External Contour Research Articles

Evaluating the performance of automated external contouring tool on dose calculation of treatment planning system

Abstract Introduction The main goal of radiation therapy is to eradicate all cancer cells and minimize the damage to healthy tissues around the tumour. Treatment planning systems are used to predict the outcome of the treatment in terms of dose distribution prior to the treatment. One of the most reliable dose calculation algorithms is Monte Carlo. The aim of this study is to evaluate the performance of automated external contouring tool on dose calculation using Monte Carlo algorithm. Materials and methods The external contour of thorax phantom was created by automated tools of Monaco treatment planning system, and then, the IAEA-TECDOC-1583 quality assurance tests were created. Then, the treatment plans were delivered to the phantom, and the dose was measured by the Farmer ionization chamber at specific points. The external contour was corrected according to the source surface distances (SSD) which are mentioned in TECDOC-1583, and the dose was re-calculated. Finally, a comparison was made between the results. Results Dosimetric tests of TECDOC-1583 showed the errors ranged from −2·8% to +2·5%. In case of editing external contour and omitting fluctuations, the errors were decreased. The comparisons indicated that the most significant variation occurred in test 4 and the least changes were related to the tests 1 and 3. Conclusions The results of the study showed that the fluctuations of the external contour affect the calculated volume of the phantom and thus the dose. In order to obtain correct results, automated external contouring tools should be used with the correct instructions and re-checked before treatment planning.

СТРАТЕГИЯ ПРОСТРАНСТВЕННОГО РАЗВИТИЯ РОССИИ: ВЕКТОРЫ ОБНОВЛЕНИЯ

The large-scale geopolitical and geo-economic changes inherent in the modern world order, complemented by prolonged economic, technological, and demographic trends, are projected onto the Russian space, correcting both its external contour and internal architecture. In this context, the discourse on targets, directions, and ways of activating the territorial socio-economic dynamics of the Russian Federation has revived, and the development of an updated strategy for its spatial development has been reinvigorated. Based on the tools of socio-geographical analysis, the study aims to identify the most important problem areas characteristic of modern Russia, dilemmas, alternatives, and priorities in the field of its spatial development, as well as to substantiate on this basis a conceptual approach to updating the key provisions of the current Spatial Development Strategy of the Russian Federation for the Period up to 2025. The paper notes the internal inconsistency of this document (the prevalence of orientation toward ‘alignment’ within the agglocentric model, the desire to combine centripetal trends with the search for formats to counteract the ‘compression’ of the developed space, etc.) and its simultaneous transitivity, susceptibility to innovation (‘municipalization’ of approaches, consideration of the ‘geopolitics factor’, etc.). The paper emphasizes the need to modify the Strategy by focusing on the exogenous determinants of Russia's spatial development (including the formation of ‘Greater Eurasia’), as well as its scientific, technological, and defense-industrial factors. We substantiate the reasonableness of a more consistent shift in emphasis to the stimulation of interregional and inter-municipal integration, to mutually supportive co-development of regions and municipalities within a single market, transport, logistics, and information space based on the balance of ‘Moscow-centrism’ with the development of other growth poles, expansion, and ‘interlayering’ of their spheres of influence.

SOFTWARE IMPLEMENTATION OF ALGORITHMS FOR SELECTING THE OUTLINES OF OBJECTS IMAGES IN INTELLECTUAL VIDEO SURVEILLANCE SYSTEMS

The rapid advancement in digital image acquisition and transmission technologies poses challenges in processing vast volumes of video information streams. Images serve as crucial sources of decision-making information across a wide range of tasks. Key objectives addressed by intelligent video surveillance systems include object identification, trajectory determination, object speed measurement, and real-time detection of critical events for securing premises. Among the primary operations in intelligent video surveillance systems is the extraction of object contours from images, as contours contain essential information for object recognition based on their shape. This approach excludes internal image points, significantly reducing the amount of processed information and enabling real-time image analysis. Contour analysis encompasses methods for selecting, describing, and processing image contours to describe, store, compare, and search for objects based on their external contours. This methodology effectively addresses fundamental challenges in pattern recognition, such as transferring, rotating, and scaling object images. The paper discusses prominent contour analysis methods and presents software implementations of algorithms for extracting object outlines in intelligent video surveillance systems. A promising future direction involves synthesizing algorithms that extract object contours using a two-scale statistical image model.

