QUANTIFYING PHOTOSTIMULABLE PHOSPHOR (PSP) PLATE ARTIFACTS TO STANDARDIZE RADIOLOGIC QUALITY ASSURANCE

Abstract

Background With every use, photostimulable phosphor (PSP) plates accumulate physical artifacts (i.e., scratches, dents) that negatively affect image quality. Dental clinicians are responsible for monitoring these artifacts and discard plates they have deemed undiagnostic. Currently, at our institution, this is accomplished by direct visual inspection of plates for signs of wear. This arbitrary process has no objective validation leading to variability in radiologic image quality and may impair diagnostic value. Objective This study aimed to develop a metric to objectively quantify the severity of physical artifacts on PSP plates. This metric will be compared against the current standard of direct visual inspection to determine the validity of this approach for PSP quality assurance. Materials and Methods Sixty random PSP plates (CS 7600; Carestream Dental, Rochester, NY) were chosen for analysis: 36 were determined to be undiagnostic by using the current quality control standard, 20 were in active circulation, and 4 brand-new plates were used as controls. The selected plates were exposed to obtain the equivalent of a posterior bitewing image (Belmont PHOT-X II s Model 505 at 70 kV, 6 mA, 0.22 seconds), scanned, and raw DICOM images exported. A custom computer algorithm (MATLAB; Mathworks, Natick, MA) was developed to measure the inhomogeneity of the image to calculate the artifact metric. By using these, the selected plates were sorted and compared against the current quality assurance standard. Preliminary Results Preliminary results showed poor correlation between plates that were selected to be discarded by direct visual inspection and artifact metrics. Many plates that were chosen to be discarded with the current standard had a lower artifact metric compared with plates that were still in circulation. Future Directions Future studies aim to validate this metric by comparing the artifact score with qualitative grading of PSP plate artifacts and to determine a threshold for when radiologic diagnosis is impeded. With every use, photostimulable phosphor (PSP) plates accumulate physical artifacts (i.e., scratches, dents) that negatively affect image quality. Dental clinicians are responsible for monitoring these artifacts and discard plates they have deemed undiagnostic. Currently, at our institution, this is accomplished by direct visual inspection of plates for signs of wear. This arbitrary process has no objective validation leading to variability in radiologic image quality and may impair diagnostic value. This study aimed to develop a metric to objectively quantify the severity of physical artifacts on PSP plates. This metric will be compared against the current standard of direct visual inspection to determine the validity of this approach for PSP quality assurance. Sixty random PSP plates (CS 7600; Carestream Dental, Rochester, NY) were chosen for analysis: 36 were determined to be undiagnostic by using the current quality control standard, 20 were in active circulation, and 4 brand-new plates were used as controls. The selected plates were exposed to obtain the equivalent of a posterior bitewing image (Belmont PHOT-X II s Model 505 at 70 kV, 6 mA, 0.22 seconds), scanned, and raw DICOM images exported. A custom computer algorithm (MATLAB; Mathworks, Natick, MA) was developed to measure the inhomogeneity of the image to calculate the artifact metric. By using these, the selected plates were sorted and compared against the current quality assurance standard. Preliminary results showed poor correlation between plates that were selected to be discarded by direct visual inspection and artifact metrics. Many plates that were chosen to be discarded with the current standard had a lower artifact metric compared with plates that were still in circulation. Future studies aim to validate this metric by comparing the artifact score with qualitative grading of PSP plate artifacts and to determine a threshold for when radiologic diagnosis is impeded.