人颅面骨三维有限元模型的建立

目的利用计算机辅助技术,建立颅面骨三维有限元模型,为颌面部火器伤的生物力学分析奠定基础。方法通过薄层螺旋CT扫描正常志愿者颌面部,将获得的颅面骨数据通过Mimics软件进行三维实体重建,利用ANSA软件进行布尔运算,生成颅面骨骼,进行网格划分。结果建立了上颌骨、下颌骨等颅面骨三维有限元模型。结论利用薄层CT,结合Mimics、ANSA软件建立的颅面骨有限元模型真实准确,建立方法实用,可根据枪弹伤情况进行不同的生物力学分析。     

基于CAD技术的个体化下颌骨正交各向异性有限元模型的建立

目的 建立个体化下颌骨正交各向异性三维有限元模型.方法 利用CT薄层扫描下颌骨获取的断层图像数据,在自主开发的USIS软件的基础上,自动分辨骨皮质和骨松质轮廓边界,并对下颌骨采用"非种子区域分割"、非平行"最佳切割曲面"及"B样条曲线拟合法"一系列新型CAD方法进行人机对话自动重建精确的几何表面模型.定义结构材料参数后划分网格,并导入有限元计算软件ANSYS9.0中完成三维有限元建模.结果 建立了结构精确的个体化下颌骨正交各向异性的三维有限元模型.结论 基于CT数据和USIS软件的新型CAD方法实现了个体化下颌骨正交各向异性三维有限元模型的建立.     

Dicom标准和Mimics软件辅助建立下颌骨三维有限元模型

目的：寻求一种更为快捷、精确的下颌骨三维有限元模型建立方法.方法：应用薄层CT,Dicom标准和Mimics软件,结合Ansys三维有限元专用软件对157层,层厚为0.5 mm的CT断层影像进行分析处理.结果：建立了更为精确,应用更为广泛的下颌骨三维有限元模型.使用Dicom标准和Mimics软件获取三维模型直接写入Ansys三维有限元软件,提高了建模效率.结论：薄层CT,Dicom标准的应用使得有限元模型的建立更为精确,同时Mimics软件直接建立三维模型,极大程度提高了建模效率.     

下颌第一磨牙种植体三维有限元模型的建立

目的详细展现三维有限元建模过程,特别是种植体模型的建立,为三维有限元分析提供数学模型,为更多关注这一领域的研究者提供参考。方法论述Pro／Engineer软件建立种植体三维模型的详细步骤;mimics软件读取cT数据,通过去噪、平滑、减点建立下颌骨模型,magcis进行网格优化。结果成功建立下颌骨及种植体模型。结论该法建立下颌骨及种植体模型简便且易操作,为以后进行三维有限元分析提供了精确的模型。     

正常人下颌升支矢状截骨术的三维有限元模拟

目的建立正常人下颌升支矢状截骨术(bilateral sagittal split ramus osteotomy,BSSRO)的三维有限元模型,为该术式的生物力学研究和分析奠定基础。方法选牙列完整、牙合关系正常的成年男性,经CT扫描后,采用坐标数据化法,利用专业有限元软件建立包括关节盘的下颌骨三维有限元模型(three dimension finite element model,3D-FEM),并在计算机上模拟改良BSSRO术进行截骨。结果获得的三维有限元模型图形逼真,并且在功能状态中的力学改变与体外力学实验得出的数据吻合程度高。结论利用有限元软件采用CT图形坐标数据化法可建立仿真程度较高的BSSRO模型。     

常温和干热环境下腹部肠管火器伤动物模型的建立

目的 建立常温环境和沙漠戈壁干热环境下的腹部肠管火器伤动物模型.方法 30头猪随机分为常温环境组(N组)、干热组Ⅰ(HⅠ组)、干热组Ⅱ(HⅡ组)3组.麻醉后将各组猪以行走位悬挂于靶场门廊上,以54式手枪弹射击猪下腹部,比较各组动物伤情和伤后24小时存活率,对死亡动物及伤后24小时仍存活动物进行剖腹探查并进行病理学检查.结果 各组动物之间肠穿孔数差异无统计学意义(P＞0.05),伤后24小时N、HⅠ、HⅡ组的存活率分别为90%、80%、0;N组和HⅠ组存活率无统计学差异(P＞0.05),N、HⅠ组存活率明显高于HⅡ组(P＜0.01);剖腹探查见N、HⅠ组死亡动物和HⅡ组动物腹腔渗出相对较多,腹压较高,恶臭明显,腹膜炎较重.结论 本实验成功建立了7.62mm枪弹腹部肠管火器伤模型,同时提示戈壁干热环境能明显降低动物存活率,伤后应立即转运后送.     

