Influência da exposição de placas de fósforo fotoestimuláveis à luz ambiente previamente à exposição a radiação X na qualidade objetiva da imagem

Abstract

This in vitro study aimed to investigate the influence of pre-exposure to ambient light on objective image quality parameters of two photostimulable phosphor (PSP) plate systems: EaglePS (Dabi Atlante) and VistaScan (Dürr Dental). Periapical radiographs of an 11-step aluminium step-wedge were obtained using fixed exposure parameters (70 kVp, 7 mA, 0.24 s), with PSP plates exposed to six storage conditions prior to X-ray exposure: control (no light exposure), and 30 min, 1, 2, 4, and 12 hours of ambient light exposure (n = 10 per group, 120 radiographs in total). Optical density, contrast variation, uniformity, and signal-to-noise ratio (SNR) were assessed using ImageJ software and compared by one-way ANOVA followed by Tukey's post-hoc test (α = 0.05). For EaglePS, optical density remained predominantly stable, with no significant differences at most steps (p > 0.05), and uniformity was unaffected by exposure time (p = 0.092). For VistaScan, optical density and uniformity decreased significantly from 4 hours of exposure onward, with the lowest values recorded at 12 hours (p < 0.001). Contrast variation was significantly influenced by exposure time in both systems (p < 0.001), with the highest values in the 4- and 12-hour groups. SNR showed system- and attenuation-dependent behaviour, increasing significantly in EaglePS after 4 and 12 hours (p < 0.001; p = 0.015), while VistaScan values fluctuated without a defined temporal trend (p < 0.001). Prior exposure to ambient light objectively altered physical image quality parameters of PSP systems in a technology-dependent manner, and measurable changes occurred within intervals shorter than the 24 hours recommended by manufacturers for a new erasure cycle.