Laser Surface Scanning Research Articles

Temporal lobe evolution in Hominidae and the origin of human lobe proportions.

Objectives Evolutionary changes in hominin social complexity have been associated with increases in absolute brain size. The temporal lobes are nestled in the middle cranial fossae (MCF) of the skull, the dimensions of which allow estimation of temporal lobe volume (TLV) in extant and fossil taxa. Materials and Methods The main aim of this study is to determine where along the hominid phylogeny, major temporal lobe size transitions occurred. We used computed tomography (CT) scans of crania, 3D photogrammetry data, and laser surface scans of endocranial casts to measure seven MCF metrics in 11 extant anthropoid taxa using multiple regressions to estimate TLV in 5 extant hominids and 10 fossil hominins. Phylogenetic comparative methods mapped temporal lobe size, brain size, and temporal lobe proportions onto phylogenetic trees broadly for Hominidae and specifically for Hominini. Results Extant Homo sapiens were not an outlier in relative brain size, temporal lobe size, or proportions of the temporal lobes, but some proportions within the lobe were uniquely altered. The most notable changes in relative temporal lobe size and proportions saw a decrease in relative temporal lobe size and proportions in the genus Pan compared to other extant great apes and fossil hominins while there was a relative increase in the temporal lobe width and length in Australopithecus-Paranthropus clade compared to the genus Homo and other extant great apes including modern humans. Discussion We do not find support for the social brain, environmental or functional craniology hypotheses alone but think it prudent to consider the implications of cerebral reorganization between the temporal lobes and other regions of the brain within the context of these hypotheses and with future investigation is warranted.

Mathematical Modeling for Robot 3D Laser Scanning in Complete Darkness Environments to Advance Pipeline Inspection

This paper introduces an autonomous robot designed for in-pipe structural health monitoring of oil/gas pipelines. This system employs a 3D Optical Laser Scanning Technical Vision System (TVS) to continuously scan the internal surface of the pipeline. This paper elaborates on the mathematical methodology of 3D laser surface scanning based on dynamic triangulation. This paper presents the mathematical framework governing the combined kinematics of the Mobile Robot (MR) and TVS. It discusses the custom design of the MR, adjusting it to use of robustized mathematics, and incorporating a laser scanner produced using a 3D printer. Both experimental and theoretical approaches are utilized to illustrate the formation of point clouds during surface scanning. This paper details the application of the simple and robust mathematical algorithm RANSAC for the preliminary processing of the measured point clouds. Furthermore, it contributes two distinct and simplified criteria for detecting defects in pipelines, specifically tailored for computer processing. In conclusion, this paper assesses the effectiveness of the proposed mathematical and physical method through experimental tests conducted under varying light conditions.

Acid-etched fracture morphology and conductivity of acid fracturing in carbonate rock using novel isolation membrane acid

In recent years, low-viscosity isolation membrane acid (ISM acid) has emerged as a novel retardant acid for matrix acidizing and acid-fracturing in carbonate reservoir. Its ability to create long wormholes in carbonate rock has been extensively studied, while its potential to etch hydraulic fracture and generate conductivity has received less attention. To address the knowledge gap, a series of experiments were conducted in this study, including rheological test, acid-etching simulation experiments, surface laser scanning of acid-fractures, and conductivity tests. The differences in rheological characteristics between ISM acid, blank HCl acid, and gelled acid were compared across different lithology along with the morphology and conductivity of the etched fractures. The viscosity of ISM acid is found to be nearly identical to that of blank HCl, which is 1/26th that of gelled acid. However, the acid-rock reaction rate of ISM acid is only 46–55% compared to blank HCl acid. In dolomite formations, the rate approximates that of gelled acid but is lower in limestone formations, indicating a strong ability for low-viscosity retarding. The heterogeneity of ISM acid etching morphology approaches that of blank HCl acid but exhibits greater retard strength than gelled acid. Under medium to high closure pressure (10–30 MPa), ISM acid generates higher conductivity and better retention ability. This study provides certain guidance for the design of ISM acid fracturing in carbonate reservoir.

