Kannan Sneha, Teo Boon-Keng Kevin, Solberg Timothy, Hill-Kayser Christine
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
J Appl Clin Med Phys. 2017 Jan;18(1):107-114. doi: 10.1002/acm2.12012. Epub 2016 Dec 10.
PURPOSE/OBJECTIVE(S): High-risk neuroblastoma (HR-NBL) requires multimodality treatment, including external beam radiation of the primary tumor site following resection. Radiotherapy planning must take into account motion of the target and adjacent normal anatomy, both of which are poorly understood in the pediatric population, and which may differ significantly from those in adults.
METHODS/MATERIALS: We examined 4DCT scans of 15 consecutive pediatric patients treated for HR-NBL, most with tumors in the abdominal cavity. The diaphragm and organs at risk were contoured at full inhale, full exhale, and on free-breathing scans. Maximum displacement of organs between full inhale and full exhale was measured in the anterior, posterior, superior, inferior, left, and right directions, as was displacement of centroids in the A/P, S/I, and L/R axes. Contours on free-breathing scans were compared to those on 4D scans.
Maximum displacement was along the S/I axis, with the superior aspects of organs moving more than the inferior, implying organ compression with respiration. Liver and spleen exhibited the largest motion, which correlated strongly with the S/I motion of the diaphragm. The maximum organ motion observed in the abdomen and thorax were 4.5 mm and 7.4 mm, respectively, while maximum diaphragm displacement was 5.7 mm. Overall findings mirrored observations in adults, but with smaller magnitudes, as expected. No consistent margins could be added to the free-breathing scans to encompass the motion determined using 4DCT.
Organ motion within the pediatric abdomen and pelvis is similar to that observed in adults, but with smaller magnitude. Precise margins to accommodate motion are patient-specific, underscoring the need for 4DCT scanning when possible.
高危神经母细胞瘤（HR-NBL）需要多模态治疗，包括在切除原发肿瘤部位后进行外照射放疗。放疗计划必须考虑靶区和相邻正常解剖结构的运动，而在儿科人群中对这两者的了解都很少，并且它们可能与成人有显著差异。
方法/材料：我们检查了15例连续接受HR-NBL治疗的儿科患者的4DCT扫描图像，大多数患者的肿瘤位于腹腔。在完全吸气、完全呼气和自由呼吸扫描时对膈肌和危及器官进行轮廓勾画。测量完全吸气和完全呼气之间器官在前后、上下、左右方向的最大位移，以及质心在前后、上下和左右轴上的位移。将自由呼吸扫描的轮廓与4D扫描的轮廓进行比较。
最大位移沿上下轴，器官上部的移动比下部更多，这意味着呼吸时器官受到挤压。肝脏和脾脏的运动最大，与膈肌的上下运动密切相关。在腹部和胸部观察到的器官最大运动分别为4.5毫米和7.4毫米，而膈肌的最大位移为5.7毫米。总体结果与成人的观察结果相似，但幅度较小，正如预期的那样。无法在自由呼吸扫描上一致地添加边缘以涵盖使用4DCT确定的运动。
儿科腹部和骨盆内的器官运动与成人观察到的相似，但幅度较小。适应运动的精确边缘是因人而异的，这突出了在可能的情况下进行4DCT扫描的必要性。