节段性缺失的犬下颌骨有限元模型的建立

 目的 建立犬下颌骨节段缺失的有限元模型.方法 运用Mimics软件读取基于实验犬下颌骨CT资料的DICOM数据形成几何模型,在Magics软件中使用cut工具对几何模型进行切割,模型由缺损侧和非缺损侧下颌骨、重建钛板组成,每个部分依靠Magics的粘接功能粘在一起,生成实体单元后在MARC软件中完成模型的力学分析.结果 建立了犬下颌骨节段缺失的有限元模型,可模拟牵张过程,观察任意点的应力、位移情况,并可选取模型的任意部分,查看其相应计算结果.结论 犬下颌骨节段缺失的有限元模型的建立,为进一步研究节段缺损下颌骨的各种生物力学状况奠定了基础.     

创伤弹道的病理形态学观察

近年来,由于高速武器的迅速发展,有关创伤弹道的研究,又重新受到了重视。高速步枪和一般制式步枪致伤后,两者在致伤力和伤道形态方面有何不同,文献上报道很少;而弄清这一问题,对于正确进行战伤的诊断和清创将会有很大帮助。为此,选用了美制M 16步枪5.56mm枪弹和国产56式制式步枪7.62mm枪弹,对狗后肢进行对比射击实验,以观察不同伤道的病理形态变化。     

螺旋CT扫描和CAD技术建立精密附着体义齿三维有限元模型的研究

目的:研究利用CT扫描和CAD技术建立按扣式和键槽缓压式两种不同的精密附着体义齿的三维模型.方法:采用CT扫描和CAD技术.结果:本研究采用该法建立了下颌骨及按扣式和键槽缓压式精密附着体的三维有限元模型.结论:①CT断层扫描影像结构完整,数据精确,扫描无创伤便于三维重建;②本研究建立的下颌骨及按扣式和键槽缓压式精密附着体的三维有限元模型科学准确.     

新型颌面部爆炸伤模型建立及损伤特点观察

目的：建立标准的颌面部爆炸伤模型，观察组织损伤特点，方法：实验选用点状爆炸源距新西兰白兔面部不同距离引爆致伤，选择合适的致伤模型，于伤后0．5，6、24、72小时，15天观察伤情，切取皮肤咬肌，面神经组织标本行光镜，透射电镜观察。结果：0．125gTNT当量炸药球距离兔左面部2mm处引爆，可致兔面部软组织挫裂伤，下颌骨粉碎性骨折，伤情可重复，动物存活，伤区皮肤坏死范围约3mm，肌肉组织坏死范围可达10mm，伤后动物出现面瘫症状，面神经水肿充血，髓鞘空泡样变性，雪旺细胞肿胀，炎细胞浸润。结论：0．125gTNT当量炸药球距离兔左面部2mm处引爆，为颌面部爆炸伤标准动物模型，爆炸可引起软组织骨、面神经损伤。     

猪后肢枪弹伤致肺远达效应损伤的容积CT和生化及病理对照研究

目的观察枪击猪后肢肌肉贯通伤所致的肺部远达效应损伤的64排螺旋容积CT（VCT）表现,深入研究肺部远达效应损伤机制及影响因素。方法动物麻醉后,使用81式步枪7．62mm子弹从左侧后肢上段股动脉前方1．0cm处由内向外30cm近距离射击,分别于致伤前后行胸部cT扫描,分析VCT图像特点,并与肺部病理结果进行对照。同时,在枪击前及枪击后不同时间点取猪静脉血,检测血浆内皮素（endothelin,ET）及皮质醇（cortisol,COR）的浓度。结果（1）枪击后12例猪VCT扫描双肺均出现大小程度不同的片状或条索状高密度影,边缘模糊,密度欠均匀,周边肺野显示透光度减低,呈磨玻璃样改变。所有动物均无肺不张、血气胸表现。肺血管及支气管管径未见显著改变。（2）枪击后12例猪肺脏大体标本肉眼均可见肺表面大小程度不同的片状、斑片状及大片出血表现,呈暗红色或鲜红色,未见脏层胸膜和肺实质破裂。病理切片可见小叶出血、实变、磨玻璃样变。镜下可见肺微血管扩张出血,毛细血管破裂,肺间质和肺泡腔内出血、水肿。肺泡隔变厚增粗、充血水肿,呈蜂窝状改变。肺泡腔内充满大量红细胞、纤维素样物质及白细胞。（3）枪击后血浆ET及COR水平较枪击前显著增高,以枪击后10min最为显著（P〈0．05）。结论枪击猪后肢可致肺远达效应损伤,VCT表现主要为片状高密度影,病理提示为炎性渗出或出血;血管内皮损伤及应激反应早期参与了远达效应致肺损伤的形成过程。     

Bullet embolus from a pulmonary vein to the right axillary artery

A case of bullet embolus from a pulmonary vein to the right axillary artery is reported. Though bullet embolization is unusual, it should be considered in any patient who has sustained a gunshot wound and does not have an exit wound, and whose plain films demonstrate a bullet far from the suspected path of the projectile.     