Analysis of factors related to the morphological evolution of Lingnan export mugs in the 18th-20th centuries in the context of one belt and one road.

As a significant trade item on the ancient Silk Road, the evolution of mug shapes represents a confluence of Eastern and Western economic history and cultural-artistic exchanges, also reflecting the flourishing export culture of Guangzhou. This paper analyzes the functional and social factors influencing the morphological changes of Lingnan mugs from 1616 to 1949 from the perspective of quantitative typological analysis. The overall design trend of these mugs transitioned from complex to simple, enhancing user comfort, while variations in mug scale reflect the diversity of consumer classes and regional drinking cultures. Among the 30 mugs analyzed, the average capacity was 356ml, with a range of 1588ml. Common shapes included cylindrical bodies and ear-shaped handles. Morphologically, the belly of the mugs transformed from arc-barrel bodies (emphasizing heat retention) to bulbous bodies, and eventually to cylindrical bodies (combining heat retention, practicality, and economy), with handles also showing signs of East-West integration. The analysis of the mug body' s inclination, with handle-side junction angles ranging from 34° to 53° and wall-side junction angles from 50° to 90°, indicates that these features are associated with stability in placement, aesthetic design, and practicality in liquid containment. These morphological evolutions reflect genuine responses to market demands and advancements in production technology, manifesting as products of market orientation and societal needs. By measuring changes in morphology, scale, volume, and external contour curves, this paper addresses how social factors shape material morphology in an academic context.

Технологическое лидерство государства: концептуальное понимание и механизмы формирования

The article shows that the technological leadership of the state should conceptually be based on such institutions as technological sovereignty, technological equality and technological cooperation. It is noted that the technological leadership of the state is a multidimensional category, including such elements as technology, scientific, technological and educational base, platforms, and interactions. The differences between the technological leadership of the company and the state are outlined. Using the author's approach to the concepts of "technological sovereignty" and "technological cooperation and equality", the mechanisms of technological leadership of the state are highlighted, which can be used by both the initiator states of partnerships and participants in these partnerships. These include, in particular, leading companies, government policies that support the effective allocation of national resources, the external contour of national leadership development, the system of scientific and technical forecasting and analytics, the national system of "soft power", joint ownership of intellectual property by friendly states, complete technological chains, platforms and standards formed within the framework of partnerships, and etc. Using the example of the state corporation Rosatom, the possibility of using leading companies as a mechanism for technological leadership in Russia is considered.

МЕХАНИЗМ ТРАНСФОРМАЦИИ БИЗНЕС-ПРОЦЕССОВ АПК В УСЛОВИЯХ СУВЕРЕНИЗАЦИИ ПРОДОВОЛЬСТВЕННОГО ПОТЕНЦИАЛА

In the current difficult business conditions in the Russian Federation, due to the restrictive measures of unfriendly countries towards the Russian economy, there is a growing need for mechanisms to effectively increase the resilience of agricultural systems to sanctions risks, trade barriers and other external threats, reinforced by the low sovereignty of the country’s food potential. In this context, significant adaptive potential is concentrated in the transformation of business processes of economic entities that are producers of agricultural products and food, taking into account constantly changing business conditions. In this regard, the issues related to the development of a mechanism for the transformation of business processes seem relevant. The purpose of the study is to develop recommendations on the formation of the structure of the mechanism for the transformation of business processes in the agro-industrial complex in the context of the sovereignization of Russia’s food potential. The following tasks are to be solved: to assess current trends in the changing environment of food producers in Russia, in particular as a result of the establishment of barriers to Russian business; to identify key areas for ensuring the sustainable functioning of economic entities in conditions of turbulence and exogenous risks; to develop a generalized structure of the mechanism of transformation of business processes of manufacturers of agricultural products. The authors propose the structure of a distributed mechanism, represented by a risk warning system on the external contour of an economic entity that poses a threat to business process disruption; a system for responding to threats of technological process disruption, providing rapid restructuring of the entire chain of business processes; a reflection system responsible for a posteriori analysis of the operation of warning and response systems. The proposed structure of the mechanism for transforming the business processes of the agro-industrial complex can form the basis for further developments on the formation of such a mechanism and its practical use in order to adapt food producers to sanctions pressure, ensure the sustainability of production, and increase the country’s food security.

