Two examples of indication specific radiation dose calculations in dental CBCT and Multidetector CT scanners

PurposeTo calculate organ doses and estimate the effective dose for justification purposes in patients undergoing orthognathic treatment planning purposes and temporal bone imaging in dental cone beam CT (CBCT) and Multidetector CT (MDCT) scanners.MethodsThe radiation dose to the ICRP reference male voxel phantom was calculated for dedicated orthognathic treatment planning acquisitions via Monte Carlo simulations in two dental CBCT scanners, Promax 3D Max (Planmeca, FI) and NewTom VGi evo (QR s.r.l, IT) and in Somatom Definition Flash (Siemens, DE) MDCT scanner. For temporal bone imaging, radiation doses were calculated via MC simulations for a CBCT protocol in NewTom 5G (QR s.r.l, IT) and with the use of a software tool (CT-expo) for Somatom Force (Siemens, DE). All procedures had been optimized at the acceptance tests of the devices.ResultsFor orthognathic protocols, dental CBCT scanners deliver lower doses compared to MDCT scanners. The estimated effective dose (ED) was 0.32 mSv for a normal resolution operation mode in Promax 3D Max, 0.27 mSv in VGi-evo and 1.18 mSv in the Somatom Definition Flash. For temporal bone protocols, the Somatom Force resulted in an estimated ED of 0.28 mSv while for NewTom 5G the ED was 0.31 and 0.22 mSv for monolateral and bilateral imaging respectively.ConclusionsTwo clinical exams which are carried out with both a CBCT or a MDCT scanner were compared in terms of radiation dose. Dental CBCT scanners deliver lower doses for orthognathic patients whereas for temporal bone procedures the doses were similar.     

牙颌面畸形患者的人格特征分析

目的:通过明尼苏达多项人格测验评估牙颌面畸形患者术前的人格特征。方法:采用随机对照的方法,选取2012年5月~2013年5月在第四军医大学口腔医学院颅颌面创伤整形外科病区就诊的先天性牙颌面畸形患者102例,利用DXC-6型软件进行筛选,将其中64例纳入病例组;同时选取第四军医大学经过征兵心理测试且成绩合格的本科学员、八年制学员及硕/博士研究生83例,利用DXC-6型软件进行筛选,将其中57例纳入对照组。以问卷调查的方式对两组进行人格特征评估并比较其结果。结果:病例组MAS量表、Si量表评分与对照组比较存在显著性差异(P0.05),病例组显著高于对照组,两组其余各因素评分比较未见显著性差异(P0.05)。不同学历、年龄及性别的牙颌面畸形患者MAS量表和Si量表各项指标评分比较均无显著性差异(P0.05)。结论:牙颌面畸形患者存在对周围人反应过于敏感,缺乏自信等心理问题,可能与其异常面容有关,而与患者的学历、年龄及性别无关。     

偏突颌畸形患者手术前后面部软组织的三维测量研究

目的:探讨偏突颌畸形患者手术后面部软组织变化规律,明确其正侧面部对称性改变及各标志点变化范围,以指导手术方案设计。方法:收集于我科行正畸正颌联合治疗的15例偏突颌畸形患者,分别在正颌手术前后采集患者面部软组织三维扫描数据,建立统一坐标系,测量术前和术后软组织解剖标志点的坐标变化。统计分析不对称性系数及各标志点变化,比较术前术后数据。结果:患者手术前后面部对称性改变结果中,颏前点、颏顶点、颏下点、双侧鼻翼基点、双侧颊点的不对称系数比较差异有统计学意义(P0.05)。患者正面像中除上唇缘点外各选择标志点水平方向的坐标变化均有统计学意义(P0.05),且可见颏顶点、颏下点、双侧鼻翼基点呈显著变化(P0.001),说明其面下1/3对称性得到改善,各标志点纠偏程度也整体呈自上而下的逐渐增强的变化趋势。结论:正颌手术能够有效改善偏突颌畸形患者面部软组织的不对称性。     

An integrated haptic-enabled virtual reality system for orthognathic surgery planning

Conventional Orthognathic surgery (OGS) planning involves cephalometric analyses and dental casts to be mounted on an articulator. Dental segments are subsequently identified, cut and repositioned to allow the fabrication of intraoral wafers that guide the positioning of the osteotomy bone segments. This conventional planning introduces many inaccuracies that affect the post-surgery outcomes. Although computer technologies have advanced computational tools for OGS planning, they have failed in providing a practical solution. Many focuses only on some specific stages of the planning process, and their ability to transfer preoperative planning data to the operating room is limited. This paper proposes a new integrated haptic-enabled virtual reality (VR) system for OGS planning. The system incorporates CAD tools and haptics to facilitate a complete planning process and is able to automatically generate preoperative plans. A clinical pre-diagnosis is also provided automatically by the system based on the patient’s digital data. A functional evaluation based on a real patient case study demonstrates that the proposed virtual OGS planning method is feasible and more effective than the traditional approach at increasing the intuitiveness and reducing errors and planning times.