计算机辅助设计在耳模制作中的应用

目的 建立一种更为高效安全的三维耳模制作方法.方法 耳背式助听器使用时,需配上按患者耳朵外形制作的耳膜.利用MIMICS医学影像三维重建软件和Solidworks三维建模软件对患者耳部CT图像进行处理,建立耳模实体模型.结果 与传统方法制作的耳模相比,计算机辅助设计制作的耳模更加符合人体结构.结论 计算机辅助设计制作方法可更加安全、方便、快捷地制作耳模.     

基于3D打印的胸部个体化剂量验证体模设计

目的:为更精确地对治疗计划进行验证,利用3D打印设计出反映患者真实情况的个体化体模。方法:依据病人定位时的CT图像重建并进行3D打印得到患者的三维立体结构空壳,然后以CT值为依据选择各组织的辐射等效材料完成填充,即得到体现病人特征的个体化剂量验证体模。结果:将合成的等效材料行CT扫描,骨组织、肺组织、软组织、肿瘤CT值分别为1 100、-747.6、-22、-471 HU,误差均小于22%。结论:最终设计的胸部体模能够较准确地体现个体之间的差异,等效材料辐射等效性较好,可用于实际剂量验证。     

计算机在中心血站质量管理中的应用

我院中心血站是国家卫生部和总后卫生部联合批准的“军内甲类采供血职能医院”。作为一个集血源管理、血液检测、采集、生产及供血为一体的中心血站 ,抓好输血管理 ,加强血液及其制品的质量控制是至关重要的。我院应用计算机对输血工作进行全方位管理 ,加大了血液生产过程中的监控力度 ,提高了医院输血管理水平     

基于体模的DSA类CT图像质量研究

目的 在血管造影（DSA）设备上,通过对等效性能的人体仿真体模进行类CT成像,分析DSA中的类CT的图像质量,为DSA设备中类CT图像质量评估提供基础。方法 分别在配置相同的西门子dTA DSA设备上和飞利浦FD20 DSA设备上,利用仿真头颅体模Kyoto Kagaku PBU-60和自制小孔体模进行类CT成像,对采集到的数据进行低对比度、空间均匀性等分析,并进行体模一致性分析。结果 这2台设备均能清晰地呈现头模内部血管结构、走行,以及相应的组织结构等信息,对于自制的体模2台设备的低对比度均为0.2 %,场均匀性2.624 07 Hu 和2.489 75 Hu。结论 这2台设备的类CT图像质量指标,包括噪声、低对比度、场均匀性等均符合检测要求,对DSA设备的类CT图像质量控制工作的开展具有一定的实际意义。     

基于仿真头颈模体研究处方等剂量线对射波刀计划质量的影响

【摘 要】 目的:基于仿真头颈模体研究不同处方等剂量线的选取对射波刀计划质量的影响。 方法:以仿真头颈模体中球方中心球体作为靶区,体积为16.9 cc,设置4个剂量限值壳层分别距离靶区表面2、20、40、60 mm,其中最内层的剂量限值为主要优化参数,通过改变其限值参数,在靶区处方覆盖率接近100%的情况下获得不同处方等剂量线计划。 结果:分别获得39%、44%、49%、57%、61%和65%处方等剂量线计划,其中49%处方等剂量线计划的剂量梯度指数、适形度指数、V5、V9、V12参数相对于其它计划各参数的最大值分别降低了17.5%、9.8%、12.9%、16.1%、21.3%,但49%处方等剂量线计划具有最多的射束数和最长的计划时间。 结论:基于仿真头颈模体的射波刀计划研究表明,颅内肿瘤计划的处方等剂量线选择须综合考虑多种因素。提高肿瘤照射剂量并减小正常脑组织照射体积有利于提高肿瘤控制率并降低放射性损伤,但与此同时增加的治疗时间要求患者具有更强的耐受性。     