Comparative Analysis of VMAT and IMRT Techniques: Evaluation of Dose Constraints and Bone Marrow Sparing in Cervical Cancer Patients Undergoing Chemoradiotherapy.

Carcinoma of the cervix is a globally significant cause of morbidity and mortality among women. Concurrent chemoradiotherapy, a standard approach for locally advanced cervical cancer, invariably involves pelvic irradiation. Although this strategy is effective, it inevitably affects the pelvic bone marrow, a crucial hematopoietic site, and leads to hematological toxicity The potential of IMRT to spare bone marrow in pelvic irradiation settings has been an area of significant interest, with the aim to mitigate the hematological toxicity associated with pelvic radiotherapy. Radiotherapy techniques have evolved in terms of conformity and normal tissue sparing. Our study intends to explore the use of BM sparing techniques among patients of carcinoma cervix. Twenty patients of carcinoma cervix FIGO Stage IIIB treated with concurrent chemoradiotherapy were selected for this study. The external contour of bones was delineated on planning CT as a surrogate for BM. We generated three plans on a single patient:1. without BM as the dose constraint, namely N-IMRT plan; 2. with BM constraint, namely BMS-IMRT plan; 3. VMAT plan in which BM constraint was given. The dose volume histogram (DVH) for planning target volume (PTV) and organs at risk (OAR) were analyzed. BM parameters: V10, V20, V30, V40, mean, maximum and minimum dose were compared. Results: PTV coverage was comparable in all techniques. VMAT plans resulted in superior BM sparing compared with N-IMRT plan (P-<0.001) and BMS-IMRT plan (P-<0.001, 0.021 and 0.001 respectively for V20, V30 and V40). VMAT plans had better CI compared with BMS-IMRT (P-0.002) and N-IMRT (P-0.001) plans. Our study adds to the growing evidence that VMAT might be the preferred technique for patients with carcinoma of the cervix undergoing concurrent chemoradiotherapy, as it provides comparable target coverage and better sparing of bone marrow compared to IMRT.

Effective Feature Information Identification of Sugarcane Based on Hybrid Deep Learning Models

Highlights MobileNetV3+U-Net lightweight network improves sugarcane segmentation accuracy and speed. The image processing algorithm removes interference information from the predicted sugarcane segmentation images. Improved YOLOX network enhances the accuracy of sugarcane stem node detection and provides better visualization. Hybrid deep learning models are utilized to extract complete feature information required for sugarcane harvesting. Abstract. The efficiency of intelligent sugarcane harvesters in harvesting depends on the effectiveness of identifying and locating the sugarcane during the harvesting process. In the actual harvesting process, accurately extracting valid features of sugarcane amidst the dense and interwoven sugarcane becomes a challenging task. To address this issue, we propose a hybrid deep learning approach to extract sugarcane stem contours and internal stem node feature information from sugarcane efficiently in the context of a complex harvest. Firstly, this study combined the MobileNetV3 and U-Net networks to segment overall images that contain information about the external contours of the sugarcane stem. Then, the extracted overall profile images were optimized using a variety of image processing techniques to meet the requirements of harvesting. Lastly, the improved YOLOX model was utilized to identify the internal stem node features of sugarcane from the optimized overall images. The experimental results on a real sugarcane dataset show that the proposed external sugarcane stem segmentation model achieves a high mean intersection over union (MIoU) of 91.68% with an average segmentation time of just 0.025 seconds. Moreover, the proposed model for internal stem node recognition in sugarcane achieves an average precision (AP) of 96.19% with an average detection time of 0.026 seconds. Additionally, this study compares image segmentation models such as PSPNet and DeepLabv3+ with target detection models such as YoloV5 and YoloV7. The experimental results show that the sugarcane feature extraction models proposed in this article all exhibit high accuracy and robustness.