Terminal ballistics of the Russian AK 74 assault rifle: two wounded patients and experimental findings.

OBJECTIVE: To study the effects of the Russian AK 74 assault rifle missile (5.45 x 39 mm) on an experimental model and on two wounded patients. DESIGN: Experimental and clinical study. SETTING: Brodarski Institute, Marine Research and Special Technologies, Zagreb, Croatia, and General Hospital, Karlovac, Karlovac, Croatia. MATERIALS AND PATIENTS: Twenty gelatin blocks used as tissue stimulants and two patients with gunshot wounds caused by AK 74 assault rifle missiles. INTERVENTIONS: After being fired at, gelatin blocks were filmed with a high-speed television camera and radiographs were made of the blocks. Wounds of our patients were treated with minimal excision and drainage. MAIN OUTCOME MEASURES: The correlation between the wound profile method and our experimental model, and the correlation between the wound profile method and the wounds of the patients we treated. RESULTS: Bullets were not found to deform or fragment in tissue stimulant. The bullet path through the gelatin block was found to differ from the path predicted according to the wound profile method. CONCLUSION: Gelatin disruption in the initial 8 to 11 cm of the bullet path is minimal. Even the highest-velocity military missiles, like the AK 74 5.45 x 39 mm bullet, may cause only minimal tissue disruption in this initial part of tissue penetration.     

Forensic value of gunpowder tattooing in identification of multiple entrance wounds from one bullet

Multiple entrance gunshot wounds can give useful information in forensic evaluation of deaths from homicide and suicide. Although the presence of multiple entrance gunshot wounds does not absolutely exclude the possibility of suicide, they are important to the forensic investigators and pathologists in cases of assault, attempted homicide and suicide as they provide important clues for determination of number of shots fired and direction of firing. We present a case of 16 years of young woman who was shot to death by her husband. External examination revealed an entrance wound with semi-lunar shot residue at the dorsal side of her left hand at 5th metacarpus, and exit wound on the hypothenar muscle. There was also a second wound entrance located on her left zygoma. Direction of the bullet was downward traveling from left-to-right. Initially it was thought that there were two close shots, but when her left hand was placed over the malar area her face, it was determined that the gunshot powder tattoos were completing the nature of a single shot from a close distance. Crime scene investigation revealed only one cartridge casing. The autopsy and radiography findings showed that the bullet was entered from dorsal site of the left hand exiting from the palm and re-entering from the zygomatic region, hit the base of the skull, and remained in the soft tissue of the right mandible after passing the soft palate. The bullet was caused an incomplete laceration of the right internal arteria carotid and she died of internal and external bleeding. Detailed investigation of gunshot residues can provide important information for clarification of close distance gunshot wounding. We present this case due to its interesting nature, and to highlight the importance of detailed investigation of the gun powder residues in cases with multiple entry wounds.     

Post mortem computed tomography: Useful or unnecessary in gunshot wounds deaths? Two case reports

Post-mortem computer tomography (PMCT) is currently an useful procedure that can elucidate patterns of injuries, providing strong medical evidence that is very useful during litigation and at trial. This technique is especially useful in gunshot wounds cases, allowing an easier location and retrieval of the bullet and/or its fragments inside the body. In such cases, the use of 3D rendering can be very useful in order to obtain essential information, such as: accurate depict of the wound track, discerning between entrance and exit wounds, show bone’s fracture and its fragments course inside the body. The authors performed analysis on two cases of death by gunshot wounds, and a PMCT before the postmortem examination was made. The obtained CT scans were evaluated using the open-source software OsiriX on a Mac OS X computer, performing 3D rendering of the DICOM images. The crime scene reconstruction was performed using the software Poser Debut® on a Mac OS X computer. In both cases, PMCT showed multiple advantages: objectivity, reproducibility, ease visualization of the wound paths, easy localization of bullet and their fragments, allowing us to clarify the cause of death before the traditional autopsy. PMCT should became a standard in forensic practice as an aid to the tradition postmortem examination to obtain as much information as possible in order to clarify the cause and manner of death.     

Confusing exit gunshot wound –“Two for the price of one”

During the post-mortem examination of a 36-year-old shooting victim, two entrance gunshot wounds in the back and only one corresponding exit wound in the chest were detected. The likelihood of a retained fragmented or whole bullet, or an embolic phenomenon was eliminated by full body x-ray examination. The only remaining plausible explanation was that the two bullet tracts had converged within the thorax, eventually exiting through a common exit wound. Dissection of the projectiles’ path confirmed this unusual phenomenon. Autopsy techniques for gunshot wound cases are discussed. Received: 25 May 2001 / Accepted: 20 August 2001