Evaluation of Bony Anatomy Versus Endobiliary Stents as Surrogates for Volumetric Image Guidance in Pancreatic Cancer

PurposeOnline treatment setup verification through cone-beam computed tomography (CBCT) in pancreatic cancer patients is limited by low soft tissue contrast. This study aims to quantify the relative positional displacements between bony anatomy and endobiliary stents as surrogates for pancreatic cancers.MethodsUnder ethics approval, 258 localization CBCT images from 15 pancreatic patients with endobiliary stents were evaluated. CBCTs were registered through two methods to assess translations and rotations: target adjacent bony anatomy through automatic registration and automatic stent registration through a shaped region of interest. Displacement vector differences between surrogate registrations were calculated and analysed.ResultsMean (±standard deviation) translational displacements in the right/left, superior/inferior, anterior/posterior directions were 0.9 ± 3.1 mm, 1.8 ± 4.2 mm, and 0.4 ± 2.5 mm for bone registrations, respectively, and 0.9 ± 5.6 mm, −1.5 ± 5.7 mm, and −0.5 ± 4.3 mm for stent registrations, respectively. Mean (±standard deviation) rotational displacements for pitch, roll, and yaw were 0.16 ± 0.97°, −0.32 ± 0.96°, and −0.77 ± 1.8° for bone registrations, respectively, and −0.94 ± 4.6°, −0.4 ± 7.4°, and −0.13 ± 6.64° for stent registrations, respectively. Mean displacement vector between surrogates was 4 mm, with 43% of fractions measuring displacement vectors >5 mm. A maximum displacement vector of 22.6 mm between surrogates was observed.ConclusionsVarying positional differences were observed between bone and stent registration for pancreas CBCT–image-guided radiation therapy. Setup errors for stent matching were larger than bone registrations. Further research is required to determine if endobiliary stent position is equivalent to the pancreas' location to determine its suitability as a surrogate.     

Image-guided Adaptive Radiotherapy for Bladder Cancer

Technological advancement has facilitated patient-specific radiotherapy in bladder cancer. This has been made possible by developments in image-guided radiotherapy (IGRT). Particularly transformative has been the integration of volumetric imaging into the workflow. The ability to visualise the bladder target using cone beam computed tomography and magnetic resonance imaging initially assisted with determining the magnitude of inter- and intra-fraction target change. It has led to greater confidence in ascertaining true anatomy at each fraction. The increased certainty of dose delivered to the bladder has permitted the safe reduction of planning target volume margins. IGRT has therefore improved target coverage with a reduction in integral dose to the surrounding tissue. Use of IGRT to feed back into plan and dose delivery optimisation according to the anatomy of the day has enabled adaptive radiotherapy bladder solutions. Here we undertake a review of the stepwise developments underpinning IGRT and adaptive radiotherapy strategies for external beam bladder cancer radiotherapy. We present the evidence in accordance with the framework for systematic clinical evaluation of technical innovations in radiation oncology (R-IDEAL).     

Influence of skeletal class in the morphology of cervical vertebrae: A study using cone beam computed tomography

Objectives:To quantify the prevalence of cervical vertebrae anomalies and to analyze any association between them and skeletal malocclusions or head posture positions in the same study.Materials and Methods:Two hundred forty patients who were attending the Department of Orthodontics of the University of Valencia for orthodontic treatment were selected and divided into three groups: skeletal Class I (control group, 0° <ANB < 4°), Class II (ANB ≥ 4°), and Class III (ANB ≤ 0°) according to ANB Steiner angle. The morphology of the first five cervical vertebrae was analyzed with cone beam computed tomography to identify any anomalies. Intra- and interobserver error methods were calculated.Results:Dehiscence and fusion of one unit (both 23.3%) and partial cleft (11.7%) were the most frequent anomalies, while occipitalization was the least common (3.3%). Dehiscence anomaly was observed when the control group was compared with Classes II and III and partial cleft anomaly when Class I was compared with Class III. Furthermore, NSBa and ss-N-sm/ANB angles were associated with partial cleft anomaly, while NSL/NL angle and extended head posture were associated with fusion anomaly.Conclusions:Fusion, dehiscence, and partial cleft were the most frequent cervical vertebrae anomalies. Dehiscence and partial cleft were found to present statistically significant differences between Class I and Classes II and III. Cervical vertebrae anomalies and head posture were associated with fusion.     

Sleep and airway assessment: A review for dentists

Introduction: Dentists can be the first professionals to recognize a patient’s potential sleep problem since they typically have more frequent contact with their patients than do physicians. It is important that dentists have a reasonable understanding of sleep disorders and how to assess their patients if they suspect such a problem so that a timely referral can be made or treatment can be provided as appropriate.

Objective: To review the key literature relevant to sleep-disordered breathing (SDB) characteristics and diagnosis, including history, examination, and investigation with an emphasis on radiographic airway analyses.

Conclusion: The authors present a concise explanation of SDB conditions and an outline for thorough patient examination and evaluation, including radiographic airway analyses. Limited two-dimensional and three-dimensional norms exist for adult patients with no SDB and even less so for children. Much more research is needed, particularly in the pediatric population.     