تأثير مدخلات الليزر Nd-YAG)) على الصلادة لصلب العدة عند درجات مختلفة من الخشونة السطحية

This research study focuses on the experimental analysis of surface hardening with laser rays for a sample of tool steel 1.2379 at different surface roughness's and laser parameters.The sample was received in an annealed condition with hardness value of 220 HV. The purpose of the experiment was to determine the effect of surface roughness and laser scanning speed on the surface hardness of the sample and the depth of the molten layer. The results showed that the surface roughness and laser scanning speed influenced the depth and hardness of the provided surface. It was observed that at slower scanning speed and a higher surface roughness, a higher hardness and a deeper cured layer thickness were achieved. A maximum surface hardness of 662 HV was achieved using a laser power of 75 W, a laser spot diameter of 0.5 mm, a pulse rate of 80 kHz, a laser processing speed of 1 mm/s, and at the higher surface roughness. Keywords: Tool Steel, Laser Surface Hardening, Surface Roughness, Microhardness, Scanning Speed.

Evaluation of the External Soft Tissue Changes Following the Correction of Class II Skeletal Malocclusion in the Adolescence Period Using Removable and Fixed Functional Appliances: A Systematic Review and Meta-Analysis.

In this systematic review, we aimed to assess the current evidence regarding the effectiveness of functional treatment with both removable and fixed appliances to normalize the external soft tissue for skeletal class II adolescent individuals. We performed a broad electronic search to retrieve relevant studies from nine databases to identify randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that investigated soft tissue changes following functional treatment and evaluated the changes using 2D lateral cephalometric radiographsand 3D-optical surface laser scanning. A total of three RCTs and eight CCTs were included. Ages ranged from 11 to 16 years with the fixed functional appliances, and from eight to 12 years with the removable ones, including 689 skeletal class II patients. Version 2 of Cochran's risk-of-bias (RoB2), and the risk of bias in non-randomized studies of interventions (ROBIN-I) were used to assess the risk of bias for the included papers. Of the 11 eligible studies, three studies were included in the meta-analysis to assess the upper and lower lip position in relation to the E-line (Ricketts's aesthetic line) in addition to the nasolabial angle. The meta-analysis showed that the upper lip retracted after functional treatment with Twin-block in relation to E-line (mean difference (MD) = -1.93; 95% CI: -2.37, -1.50; p < 0.00001; χ² = 5.43; p = 0.07; I2 = 63%), while the lower lip position did not change after functional treatment with Twin-block in relation to E-line (MD = 0.03; 95% CI: -0.56, 0.61; p = 0.92; χ² = 1.74; p = 0.42; I2 = 0%). The nasolabial angle increased after Twin-block treatment (MD = 5.75; 95% CI: 4.57, 6.93;p < 0.00001; χ² = 6.77; p = 0.03; I2 = 70%). The mentolabial angle and Z-angle also increased after functional therapy, where the facial convexity angle decreased, regardless of the functional devices used. On the other hand, using the 3D-optical surface laser scanning showed that the upper lip length and the commissural width did not change following therapy, but the lower lip increased in length, as well as the total face height. More high-quality RCTs are required to obtain accurate evidence in this field.