Nondestructive testing of internal defects by ring-laser-excited ultrasonic

ABSTRACT To improve the excitation efficiency, detection utilisation rate, and signal-to-noise ratio of the laser ultrasonic non-destructive testing of internal defects, the spatial distribution of the excitation light source was changed to a ring-shaped laser source to excite ultrasound. Finite element analysis method was used to simulate and analyse the ultrasonic characteristics excited by the ring laser. The superposition of shear waves on the central axis of a ring laser exhibits considerable advantages for internal defect detection. Consequently, a method was proposed for detecting internal defects using a ring laser to excite and receive ultrasonic waves at the concentric and opposite positions of the ring laser. A ring-source laser ultrasonic detection system was designed to scan and detect circular hole defects with different diameters as well as crack defects with different depths, lengths, and inclination angles. The experimental results showed that the ring-source laser ultrasonic technique could effectively detect defect positions and depths and describe the defect length and external contour under certain conditions. Moreover, it could achieve more complex detection tasks. This study provides an effective reference for the application of laser ultrasonic non-destructive testing of internal defects.

A quantitative framework for patient-specific collision detection in proton therapy.

Beam modifying accessories for proton therapy often need to be placed in close proximity of the patient for optimal dosimetry. However, proton treatment units are larger in size and as a result the planned treatment geometry may not be achievable due to collisions with the patient. A framework that can accurately simulate proton treatment geometry is desired. A quantitative framework was developed to model patient-specific proton treatment geometry, minimize air gap, and avoid collisions. The patient's external contour is converted into the International Electrotechnique Commission (IEC) gantry coordinates following the patient's orientation and each beam's gantry and table angles. All snout components are modeled by three-dimensional (3D) geometric shapes such as columns, cuboids, and frustums. Beam-specific parameters such as isocenter coordinates, snout type and extension are used to determine if any point on the external contour protrudes into the various snout components. A 3D graphical user interface is also provided to the planner to visualize the treatment geometry. In case of a collision, the framework's analytic algorithm quantifies the maximum protrusion of the external contour into the snout components. Without a collision, the framework quantifies the minimum distance of the external contour from the snout components and renders a warning if such distance is less than 5cm. Three different snout designs are modeled. Examples of potential collision and its aversion by snout retraction are demonstrated. Different patient orientations, including a sitting treatment position, as well as treatment plans with multiple isocenters, are successfully modeled in the framework. Finally, the dosimetric advantage of reduced air gap enabled by this framework is demonstrated by comparing plans with standard and reduced air gaps. Implementation of this framework reduces incidence of collisions in the treatment room. In addition, it enables the planners to minimize the air gap and achieve better plan dosimetry.

Adding a Small Field of View for Increased Resolution in Contouring: An Effective and Quick Method

Image resolution is paramount when contouring complex anatomy, as in head and neck planning. It is notable that when diagnostic radiologists perform a computed tomography scan of the neck, they always use a small field of view because it gives the best image resolution. When planning for radiation treatment, however, it is also necessary to have a large field of view to provide a comprehensive external contour that allows for radiation dose calculation. We present a simple method to obtain both small and large fields of view at the time of computed tomography simulation.

