Abstract

The aim of this work was to estimate patient’s organ absorbed doses from pediatric helical head computed tomography (CT) examinations using the Size-Specific Dose Estimate (SSDE) methodology and to determine organ dose to SSDE conversion coefficients for clinical routine. Patient-specific organ and tissue absorbed doses from 139 Head CT scans performed in pediatric patients from 0 to 15 years old in a Public Hospital in Tunja, Colombia were estimated. The calculations were made through Monte Carlo simulations, based on patient-specific information, dosimetric CT quantities (CTDI_vol, DLP) and age-specific computational human phantoms matched to patients on the basis of gender and size. SSDE showed to be a good quantity for estimate patient-specific organ doses from pediatric head CT examinations when appropriate phantom’s attenuation-based size metrics are chosen to match for any patient size. Strong correlations between absorbed dose and SSDE were found for skin (R² = 0.99), brain (R² = 0.98) and eyes (R² = 0.97), respectively. Besides, a good correlation between SSDE and absorbed dose to the red bone marrow (tissue extended outside the scan coverage) was observed (R² = 0.94). SSDE-to-organ-dose conversion coefficients obtained in this study provide a practical way to estimate patient-specific organ head CT doses.

中文翻译：

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儿科头部CT检查的患者特定有机剂量

摘要

这项工作的目的是使用特定于剂量的剂量估计（SSDE）方法从小儿螺旋头部计算机断层扫描（CT）检查中估计患者的器官吸收剂量，并确定临床常规的器官剂量到SSDE转换系数。估计了在哥伦比亚Tunja的一家公立医院的0至15岁的儿科患者中进行的139次头部CT扫描得出的患者特定器官和组织的吸收剂量。这些计算是通过Monte Carlo模拟进行的，基于患者的特定信息，剂量CT量（CTDI _vol，DLP）和根据年龄和性别而定的特定计算人体模型与患者匹配。SSDE显示是为特定患者的估计器官剂量从小儿头部CT检查一个良好的数量在适当的时候幻影的基于衰减的尺寸指标，要选择符合任何患者的大小。发现皮肤（R ²  = 0.99），大脑（R ²  = 0.98）和眼睛（R ²  = 0.97）的吸收剂量与SSDE之间有很强的相关性。此外，观察到SSDE与红骨髓吸收剂量（组织扩展到扫描范围之外）之间有良好的相关性（R ² = 0.94）。在这项研究中获得的SSDE到器官剂量的转换系数为估算患者特定的器官头部CT剂量提供了一种实用的方法。