Superhydrophobic, antibacterial, and EMI shielding properties of Ag/PDMS-coated cotton fabrics

In this study, three functionalities of superhydrophobicity, antibacterial activity and electromagnetic interference (EMI) shielding of cotton fabrics coated with Ag/PDMS were studied, and the role of coating composition was discussed. Special attention was paid to understanding the relationships between the surface roughness of coated fibres with the developed superhydrophobicity and antibacterial activity. The superhydrophobicity of fabrics was analysed based on water contact angle (WCA) and contact angle hysteresis (CAH) values while the antibacterial activity was tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. It was found that the surface roughness on fibres, which changed by altering the concentrations of Ag NPs (0.2–4 g/L) and PDMS (20 and 40 g/L), affected the obtained superhydrophobicity. The most superhydrophobic fabric (WCA 171°) was coated with a formulation containing Ag NPs (2 g/L), and PDMS (20 g/L), and had the highest surface roughness. Increasing the ingredients’ concentrations, however, deteriorated the optimum roughness as measured using a 3D Surface Laser Scanning Microscopy method. The coated fabrics showed efficacy against both types of bacteria, and it was confirmed that the Ag NPs content was the key factor in determining the antibacterial performance. Moreover, testing the EMI shielding performance of fabrics demonstrated that increasing the concentrations of Ag NPs and PDMS both enhanced the reflection coefficient (R) of fabrics against incident X-band electromagnetic (EM) wave by around >500%, which was due to the deposition of a higher amount of Ag NPs on fabrics. The superhydrophobicity of fabrics was durable after 1000 abrasion cycles, and the fabrics retained their antibacterial activity even after numerous washings.Graphical

Adaptive Ant Colony Optimization with Sub-Population and Fuzzy Logic for 3D Laser Scanning Path Planning.

For the precise measurement of complex surfaces, determining the position, direction, and path of a laser sensor probe is crucial before obtaining exact measurements. Accurate surface measurement hinges on modifying the overtures of a laser sensor and planning the scan path of the point laser displacement sensor probe to optimize the alignment of its measurement velocity and accuracy. This manuscript proposes a 3D surface laser scanning path planning technique that utilizes adaptive ant colony optimization with sub-population and fuzzy logic (SFACO), which involves the consideration of the measurement point layout, probe attitude, and path planning. Firstly, this study is based on a four-coordinate measuring machine paired with a point laser displacement sensor probe. The laser scanning four-coordinate measuring instrument is used to establish a coordinate system, and the relationship between them is transformed. The readings of each axis of the object being measured under the normal measuring attitude are then reversed through the coordinate system transformation, thus resulting in the optimal measuring attitude. The nominal distance matrix, which demonstrates the significance of the optimal measuring attitude, is then created based on the readings of all the points to be measured. Subsequently, a fuzzy ACO algorithm that integrates multiple swarm adaptive and dynamic domain structures is suggested to enhance the algorithm's performance by refining and utilizing multiple swarm adaptive and fuzzy operators. The efficacy of the algorithm is verified through experiments with 13 popular TSP benchmark datasets, thereby demonstrating the complexity of the SFACO approach. Ultimately, the path planning problem of surface 3D laser scanning measurement is addressed by employing the proposed SFACO algorithm in conjunction with a nominal distance matrix.

Assessment of Residual Stresses in Laser Powder Bed Fusion Manufactured IN 625.

Residual stresses pose significant challenges in the powder bed fusion of metals using a laser (PBF-LB/M), impacting both the dimensional accuracy and mechanical properties. This study quantitatively analyzes deformation and residual stresses in additively manufactured Inconel 625. Investigating both as-built and stress-relieved states with varied scanning strategies (90°, 67°, strip, and 90° chessboard) in PBF-LB/M/IN625, distortion is evaluated using the bridge curvature method. Quantitative measurements are obtained through 3D laser surface scanning on pairs of bridge specimens-one measured before and after detachment from the build plate, and the other undergoing stress-relieving heat treatment at 870 °C for 1 h. The findings reveal that, among as-built specimens, the 90° and 90° strip strategies induce the least distortion, followed by the 67° and chessboard 90° strategies. Furthermore, stress-relief treatment significantly reduces residual stress levels. After post-treatment, the deformation in X-axis samples with 90° and 90° strip strategies decreases by 39% and 42%. In contrast, the samples with the 67° and 90° checkerboard strategies exhibit more pronounced reductions of 44% and 63%, respectively. These quantitative results contribute useful insights for optimizing PBF-LB/M/IN625 processes in additive manufacturing.

