[论文解读] A gel wax phantom for performance evaluation in diagnostic ultrasound: assessment of image uniformity, geometric accuracy, and diameter of a hyperechoic target

Debjani Phani, R Varadarajulu+8 more|arXiv (Cornell University)|Dec 14, 2022

Ultrasound Imaging and Elastography被引用 5

一句话总结

本研究提出一种低成本、稳定的凝胶蜡假体，用于超声性能评估，通过嵌入不锈钢圆盘和尼龙丝来评估图像均匀性、几何准确性及目标直径。该假体表现出高稳定性（62周内体积损失仅1.8%），超声成像中最大距离误差为7.1%，验证了其在诊断超声质量控制中的适用性。

ABSTRACT

Purpose: To develop and validate a phantom for diagnostic ultrasound (US) scanners by embedding targets in gel wax to determine the image uniformity, lateral and axial resolution, and diameter of a stainless-steel disc. Materials and Methods: Acoustic property (AP), which includes the velocity of US (cus), acoustic impedance (Z), and attenuation coefficient in gel wax were determined. The cus, and attenuation coefficient were estimated using the pulse-echo technique. Z was obtained from the product of sample density ( {ho}) and cus. Two rectangular frames using polytetrafluoroethylene (PTFE) sheets with holes separated by 5, 10, and 20 mm distances were constructed. Nylon filaments and SS-disc (diameter = 16.8 mm) were threaded through the frames and suitably placed in melted gel wax to obtain orthogonal targets. The targets were measured using computerized tomography (CT) and a 2-9 MHz US probe. Results: The AP of gel wax were cus=1418 m/s, {ho}= 0.87 g/cm3, Z=1.23 MRayls, attenuation coefficient= 0.88 dB/cm/MHz. The results of US imaging of the targets were compared with their physical sizes and served as baselines for the scanner and probe. The maximum error in distance measurement in the phantom US images was 7.1%, and the phantom volume decreased by 1.8% over 62 weeks. Conclusion: Gel wax can be useful in developing affordable, highly stable, and customizable diagnostic US phantoms that can be implemented widely.

研究动机与目标

• 开发一种经济实惠、稳定且可定制的假体，用于诊断超声性能评估。
• 评估超声成像中高回声目标的图像均匀性、几何准确性和直径测量。
• 验证凝胶蜡作为超声假体合适介质的声学特性。
• 通过CT和超声成像的物理测量结果，为扫描仪和探头性能提供基准参考。
• 通过低成本、易获取的材料，支持该假体在临床和研究环境中的广泛应用。

提出的方法

• 使用脉冲回波法测量凝胶蜡的声学特性，以确定声速（cus）、声阻抗（Z）和衰减系数。
• 制作两个由聚四氟乙烯（PTFE）制成的矩形框架，孔间距分别为5、10和20 mm，用于定位目标。
• 将直径16.8 mm的不锈钢圆盘和尼龙丝嵌入熔化的凝胶蜡中，形成正交目标。
• 使用2–9 MHz超声探头和CT对假体进行扫描，以验证其物理尺寸。
• 通过将超声测量结果与CT获得的物理尺寸进行比较，评估图像均匀性、侧向和轴向分辨率以及目标直径。

实验结果

研究问题

• RQ1 凝胶蜡能否作为具有稳定且一致声学特性的诊断超声假体介质，且成本低廉？
• RQ2 与物理测量相比，超声系统在凝胶蜡假体中测量距离和目标直径的准确性如何？
• RQ3 在长时间尺度上，凝胶蜡假体在尺寸和声学完整性方面表现出怎样的长期稳定性？
• RQ4 该假体在多大程度上支持对超声成像中图像均匀性和几何准确性进行可靠评估？
• RQ5 该假体是否可在不同超声系统中可靠地复制和使用，以实现质量控制？

主要发现

• 凝胶蜡的声学特性测量结果为：声速（cus）= 1418 m/s，密度（ρ）= 0.87 g/cm³，声阻抗（Z）= 1.23 MRayls，衰减系数 = 0.88 dB/cm/MHz。
• 超声图像与物理尺寸之间的最大距离测量误差为7.1%，表明具有良好的几何准确性。
• 该假体在62周内体积仅减少1.8%，表现出优异的长期稳定性。
• 该假体能够一致地评估图像均匀性和目标直径，其结果与基于CT的物理测量结果相当。
• 使用不锈钢圆盘和尼龙丝可实现高回声目标在2D超声成像中清晰可视化，并实现准确测量。