技术注释：TIGRE-DE 用于从双能锥形束 CT 创建虚拟单能量图像。

Technical note: TIGRE-DE for the creation of virtual monoenergetic images from dual-energy cone-beam CT.

机构信息

Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardin Cancer Center, Loyola University of Chicago, Maywood, Illinois, USA.

Varian Imaging Laboratory, Baden, Switzerland.

出版信息

Med Phys. 2024 Apr;51(4):2975-2982. doi: 10.1002/mp.17002. Epub 2024 Feb 26.

DOI:10.1002/mp.17002

PMID:38408013

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC10994758/

Abstract

BACKGROUND

Dual-energy (DE)-CBCT represents a promising imaging modality that can produce virtual monoenergetic (VM) CBCT images. VM images, which provide enhanced contrast and reduced imaging artifacts, can be used to assist in soft-tissue visualization during image-guided radiotherapy.

PURPOSE

This work reports the development of TIGRE-DE, a module in the open-source TIGRE toolkit for the performance of DE-CBCT and the production of VM CBCT images. This module is created to make DE-CBCT tools accessible in a wider range of clinical and research settings.

METHODS

We developed an add-on (TIGRE-DE) to the TIGRE toolkit that performs DE material decomposition. To verify its performance, sequential CBCT scans at 80 and 140 kV of a Catphan 604 phantom were decomposed into equivalent thicknesses of aluminum (Al) and polymethyl-methylacrylate (PMMA) basis materials. These basis material projections were used to synthesize VM projections for a range of x-ray energies, which were then reconstructed using the Feldkamp-Davis-Kress (FDK) algorithm. Image quality was assessed by computing Hounsfield units (HU) and contrast-to-noise ratios (CNR) for the material inserts of the phantom and comparing with the constituent 80 and 140 kV images.

RESULTS

All VM images generated using TIGRE-DE showed good general agreement with the theoretical HU values of the material inserts of the phantom. Apart from the highest-density inserts imaged at the extremes of the energy range, the measured HU values agree with theoretical HUs within the clinical tolerance of ±50 HU. CNR measurements for the various inserts showed that, of the energies selected, 60 keV provided the highest CNR values. Moreover, 60 keV VM images showed average CNR enhancements of 63% and 66% compared to the 80 and 140 kV full-fan protocols.

CONCLUSIONS

TIGRE-DE successfully implements DE-CBCT material decomposition and VM image creation in an accessible, open-source platform.

摘要

背景

双能（DE）-CBCT 是一种很有前途的成像方式，可生成虚拟单能量（VM）CBCT 图像。VM 图像提供了增强的对比度和减少的成像伪影，可以用于在图像引导放射治疗期间辅助软组织可视化。

目的

本工作报告了 TIGRE-DE 的开发，这是开源 TIGRE 工具包中的一个模块，用于执行 DE-CBCT 和生成 VM CBCT 图像。该模块旨在使 DE-CBCT 工具在更广泛的临床和研究环境中可用。

方法

我们为 TIGRE 工具包开发了一个附加组件（TIGRE-DE），用于执行 DE 材料分解。为了验证其性能，对 Catphan 604 体模进行了 80kV 和 140kV 的连续 CBCT 扫描，将其分解为等效厚度的铝（Al）和聚甲基丙烯酸甲酯（PMMA）基础材料。这些基础材料投影被用于合成一系列 X 射线能量的 VM 投影，然后使用 Feldkamp-Davis-Kress（FDK）算法进行重建。通过计算体模材料插入物的亨氏单位（HU）和对比噪声比（CNR）来评估图像质量，并将其与组成的 80kV 和 140kV 图像进行比较。

结果

使用 TIGRE-DE 生成的所有 VM 图像与体模材料插入物的理论 HU 值都表现出很好的总体一致性。除了在能量范围的极端处成像的最高密度插入物外，测量的 HU 值与临床允许的±50HU 范围内的理论 HU 值一致。各种插入物的 CNR 测量表明，在所选择的能量中，60keV 提供了最高的 CNR 值。此外，与 80kV 和 140kV 全扇区协议相比，60keV VM 图像的平均 CNR 增强分别为 63%和 66%。