Relationship between bite force, occlusal contact area, and three-dimensional facial soft tissue in dentofacial deformities.

This study aimed to investigate three-dimensional facial soft tissue dimensions, maximum bite force (MBF), and occlusal contact area in patients with DFD. In addition, we analyzed the relationship between MBF and the three-dimensional facial measurements. Thirty-two patients with skeletal Class III DFD and 20 patients with Class II DFD underwent a soft tissue evaluation using surface laser scanning, as well as MBF and occlusal contact area assessments. The DFD groups were compared with each other and with 25 healthy subjects. Significant morphological differences were found in the transversal, vertical, and anteroposterior dimensions between Class II DFD and Class III DFD. Both DFD groups presented an increased linear distance of chin height, which was strongly related with decreased MBF magnitude. The DFD groups exhibited lower MBF and occlusal contact area, with no significant differences between Class II and Class III DFD. The presence of DFD affected 3D measurements of facial soft tissue, causing variations beyond normal limits, lower MBF, and occlusal contact area in both Class II and Class III DFD patients. The vertical dimension might have influenced the lower MBF magnitude in the studied skeletal deformities.

Biomechanical comparative finite element analysis between a conventional proximal interphalangeal joint flexible hinge implant and a novel implant design using a rolling contact joint mechanism

BackgroundThe rolling contact joint (RCJ) mechanism is a system of constraint that allows two circular bodies connected with flexible straps to roll relative to one another without slipping. This study aims to compare the biomechanical characteristics between the conventional proximal interphalangeal joint (PIPJ) flexible hinge (FH) implant and the novel PIPJ implant adopting a RCJ mechanism during PIPJ range of motion using finite element (FE) analysis.MethodsThe three-dimensional (3D) surface shape of a conventional PIPJ FH implant was obtained using a 3D laser surface scanning system. The configuration and parameters of the novel PIPJ implant were adapted from a previous study. The two implants were assumed to have the same material characteristics and each implant was composed of a hyperelastic material, silicone elastomers. The configuration data for both implants were imported to a computer-aided design program to generate 3D geometrical surface and hyperelastic models of both implants. The hyperelastic models of both implants were imported into a structural engineering software to produce the FE mesh and to perform FE analysis. The FE analysis modeled the changes of mechanics during flexion–extension motion between 0° and 90° of two PIPJ implants. The mean and maximum values of von-Mises stress and strain as well as the total moment reaction based on the range of motion of the PIPJs were calculated. The mean values within the PIPJ’s functional range of motion of the mean and maxinum von-Mises stress and strain and the total moment reaction were also determined.ResultsThe maximum values for the von-Mises stress, and strain, as well as the total moment reactions of the conventional PIPJ FH and novel PIPJ implants were all at 90° of PIPJ flexion. The maximum value of each biomechanical property for the novel PIPJ implant was considerably lower compared with that of the conventional PIPJ FH implant. The mean values within the PIPJ’s functional range of motion of the maximum von-Mises stress and strain for the novel PIPJ implant was approximately 6.43- and 6.46-fold lower compared with that of the conventional PIPJ FH implant, respectively. The mean value within a PIPJ’s functional range of motion of the total moment reaction of the novel PIPJ implant was approximately 49.6-fold lower compared with that of the conventional PIPJ FH implant.ConclusionsThe novel PIPJ implant with an RCJ mechanism may offer improved biomechanical performance compared with conventional PIPJ FH implant.

Looking back over the shoulder: New insights on the unique scapular anatomy of the tapir (Perissodactyla: Tapiridae).