Второй этап формирования исламского права в Мавераннахре периода предмодерна: свидетельство рукописей

The collapse of the Timurid empire set in motion the complex mechanisms of the political reorgani-zation of Eurasia and led to the emergence of new political formations. The nomadic dynasty, Shi-banids Abu’l-khayrids (906–1007/1500–99), having established their power in Maverannahr, though powerful, but still a marginal stratum, as the Qarakhanids (381/606–991/1209), sought to reinforce their influence and authority. Both dynasties staked their claim on Sunni orthodoxy, which unified the basis of societal development. The struggle on the external contour against Shi’ism, which be-came the state ideology of Iran, required a reaffirmation of their legitimacy as an “al-firqa al-nājiyya”. In their state management, they needed a strong legal base. The region’s dominant Hanafi interpretative community, ulama, and faqihs launched a process of rethinking the Islamic legal her-itage. Ву identifying manuscripts of legal works in research holdings of Tajikistan and Uzbekistan, the author attempts to outline the corpus of writings that could help more accurately recreate the political-legal sphere of the Abu’l-khayrids khanate in the era considered as the second stage in the formation of Islamic law in pre-modern Eurasia.

Systematic Review and Meta-Analysis of Nonoperative Management for SVS Grade II Blunt Traumatic Aortic Injury

SVS Grade II blunt traumatic aortic injury is defined as intramural hematoma with or without external contour abnormality. It is uncertain whether this aortic injury pattern should be treated with endovascular stent-grafting or nonoperative measures. Since the adoption of the SVS Guidelines on endovascular repair of blunt traumatic aortic injury, the practice pattern for management of grade II injuries has been heterogenous. The objective of the study was to report natural history outcomes of grade II blunt traumatic aortic injury. A systematic review of published traumatic aortic injury studies was performed. Online database searches were current to November 2022. Eligible studies included data on aortic injuries that were both managed nonoperatively and classified according to the SVS 2011 Guidelines. Data points on all-cause mortality, aorta-related mortality and early aortic intervention were extracted and underwent meta-analysis. The methodology was conducted in accordance with PRISMA guidance. Thirteen studies were included in the final analysis with a total of 204 cases of SVS grade II blunt traumatic aortic injury treated nonoperatively. The outcomes rates were estimated at 10.4% (95% CI 6.7% - 14.9%) for all-cause mortality, 2.9% (95% CI 1.1% - 5.7%) for aorta-related mortality and 3.3% (95% CI 1.4% - 6.2%) for early aortic intervention. The studies included in the analysis were of fair quality with a mean Downs and Black score 15 (±1.8). Grade II blunt traumatic aortic injury follows a relatively benign course with few instances of aortic-related mortality. Death in the setting of this injury pattern is more often attributable to sequelae of multisystem trauma and not directly related to aortic injury. The current data supports nonoperative management and imaging surveillance for grade II blunt traumatic aortic injury instead of endovascular repair. Longer-term effects on the aorta at the site of injury are unknown.

A Photograph-Based Visualization and Prediction Framework for Radiation-Induced Dermatitis.

This study aimed to suggest a photograph-based prediction system for acute radiation-induced dermatitis (RID), which can be applied to notify patients about the risk of the development of skin discomfort during radiotherapy. The proposed system compared the spatial dose distribution with the RID region using the following methods. Skin photographs of patients were taken using an RGB-depth camera to acquire the shape information of RID. The skin surface data measured from the camera was registered with the shape of the external body contour using an iterative closest point algorithm. Spatial dose distribution of skin was extracted from the external body contour to a depth of 2 mm and projected onto the plane of the skin photograph using a transformation matrix for skin depth data. To compare the spatial distribution of skin dose with the shape of RID, the region of RID in patients' skin was delineated on photographs into three toxicity symptoms referring to the CTCAE criteria grade 1 (skin redness), grade 2 (dry desquamation), and grade 3 (moist desquamation). The degree of overlap between the shape of each RID and skin dose distribution was evaluated using the dice similarity coefficient (DSC). Threshold doses for predicting RID occurrence were estimated by skin isodose lines with the highest DSC. The developed system was validated using data from 19 patients who received volumetric modulated arc therapy for head-neck cancer at a single institution. Threshold doses for RID grades 1, 2, and 3 were estimated using 18, 18, and 2 individual RID labels delineated on skin photographs, respectively. Isodose lines with the highest DSC for RID grades 1, 2, and 3 were calculated as 26.0 Gy, 36.5 Gy, and 54.0 Gy, respectively. A strong overlap (average DSC > 0.6) was observed between isodose skin lines and the shape of RID labels in all RID grades. Assessing the spatial information of skin dose can be helpful in predicting acute RID. The region of RID shows a strong similarity with the skin dose distribution in head-neck patients. Visualization of skin dose on the patient photograph is potent to patient education for preparing the cosmetic discomfort during radiotherapy, which may lead to the improvement of the patient satisfaction in treatment.

