Subjective evaluation of photon counting sensor for interproximal caries detection

Abstract

Objective

Photon-counting sensors (PCS), as the name indicates, are a new kind of sensor that creates the image by counting photons. PCS are, in theory, less sensitive to image blur and might be more sensitive to early caries detection. The objective of this in vitro study is to present a subjective evaluation of bitewing radiographs captured with PCS when compared with traditional digital sensors like complementary metal oxide semiconductor (CMOS) sensors and photo-stimulable phosphor (PSP) plates.

Study Design

Extracted teeth with no carious lesions were mounted in a modular stage to replicate the configuration of (1) maxillary and (1) mandibular bitewing radiographs. The stage allowed repetitive installation of interchangeable holders for the 2 digital sensors and the PSP plate ensuring that the geometry of the radiographs was consistent for all technologies. Multiple bitewing radiographs were acquired at 70 kVp and 7 mA with varying exposure times (0.02, 0.08, 0.125, and 0.250 seconds). Two teeth were then drilled using a 0.5-mm diameter bur to simulate an incipient interproximal lesion, and images were recaptured with the previously mentioned exposure parameters. Six examiners—1 oral radiologist and 5 oral radiology residents—were asked to subjectively rate the diagnostic value and image quality metrics (i.e., spatial resolution, contrast resolution, dynamic range, and noise) of the bitewing radiographs.

Results

Image quality metrics like spatial resolution and noise characteristics of PCS ranked above the CMOS sensor and PSP plate, CMOS sensors were ranked as the technology with the best contrast resolution, and PSP plates had the best dynamic range. PCS were overall ranked as the preferred technology for defect detection and outperformed CMOS sensors and PSP plates when exposure parameters were not ideal.

Conclusion

PCS have the potential to provide clinical information with high diagnostic value. More research is needed to further evaluate the sensitivity and specificity of this technology.