Developing an unmanned aerial vehicle-based rapid mapping system for traffic accident investigation

After a traffic accident, a diagram of the scene needs to be prepared as evidence in on-scene investigation. However, traditional methods to measure and map have their own defects. The aim of this study is the development of an unmanned aerial vehicle (UAV)-based mapping system to acquire scene diagrams rapidly. The camera calibration is explained in the study. This system provides approaches for lens distortion and perspective distortion elimination. A method for scene mapping from rectified images is also explained. The performance models for estimating the position error is developed and tested in different levels. The results show that the total root mean square error (RMSE) of the rectified image is 3.6 pixels, and the relative error of measurement in the rectified image can be controlled to –2.5%~2.5% when the UAV is at 11–112 m flight altitudes. This proposed method to draw scene diagrams is faster and easier than hand-drawing. It is indicated that the system provides a feasible method to obtain a scene diagram of a traffic accident.     

道路交通伤机动车碰撞类型比较研究

目的：研究道路交通伤的临床流行病学特点与机动车碰撞类型的关系。方法；将14779例由机动车碰撞所致的道路交通伤患者按其碰撞类型分组，对致伤方式、受伤部位、创伤严重程度、生理改变以及预测预后等方面进行比较和统计学分析。结果：机动车与行人和机动车碰撞为道路交通伤机动车主要碰撞类型，机动车与行人和摩托车碰撞致伤者损伤严重程度评分（ISS）分值较高，生存概率（Ps )预测值较低，且死亡所占比例较大（51．98％，92／177）；2个部位损伤为各种碰撞类型的主要受伤形式，其中头部及四肢骨骼伤较为常见，胸及腹部简明损伤定级（AIS）高会值伤较多；车外人员伤后生理紊乱较车内人员更为显著（P＜0．0）。结论：机动车所致的道路交通临床特点根据碰撞类型不同而有明显区别，高危伤情、高发部位及高危区为非对称性分布，机动车外交通伤比车内交通伤更为严重。     

Reconstruction of the dynamic in a fatal traffic accident with prolonged dragging of the victim

The post-mortem examination of victims of fatal road crashes and the reconstruction of the dynamic of traffic accidents are fundamental in vehicular homicides, where the degree of negligence/careless of the driver has to be established. Here we present a case in which a pedestrian was dragged along an SUV for 3.5 km, until the vehicle was parked at the house of the driver, arising the suspect of vehicular manslaughter and failure to provide assistance.On the basis of death scene investigation, analysis of video recording from a surveillance camera, post-mortem computerized tomography (PMCT) and complete post-mortem examination, including gross and microscopical findings, the accident was reconstructed as a frontal collision between the right portion of the bumper and the right side of the body of a standing pedestrian, with deformation of the bumper and production of a metal sheet hook; secondary run-over the right feet, cranio-facial trauma against the bodywork of the vehicle and hooking of the right hand of the victim to the metal sheet; prolonged dragging of the pedestrian over the road surface and severe bleeding.A multidisciplinary-multimodal methodology, including PMCT, allowed to assess the cause of death as hemorrhagic shock, suggested that the victim would have likely survived if the vehicle had stopped, and is increasingly recommendable in fatal road accidents.     

Fatal thoracic impalement on postmortem imaging

In the present paper, the authors describe a case of fatal thoracic impalement in a victim of a road traffic accident, by penetration of a metal handrail. The driver lost control of his car while overtaking three cars. Due to the force of the vehicle collision with a metal railing, the upper cross bar penetrated the front of the car and subsequently the driver was pierced by the center-pillar in the car. Death occurred at the scene of the accident. Postmortem, computed tomography, computed tomography angiography and a magnetic resonance tomography were performed and revealed severe heart destruction and hemorrhage as cause of death. The present case report shows that postmortem imaging might have value as a screening method to decide whether arising forensic questions can be answered just by imaging like in the presented case or if further examinations such as conventional autopsy are required.     

