Allert Keana D, Vangala Sravanthi, Dibianca Frank A
Department of BioImaging, College of Health Science Engineering, The University of Tennessee Health Science Center, 920 Madison Avenue, Suite 1005, Memphis, Tennessee 38163.
J Xray Sci Technol. 2007;15(1):9-18.
Acceptance testing and quality control of computed tomography (CT) scanners are of great importance. While most procedures and phantoms for testing other parameters are widely accepted, there is still discussion and uncertainty about low-contrast (LC) performance tests that measure the capability of a CT scanner to discriminate low-contrast objects. This work investigated the development of LC phantoms with available, low-cost polystyrene resin materials and some selected additives. We designed and tested phantoms with several different contrast steps by generating contrast in two different ways, one based on 'physical density difference' and the other on 'atomic number difference'. Physical density difference was achieved by adding a small amount of glycerin to the polystyrene resin, both having similar low atomic-number elements but differing in the density of their atoms. Atomic number difference was achieved by adding a small amount of iodobenzene to the resin, both having approximately the same physical density (less than 1% variation in density) but different atomic (i.e., elemental) composition. Prototypes were evaluated using a Philips Tomoscan LX system and varying beam properties. The behavior and validity of the results are discussed.
计算机断层扫描（CT）扫描仪的验收测试和质量控制非常重要。虽然测试其他参数的大多数程序和体模已被广泛接受，但对于测量CT扫描仪辨别低对比度物体能力的低对比度（LC）性能测试仍存在讨论和不确定性。这项工作研究了使用可用的低成本聚苯乙烯树脂材料和一些选定添加剂开发LC体模。我们通过两种不同的方式产生对比度，设计并测试了具有几种不同对比度步长的体模，一种基于“物理密度差异”，另一种基于“原子序数差异”。通过向聚苯乙烯树脂中添加少量甘油来实现物理密度差异，二者都含有类似的低原子序数元素，但原子密度不同。通过向树脂中添加少量碘苯来实现原子序数差异，二者的物理密度大致相同（密度变化小于1%），但原子（即元素）组成不同。使用飞利浦Tomoscan LX系统和不同的光束特性对原型进行了评估。讨论了结果的行为和有效性。