The musculoskeletal anatomy of the shoulder of many ungulates has been inferred from veterinary model taxa, with uniformity in muscle arrangements and attachment sites often assumed. In this study, I investigated the muscular and osteological anatomy of tapirs and their relatives (Perissodactyla: Tapiroidea), using a combination of gross dissection and digital imaging (photography and laser surface scanning). Dissections of three modern tapir species revealed that the m. infraspinatus originates from both supraspinous and infraspinous fossae for all species, lying on both sides of the distal scapular spine. The epimysial border between the m. supraspinatus and m. infraspinatus origin sites are marked in all species by an ossified ridge, sometimes extending the length of the scapular spine. This "supraspinous ridge" is clearly visible on the scapular surface of both modern and extinct Tapirus scapulae; however, the ridge does not appear present in any non-Tapirus tapiroids examined (e.g., Helaletes, Nexuotapirus), nor in other perissodactyls or artiodactyls. Moreover, the ridge exhibits a clearly distinct morphology in Tapirus indicus compared to all other Tapirus species examined. Combined, these findings indicate that the presence and position of the "supraspinous ridge" may represent a robust phylogenetic character for reconstructing relationships within tapiroids. Unfortunately, any functional locomotor outcomes or benefits of the m. infraspinatus straddling the scapular spine remains elusive. This study represents a firm reminder for anatomists, veterinarians, and paleontologists to (where possible) look beyond veterinary model systems when inferring musculoskeletal form or function in non-model organisms.

Heparin-collagen I bilayers stimulate FAK/ERK½ signaling via α2β1 integrin to support the growth and anti-inflammatory potency of mesenchymal stromal cells.

Understanding mesenchymal stromal cells (MSCs) growth mechanisms in response to surface chemistries is essential to optimize culture methods for high-quality and robust cell yields in cell manufacturing applications. Heparin (HEP) and collagen 1 (COL) substrates have been reported to enhance cell adhesion, growth, viability, and secretory potential in MSCs. However, the biomolecular mechanisms underlying the benefits of combined HEP/COL substrates are unknown. This work used HEP/COL bilayered surfaces to investigate the role of integrin-HEP interactions in the advantages of MSC culture. The layer-by-layer approach (LbL) was used to create HEP/COL bilayers, which were made up of stacks of 8 and 9 layers that combined HEP and COL in an alternate arrangement. Surface spectroscopic investigations and laser scanning microscopy evaluations verified the biochemical fingerprint of each component and a total stacked bilayer thickness of roughly 150 nm. Cell growth and apoptosis in response to IC50 and IC75 levels of BTT-3033 and Cilengitide, α2β1 and αvβ3 integrin inhibitors respectively, were evaluated on HEP/COL coated surfaces using two bone marrow-derived MSC donors. While integrin activity did not affect cell growth rates, it significantly affected cell adhesion and apoptosis on HEP/COL surfaces. HEP-ending HEP/COL surfaces significantly increased FAK-ERK½ phosphorylation and endogenous cell COL deposition compared to COL, COL-ending HEP/COL and uncoated surfaces. BTT-3033 but not Cilengitide treatment markedly affected FAK-ERK½ activity levels on HEP-ending HEP/COL surfaces supporting a major role for α2β1 activity. BTT-3033 treatment on HEP-ending bilayers reduced MSC-mediated macrophage inhibitory activity and altered the cytokine profile of co-cultures. Overall, this study supports a novel role for HEP in regulating the survival and potency of MSCs via enhancing the α2β1-FAK-ERK½ signaling mechanism.

