Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Dentomaxillofac Radiol. 2020 Sep 1;49(6):20190378. doi: 10.1259/dmfr.20190378. Epub 2020 May 7.
To quantify and validate the effect of pixel size on a digital intraoral radiographic system according to International Electrotechnical Commission standards through physical and visual evaluations.
The digital intraoral radiographic system used was the photostimulable phosphor imaging plate and scanner system. The system had three image capture modes: high-speed (HS), high-resolution (HR), and super high-resolution (SHR) with different pixels. The physical characteristics of the system were evaluated using presampled modulation transfer function (MTF) and the normalized noise power spectrum (NNPS). An aluminum (Al) step phantom with different depths of holes was used to acquire images under various exposure conditions. The average number of perceptible holes from all steps was plotted against each exposure dose. The results were compared to analyze the effects of pixel size on image quality of intraoral radiographs.
The MTF was slightly higher with SHR than with HR and HS. The NNPS with SHR showed about a 40% decrease in magnitude compared to HS. The total number of perceptible holes in the Al step phantom was higher with SHR than with HS and HR in all exposure conditions.
The MTF and NNPS obtained with different pixel size could be quantified by physical evaluation, and the differences were visually validated with Al step phantom. The SHR mode has the potential to decrease the radiation dose without compromising the image quality.
根据国际电工委员会标准，通过物理和视觉评估来量化和验证像素大小对数字口腔内放射系统的影响。
所使用的数字口腔内放射系统是光激励磷光成像板和扫描仪系统。该系统有三种图像采集模式：高速（HS）、高分辨率（HR）和超高分辨率（SHR），具有不同的像素。系统的物理特性使用预采样调制传递函数（MTF）和归一化噪声功率谱（NNPS）进行评估。使用具有不同深度孔的铝（Al）台阶体模在各种曝光条件下获取图像。绘制所有台阶的可察觉孔的平均数量与每个曝光剂量的关系。将结果进行比较，以分析像素大小对口腔内射线照相图像质量的影响。
SHR 的 MTF 略高于 HR 和 HS。与 HS 相比，SHR 的 NNPS 幅度降低了约 40%。在所有曝光条件下，Al 台阶体模中的可察觉孔总数在 SHR 模式下均高于 HS 和 HR。
可以通过物理评估来量化不同像素大小获得的 MTF 和 NNPS，并且可以使用 Al 台阶体模进行视觉验证。SHR 模式有可能在不影响图像质量的情况下降低辐射剂量。
