Wagner A J, Frey G D
Department of Radiology, Medical University of South Carolina, Charleston 29425, USA.
Med Phys. 1995 Feb;22(2):127-32. doi: 10.1118/1.597462.
Mammographic contrast is commonly evaluated by visualizing small objects of varying size or mass divided by projected area. These qualitative contrast determinations are commonly performed by imaging a phantom like the American College of Radiology accreditation phantom at clinical mammographic settings. However, this contrast assessment does not take into account the kVp of the machine. This work describes a quantitative mammography contrast threshold test tool which examines light object contrast on a uniform background for a contrast range of 0.32% to 1.38% at 25 kVp. For this mammography contrast threshold test tool, contrast is defined by delta I/I = loge (psi O/ psi b), where psi O is the target energy flux, and psi b is the background energy flux. Contrast threshold is defined as the lowest contrast value for which the objects are visible. Unlike traditional assessments of mammographic contrast, this measurement of contrast threshold is kVp corrected. The mammography contrast threshold test tool is constructed out of common plastics and provides a quantitative means of assessing contrast threshold for individual mammographic units and total mammographic systems.
乳腺X线摄影对比度通常通过观察不同大小或质量的小物体除以投影面积来评估。这些定性对比度测定通常是在临床乳腺X线摄影条件下对类似美国放射学会认证体模的体模进行成像来完成的。然而，这种对比度评估没有考虑机器的千伏峰值（kVp）。这项工作描述了一种定量乳腺X线摄影对比度阈值测试工具，该工具在25 kVp下检查均匀背景上的轻物体对比度，对比度范围为0.32%至1.38%。对于这种乳腺X线摄影对比度阈值测试工具，对比度定义为ΔI/I = loge(ψO / ψb)，其中ψO是目标能量通量，ψb是背景能量通量。对比度阈值定义为物体可见的最低对比度值。与传统的乳腺X线摄影对比度评估不同，这种对比度阈值测量是经过kVp校正的。乳腺X线摄影对比度阈值测试工具由普通塑料制成，为评估单个乳腺X线摄影单元和整个乳腺X线摄影系统的对比度阈值提供了一种定量方法。
