Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA; Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
Clin Oncol (R Coll Radiol). 2023 Apr;35(4):245-254. doi: 10.1016/j.clon.2023.01.013. Epub 2023 Jan 24.
To characterize on-treatment changes in GTV morphology in children with parameningeal rhabdomyosarcoma receiving upfront proton therapy with concurrent chemotherapy and thereby provide guidance on the timing of on-treatment imaging and adaptive replanning.
GTV was delineated on 86 simulation and weekly MR images of 15 prospectively enrolled patients (aged 1-21 years). Temporal changes from baseline in volume and surface (95% Hausdorff distance) were analyzed in relation to the need for plan verification and the resultant doses with hypothetical no treatment adaptation.
The median time was 6 days from the initiation of chemotherapy to CT+MR simulation and 15 days from the simulation to the start of radiotherapy. All but 1 patient showed a continuous decrease in GTV (0.16-1.52%/day) after simulation. At 3 weeks from simulation, 10 of 15 patients exhibited a significant reduction in volume (median, 20%; range, 6-29%). Without replanning, these changes could lead to a reduction in CTV V95 by 7-14% (n = 2) and/or an increase in D0.01 cc/Dmean of adjacent organs at risk by 6-21% of the prescribed target dose (n = 7). Significant dosimetric consequences occurred in cases with (1) a considerable weight gain, (2) shrinkage of the skin surface, or (3) tumor regression in the oral or nasal cavity and sinus that altered air-tissue components in the beam path. The subsequent GTV and dosimetry after 3 weeks from simulation (4 weeks from chemotherapy initiation) demonstrated a relatively stable trend.
On-treatment imaging at 3 weeks after simulation is recommended, if the simulation is performed at 1 week after the initiation of chemotherapy, to detect significant anatomic changes that could result in >5% deviation from planned target coverage and/or organ doses in pediatric patients with parameningeal rhabdomyosarcoma receiving early proton therapy.
描述接受质子同步放化疗的头颈部横纹肌肉瘤患儿治疗过程中 GTV 形态的变化，从而为治疗期间影像学检查和适应性计划调整的时机提供指导。
在 15 名前瞻性入组的患者（年龄 1-21 岁）的 86 次模拟和每周 MRI 图像上勾画 GTV。分析从基线开始的体积和表面（95% Hausdorff 距离）的时间变化，与计划验证的需要以及假设无治疗适应性的结果剂量相关。
从化疗开始到 CT+MR 模拟的中位时间为 6 天，从模拟到放疗开始的中位时间为 15 天。除 1 例患者外，所有患者在模拟后 GTV 持续减小（0.16-1.52%/天）。在模拟后 3 周时，15 例患者中有 10 例体积明显缩小（中位数为 20%；范围为 6-29%）。如果不进行计划调整，这些变化可能导致 CTV V95 减少 7-14%（n=2）和/或危及器官 D0.01cc/Dmean 增加 6-21%（n=7）。当存在以下情况时，会出现显著的剂量学后果：（1）体重显著增加；（2）皮肤表面收缩；（3）口腔或鼻腔和鼻窦内肿瘤消退，改变了射束路径中的气-组织成分。模拟后 3 周（化疗开始后 4 周）的后续 GTV 和剂量学显示出相对稳定的趋势。
如果模拟在化疗开始后 1 周进行，建议在模拟后 3 周进行治疗期间影像学检查，以检测可能导致计划靶区覆盖和/或接受早期质子治疗的头颈部横纹肌肉瘤患儿器官剂量偏差>5%的显著解剖变化。