应用动态双平面成像技术研究在体肘关节主动屈伸运动特征

目的 探讨健康肘关节屈伸运动时关节的相对位移和旋转角度变化,为肘关节不稳以及严重肘关节损伤的治疗提供参考。方法 选取10名健康并且无上肢外伤史的受试者。应用动态双平面X线透视成像系统,测量右侧肘关节从旋后最大伸直位至旋后最大屈曲位运动过程中,肱桡与肱尺关节6自由度运动学数据。使用相关性分析评价肘关节不同自由度运动的耦合度。结果 从最大伸直位到最大屈曲位,肱尺关节外翻角从15.2°±3.1°降低到5.3°±2.3°,肱桡关节外翻角从19.7°±4.2°减小到8.2°±2.4°, 肱尺与肱桡关节外翻角与屈曲角呈线性相关;肱尺关节内外旋角先内旋后外旋,呈二次非线性相关,在屈曲110°时达到最大内旋值（4.0°±4.9°）,后达到最大外旋值（5.1°±4.2°）;肱桡关节一直呈内旋增大变化,从内旋3.2°±16.0°增加到内旋27.2°±18.0°。结论 在正常肘关节屈伸过程中,肱尺关节存在外翻角线性减小、内外旋角先内旋后外旋的非线性变化,肱桡关节存在外翻角线性减小、内旋角线性增大的变化。在屈伸过程中,肘关节并非单纯铰链关节,并且肱尺、肱桡关节存在运动学差异。临床上治疗复杂肘关节损伤、肘关节不稳以及肘关节置换手术时,应考虑关节间不同运动特征,以提高术后临床效果。     

虚拟心脏仿真研究进展及其在临床中的应用

虚拟心脏就是利用计算机来模拟心脏的生理结构及功能,对心血管疾病的研究有重要意义。目前在心脏的各种仿真研究中,不同学科的研究小组所用的计算机模型相差较大,尚无统一的跨学科研究平台。本文从微观层次和宏观层次综述了虚拟心脏在功能性建模方面的研究进展,并对心脏疾病的模拟仿真以及虚拟心脏在临床上的应用进行了综述。最后,简要地分析了虚拟心脏建模在临床应用中的优势,并对虚拟心脏发展方向进行了展望。虚拟心脏可以定量分析所有对心脏疾病诊断和治疗极为有价值的生理信息,从而系统地揭示心脏内部运行的机制,它是现代医学科学发展的重要方向。     

质量控制和管理在计算机X线摄影(CR)中的作用

计算机X线摄影系统与传统的X线照片相比，曝光量仅在传统X线摄影的1／2以下。其成像质量、宽容度、信息量都优于传统X线照片，且所得信息可按诊断要求处理，为X线影像长期保存和检索提供了可能性。现就CR系统的质量控制进行探讨。     

Application of dynamic computed tomography for measurements of local aortic elastic modulus

A novel computed tomographic (CT) technique used for the instantaneous measurement of the dynamic elastic modulus of intact excised porcine aortic vessels subjected to physiological pressure waveforms is described. This system was comprised of a high resolution X-ray image intensifier based computed tomographic system with limiting spatial resolution of 3.2mm⁻¹ (for a 40mm field of view) and a computer-controlled flow simulator. Utilising cardiac gating and computer control, a time-resolved sequence of 1 mm thick axial tomographic slices was obtained for porcine aortic specimens during one simulated cardiac cycle. With an image acquisition sampling interval of 16.5 ms, the time sequences of CT slices were able to quantify the expansion and contraction of the aortic wall during each phase of the cardiac cycle. Through superficial tagging of the adventitial surface of the specimens with wire markers, measurement of wall strain in specific circumferential sectors and subsequent calculations of localised dynamic elastic modulus were possible. The precision of circumferential measurements made from the CT images utilising a cluster-growing segmentation technique was approximately ±0.25mm and allowed determination of the dynamic elastic modulus (E_dyn) with a precision of ±8kPa. Dynamic elastic modulus was resolved as a function of the harmonics of the physiological pressure waveform and as a function of the angular position around the vessel circumference. Application of this dynamic CT (DCT) technique to seven porcine thoracic aortic specimens produced a circumferential average (over all frequency components) E_dyn of 373±29kPa. This value was not statistically different (p<0.05) from the values of 430±77 and 390±47kPa obtained by uniaxial tensile testing and volumetric measurements respectively.     

The association between wedging of the aorta and cardiac structural anatomy as revealed using multidetector‐row computed tomography

