath tumor of the cauda equina with craniospinal metastasis

Intradural spinal malignant peripheral nerve sheath tumors (MPNST) are extremely rare, with only 20 adult patients reported to our knowledge, and only four primary tumors arising from the cauda equina. A 49-year-old man presented with back pain, constipation, and lower extremity weakness and was found to have a large intradural lesion involving the cauda equina. Imaging of the rest of his neuraxis revealed additional small left temporal lobe, cervical, and thoracic lesions. The patient underwent laminectomy for tumor debulking and biopsy, as gross total resection was not possible due to envelopment of the cauda equina. Histopathology revealed a MPNST with high cellularity, elevated proliferative indices, and nerve fascicle invasion. After the debulking, the patient reported improvement in his symptoms. However, 6 weeks later, the patient began having severe headaches, and his left temporal lobe lesion was found to have increased significantly in size, requiring craniotomy for palliative resection. The authors report the first adult patient with sporadic spinal MPNST with craniospinal metastasis to our knowledge. Imaging of the entire neuraxis is recommended for initial workup of these lesions, which are capable of intradural spread. The best treatment approach is unclear, but total surgical resection should be attempted, barring infiltration and engulfment of the nerve roots or widespread dissemination.     

一种新型全脑全脊髓放疗技术

介绍并探讨新型全中枢放疗技术。新方法对患者进行仰卧体位固定．采用等中心照射的技术、热塑料面膜和真空袋固定技术、直线加速器半柬照射和全柬照射技术、相邻两野相切技术及低熔点挡铅技术等。较传统的照射技术存在定位方便简捷、重复性较好、剂量分布均匀等优点．有利于在临床工作中推广应用。     

全中枢放射治疗的进展

全中枢放射治疗是治疗易沿脑脊液或脑膜播散的脑恶性肿瘤的有效方法,但最佳的治疗方案,包括照射野的设计、照射剂量、照射技术以及是否联合化疗一直存在争议。该文探讨了降低全中枢剂量的可行性、联合化疗是否必要、不同放疗技术在全中枢治疗中的优劣势及应用前景,认为不应该盲目降低放疗剂量,螺旋断层放疗在全中枢放疗中具有剂量的均匀性、适行性及对正常组织保护的优势。     

通过多种技术方法的综合使用优化全脑全脊髓照射技术

全脑全脊髓照射是针对多种癌症的治疗流程中一个重要的组成部分。为了达到最佳的肿瘤控制,需要在靶区体积的确定、重要正常组织的保护、剂量均匀度、射野交接区域以及剂量测定方面都特别注意。本文提出了一种适用于大多数治疗情况的优化了的全脑全脊髓照射治疗技术,以一名因生殖细胞瘤需接受全脑全脊髓照射治疗的17岁男性患者为例,通过综合使用半野衔接技术、扩展半影的射野衔接技术和多叶光拦子野技术,制定临床可实行的治疗计划,大大改善了脊髓靶区内的剂量均匀度,将剂量最大点由处方剂量的124%降低到处方剂量的108%。对仿真人体模进行的实际测量值与计算值的比较表明,测量值和计算值是基本一致的。     

儿童髓母细胞瘤术后全脑全脊髓放疗的血液学不良反应及近期疗效观察

目的 分析儿童髓母细胞瘤术后行全脑全脊髓放疗的疗效及影响预后的因素,并分析放疗期间血液学不良反应对预后的影响。方法 回顾性分析髓母细胞瘤术后行全脑全脊髓放疗的儿童87例。血液学不良反应按美国肿瘤放射治疗协作组(RTOG)早期放射反应标准评分进行评价。分析性别、年龄、肿瘤部位、手术与放疗的时间间隔、放疗间断时间以及全脑全脊髓和后颅窝的照射顺序对生存率的影响。结果 本组患者1、2、3年的总生存率(OS)分别为95.0%,92.4%和84.9%,无进展生存率(PFS)分别为93.7%,89.8%和80.8%。90.8%的患者出现2~3级的白细胞下降。70.1%的患者出现1~2级的血小板下降。1.1%的患者出现3级的血小板下降。16.1%的患者出现1~2级的血红蛋白下降,未出现3~4级的血红蛋白下降。Kaplan-Meier生存分析显示,血小板分级在0~1级和2~4级的3年PFS分别为84.1%和49.2%,差异有统计学意义(χ²=3.936, P<0.05)。血红蛋白分级在0级和1~4级的3年PFS分别为86.6%和29.1%,差异有统计学意义(χ²=10.269, P<0.05);3年OS分别为91.6%和58.2%,差异有统计学意义(χ²=9.336, P<0.05)。中断放疗时间<3 d和≥3 d的两组患者3年PFS分别为84.6%和68.6%,差异有统计学意义(χ²=4.413, P<0.05)。结论 儿童髓母细胞瘤术后行全脑全脊髓放疗期间的血液学不良反应以及由此导致的放疗中断均对预后有一定的影响。