Li B, Lee H C, Duan X, Shen C, Zhou L, Jia X, Yang M
Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States of America. Department of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong 510515, People's Republic of China.
Phys Med Biol. 2017 Aug 9;62(17):7056-7074. doi: 10.1088/1361-6560/aa7dc9.
The dual-energy CT-based (DECT) approach holds promise in reducing the overall uncertainty in proton stopping-power-ratio (SPR) estimation as compared to the conventional stoichiometric calibration approach. The objective of this study was to analyze the factors contributing to uncertainty in SPR estimation using the DECT-based approach and to derive a comprehensive estimate of the range uncertainty associated with SPR estimation in treatment planning. Two state-of-the-art DECT-based methods were selected and implemented on a Siemens SOMATOM Force DECT scanner. The uncertainties were first divided into five independent categories. The uncertainty associated with each category was estimated for lung, soft and bone tissues separately. A single composite uncertainty estimate was eventually determined for three tumor sites (lung, prostate and head-and-neck) by weighting the relative proportion of each tissue group for that specific site. The uncertainties associated with the two selected DECT methods were found to be similar, therefore the following results applied to both methods. The overall uncertainty (1σ) in SPR estimation with the DECT-based approach was estimated to be 3.8%, 1.2% and 2.0% for lung, soft and bone tissues, respectively. The dominant factor contributing to uncertainty in the DECT approach was the imaging uncertainties, followed by the DECT modeling uncertainties. Our study showed that the DECT approach can reduce the overall range uncertainty to approximately 2.2% (2σ) in clinical scenarios, in contrast to the previously reported 1%.
与传统的化学计量校准方法相比，基于双能CT（DECT）的方法有望降低质子阻止本领比（SPR）估计中的总体不确定性。本研究的目的是分析使用基于DECT的方法时SPR估计不确定性的影响因素，并得出治疗计划中与SPR估计相关的射程不确定性的综合估计值。在西门子SOMATOM Force DECT扫描仪上选择并实施了两种最先进的基于DECT的方法。不确定性首先被分为五个独立类别。分别对肺、软组织和骨组织估计了与每个类别相关的不确定性。最终通过加权特定部位每个组织组的相对比例，为三个肿瘤部位（肺、前列腺和头颈部）确定了一个单一的综合不确定性估计值。发现与两种选定的DECT方法相关的不确定性相似，因此以下结果适用于这两种方法。基于DECT的方法在SPR估计中的总体不确定性（1σ）估计对于肺、软组织和骨组织分别为3.8%、1.2%和2.0%。DECT方法中导致不确定性的主要因素是成像不确定性，其次是DECT建模不确定性。我们的研究表明，与之前报道的1%相比，在临床场景中，DECT方法可将总体射程不确定性降低至约2.2%（2σ）。
