1 Section of Oral Radiology, Department of Oral and Maxillofacial Surgery, University Medical Center of the Johannes Gutenberg-University , Mainz , Germany.
2 Private Dental Office , Betzdorf , Germany.
Dentomaxillofac Radiol. 2019 May;48(4):20180350. doi: 10.1259/dmfr.20180350. Epub 2019 Feb 28.
To develop a simple way to compute the approximated modulation transfer function (MTF) manually using conventional spreadsheet software.
Basing on an edge-image a method was developed, facilitating computation of the edge spread and line spread function in open-source spreadsheet software (Gnumeric; http://projects.gnome.org/gnumeric/downloads.shtml ). By means of the integrated fast Fourier transformation Fourier coefficients are obtained from the line spread function which can then be plotted spatial frequency to obtain MTF-plots. For the experimental evaluation an edge test object was exposed in five commercial CBCT devices for maxillofacial applications.
The MTF as obtained from the above-described manual method at 10% modulation ranged between 1.6 and 2.3 cycles/mm. Reproducibility as expressed as relative differences between single assessments ranging between 3% and 11%. The computed MTF-values compare well with results from the literature.
The method introduced can be used to manually and reliably estimate a CBCTs' MTF as one central parameter for the imaging systems' performance.
开发一种使用常规电子表格软件手动计算近似调制传递函数（MTF）的简单方法。
基于边缘图像，开发了一种方法，以促进在开源电子表格软件（Gnumeric；http://projects.gnome.org/gnumeric/downloads.shtml）中计算边缘扩散和线扩散函数。通过集成的快速傅里叶变换，可以从线扩散函数中获得傅里叶系数，然后可以将其绘制到空间频率上以获得 MTF 图。为了进行实验评估，在五个用于颌面的商用 CBCT 设备中对边缘测试物体进行了曝光。
以 10%调制获得的 MTF 范围在 1.6 到 2.3 个周期/mm 之间。表示为单个评估之间的相对差异的重现性在 3%到 11%之间。计算出的 MTF 值与文献中的结果相当吻合。
本文介绍的方法可用于手动且可靠地估计 CBCT 的 MTF，作为成像系统性能的一个核心参数。
