Stewart B K, Carter S J, Cook J N, Abbe B S, Pinck D, Rowberg A H
Department of Radiology, University of Washington School of Medicine, Seattle, USA.
J Digit Imaging. 1999 May;12(2):68-76. doi: 10.1007/BF03168845.
The authors have investigated the application of the NASA Advanced Communications Technology Satellite (ACTS) to teleradiology and telemedicine using the Jet Propulsion Laboratory (JPL)-developed ACTS Mobile Terminal (AMT) uplink. In this experiment, bidirectional 128, 256, and 384 kbps satellite links were established between the ACTS/AMT, the ACTS in geosynchronous orbit, and the downlink terrestrial terminal at JPL. A terrestrial Integrated Digital Services Network (ISDN) link was established from JPL to the University of Washington Department of Radiology to complete the bidirectional connection. Ultrasound video imagery was compressed in real-time using video codecs adhering to the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Recommendation H.261. A 16 kbps in-band audio channel was used throughout. A five-point Likert scale was used to evaluate the quality of the compressed ultrasound imagery at the three transmission bandwidths (128, 256, and 384 kbps). The central question involved determination of the bandwidth requirements to provide sufficient spatial and contrast resolution for the remote visualization of fine- and low-contrast objects. The 384 kbps bandwidth resulted in only slight tiling artifact and fuzziness owing to the quantizer step size; however, these motion artifacts were rapidly resolved in time at this bandwidth. These experiments have demonstrated that real-time compressed ultrasound video imagery can be transmitted over multiple ISDN line bandwidth links with sufficient temporal, contrast, and spatial resolution for clinical diagnosis of multiple disease and pathology states to provide subspecialty consultation and educational at a distance.
作者们利用喷气推进实验室（JPL）开发的先进通信技术卫星（ACTS）移动终端上行链路，研究了ACTS在远程放射学和远程医疗中的应用。在该实验中，在ACTS/移动终端、地球同步轨道上的ACTS以及JPL的地面下行终端之间建立了双向128、256和384 kbps的卫星链路。从JPL到华盛顿大学放射科建立了一条地面综合数字服务网络（ISDN）链路，以完成双向连接。超声视频图像使用符合国际电信联盟电信标准化部门（ITU-T）H.261建议的视频编解码器进行实时压缩。全程使用16 kbps的带内音频通道。采用五点李克特量表来评估三种传输带宽（128、256和384 kbps）下压缩超声图像的质量。核心问题涉及确定为远程可视化精细和低对比度物体提供足够空间和对比度分辨率所需的带宽。由于量化步长，384 kbps带宽仅导致轻微的平铺伪像和模糊；然而，在该带宽下，这些运动伪像能迅速及时得到解决。这些实验表明，实时压缩超声视频图像可以通过多个ISDN线路带宽链路进行传输，具有足够的时间、对比度和空间分辨率，用于多种疾病和病理状态的临床诊断，以提供远程亚专业会诊和教育。
