Mozzo P, Procacci C, Tacconi A, Martini P T, Andreis I A
Department of Medical Physics, University Hospital, Verona, Italy.
Eur Radiol. 1998;8(9):1558-64. doi: 10.1007/s003300050586.
The objective of this paper is to present a new type of volumetric CT which uses the cone-beam technique instead of traditional fan-beam technique. The machine is dedicated to the dento-maxillo-facial imaging, particularly for planning in the field of implantology. The main characteristics of the unit are presented with reference to the technical parameters as well as the software performance. Images obtained are reported as various 2D sections of a volume reconstruction. Also, measurements of the geometric accuracy and the radiation dose absorbed by the patient are obtained using specific phantoms. Absorbed dose is compared with that given off by spiral CT. Geometric accuracy, evaluated with reference to various reconstruction modalities and different spatial orientations, is 0.8-1% for width measurements and 2.2% for height measurements. Radiation dose absorbed during the scan shows different profiles in central and peripheral axes. As regards the maximum value of the central profile, dose from the new unit is approximately one sixth that of traditional spiral CT. The new system appears to be very promising in dentomaxillo-facial imaging and, due to the good ratio between performance and low cost, together with low radiation dose, very interesting in view of large-scale use of the CT technique in such diagnostic applications.
本文的目的是介绍一种新型的容积CT，它采用锥束技术而非传统的扇束技术。该机器专门用于牙颌面成像，特别是在种植学领域的规划。结合技术参数和软件性能介绍了该设备的主要特性。所获得的图像以容积重建的各种二维截面形式呈现。此外，使用特定的体模获得了几何精度和患者吸收的辐射剂量的测量值。将吸收剂量与螺旋CT的剂量进行了比较。参照各种重建方式和不同的空间方向评估，宽度测量的几何精度为0.8 - 1%，高度测量的几何精度为2.2%。扫描过程中吸收的辐射剂量在中心轴和外周轴上呈现出不同的分布。关于中心分布的最大值，新设备的剂量约为传统螺旋CT剂量的六分之一。新系统在牙颌面成像方面似乎非常有前景，并且由于性能与低成本之间的良好比例，再加上低辐射剂量，鉴于CT技术在这种诊断应用中的大规模使用，非常具有吸引力。
