Impact of exposure settings variations on contrast and spatial resolution in complementary metal oxide semiconductor and direct-conversion complementary metal oxide semiconductor intraoral sensors
Daniela Pita de Melo, Luiz Eduardo Marinho-Vieira, Caroline Hoang, Crystal Ly, Ryan Kuhn, Jacqueline Tkachuk, Saulo L Sousa MeloAbstract
Objectives
To evaluate the impact of exposure setting variations on contrast and spatial resolution (SR) in complementary metal oxide semiconductor (CMOS) and direct-conversion CMOS (DC-CMOS) intraoral sensors.
Methods
Ten images of a digital dental quality assurance (DDQA) phantom were acquired for each assessed condition using 3 sensors (CMOS-I, CMOS-S, DC-CMOS) and 2 X-ray units (HH: handheld; WM: wall-mounted). HH was set at 60 kVp/2.5 mA, and WM was set at 60 kVp/7 mA and 70 kVp/7 mA. Each combined sensor-X-ray unit condition was exposed at 0.02, 0.04, 0.05, 0.08, 0.10, 0.16, 0.20, 0.25, 0.32, 0.40, 0.50, 0.63, 0.80, and 1.00 s. One observer selected 2 × 2 mm ROIs from the third and fifth steps of the DDQA step-wedge and measured their mean gray values using Fiji macro. Contrast was calculated by subtracting the mean gray value of the third step from the fifth step for each group. SR was determined by identifying the line pair with the highest value, in which 5 peaks and 4 valleys were distinguishable. Descriptive statistics were calculated for SR and 3-way ANOVA and Tukey’s post hoc tests for contrast (α = 0.05).
Results
Across all exposure parameters, CMOS-I exhibited the highest mean contrast, followed by DC-CMOS and CMOS-S (P < .001). HH yielded the highest mean contrast, which was significantly greater than WM (P < .001). CMOS-S exhibited the highest SR, and DC-CMOS the lowest, although SR remained constant for DC-CMOS across all exposure times.
Conclusions
Sensor type, X-ray unit, and exposure time influenced image contrast and spatial resolution, while variations in kVp had minimal impact on these image quality parameters.