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41.
Petter Risholm Firdaus Janoos Isaiah Norton Alex J. Golby William M. Wells 《Medical image analysis》2013,17(5):538-555
In settings where high-level inferences are made based on registered image data, the registration uncertainty can contain important information. In this article, we propose a Bayesian non-rigid registration framework where conventional dissimilarity and regularization energies can be included in the likelihood and the prior distribution on deformations respectively through the use of Boltzmann’s distribution. The posterior distribution is characterized using Markov Chain Monte Carlo (MCMC) methods with the effect of the Boltzmann temperature hyper-parameters marginalized under broad uninformative hyper-prior distributions. The MCMC chain permits estimation of the most likely deformation as well as the associated uncertainty. On synthetic examples, we demonstrate the ability of the method to identify the maximum a posteriori estimate and the associated posterior uncertainty, and demonstrate that the posterior distribution can be non-Gaussian. Additionally, results from registering clinical data acquired during neurosurgery for resection of brain tumor are provided; we compare the method to single transformation results from a deterministic optimizer and introduce methods that summarize the high-dimensional uncertainty. At the site of resection, the registration uncertainty increases and the marginal distribution on deformations is shown to be multi-modal. 相似文献
42.
Thomas Hampshire Holger R. Roth Emma Helbren Andrew Plumb Darren Boone Greg Slabaugh Steve Halligan David J. Hawkes 《Medical image analysis》2013,17(8):946-958
Computed Tomographic (CT) colonography is a technique used for the detection of bowel cancer or potentially precancerous polyps. The procedure is performed routinely with the patient both prone and supine to differentiate fixed colonic pathology from mobile faecal residue. Matching corresponding locations is difficult and time consuming for radiologists due to colonic deformations that occur during patient repositioning.We propose a novel method to establish correspondence between the two acquisitions automatically. The problem is first simplified by detecting haustral folds using a graph cut method applied to a curvature-based metric applied to a surface mesh generated from segmentation of the colonic lumen. A virtual camera is used to create a set of images that provide a metric for matching pairs of folds between the prone and supine acquisitions. Image patches are generated at the fold positions using depth map renderings of the endoluminal surface and optimised by performing a virtual camera registration over a restricted set of degrees of freedom. The intensity difference between image pairs, along with additional neighbourhood information to enforce geometric constraints over a 2D parameterisation of the 3D space, are used as unary and pair-wise costs respectively, and included in a Markov Random Field (MRF) model to estimate the maximum a posteriori fold labelling assignment.The method achieved fold matching accuracy of 96.0% and 96.1% in patient cases with and without local colonic collapse. Moreover, it improved upon an existing surface-based registration algorithm by providing an initialisation. The set of landmark correspondences is used to non-rigidly transform a 2D source image derived from a conformal mapping process on the 3D endoluminal surface mesh. This achieves full surface correspondence between prone and supine views and can be further refined with an intensity based registration showing a statistically significant improvement (p < 0.001), and decreasing mean error from 11.9 mm to 6.0 mm measured at 1743 reference points from 17 CTC datasets. 相似文献
43.
