Department of Radiation Oncology, Cancer Center Amsterdam, Amsterdam UMC, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia.
Radiat Oncol. 2024 Nov 20;19(1):166. doi: 10.1186/s13014-024-02548-w.
During the day-night cycle, gravity and applied stress to the body mass and spine causes a decrease in body height, which is restored overnight. This diurnal spine length variation has not yet been quantified during radiotherapy. Therefore, we aimed to quantify diurnal spine length variation on cone beam CTs (CBCTs) of pediatric patients (< 18 years) who underwent radiotherapy.
For this retrospective study, we included 32 patients (mean age 10.0, range 2.7-16.1 years) who received image guided radiotherapy between 2012 and 2018 in two institutes. Patients were included when they had two fractions per day, or when fractions were scheduled on varying time slots over the course of treatment. Daily CBCTs were registered to the planning CTs using two automatic registrations relative to the bony anatomy; one to vertebra T11 and one to vertebra L4. For each CBCT, the differences between the cranial-caudal (CC) position of the T11 and L4 vertebrae were calculated. To determine the diurnal spine length variation, the difference in vertebrae position between the morning and afternoon CBCTs was calculated. Furthermore, we investigated the possible correlation of diurnal spine length variation with the time slot differences (time interval) between CBCTs (Spearman's ρ).
Overall, the median spine length variation was -1.0 (range -3.9-0.1) mm, and we found a significant reduction in spine length over the day (p < 0.001) with substantial variations between patients. Time intervals between CBCTs ranging from 4.0 to 9.5 h were not correlated with spine length reduction (ρ=-0.01; p = 0.95).
We found a small but significant reduction in spine length (vertebrae T11 to L4) over the course of day in pediatric patients undergoing radiotherapy, measured on CBCT imaging. Spine length reduction did not correlate with CBCT time intervals. However, our results indicate that diurnal spine length reduction could induce a setup error during treatment, and therefore should be considered in pediatric radiotherapy.
在昼夜周期中，重力和对体重和脊柱的施加的力会导致身体高度降低，这种降低在夜间得到恢复。这种日间脊柱长度变化尚未在放射治疗期间的锥形束 CT（CBCT）中进行量化。因此，我们旨在量化接受放射治疗的儿科患者（<18 岁）的 CBCT 上的日间脊柱长度变化。
在这项回顾性研究中，我们纳入了 2012 年至 2018 年在两个机构接受图像引导放射治疗的 32 名患者（平均年龄 10.0 岁，范围 2.7-16.1 岁）。当患者每天接受两次分割照射，或者在治疗过程中不同时间段安排分割照射时，患者将被纳入研究。使用两种基于骨性解剖结构的自动配准方法将每日 CBCT 与计划 CT 配准；一种是与 T11 椎体相对应，另一种是与 L4 椎体相对应。对于每一次 CBCT，计算 T11 和 L4 椎体的头尾（CC）位置之间的差异。为了确定日间脊柱长度变化，计算上午和下午 CBCT 之间椎体位置的差异。此外，我们还研究了日间脊柱长度变化与 CBCT 时间间隔（Spearman's ρ）之间的可能相关性。
总体而言，脊柱长度变化的中位数为-1.0（范围-3.9-0.1）mm，我们发现脊柱长度在日间显著缩短（p<0.001），且患者之间存在显著差异。CBCT 之间的时间间隔在 4.0 至 9.5 小时之间与脊柱长度缩短无相关性（ρ=-0.01；p=0.95）。
我们发现，在接受放射治疗的儿科患者中，在 CBCT 成像上测量的日间脊柱长度（T11 至 L4 椎体）出现了较小但具有统计学意义的缩短。脊柱长度缩短与 CBCT 时间间隔无相关性。然而，我们的结果表明，日间脊柱长度缩短可能会在治疗过程中导致摆位误差，因此应在儿科放射治疗中加以考虑。
