Assessment and quantification of photostimulable phosphor plate artifacts

Abstract

<h3>Background</h3> Photostimulable phosphor (PSP) plate artifacts can result in radiopaque areas superimposed over radiologic images, which can affect interpretation. There is currently no objective metric for artifact severity, which could help determine the impact on diagnostic interpretation. <h3>Objectives</h3> To develop a method to objectively quantify artifact severity on PSP plates. <h3>Study Design</h3> Artifacts were identified on clinically used and damaged PSP plates, and assessed using three parameters: surface area, intensity, and location. A grid system was used to quantify the surface area. For intensity, histogram analyses resulted in the development of pixel value thresholds. Location was binarized as grids within and outside a "critical zone." The critical zone is operationalized as an area within which carious lesions are more frequently identified. To define this area, unrestored interproximal carious lesions identified on 190 complementary metal oxide semiconductor (CMOS) images, acting as the artifact-free gold standard, were traced to create a heatmap. Together, these three metrics allowed for the development of an artifact scoring system. <h3>Results</h3> The image critical zone occupied 32.3% of the total sensor area. Two different peaks were identified on the plate histograms, which visually correlated with two distinct types of artifacts. Bending and phosphor degradation resulted in increased numbers of grids that were within a lower pixel value range (40 to 100). In comparison, scratches and surface peeling resulted in increased numbers of grids within a higher pixel value range (above 100). <h3>Conclusion</h3> An image "critical zone" was defined where carious lesions are imaged more frequently. Intensity and surface area have been combined to quantify artifact severity. These metrics allowed for the development of an artifact scoring system, which can then be used to assess the impact on image interpretation. This research lays the groundwork for the future development of a quality control protocol for PSP plates. <b>Statement of Ethical Review</b> Human/Animal subjects were used and this study was approved by an institutional ethics panel.