An evaluation of concordance between linear measurements obtained from conventional, digital and reconstructed three-dimensional printed orthodontic models: An in vitro study

Abstract Objective: To evaluate the potential use of digital and reconstructed three-dimensional printed models as an alternative to conventional plaster models by assessing the accuracy of their linear measurements. Methodology: Pre-treatment plaster models of 45 patients were selected from the archives of the Department of Orthodontics. Each physical plaster model was scanned and digitized using a three-dimensional (3D) laser surface scanning system (inEOS X5, Dentsply Sirona, Bensheim, Germany). The scanned STL files were later used to reconstruct models by 3D printing using Figure4® standalone 3D printer (3D systems, Rock Hill, South Carolina). Measurements of teeth 11 and 16, the transverse width of the upper jaw between the first molars (MM - intermolar width) and canines (CC - intercanine width) were done manually using a digital vernier caliper (Mitutoyo, Kawasaki, Japan), and the CAD Assistant software (Open cascade, Guyancourt, France). Intra examiner data, Intraobserver variability, and measurement accuracy were evaluated using Intraclass Correlation Coefficient (ICC) analysis was done using SPSS 20.0. Results: The intraclass correlation coefficients were &gt;0.8 indicating high reproducibility and reliability. Significant differences were found between the physical and the digital models but to a small proportion which were deemed not clinically relevant. Conclusion: Both the digital models and reconstructed three-dimensional printed models using Figure4® technology were clinically permissible in terms of accuracy and reproducibility. The digital storage, transmission, and treatment planning in an environmentally friendly manner should promote digital over conventional records.

A Preliminary Exploratory Study of Autologous Fat Transplantation in Breast Augmentation With Different Fat Transplantation Planes.

BackgroundAutologous fat transfer is common in breast augmentationor reconstruction. However, AFG recipient site in the breast for fat grafting has not been carefully investigated.MethodsForty female patients requiring breast augmentation with fat grafting were randomly assigned into two groups. The retromammary group received 2/3 fat into the retromammary space and the other 1/3 into the subcutaneous and retropectoral planes. The retropectoral group received 2/3 fat into the retropectoral plane and the other 1/3 into the subcutaneous and retromammary planes. The fat grafting result at 6 months was assessed by 3D laser surface scanning and then ultrasound. Any complications were recorded during follow-up. Samples from a patient who underwent fat grafting for 6 months was obtained and histological examination was conducted.ResultsNo significant difference in the retention rate after 6 months was observed between the two groups (retromammary group: 35.9% ± 6.6; retropectoral group: 39.3% ± 5.1, p = 0.1076). The retromammary grouphad a higher incidence of oil cyst formation than the retropectoral group. Histological examination showed that there were more oil cysts and mac2 positive macrophage infiltration in the fat cells in retromammary group, while retropectoral group had more small-size adipocytes.ConclusionAlthough fat grafting into the retropectoral plane did not provide a superior fat graft retention rate, it did lower the incidence of complications. The retropectoral space show great potential to become a favorable recipient site.

Plasma Electroless Reduction: A Green Process for Designing Metallic Nanostructure Interfaces onto Polymeric Surfaces and 3D Scaffolds.

The design of metal nanoparticle-modified polymer surfaces in a green and scalable way is both desirable and highly challenging. Herein, a new green low-temperature plasma-based in situ surface reduction strategy termed plasma electroless reduction (PER) is reported for achieving in situ metallic nanostructuring on polymer surfaces. Proof of concept for this new method was first demonstrated on hydrophilic cellulose papers. Cellulose papers were dip-coated with different metal ion (Ag+ and Au3+) solutions and then subjected to hydrogen plasma treatment for this PER process. Transmission electron microscopy (TEM) analysis has revealed that this PER process caused anisotropic growth of either gold or silver nanoparticles, resulting in the time-dependent formation of both distinct spherical nanoparticles (∼20 nm) and anisotropic 2D nanosheets. Furthermore, we have demonstrated the adaptability of this process by applying it to hydrophobic fibrous and 3D printed polymeric materials such as surgical face masks and 3D printed polylactic acid scaffolds. The PER process on these hydrophobic polymer surfaces was accomplished via a sequential combination of air plasma and hydrogen plasma treatment. The metallic nanostructuring caused by the PER process on these hydrophobic surfaces was systematically studied using different surface imaging techniques including 3D confocal laser surface scanning microscopy and scanning electron microscopy. We have also systematically optimized the PER process on the surface of 3D scaffolds via varying the concentration of the silver ion precursor and by different postprocessing methods such as sonication and medium soaking. These optimization processes were found to be very important in generating uniform metallic nanoparticle-modified 3D printed scaffolds while simultaneously improving cytocompatibility. Through joint disk diffusion and inhibitory concentration testing, the antibacterial efficacy of silver coatings on face masks and 3D scaffolds was established. Altogether, these results clearly suggest the excellent futuristic potential of this new PER method for designing metallic nanostructured interfaces for different biomedical applications.