Herbst双期拔牙矫治对颞下颌关节位置影响的CBCT研究

目的:探讨Herbst双期拔牙矫治对颞下颌关节位置关系的影响.方法:纳入15例恒牙列早期安氏Ⅱ类错(牙合)下颌后缩患者,一期矫治采用Herbst矫治器,然后拔除每位患者的4个前磨牙;二期矫治采用edgewise固定矫治器.在Herbst矫治器矫治前两周(T1期)、Herbst矫治器初戴入矫治时(T2期)、Herbst矫治器拆除时(T3期)及二期固定矫治器拆除时(T4期)分别拍摄锥形束CT(cone beam computed tomography,CBCT).应用InvivoDental软件对CBCT图像进行三维重建,再对颞下颌关节间隙进行测量,并进行统计分析.结果:T1-T2-T3期,关节前间隙先减小后增大,关节上间隙、关节后间隙先增大后减小;T3-T4期,关节上、后间隙进一步减小,关节前间隙无明显变化;与T1期比,T4各关节间隙的变化均无明显差异.结论:髁突在关节窝中的位置在Herbst矫治开始时向前下移位,一期功能矫治结束时尤其双期矫治结束时几乎回到了治疗前的位置.     

基于CBCT对汉族人下颌第一恒磨牙髓室高度及牙本质厚度与年龄关系的研究

目的:应用CBCT研究汉族人下颌第一恒磨牙髓室高度和牙本质厚度与年龄的关系.方法:收集汉族受试者420 例(男、女各210 例)下颌第一磨牙CBCT影像资料,分6 组(15~24 岁、25~34 岁、35~44 岁、45~54 岁、55~64 岁、65~74岁).运用CBCT自带软件测量牙齿中轴线上髓室的高度和牙本质厚度,进行统计学分析.结果:髓室高度:男性(0.85±0.54) mm、女性(0.79±0.51) mm;髓室顶牙本质厚度:男性(3.60±0.49) mm,女性(3.50±0.49) mm;髓室底牙本质厚度:男性(2.57±0.52) mm,女性(2.49±0.51) mm,随年龄增长髓室高度减小,牙本质厚度增加,与年龄有相关关系(P<0.05),髓室底牙本质厚度增大速率明显高于髓室顶(P<0.05),性别间均无统计学差异(P>0.05).结论:随年龄增长汉族人下颌第一磨牙髓室高度减小,牙本质厚度增大,髓室底牙本质厚度增加较髓室顶更明显.     

上颌第三磨牙根管形态的CBCT研究

目的：应用锥形束CT（cone?beam computed tomography ,CBCT）技术研究上颌第三磨牙的根管形态,为临床治疗提供解剖学依据。方法随机调取397颗上颌第三磨牙的CBCT资料,分析上颌第三磨牙的牙根数目、根管数目、根管分类等。结果397颗上颌第三磨牙中,三根牙最多,占43.07%;融合根牙次之,占40.30%。分析根管数目显示,三根管最多,占47.86%;单根管次之,占28.21%。根据Vertucci根管分类,89.6%的牙根以Ⅰ型根管为主,但仍会出现根管治疗时较难操作的Ⅱ型、Ⅲ型、Ⅴ型、其他型等根管。结论上颌第三磨牙根管解剖形态多样,根管系统复杂、变异大。     

Canal transportation caused by one single-file and two multiple-file rotary systems: A comparative study using cone-beam computed tomography

Aim

This ex-vivo study aimed to compare canal transportation in mesio-buccal canal of mandibular first molars prepared with Mtwo and Revo-S multi-file and Neoniti single-file nickel–titanium (Ni–Ti) rotary systems using cone-beam computed tomography (CBCT).

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??Objective??To propose a new panoramic tomographic predictor of maxillary impact canines by the analysis of the sector of crown and root??the inclination of the dental axis and the teeth length of the maxillary impacted canines on panoramic tomographs and by comparing the position of maxillary impact canines with that on cone-beam computed tomographys??CBCT??. Methods??Collect the general datas of 135 patients who had unilateral impacted maxillary canines. A total of 135 maxillary impacted canines were included as the experimental group??the 135 non-impacted canines on the opposite side in the same patients were as the control group. ??1??The NNT Viewer software and Planmeca Dimaxis Pro software were used to measure the cone-beam computed tomographys and panoramic tomographs respectively. The mesial and distal position of the maxillary impacted canine in the panoramic tomographs was divided into 5 sectors???? ~ ?? sector????the position of labiopalatal side was determined by CBCT??and the relationship between them was analyzed. ??2??The difference between the mesial and distal position distribution of crown and root??the inclination of the dental axis and the teeth length of the teeth of the experimental group and the control group was measured and analyzed in the panoramic tomographs. Results????1??The labiopalatal distribution of the maxillary impacted canines was significantly different between sexes??χ2 = 13.542??P = 0.001??. A statistically significant association was observed between the labiopalatal positions in the cone-beam computed tomographys and the root sectors in panoramic tomographs of the impacted canines ??r = 0. 225??P = 0.009????but not the crown sectors??r = 0.001??P = 0.991??.??2??There are differences in the distribution of the mesial and distal positions of the crown and root between the two groups??χ2 = 219.263??68.447??both P < 0.001??. The maxillary impacted canine of the experimental group was shorter than that of the control group??and the dental axis was more inclined??P < 0.05??. Conclusion??The labiopalatal position can be predicted by the location of the mesial and distal position of the maxillary impacted canine root in the panoramic tomographs. The sector of root and the tooth length can be used to predict the probability of maxillary impacted canines.