1,721,001 research outputs found
An average three-dimensional virtual human skull for a template-assisted maxillofacial surgery
No full textIntroduction: Although many advances have been made in three-dimensional virtual planning in maxillofacial surgery, facial harmony is still difficult to achieve and is heavily dependent on the surgeon's experience. The aim of the study is to present a method to build up an average three-dimensional virtual human skull to be used as a reference template for bone repositioning and reconstruction during maxillofacial surgical interventions. Methods: A total of 20 patients (10 females and 10 males) were selected for the optimal outcome after orthognathic surgery. Postoperative cone-beam computed tomography scans were collected and processed in order to obtain three-dimensional digital models of each skull. For male and female subgroups, the three-dimensional skull models were registered and an average three-dimensional virtual skull model was computed. Deviation color maps were calculated to show differences between each postoperative skull model in the population and the obtained average three-dimensional skull. A clinical use case of genioplasty treatment assisted by the provided average three-dimensional skull template was presented. Results: The overall mean deviation from the average three-dimensional skull model was 1.3 +/- 0.6 and 1.6 +/- 0.5 mm in male and female subgroups, respectively. For both groups, the greatest deviations were at the area of the mandible, while almost no deviation was found at the zygomatic and orbital areas. In the presented use case, the female average three-dimensional skull model was effectively used for guiding surgical planning. Conclusion: The presented method of obtaining an average three-dimensional virtual human skull may offer the interesting perspective of performing an innovative template-assisted maxillofacial surgery
Development of a CO2 sensor for extracorporeal life support applications
Full text linkMeasurement of carbon dioxide (CO2) in medical applications is a well-established method for monitoring patient’s pulmonary function in a noninvasive way widely used in emergency, intensive care, and during anesthesia. Even in extracorporeal-life support applications, such as Extracorporeal Carbon Dioxide Removal (ECCO2R), Extracorporeal Membrane Oxygenation (ECMO), and cardiopulmonary by-pass (CPB), measurement of the CO2 concentration in the membrane oxygenator exhaust gas is proven to be useful to evaluate the treatment progress as well as the performance of the membrane oxygenator. In this paper, we present a new optical sensor specifically designed for the measurement of CO2 concentration in oxygenator exhaust gas. Further, the developed sensor allows measurement of the gas flow applied to the membrane oxygenator as well as the estimation of the CO2 removal rate. A heating module is implemented within the sensor to avoid water vapor condensation. Effects of temperature on the sensor optical elements of the sensors are disclosed, as well as a method to avoid signal–temperature dependency. The newly developed sensor has been tested and compared against a reference device routinely used in clinical practice in both laboratory and in vivo conditions. Results show that sensor accuracy fulfills the requirements of the ISO standard, and that is suitable for clinical applications
First Ex Vivo Animal Study of a Biological Heart Valve Prosthesis Sensorized with Intravalvular Impedance
Full text linkIntraValvular Impedance (IVI) sensing is an innovative concept for monitoring heart valve prostheses after implant. We recently demonstrated IVI sensing feasible in vitro for biological heart valves (BHVs). In this study, for the first time, we investigate ex vivo the IVI sensing applied to a BHV when it is surrounded by biological tissue, similar to a real implant condition. A commercial model of BHV was sensorized with three miniaturized electrodes embedded in the commissures of the valve leaflets and connected to an external impedance measurement unit. To perform ex vivo animal tests, the sensorized BHV was implanted in the aortic position of an explanted porcine heart, which was connected to a cardiac BioSimulator platform. The IVI signal was recorded in different dynamic cardiac conditions reproduced with the BioSimulator, varying the cardiac cycle rate and the stroke volume. For each condition, the maximum percent variation in the IVI signal was evaluated and compared. The IVI signal was also processed to calculate its first derivative (dIVI/dt), which should reflect the rate of the valve leaflets opening/closing. The results demonstrated that the IVI signal is well detectable when the sensorized BHV is surrounded by biological tissue, maintaining the similar increasing/decreasing trend that was found during in vitro experiments. The signal can also be informative on the rate of valve opening/closing, as indicated by the changes in dIVI/dt in different dynamic cardiac conditions
Architecture of a Hybrid Video/Optical See-through Head-Mounted Display-Based Augmented Reality Surgical Navigation Platform