The aortic root is wedged within the cardiac base. The precise extent of aortic wedging, however, and its influence on the surrounding cardiac structures, has not been systematically investigated. We analysed 100 consecutive patients, who underwent coronary arterial computed tomographic angiography. We assessed the extent of aortic wedging by measuring the vertical distance between the non‐adjacent aortic sinus and the inferior epicardium. A shorter distance indicates deeper aortic wedging. We assessed the tilt angle and diameter of the ascending aorta, the relative heights of the left atrial roof and the oval fossa, the shape of the proximal right coronary artery, the angle of the aorta relative to the left ventricular axis, and the lung volume. The mean extent of wedging was 42.7 ± 9.8 mm. Multivariate analysis revealed that ageing, male gender, increased body mass index, patients without cardiomyopathy, the extent of tilting and dilation of the ascending aorta, and lung volume were all independent predictors for deeper aortic wedging (R² = 0.7400, P < 0.0001). The extent of wedging was additionally correlated with a relatively high left atrial roof (R² = 0.1394, P < 0.0001) and oval fossa (R² = 0.1713, P < 0.0001), the shepherd's crook shape of the proximal right coronary artery (R² = 0.2376, P < 0.0001), and the narrowness of the angulation of the root relative to the left ventricular axis (R² = 0.2544, P < 0.0001). In conclusion, ageing, male gender, obesity, background cardiac disease, aortic tilting and dilation, and lung volume are all correlated with the extent of wedging of the aortic root within the cardiac base.     

Accuracy of high-resolution peripheral quantitative computed tomography for measurement of bone quality

The introduction of three-dimensional high-resolution peripheral in vivo quantitative computed tomography (HR-pQCT) (XtremeCT, Scanco Medical, Switzerland; voxel size 82 μm) provides a new approach to monitor micro-architectural bone changes longitudinally. The accuracy of HR-pQCT for three important determinants of bone quality, including bone mineral density (BMD), architectural measurements and bone mechanics, was determined through a comparison with micro-computed tomography (μCT) and dual energy X-ray absorptiometry (DXA). Forty measurements from 10 cadaver radii with low bone mass were scanned using the three modalities, and image registration was used for 3D data to ensure identical regions were analyzed.

The areal BMD of DXA correlated well with volumetric BMD by HR-pQCT despite differences in dimensionality (R² = 0.69), and the correlation improved when non-dimensional bone mineral content was assessed (R² = 0.80). Morphological parameters measured by HR-pQCT in a standard patient analysis, including bone volume ratio, trabecular number, derived trabecular thickness, derived trabecular separation, and cortical thickness correlated well with μCT measures (R² = 0.59–0.96). Additionally, some non-metric parameters such as connectivity density (R² = 0.90) performed well. The mechanical stiffness assessed by finite element analysis of HR-pQCT images was generally higher than for μCT data due to resolution differences, and correlated well at the continuum level (R² = 0.73).

The validation here of HR-pQCT against gold-standards μCT and DXA provides insight into the accuracy of the system, and suggests that in addition to the standard patient protocol, additional indices of bone quality including connectivity density and mechanical stiffness may be appropriate to include as part of a standard patient analysis for clinical monitoring of bone quality.     

儿童胰腺实性假乳头状瘤多排螺旋CT表现

目的:探讨儿童胰腺实性假乳头状瘤（SPTP）的多排螺旋CT（MDCT）表现。 方法:回顾性分析经手术病理证实为SPTP的10例患儿临床及MDCT资料,分析总结其特征表现。 结果:10例患儿均为女性,SPTP均为单发病灶,位于胰腺头颈部3例,胰腺体尾部7例。肿瘤最大径为2.5~13.8 cm,平均值为5.94 cm。8例呈类圆形,2例呈分叶状。10例均边界清晰,8例有完整包膜。平扫1例肿瘤呈均匀低密度,增强无明显强化;其余9例呈囊实性,8例以实性为主,1例囊实性比例相当,其中1例可见包膜下弧形钙化,实性成分动脉期呈轻度强化,强化程度低于正常胰腺组织,门脉期呈渐进性不均匀强化,囊性成分无强化。1例肿瘤出现肝内胆管和主胰管轻度扩张,1例出现主胰管轻度扩张。所有肿瘤均未见肝脏及淋巴结转移。 结论:儿童SPTP好发于女性,其CT表现具有一定的特征性,对诊断和鉴别诊断具有一定意义。     

High-resolution in vivo imaging of the cross-sectional deformations of contracting embryonic heart loops using optical coherence tomography.

The embryonic heart tube consists of an outer myocardial tube, a middle layer of cardiac jelly, and an inner endocardial tube. It is said that tubular hearts pump the blood by peristaltoid contractions. The traditional concept of cardiac peristalsis sees the cyclic deformations of pulsating heart tubes as concentric narrowing and widening of tubes of circular cross-section. We have visualized the cross-sectional deformations of contracting embryonic hearts in chick embryos (HH-stages 9-17) using real-time high-resolution optical coherence tomography. Cardiac contractions are detected from HH-stage 10 onward. During the cardiac cycle, the myocardial tube undergoes concentric narrowing and widening while the endocardial tube undergoes eccentric narrowing and widening, having an elliptic cross-section at end-diastole and a slit-shaped cross-section at end-systole. The eccentric deformation of the endocardial tube is the consequence of an uneven distribution of the cardiac jelly. Our data show that the cyclic deformations of pulsating embryonic heart tubes run other than originally thought. There is evidence that heart tubes of elliptic cross-section might pump blood with a higher mechanical efficiency than those of circular-cross section. The uneven distribution of cardiac jelly seems to prefigure the future AV and cono-truncal endocardial cushions.     