重庆市高速公路部分交通事故死亡案例的特点分析

目的 对重庆市2006年～2010年高速公路部分致死性交通事故的资料进行收集和分析,探讨其事故特征.方法 对重庆法医验伤所2006年1月～2010年6月高速公路部分致死性事故死亡人员尸检报告及重庆市交通行政执法总队高速公路支队所提供的事故情况报告进行分类、归纳、整理与统计.结果 (1)共693起致死性交通事故,死亡人数...     

Monte Carlo modeling of a conventional X-ray computed tomography scanner for gel dosimetry purposes

Our purpose in the current study was to model an X-ray CT scanner with the Monte Carlo (MC) method for gel dosimetry. In this study, a conventional CT scanner with one array detector was modeled with use of the MCNPX MC code. The MC calculated photon fluence in detector arrays was used for image reconstruction of a simple water phantom as well as polyacrylamide polymer gel (PAG) used for radiation therapy. Image reconstruction was performed with the filtered back-projection method with a Hann filter and the Spline interpolation method. Using MC results, we obtained the dose–response curve for images of irradiated gel at different absorbed doses. A spatial resolution of about 2 mm was found for our simulated MC model. The MC-based CT images of the PAG gel showed a reliable increase in the CT number with increasing absorbed dose for the studied gel. Also, our results showed that the current MC model of a CT scanner can be used for further studies on the parameters that influence the usability and reliability of results, such as the photon energy spectra and exposure techniques in X-ray CT gel dosimetry.     

中国高速公路2007-2009年交通伤害的流行病学研究

目的 分析中国高速公路交通伤害的流行病学特点,为高速公路交通伤害的预防与控制提供科学依据.方法 分析1994-2009年中国高速公路交通伤害的长期趋势和流行特征,以里程事故率、里程死亡率、事故致死率等指标评价中国高速公路交通伤害的严重性,通过聚类分析比较地区间里程死亡率和事故致死率的差别.结果 1994-2009年中国高速公路交通伤害的长期趋势除事故致死率逐年上升,里程事故率和死亡率波动下降外,其他指标均先上升后下降,下降后的各指标仍高于1994年水平.在交通伤害的四项基本指标中除事故起数外,其他三项指标(受伤人数、死亡人数和直接财产损失)在路网交通伤害中所占的比重逐年递增,以直接财产损失最明显,2006年以来占的比重均在30％以上.2007-2009年高速公路交通伤害的资料显示,4∶00和16∶00前后为事故高发时段,事故中驾驶员因素占93.02％,其中驾龄＜5年的驾驶员引起的事故占40.92％,行人和乘车人是高速公路的弱势人群,其事故致死率高达72.75％;尾随相撞(44.17％)和撞向固定物(16.35％)是主要的事故形态,路面干燥和晴天时事故比例高,分别为77.60％和65.93％.结论 中国高速公路交通伤害的严重性与日俱增,应根据该类伤害的流行病学特点,有针对性地采取加强道路管理、道路使用者的宣传教育和提高急救医疗服务水平等措施.     

Encoding of electrophysiology and other signals in MR images

PURPOSE: To develop a gradient insensitive, generic technique for recording of non-MR signals by use of surplus scanner bandwidth. MATERIALS AND METHODS: Relatively simple battery driven hardware is used to transform one or more signals into radio waves detectable by the MR scanner. Similar to the "magstripe" technique used for encoding of soundtracks in motion pictures, the electrical signals are in this way encoded as artifacts appearing in the MR images or spectra outside the region of interest. The encoded signals are subsequently reconstructed from the signal recorded by the scanner. RESULTS: Electrophysiological (EP) eye and heart muscular recording (electrooculography [EOG] and electrocardiography [ECG]) during fast echo planar imaging (EPI) is demonstrated with an expandable, modular 8-channel prototype implementation. The gradient artifacts that would normally be dominating EOG are largely eliminated. CONCLUSION: The method provides relatively inexpensive sampling with inherent microsecond synchronization and it reduces gradient artifacts in physiological recordings significantly. When oversampling is employed, the method is compatible with all MR reconstruction and postprocessing techniques.     