Full text linkIn the context of image-guided surgery, augmented reality (AR) represents a ground-breaking enticing improvement, mostly when paired with wearability in the case of open surgery. Commercially available AR head-mounted displays (HMDs), designed for general purposes, are increasingly used outside their indications to develop surgical guidance applications with the ambition to demonstrate the potential of AR in surgery. The applications proposed in the literature underline the hunger for AR-guidance in the surgical room together with the limitations that hinder commercial HMDs from being the answer to such a need. The medical domain demands specifically developed devices that address, together with ergonomics, the achievement of surgical accuracy objectives and compliance with medical device regulations. In the framework of an EU Horizon2020 project, a hybrid video and optical see-through augmented reality headset paired with a software architecture, both specifically designed to be seamlessly integrated into the surgical workflow, has been developed. In this paper, the overall architecture of the system is described. The developed AR HMD surgical navigation platform was positively tested on seven patients to aid the surgeon while performing Le Fort 1 osteotomy in cranio-maxillofacial surgery, demonstrating the value of the hybrid approach and the safety and usability of the navigation platform
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Comparison of Bone Segmentation Software over Different Anatomical Parts
Full text linkThree-dimensional bone shape reconstruction is a fundamental step for any subject-specific musculo-skeletal model. Typically, medical images are processed to reconstruct bone surfaces via slice-by-slice contour identification. Freeware software packages are available, but commercial ones must be used for the necessary certification in clinics. The commercial software packages also imply expensive hardware and demanding training, but offer valuable tools. The aim of the present work is to report the performance of five commercial software packages (Mimics®, AmiraTM, D2PTM, SimplewareTM, and Segment 3D PrintTM), particularly the time to import and to create the model, the number of triangles of the mesh, and the STL file size. DICOM files of three different computed tomography scans from five different human anatomical areas were utilized for bone shape reconstruction by using each of these packages. The same operator and the same hosting hardware were used for these analyses. The computational time was found to be different between the packages analyzed, probably because of the pre-processing implied in this operation. The longer “time-to-import” observed in one software is likely due to the volume rendering during uploading. A similar number of triangles per megabyte (approximately 20 thousand) was observed for the five commercial packages. The present work showed the good performance of these software packages, with the main features being better than those analyzed previously in freeware packages
AEducAR3.0: An Exciting Hybrid Educational Platform for a Comprehensive Neuroanatomy Learning
No full textAnatomical education is essential for medical students and future surgeons. Currently, training on cadavers represents the main instructional tool able to provide effective three-dimensional (3D) and topographical comprehension. Innovative technologies like Augmented Reality (AR) and 3D printing may offer additional educational toolswith great potential. This study aimed to present AEducAR3.0, a "hybrid" educational platform exploiting both AR and 3D printing technologies for neuroanatomy learning. The platform is an evolution of preliminary experiences on orbital and facial anatomies. As novelty, AEducAR3.0 allows to study neuroanatomy at different learning levels: 1. Notional Learning; 2. Notional Learning in the Context; 3. Topographical learning. Three consecutive learning phases are provided, with integrated testing sessions and practical tasks on 3D-printed phantoms at each learning level. We experienced the platform with 70 second-year medical students of the University of Bologna, who had not yet taken any traditional lectures on neuroanatomy. The results demonstrated that AEducAR3.0 is technically sound and may facilitate neuroanatomy learning and students' engagement. Students appreciated the interactive features of the tool and the integrated quizzes during the learning session. Results showed that the provided quizzes were well-balanced in terms of difficulty (mean rate of correct answers of 60%, 70% and 58%, for Levels 1, 2, and 3 respectively). Overall, about half of the students (51%) scored higher than sufficient. AEducAR3.0 is intended to be a comprehensive tool that may contribute to increasing long-term memory retention and understanding of the 3D spatial arrangement of anatomical structures, preparing the learner also for surgical practice
3D Printing Of A Cranial Implant With Energy-Absorbing Polymer Via Arburg Plastic Freeforming Technology
Full text linkAdditive Manufacturing (AM) brings ground-breaking opportunities to provide customized healthcare solutions with reasonable time and cost. These benefits become more evident if reducing the distance between the printing process and surgery. In this direction, the Arburg Plastic Freeforming (APF) process offers unprecedented opportunities. The absence of hazardous feedstock materials such as powders allows for the utilization of this technology within hospitals. Also, unlike traditional AM processes, APF makes it possible to process medically approved standard granulates without compromising their certification.In this study, APF has been used to manufacture, for the first time, a patient-specific cranial implant (PSCI) using a biocompatible polymer with a high energy absorption capability, namely, PolyCarbonate Urethane (PCU). The main technological issue was represented by the lack of a solvable support material compatible with PCU. This obstacle was overcome by a custom support structure made of the same material, which can be removed at the end of the process with limited damage to the PSCI. The orientation of the part within the building chamber was chosen to optimize the accuracy of critical features and the surface quality of the regions facing the brain. The 3D-printed cranial implant showed high toughness during mechanical impact tests
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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