Quantitative analysis of microscopic X‐ray computed tomography imaging: Japanese quail embryonic soft tissues with iodine staining

Rapid three‐dimensional imaging of embryos to better understand the complex process of morphogenesis has been challenging. Recently introduced iodine staining protocols (I₂KI and alcoholic iodine stains) combined with microscopic X‐ray computed tomography allows visualization of soft tissues in diverse small organisms and tissue specimens. I₂KI protocols have been developed specifically for small animals, with a limited number of quantitative studies of soft tissue contrasts. To take full advantage of the low X‐ray attenuation of ethanol and retain bound iodine while dehydrating the specimen in ethanol, we developed an ethanol I₂KI protocol. We present comparative microscopic X‐ray computed tomography analyses of ethanol I₂KI and I₂KI staining protocols to assess the performance of this new protocol to visualize soft tissue anatomy in late stage Japanese quail embryos using quantitative measurements of soft tissue contrasts and sample shrinkage. Both protocols had only 5% shrinkage compared with the original harvested specimen, supporting the use of whole mounts to minimize tissue shrinkage effects. Discrimination within and among the selected organs with each staining protocol and microscopic X‐ray computed tomography imaging were comparable to those of a gray scale histological section. Tissue discrimination was assessed using calibrated computed tomography values and a new discrimination index to quantify the degree of computed tomography value overlaps between selected soft tissue regions. Tissue contrasts were dependent on the depth of the tissue within the embryos before the embryos were saturated with each stain solution, and optimal stain saturations for the entire embryo were achieved at 14 and 28 days staining for I₂KI and ethanol I₂KI, respectively. Ethanol I₂KI provided superior soft tissue contrasts by reducing overstaining of fluid‐filled spaces and differentially modulating staining of some tissues, such as bronchial and esophageal walls and spinal cord. Delineating the selected soft tissues using optimal threshold ranges derived from the quantitative analyses of the contrast enhancement in optimally stained embryos is possible. The protocols presented here are expected to be applicable to other organisms with modifications to staining time and contribute toward rapid and more efficient segmentation of soft tissues for three‐dimensional visualization.     

High-resolution simulation of B0 field conditions in the human heart from segmented computed tomography images

B₀ inhomogeneity leads to imaging artifacts in cardiac magnetic resonance imaging (MRI), in particular dark band artifacts with steady-state free precession pulse sequences. The limited spatial resolution of MR-derived in vivo B₀ maps and the lack of population data prevent systematic analysis of the problem at hand and the development of optimized B₀ shim strategies. We used readily available clinical computed tomography (CT) images to simulate the B₀ conditions in the human heart at high spatial resolution. Calculated B₀ fields showed consistency with MRI-based B₀ measurements. The B₀ maps for both the simulations and in vivo measurements showed local field inhomogeneities in the vicinity of lung tips with dominant Z3 spherical harmonic terms in the field distribution. The presented simulation approach allows for the derivation of B₀ field conditions at high spatial resolution from CT images and enables the development of subject- and population-specific B₀ shim strategies for the human heart.     

术中光子立体定向放射治疗的质量保证和质量控制

【摘要】目的:从术中光子立体定向放疗设备物理剂量学方面,总结和分析术中放疗质量保证的内容和方法以及术中放疗实际应用中的注意事项,保证术中放疗物理剂量准确性,旨在建立该系统的日常质量保证程序。方法:利用蔡司公司提供的水箱、剂量仪、电离室等,测量术中立体定向放射外科系统的临床运用数据。监测内容主要包括剂量线性、稳定性、均匀性、射线几何聚焦的位置、绝对剂量标定以及在水模体的衰减等。结果:术中光子立体定向放疗仪产生50 kV低能射线。剂量线性、均匀性良好,短期稳定性也在临床接受的误差范围以内,36 h内剂量误差小于1%。对比24个月的剂量测量值,其误差达到-4.5%。结论:该设备稳定性良好,各检测指标均在临床要求精度范围以内。通过测量了解了卡尔蔡司公司的INTRABEAM术中放射治疗设备临床应用特性,获得了临床使用数据,为临床提供了质量保证方法。