The use of 3-dimensional CT reconstruction in childhood. Technics and dosimetry

A new computer method has been developed that allows the reprocessing of standard CT scans to produce 3D surface images. We employed the 3D reconstruction program developed by Hitachi Medical System using an Ansaldo A-TOM XR 1200 scanner. The process requires only standard CT scanner hardware, and reconstruction time is comparable to that of sagittal and coronal reconstructions. The applications of this technique and methodology to pediatric patients are discussed. In order to assess the relationship between image quality and radiation dose, we performed many CT scans with different protocols. A skull was employed for phantom, and plunged into a physiological solution, which helped us to determine the radiation exposure dose from every single CT scan. The measurements were taken with film and thermoluminescent crystal dosimeters (TLD). The results confirm that low-dose techniques allow a significant reduction in the total exposure. The authors discuss the clinical indications and the eventual applications of these techniques.     

兰州市2004年度道路交通事故伤流行病学分析

目的：探讨兰州市2004年度道路交通事故伤流行病学特征，为减少城市道路交通事故伤的发生提供科学依据。方法：收集2004年兰州市发生的交通事故资料，分析交通事故的流行病学特征。结果：伤亡人员年龄以21～40岁为多，男性为主；行人及骑自行车者为交通事故的最大受害者；机动车司机的过失是导致事故的最主要原因。结论：完善城市道路建设及规划；加强交通管理，严禁违规行车；加强道路交通法规和安全教育，提高驾乘人员和行人安全意识等是降低交通事故的主要措施。     

放射外照射事故剂量重建中的蒙特卡罗模拟方法

目的 建立放射外照射事故剂量重建的计算机系统。方法 基于MIRD的人体及其器官的数学模型，采用蒙特卡罗(MC)方法，结合 放射事故的受照模式，建立放射外照射事故剂量重建的计算机系统。结果 成功研制了放射事故剂量重建的计算机系统。用这个系统计算了河南省^60Co放射事故危重病人的剂量，其计算结果与实验模拟测量和生物剂量检测结果十分一致。结论 本系统方便、快捷，它不但可估算事故受照人员的器官剂量和全身剂量，而且也能用于事故早期剂量的估计。     

Performance measurement of PSF modeling reconstruction (True X) on Siemens Biograph TruePoint TrueV PET/CT

Objective

The Siemens Biograph TruePoint TrueV (B-TPTV) positron emission tomography (PET) scanner performs 3D PET reconstruction using a system matrix with point spread function (PSF) modeling (called the True X reconstruction). PET resolution was dramatically improved with the True X method. In this study, we assessed the spatial resolution and image quality on a B-TPTV PET scanner. In addition, we assessed the feasibility of animal imaging with a B-TPTV PET and compared it with a microPET R4 scanner.

Methods

Spatial resolution was measured at center and at 8 cm offset from the center in transverse plane with warm background activity. True X, ordered subset expectation maximization (OSEM) without PSF modeling, and filtered back-projection (FBP) reconstruction methods were used. Percent contrast (% contrast) and percent background variability (% BV) were assessed according to NEMA NU2-2007. The recovery coefficient (RC), non-uniformity, spill-over ratio (SOR), and PET imaging of the Micro Deluxe Phantom were assessed to compare image quality of B-TPTV PET with that of the microPET R4.

Results

When True X reconstruction was used, spatial resolution was <3.65 mm with warm background activity. % contrast and % BV with True X reconstruction were higher than those with the OSEM reconstruction algorithm without PSF modeling. In addition, the RC with True X reconstruction was higher than that with the FBP method and the OSEM without PSF modeling method on the microPET R4. The non-uniformity with True X reconstruction was higher than that with FBP and OSEM without PSF modeling on microPET R4. SOR with True X reconstruction was better than that with FBP or OSEM without PSF modeling on the microPET R4.

Conclusions

This study assessed the performance of the True X reconstruction. Spatial resolution with True X reconstruction was improved by 45 % and its % contrast was significantly improved compared to those with the conventional OSEM without PSF modeling reconstruction algorithm. The noise level was higher than that with the other reconstruction algorithm. Therefore, True X reconstruction should be used with caution when quantifying PET data.     