A Workflow for Digitizing Anatomical Specimens by Combining Photogrammetry and 3D Scanning

The 3D visualization of anatomical specimens relies on two main technologies: 3D laser surface scanning and photogrammetry (PGM). While 3D laser scanning provides the most accurate 3D model, photogrammetry provides the best, photorealistic surface texture. Typically, a specimen would be assessed to see which technology is best to capture it ‐ in this study we set out to investigate whether it is feasible to combine both methods, incorporating the advantages of both. Artec Space Spider scanner was used to capture accurate geometry of specimens and create a mesh with high polygon count and topological accuracy in Artec Studio 15, and Reality Capture was used to capture photographs around the specimen at regular 5 degree increments until the entire surface was captured to produce a high‐resolution textured mesh. The meshes were combined in Artec Studio 15 by matching their geometric centers in 3D space and ensuring that all polygons are precisely overlapped ‐ even a minor amount of deviation would result in blurry reprojection of texture. This is followed by mapping and reprojecting the PGM texture on the 3D scanned mesh (now aligned and scaled) in Reality Capture and cleaning up the produced texture map in Adobe Photoshop to ensure that any artifacts are cleaned up. Through this combination, models that gather ‘best of both worlds’ qualities from 3D scanning and photogrammetry ‐ laser accurate geometry and photorealism. We determined that 3D scanning is sufficient for specimens with simple texture, and photogrammetry is effective for specimens with complex texture and simple geometry; the combination method shines where great detail and high resolution texture is required to meet the learning objectives, such as organs and musculoskeletal specimens and other specimens with key topological details and colorations. Gathering both PGM and 3D scanning data allows for error correction, especially when performed in collaboration with a content expert and a 3D artist. Availability of these methods to produce photorealistic and accurate scans of specimens lends to accessibility of high quality online anatomy educational materials for students. This technology may also be useful in museum settings and to scan rare collections where to date a single method was not able to capture the complexity of the specimens.

Investigation of Scanning Strategies and Laser Remelting Effects on Top Surface Deformation of Additively Manufactured IN 625.

The main drawbacks of the Laser Powder Bed Fusion (LPBF) process are the surface quality and dimensional accuracy of manufactured parts due to the edge and corner effects. These effects can be diminished by using an appropriate balance of the process parameters and scanning strategies. This paper focuses on the assessment of reducing the edge and corner effects that occur in additively manufactured IN 625 alloy via the LPBF technique by varying the hatch angle rotation (by 45°, 67°, and 90°) and volumetric energy density (VED), and using the laser top surface remelting technique (LSR). The edge and corner effects of the cubic samples were quantitatively evaluated on the top surface by 3D laser surface scanning. It was found that the edge and corner effects became more pronounced in the cases of samples built with no contour and hatch angles of 45° and 67°, while the smallest deformations were obtained when the hatch angle was rotated by 90°. Moreover, the heights of both the edge and corner ridges increase as the number of remeltings passing the top layer increases. Conversely, when a lower VED was used for melting the top layer(s) of the samples, the edge and corner ridges were slightly reduced.

Application of digital guide plate based on drill-hole sharing in oral and maxillofacial surgery.