F. Lekkerkerker J. A. Kanis N. Alsayed G. Bouvenot N. Burlet D. Cahall A. Chines P. Delmas R.-L. Dreiser D. Ethgen N. Hughes J.-M. Kaufman S. Korte G. Kreutz A. Laslop B. Mitlak V. Rabenda R. Rizzoli A. Santora R. Schimmer Y. Tsouderos P. Viethel J.-Y. Reginster 《Osteoporosis international》2007,18(10):1311-1317
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目的:分析CT、MRI圆孔、卵圆孔及棘孔的显像及特征表现,探讨CT、MRI显示的圆孔、卵圆孔及棘孔在鼻咽癌放射治疗靶区勾画的意义。材料和方法:20例未经治疗的无脑神经侵犯鼻咽癌患者行CT、MRI扫描,在Pinnacle37.0工作站上采用互信息法配准后分析、评价圆孔、卵圆孔及棘孔在CT、MRI图像上显示特点。结果:在CT骨窗上圆孔显示为低密度的管状结构,卵圆孔及棘孔显示为低密度的孔状结构。7例(35%)圆孔在CT上为双侧显示,5例(25%)为单侧显示,8例(40%)未见显示。全部患者卵圆孔、棘孔在CT上均为双侧显示,卵圆孔两侧对称者13例(65%),不对称者7例(35%)。卵圆孔呈圆形8侧(20%),呈椭圆形32侧(80%)。棘孔两侧对称3例(15%),两侧不对称者17例(85%)。全部病例圆孔在MRI各个序列上均未见显示,卵圆孔及棘孔在T1WI、T2WI上均未见显示,在增强T1WI上表现为高信号血管影。全部患者卵圆孔及棘孔在增强T1WI上为双侧显示,卵圆孔两侧对称13例(65%),两侧不对称7例(35%);呈圆形8侧(20%),呈椭圆形32侧(80%)。增强CT未见圆孔、卵圆孔及棘孔内血管显示。结论:在MRI上对圆孔的识别还有很大困难,但是MRI可以显示正常卵圆孔及棘孔,为今后直接在MRI勾画鼻咽癌靶区(卵圆孔)制定放疗计划提供了影像解剖及靶区确定的依据。R 相似文献
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目的:为完善中国执业药师注册和考试提供参:等。方法:通过对新西兰药学会(PCNZ)和新西兰药师协会(PSNZ)等网站相关内容的翻译整理,以及国内外相关文献的查阅进行综合分析,并提出完善中国执业药师注册和考试的建议。结果与结论:新西兰的执业药师注册和考试有章可循,药师作用得以体现,其实习药师模式、考试形式和内容以及能力审查这三点特别值得学习。建议中国药师应以针对性的实习为基础,加强实习药师的监督和考核,确保实习经验的获取;考试形式多样化,注重考查药师的药学服务能力,考试内容中增加临床及医学等内容;建立患者申诉机制,增加能力审查来确保药师执业过程中的服务质量,提升药师业务水平。 相似文献
48.
目的为保障医疗安全,防范护患纠纷,分析患者应用贵重药品中存在的主要缺陷,探讨一种提高贵重药品管理的有效方法。方法通过对2011年1月~2012年7月我科收治的患者中凡使用贵重药品的均在贵重药品登记本上记录,护士执行后并由家属确认使用后方可签字,并加以规范管理,使用此管理方法后和对照组(2011年前)进行对照分析。结果观察组患者满意度调查达到98%以上,护患纠纷发生率与实施前相比明显降低,差异有显著性意义(P<0.01)。结论采取针对性的防范措施,持续抓好护理环节质量控制,建立贵重药品登记本能赢得患者及家属的信赖,提高患者满意度,构建和谐护患关系,避免护患纠纷,确保医疗安全。 相似文献
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W. Zhou S. Fan F. Wang W. Huang F.Z. Jamjoom Y. Wu 《International journal of oral and maxillofacial surgery》2021,50(1):116-120
Zygomatic implants (ZIs) are used for the oral rehabilitation of patients with maxillectomy defects as an alternative to extensive bone grafting surgeries. New technologies such as computer-assisted navigation systems can improve the accuracy and safety of ZI placement. The intraoral anchorage of fiducial markers necessary for navigation registration is not possible in the case of a severe maxillary defect and lack of residual bone. This technical note presents a novel extraoral registration method for a dynamic navigation system guiding ZI placement in patients with maxillectomy defects. Titanium microscrews were inserted in the mastoid process, supraorbital ridge, and posterior zygomatic arch as registration markers. The mean fiducial registration error (FRE) was 0.53 ± 0.20 and the deviations between the planned and placed ZIs were 1.56 ± 0.54 mm (entry point), 1.87 ± 0.63 mm (exit point), and 2.52 ± 0.84° (angulation). The study results indicate that the placement of fiducial markers at extraoral sites can be used as a registration technique to overcome anatomical limitations in patients after maxillectomy, with a clinically acceptable registration accuracy. 相似文献