Incomplete decapitation with exenteration of the brain in a motorcyclist run over by a semitrailer

Although decapitation is a well-known traumatic mechanism in road traffic deaths, incomplete decapitation of a motorcyclist with exenteration of the brain has not yet been reported in the forensic literature in a victim run over by a vehicle. This paper deals with an autopsy case of a 69-year-old motorcyclist, who had been run over by a semitrailer, as a result of which flattening of the head with extrusion of the brain and incomplete decapitation occurred at the level of the fourth cervical vertebra. This constellation allows to define a special mechanism of accident-related decapitation. Moreover, the case underlines the importance of a multidisciplinary approach for the reconstruction of the accident as well as for the assessment of its judicial consequences. On the suspicion of a hit-and-run accident, simulation tests were performed by technical experts. These tests revealed that the motorcycle may not have been conspicuous for the truck driver prior to and during the accident. Consequently, the charge of manslaughter and failure to render assistance against the truck driver was dropped.     

Decapitation with egg shelling of the skull in a road traffic accident: a case report

A 40-year-old lady was found dead on a road early one morning. She had allegedly been run over by a speeding vehicle. The head of the deceased had been decapitated, with egg shelling of the skull from the scalp and face. The skull was lying a little distance away from the rest of the body. Although decapitation is not an unknown entity in a road traffic accident, subsequent egg shelling of the skull, leaving behind scalp and face tissue, has not been reported in a road traffic accident in the forensic literature.     

重庆市某区道路交通事故流行病学分析

目的探讨城市发展新区道路交通事故(简称事故)的分布特征,区域性事故预防和控制研究奠定基础。方法对重庆市道路交通管理局收集2000~2006年的事故登记信息,以流行病学方法进行资料整理,分析描述近年来重庆市城市发展新区(以某区为例)事故发生的现状及分布规律。结果2000~2006年,重庆市某区共发生事故13 685起,其中一般及轻微事故13 170起,重大事故515起。7年间,从事故的时间分布特征看,一般及轻微事故年均发生1 881起,其中2000年、2001年和2005年发生均在1 600起以下,2003年、2004年和2006年发生均超过2 000起,2004年事故最高,为2 102起,占总数的15.96%;月均事故发生为157起,其中1月、7月和11月为事故的高发期;每月的下旬事故有下降趋势;每周星期六发生事故次数最多,周三最低;单日事故发生最高分别是每月的1号和14号;每日24小时事故中,一般从早上7点开始逐渐上升,11点达高峰,以后逐渐下降;白天的事故发生案例明显高于晚上。重大事故的分布特点与一般及轻微事故有一定区别,主要体现在从2002年后发生开始下降,至2006年一直稳定在年60起左右;每年5月、9月和11月和每周的星期三和周四为高发时间;每日以上午10点左右最高,下午在4点左右次高。结论2000~2006年某区事故发生维持在较高的水平,重大事故发生有降低趋势;事故的发生在时间分布上有明显的特征,但一般及轻微事故与重大事故的分布特征有一定的差别,相关分析信息可作为制定交通事故控制措施的参考依据。     

The use of frame fixation in the management of open distal extensor mechanism avulsion fracture in a dislocated knee

An avulsion fracture of the tibial tubercle is a common injury in traffic accident. If the fracture is closed, then a comparatively good prognosis can be expected through reinforcement of the bone via osteosynthesis and the use of artificial ligaments. In this case, an open wound was observed in the tibial tubercle, and the wound was so polluted that the healing process was significantly delayed. It was therefore difficult to provide simultaneous surgical treatment and so three operations were required to perform the reconstruction of the extensor mechanism. The reconstruction of extensor mechanism and the frame fixation between the patella and tibia was performed. Six months after the injury, the patient was able to walk without aid, had a range of movement from 5°to 130°, and did not show any indications of ADL disorder. Using this method of frame fixation between the patella and tibia proved to be an effective technique for the reconstruction of the open knee extension mechanism injury.     

