Varshowsaz Masoud, Goorang Sepideh, Ehsani Sara, Azizi Zeynab, Rahimian Sepideh
Oral and Maxillofacial Radiologist, Tehran, Iran.
Assistant Professor of Oral and Maxillofacial Radiology, Oral and Maxillofacial Radiology Department, Shahed University of Medical Sciences, Dental School, Tehran, Iran.
J Dent (Tehran). 2016 Mar;13(2):108-115.
Bone quality and quantity assessment is one of the most important steps in implant treatment planning. Different methods such as computed tomography (CT) and recently suggested cone beam computed tomography (CBCT) with lower radiation dose and less time and cost are used for bone density assessment. This in vitro study aimed to compare the tissue density values in Hounsfield units (HUs) in CBCT and CT scans of different tissue phantoms with two different thicknesses, two different image acquisition settings and in three locations in the phantoms.
Four different tissue phantoms namely hard tissue, soft tissue, air and water were scanned by three different CBCT and a CT system in two thicknesses (full and half) and two image acquisition settings (high and low kVp and mA). The images were analyzed at three sites (middle, periphery and intermediate) using eFilm software. The difference in density values was analyzed by ANOVA and correction coefficient test (P<0.05).
There was a significant difference between density values in CBCT and CT scans in most situations, and CBCT values were not similar to CT values in any of the phantoms in different thicknesses and acquisition parameters or the three different sites. The correction coefficients confirmed the results.
CBCT is not reliable for tissue density assessment. The results were not affected by changes in thickness, acquisition parameters or locations.
骨质量和骨量评估是种植治疗计划中最重要的步骤之一。诸如计算机断层扫描（CT）以及最近提出的具有较低辐射剂量、更短时间和更低成本的锥形束计算机断层扫描（CBCT）等不同方法被用于骨密度评估。这项体外研究旨在比较不同厚度、两种不同图像采集设置以及模型三个位置处的不同组织模型在CBCT和CT扫描中以亨氏单位（HUs）表示的组织密度值。
使用三种不同的CBCT和一个CT系统对四种不同的组织模型（即硬组织、软组织、空气和水）进行扫描，扫描厚度为两种（全厚和半厚），图像采集设置为两种（高千伏峰值和毫安以及低千伏峰值和毫安）。使用eFilm软件在三个部位（中间、周边和中间位置）对图像进行分析。通过方差分析和校正系数检验分析密度值的差异（P<0.05）。
在大多数情况下，CBCT和CT扫描的密度值之间存在显著差异，并且在不同厚度、采集参数或三个不同部位的任何模型中，CBCT值均与CT值不相似。校正系数证实了这些结果。
CBCT用于组织密度评估不可靠。结果不受厚度、采集参数或位置变化的影响。