Unsupervised registration of 3D knee implant components to biplanar X-ray images

BackgroundRegistration of three-dimensional (3D) knee implant components to radiographic images provides the 3D position of the implants which aids to analyze the component alignment after total knee arthroplasty.MethodsWe present an automatic 3D to two-dimensional (2D) registration using biplanar radiographic images based on a hybrid similarity measure integrating region and edge-based information. More precisely, this measure is herein defined as a weighted combination of an edge potential field-based similarity, which represents the relation between the external contours of the component projections and an edge potential field estimated on the two radiographic images, and an object specificity property, which is based on the distinction of the region-label inside and outside of the object.ResultsThe accuracy of our 3D/2D registration algorithm was assessed on a sample of 64 components (32 femoral components and 32 tibial components). In our tests, we obtained an average of the root mean square error (RMSE) of 0.18 mm, which is significantly lower than that of both single similarity methods, supporting our hypothesis of better stability and accuracy with the proposed approach.ConclusionOur method, which provides six accurate registration parameters (three rotations and three translations) without requiring any fiducial markers, makes it possible to perform the important analyses on the rotational alignment of the femoral and tibial components on a large number of cases. In addition, this method can be extended to register other implants or bones.

The influence of patient positioning and immobilization equipment on MR image quality and image registration in radiation therapy.

MRI is preferred for brain tumor assessment, while CT is used for radiotherapy simulation. This study evaluated immobilization equipment's impact on CT-MRI registration accuracy and MR image quality in RT setup. We included CT and MR images from 11 patients with high-grade glioma, all of whom were immobilized with a thermoplastic mask and headrest. T1- and T2-weighted MR images were acquired using an MR head coil in a diagnostic setup (DS) and a body matrix coil in RT setup. To assess MR image quality, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were considered in some dedicated regions of interest. We also evaluated the impact of immobilization equipment on CT-MRI rigid registration using line profile and external contour methods. The CNR and SNR reduction was in the RT setup of imaging. This was more evident in T1-weighted images than in T2-weighted ones. The SNR decreased by 14.91% and 12.09%, while CNR decreased by 25.12% and 20.15% in T1- and T2-weighted images, respectively. The immobilization equipment in the RT setup decreased the mean error in rigid registration by 1.02mm. The external contour method yielded Dice similarity coefficients (DSC) of 0.84 and 0.92 for CT-DS MRI and CT-RT MRI registration, respectively. The image quality reduction in the RT setup was due to the imaged region's anatomy and its position relative to the applied coil. Furthermore, optimizing the pulse sequence is crucial for MR imaging in RT applications. Although the use of immobilization equipment may decrease the image quality in the RT setup, it does not affect organ delineation, and the image quality is still satisfactory for this purpose. Also, the use of immobilization equipment in the RT setup has increased registration accuracy.

A technique to convert a 3D printed cast used in the fabrication of an interim implant-supported crown into a definitive cast capturing the acquired emergence profile.

