Reduction Of Edge Position Uncertainty On Computed Tomographic (CT) Scans

The perception of edges on computed tomographic (CT) scans appears easy but in fact is difficult. Such perception is important because it is necessary to make quantitative determinations. Diagnosis of such entities as spinal stenosis (narrowing of the spinal canal with encroachment on spinal cord and nerve roots) hinges upon an accurate knowledge of cross -sectional areas. Smoothing of edges occurs both in the averaging effect of finite beam width as well as in the deconvolution /back -projection algorithms used in generating CT scans, and results in edge ambiguity. Rather than devise new deconvolution algorithms, we reasoned that the information was probably present in routine scans and could be made available for clinical use A previousl attempt relied upon correlation of directly measured in v-tno distances with those from images obtained at successive window levels and widths. A pn -LoYi this approach should work. It encounters difficulty, however, in the fact that CT scanners in general have unreliable absolute density measurements. What is reasonable to expect of commercially available scanners is stable relative density measurements which are internally consistent.