Chang Chih-Wei, Goette Matt, Kadom Nadja, Wang Yinan, Wynne Jacob, Wang Tonghe, Liu Tian, Esiashvili Natia, Zhou Jun, Eaton Bree R, Yang Xiaofeng
Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
Department of Radiology and Imaging Sciences, Emory University and Children's Healthcare of Atlanta, Atlanta, Georgia.
Adv Radiat Oncol. 2023 May 7;8(5):101267. doi: 10.1016/j.adro.2023.101267. eCollection 2023 Sep-Oct.
Proton vertebral body sparing craniospinal irradiation (CSI) treats the thecal sac while avoiding the anterior vertebral bodies in an effort to reduce myelosuppression and growth inhibition. However, robust treatment planning needs to compensate for proton range uncertainty, which contributes unwanted doses within the vertebral bodies. This work aimed to develop an early in vivo radiation damage quantification method using longitudinal magnetic resonance (MR) scans to quantify the dose effect during fractionated CSI.
Ten pediatric patients were enrolled in a prospective clinical trial of proton vertebral body sparing CSI, in which they received 23.4 to 36 Gy. Monte Carlo robust planning was used, with spinal clinical target volumes defined as the thecal sac and neural foramina. T1/T2-weighted MR scans were acquired before, during, and after treatments to detect a transition from hematopoietic to less metabolically active fatty marrow. MR signal intensity histograms at each time point were analyzed and fitted by multi-Gaussian models to quantify radiation damage.
Fatty marrow filtration was observed in MR images as early as the fifth fraction of treatment. Maximum radiation-induced marrow damage occurred 40 to 50 days from the treatment start, followed by marrow regeneration. The mean damage ratios were 0.23, 0.41, 0.59, and 0.54, corresponding to 10, 20, 40, and 60 days from the treatment start.
We demonstrated a noninvasive method for identifying early vertebral marrow damage based on radiation-induced fatty marrow replacement. The proposed method can be potentially used to quantify the quality of CSI vertebral sparing and preserve metabolically active hematopoietic bone marrow.
质子椎体保留型全脑脊髓照射（CSI）在治疗硬脊膜囊的同时避免照射椎体前部，以减少骨髓抑制和生长抑制。然而，精确的治疗计划需要补偿质子射程的不确定性，这会在椎体内产生不必要的剂量。本研究旨在开发一种早期体内辐射损伤量化方法，利用纵向磁共振（MR）扫描来量化分次CSI治疗期间的剂量效应。
10名儿科患者参加了质子椎体保留型CSI的前瞻性临床试验，他们接受了23.4至36 Gy的照射。采用蒙特卡罗稳健计划，将脊髓临床靶体积定义为硬脊膜囊和神经孔。在治疗前、治疗期间和治疗后进行T1/T2加权MR扫描，以检测从造血活跃的骨髓向代谢活性较低的脂肪骨髓的转变。分析每个时间点的MR信号强度直方图，并通过多高斯模型进行拟合，以量化辐射损伤。
在治疗的第五次分割时，MR图像中就观察到了脂肪骨髓的滤过。最大辐射诱导的骨髓损伤发生在治疗开始后的40至50天，随后是骨髓再生。平均损伤率分别为0.23、0.41、0.59和0.54，分别对应治疗开始后的10、20、40和60天。
我们展示了一种基于辐射诱导的脂肪骨髓替代来识别早期椎体骨髓损伤的非侵入性方法。所提出的方法可能用于量化CSI椎体保留的质量，并保护代谢活跃的造血骨髓。
