Reducing radiation-induced side effects is one of the most important challenges in paediatric cancer treatment. Recently, there has been growing interest in using spatial normalisation to enable voxel-based analysis of radiation-induced toxicities in a variety of patient groups. The need to consider three-dimensional distribution of doses, rather than dose-volume histograms, is desirable but not yet explored in paediatric populations. In this paper, we investigate the feasibility of atlas construction and spatial normalisation in paediatric radiotherapy. We used planning computed tomography (CT) scans from twenty paediatric patients historically treated with craniospinal irradiation to generate a template CT that is suitable for spatial normalisation. This childhood cancer population representative template was constructed using groupwise image registration. An independent set of 53 subjects from a variety of childhood malignancies was then used to assess the quality of the propagation of new subjects to this common reference space using deformable image registration (i.e. spatial normalisation). The method was evaluated in terms of overall image similarity metrics, contour similarity and preservation of dose-volume properties. After spatial normalisation, we report a dice similarity coefficient of 0.950.05, 0.850.04, 0.960.01, 0.910.03, 0.830.06 and 0.650.16 for brain and spinal canal, ocular globes, lungs, liver, kidneys and bladder. We then demonstrated the potential advantages of an atlas-based approach to study the risk of second malignant neoplasms after radiotherapy. Our findings indicate satisfactory mapping between a heterogeneous group of patients and the template CT. The poorest performance was for organs in the abdominal and pelvic region, likely due to respiratory and physiological motion and to the highly deformable nature of abdominal organs. More specialised algorithms should be explored in the future to improve mapping in these regions. This study is the first step toward voxel-based analysis in radiation-induced toxicities following paediatric radiotherapy.

减少辐射引起的副作用是儿科癌症治疗中最重要的挑战之一。最近，人们越来越关注使用空间归一化来对各种患者群体的辐射引起的毒性进行基于体素的分析。考虑剂量的三维分布而不是剂量体积直方图的需要是可取的，但尚未在儿科人群中进行探索。在本文中，我们研究了图谱构建和空间归一化在儿科放射治疗中的可行性。我们使用计划计算机断层扫描 (CT) 扫描来自 20 名曾接受颅脊髓照射治疗的儿科患者，以生成适用于空间标准化的模板 CT。这个儿童癌症人群代表模板是使用分组图像配准构建的。然后使用来自各种儿童期恶性肿瘤的 53 名受试者的独立集合，使用可变形图像配准（即空间归一化）评估新受试者传播到该公共参考空间的质量。该方法在整体图像相似性指标、轮廓相似性和剂量-体积特性的保留方面进行了评估。空间归一化后，我们报告了脑和椎管、眼球、肺、肝、肾和膀胱的骰子相似系数分别为 0.950.05、0.850.04、0.960.01、0.910.03、0.830.06 和 0.650.16 . 然后，我们展示了基于图谱的方法研究放射治疗后第二次恶性肿瘤风险的潜在优势。我们的研究结果表明异质患者组与模板 CT 之间的映射令人满意。最差的表现是腹部和骨盆区域的器官，可能是由于呼吸和生理运动以及腹部器官的高度可变形性质。未来应该探索更专业的算法来改进这些区域的映射。这项研究是在儿科放疗后基于体素分析辐射诱发毒性的第一步。未来应该探索更专业的算法来改进这些区域的映射。这项研究是在儿科放疗后基于体素分析辐射诱发毒性的第一步。未来应该探索更专业的算法来改进这些区域的映射。这项研究是在儿科放疗后基于体素分析辐射诱发毒性的第一步。