Surface laser scanning to routinely produce casts for patient immobilization during radiotherapy

Immobilization casts are used to reduce patient movement during the radiotherapy of head and neck and brain malignancies. Polyethylene-based casts are produced by first taking a Plaster of Paris 'negative' impression of the patient. A 'positive' mould is then made, which is used to vacuum form an immobilization cast. Taking the 'negative' cast can be messy, stressful for patients and labour intensive. Recently, lightweight hand-held laser surface scanners have become available. These allow an accurate 3-D representation of objects to be generated non-invasively. This technology has now been applied to the production of casts for radiotherapy. Each patient's face and head is digitized using the Polhemus FastSCAN (Polhemus, Colchester, VT, USA) scanner. The electronic data are transferred to a computer numerical controlled mill, where a positive impression is machined. The feasibility of the process was examined, the labour required and radiation therapists' satisfaction with aspects of the produced masks assessed. The scanner-based method of mask production was found to be simple, accurate and non-invasive. There was a reduction in radiation therapist labour required. Masks produced with the scanner-based method were reported to result in improved mask fitting, daily reproducibility, patient immobilization and patient comfort.     

Restoration of lost frequency in OpenPET imaging: comparison between the method of convex projections and the maximum likelihood expectation maximization method

We are developing a new PET scanner based on the “OpenPET” geometry, which consists of two detector rings separated by a gap. One item to which attention must be paid is that OpenPET image reconstruction is classified into an incomplete inverse problem, where low-frequency components are truncated. In our previous simulations and experiments, however, the OpenPET imaging was made feasible by application of iterative image reconstruction methods. Therefore, we expect that iterative methods have a restorative effect to compensate for the lost frequency. There are two types of reconstruction methods for improving image quality when data truncation exists: one is the iterative methods such as the maximum-likelihood expectation maximization (ML-EM) and the other is an analytical image reconstruction method followed by the method of convex projections, which has not been employed for the OpenPET. In this study, therefore, we propose a method for applying the latter approach to the OpenPET image reconstruction and compare it with the ML-EM. We found that the proposed analytical method could reduce the occurrence of image artifacts caused by the lost frequency. A similar tendency for this restoration effect was observed in ML-EM image reconstruction where no additional restoration method was applied. Therefore, we concluded that the method of convex projections and the ML-EM had a similar restoration effect to compensate for the lost frequency.     

System matrix modelling of externally tracked motion

BACKGROUND AND AIM: In high-resolution emission tomography imaging, even small patient movements can considerably degrade image quality. The aim of this work was to develop a general approach to motion-corrected reconstruction of motion-contaminated data in the case of rigid motion (particularly brain imaging) which would be applicable to any PET scanner in the field, without specialized data-acquisition requirements. METHODS: Assuming the ability to externally track subject motion during scanning (e.g., using the Polaris camera), we proposed to incorporate the measured rigid motion information into the system matrix of the expectation maximization reconstruction algorithm. Furthermore, we noted and developed a framework to incorporate the additional effect of motion on modifying the attenuation factors. A new mathematical brain phantom was developed and used along with elaborate combined Simset/GATE simulations to compare the proposed framework with the cases of no motion correction. RESULTS AND CONCLUSION: Clear qualitative and quantitative improvements were observed when incorporating the proposed framework. The method is very practical to implement for any scanner in the field, not requiring any hardware modifications or access to the list-mode acquisition capability.     

The assessment of lens opacity postmortem and its implication in forensics

Visual impairment, mostly due to cataracts, has been demonstrated to be an important factor associated with traffic accidents. Although vision screening is standard procedure during licensing in order to prevent motor vehicle accidents, an eye exam is not typically administered after an accident has already occurred.Postmortem assessment of lens opacity in victims of car accidents would provide helpful information for attesting to the liability of the parties in specific accidents, determining the circumstances of the accident, and developing preventive measures for both drivers and pedestrians alike.In this paper, we explore the use of different methods and their limitations for assessing lens opacity postmortem. We discuss the possible use and benefits of a simple, but as-yet untested method: retrobulbar translucency. The method would be based on the recording of shadows formed by opaque regions of the lens while the eye is illuminated from the back with a rigid source of light. The efficacy and objectivity of the method, its reproducibility, and the inter- and intra-observer error should be tested before implementing such a technique to be regularly used to determine lens opacity in cadavers.