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目的 :通过测量长方形金属标志物的垂直和水平距离以及角度变化,评估体面断层片拍摄成像后的曲变失真情况。方法:由同一医师将大小为1.0 cm×0.6 cm的金属标志物置于115例患者面部的不同位置,分为2组记录,第1组将3个相同规格的金属标志物沿下颌骨下缘置于颏部、下颌前磨牙区、下颌磨牙区,均紧贴于下颌骨下缘。第2组将3个相同规格的金属片分别置于磨牙区牙根中1/3、前磨牙区牙根中1/3以及切牙区牙根中1/3,均靠近牙槽嵴顶。拍摄数字曲面体层X线片时由同一技师选用同一台机器进行拍摄。曲面体层X线片中的金属标志物的长度、宽度、垂直距离和近中角度(曲变度α)均由2名医师独立测量,每名医师间隔1周随机测量2次并记录数据,取均值作为最终测量结果。所有数据均利用Photoshop CS6软件测量。应用SPSS 23.0软件包对数据进行统计学分析。结果:全景片中,第2组(G2)标志点垂直距离的平均放大率约为105.6%,切牙区的放大率最大,前磨牙区次之,磨牙区最小。而第1组(G1)标志点垂直距离均缩小。相比垂直距离,无论是第1组还是第2组,水平距离均缩小。2组3个区域的角度均有变化,表明存在一定曲变。结论:数字曲面体层X线片不同部位的曲变情况不同。分析特定区域的曲变情况,需要参照相应的变形系数。临床医师根据数字全景片分析种植区的骨量或拔除阻生牙时,需要考虑全景片的这一特点。
OBJECTIVE: To evaluate the distortion of curved distortion after the radiographic imaging of the normal sectional slice by measuring the vertical and horizontal distances and angle changes of the rectangular metal markers. Methods: The same physician placed a metal marker of 1.0 cm × 0.6 cm in different positions on the face of 115 patients and divided them into two groups. In group 1, three metal markers with the same specifications were placed along the lower edge of the mandible In the chin, premolar mandibular area, mandibular molars, are close to the lower edge of the mandible. In the second group, three metal sheets with the same specifications were placed in 1/3 of the root area of the molar area, 1/3 of the root area of the premolar area and 1/3 of the root area of the incisal area, respectively, and were close to the crest of the alveolar ridge. When shooting digital surface tomography X-ray film by the same technician selected the same machine for shooting. The length, width, vertical distance and near-mid-angle (degree of curvature α) of the metal markers in the surface tomography were measured independently by two physicians. Each physician measured randomly twice a week and recorded the data. Take the average as the final measurement. All data is measured using Photoshop CS6 software. Data were statistically analyzed using SPSS 23.0 software package. Results: In the panoramic film, the average magnification of the vertical distance from the G2 group was about 105.6%. The magnification of the incisor area was the highest, followed by the premolar area and the molar area was the smallest. The first group (G1) mark vertical distance are reduced. Compared to the vertical distance, either the first group or the second group, the horizontal distance is reduced. The angles of the two groups of 3 regions all have changes, indicating that there is a certain curvature. CONCLUSION: Curvature changes in different parts of digital surface tomography are different. Analysis of the curvature of a particular area, the need to refer to the corresponding deformation coefficient. Clinicians based on digital panoramic film analysis of planting bone mass or removal of impacted teeth, the need to consider this feature panoramic.