An esthetic peri-implant soft tissue contour is a critical element of the success of implant restorations in the esthetic zone. Once the optimal transmucosal soft tissue profile is formed, it needs to be accurately replicated on the master cast. This clinical technique involves the utilization of a silicone putty positioning index placed in the patient's mouth to accurately duplicate the external contour of teeth and soft tissue. By combining this positioning index with the implant-supported interim crown, the 3D-printed initial cast, which was used to fabricate the interim crown, can be conveniently and efficiently transformed into a definitive master cast.

Localization of image fragments with high frequency intensity oscillation

&lt;p&gt;The problem of detecting image fragments characterized by high-frequency fluctuations in spatial intensity in the general case has not been previously considered in the literature. The article researches a sequence of known and new algorithms that allows detection and localization of such fragments. The geometric localization of the fragments is based on the Hough transform of the pixel array of the external contours of the connected components. The components connecting becomes possible due to the use of the oscillation function proposed by the authors. The oscillation function turns out to be an effective tool for highlighting intensity fluctuations zones in an image and is superior in reliability to alternative methods for detecting such zones, based, for example, on gradient methods. The article demonstrates examples of localization of the image fragments with different levels of background complexity.&lt;/p&gt;

The Optimization of Welding Spots’ Arrangement in A-Pillar Patchwork Blank Hot Stamping

With increasingly severe environmental problems, energy saving and environmental protection have become two important issues to be solved in the automobile industry. Patchwork blank hot-stamping technology can be used to obtain light-weight and high-strength parts and is thus increasingly used in the manufacture of autobody parts. Because the main blank and the patched blank need to be connected through spot welding before forming, the welding spots’ arrangement has a great influence on the formability of the part. In this study, a thermal–mechanical coupling finite element analysis model of A-pillar patchwork blanks was established. With the thickness of the patched blank, the distance between the welding spot and the external contour of the patched blank, and the number of welding spots as optimization variables, together with the maximum thinning rate and the maximum welding spot force as objectives, the influence of welding spot arrangement on forming quality was analyzed, and the welding spots’ arrangement was optimized using a central composite design (CCD), the response surface method (RSM), and the genetic algorithm (GA). The results showed that when the initial welding spot was located close to the contour of the patched blank, the bending moment was greater when the weld spot passed through the die corner, leading to the rupture of the welding spot or its surrounding base material due to the greater thinning rate. When the patched blank was thicker than the main blank, the main blank cracked during the forming process due to a greater increase in the thinning rate. The optimal solution of the weld spot arrangement on the A-pillar patchwork blanks was a 1.2 mm thick main blank, 0.8 mm thick patched blank, a distance of 29 mm between the weld spot and the contour line of the patched blank, and 16 weld spots. Hot-stamping experiments were conducted using the optimized weld spots’ arrangement, and high-quality parts were obtained.

3D biplanar reconstruction of lower limbs using nonlinear statistical models.

Three-dimensional (3D) reconstruction of lower limbs is of great interest in surgical planning, computer assisted surgery, and for biomechanical applications. The use of 3D imaging modalities such as computed tomography (CT) scan and magnetic resonance imaging (MRI) has limitations such as high radiation and expense. Therefore, three-dimensional reconstruction methods from biplanar X-ray images represent an attractive alternative. In this paper, we present a new unsupervised 3D reconstruction method for the patella, talus, and pelvis using calibrated biplanar (45- and 135-degree oblique) radiographic images and a prior information on the geometric/anatomical structure of these complex bones. A multidimensional scaling (MDS)-based nonlinear dimensionality reduction algorithm is applied to exploit this prior geometric/anatomical information. It represents relevant deformations existing in the training set. Our method is based on a hybrid-likelihood using regions and contours. The edge-based notion represents the relation between the external contours of the bone projections and an edge potential field estimated on the radiographic images. Region-based notion is the non-overlapping ratio between segmented and projected bone regions of interest (RoIs). Our automatic 3D reconstruction model entails stochastically minimizing an energy function allowing an estimation of deformation parameters of the bone shape. This 3D reconstruction method has been successfully tested on 13 biplanar radiographic image pairs, yielding very promising results.