This study aimed to investigate the application of digital guide plate based on the drill-hole sharing concept in orthognathic surgery and mandibular reconstruction. Sixteen patients with maxillofacial deformity requiring orthognathic surgery and 10 patients requiring mandibular reconstruction were selected as the research objects. Patients with maxillofacial deformity were scanned by computed tomography (CT), gypsum mold of the maxilla and mandibular arch were scanned using a laser surface scanner, and the fibula or iliac bone of the patients who needed mandibular reconstruction were scanned by CT to create a 3D model. The osteotomy and repositioning guides based on the drill-hole sharing concept were manufactured by digital technology. The guide plate was used to guide osteotomy and reposition the bone segment. Postoperative CT scan was performed. The displacement error of the bone segment was compared between the preoperative virtual surgery and the actual surgery to evaluate the accuracy of the guide plate, by measuring the distance between the landmarks and three reference planes and the distance between the two landmarks. The wounds healed well in all patients, and no serious complications were observed. The maximum mean values of LeFort Ⅰ osteotomy, genioplasty, fibular reconstruction, and iliac reconstruction were 0.84, 0.64, 1.27, and 1.18 mm, respectively; these values were acceptable by clinical standards. The digital guide plate based on the drill-hole sharing concept has high accuracy and clinical application value in orthognathic surgery and mandibular reconstruction.

Evaluating the efficiency of isolated calvaria bones shape changes in the identification and differentiation of artificial cranial modification techniques among pre-Hispanic western and central Mesoamerican populations

IntroductionArtificial cranial modification (ACM) is a widespread cultural phenomenon that has been reported in human populations from Late Pleistocene to present day all over the world. Although ACM techniques have been documented in western and central Mesoamerica, the state of preservation of bone has occasionally limited the possibility of diagnosing and differentiating ACM variants. To explore how informative fragmentary skull remains can be in this matter, here we used 3D geometric morphometrics to quantify shape variation of isolated calvaria bones. Materials and Methods49 well preserved individuals from west and central Mesoamerica were selected and divided into five groups: four showing distinct forms of ACM, and a control group of unmodified skulls. Using medical computed tomography and laser surface scanning, we measured the 3D shape changes in three isolated calvaria bones. We calculated the morphological differences within and between groups by computing pairwise Procrustes distances for all possible combinations of individuals. Finally, we used 3D digital meshes to describe the shape changes in an ACM variant compared to the other ones and to the control group. ResultsIrrespective of which bone of the calvaria is considered, the variation between the individuals showing ACM and the unmodified individuals always exceeds the variation measured within the unmodified group. Furthermore, some ACM variants can be characterized by examining certain calvaria bones in isolation. DiscussionThe study of isolated calvaria bones can help to identify individuals with ACM from the background physiological variation. Our study also provides information pertaining to the techniques employed to produce certain ACM variants and we discuss the standardization of these processes.

Evaluation of four surface surrogates for modeling lung tumor positions over several fractions in radiotherapy

Patient breathing during lung cancer radiotherapy reduces the ability to keep a sharp dose gradient between tumor and normal tissues. To mitigate detrimental effects, accurate information about the tumor position is required. In this work, we evaluate the errors in modeled tumor positions over several fractions of a simple tumor motion model driven by a surface surrogate measure and its time derivative. The model is tested with respect to four different surface surrogates and a varying number of surrogate and image acquisitions used for model training. Fourteen patients were imaged 100 times with cine CT, at three sessions mimicking a planning session followed by two treatment fractions. Patient body contours were concurrently detected by a body surface laser scanning system BSLS from which four surface surrogates were extracted; thoracic point TP, abdominal point AP, the radial distance mean RDM, and a surface derived volume SDV. The motion model was trained on session 1 and evaluated on sessions 2 and 3 by comparing modeled tumor positions with measured positions from the cine images. The number of concurrent surrogate and image acquisitions used in the training set was varied, and its impact on the final result was evaluated. The use of AP as a surface surrogate yielded the smallest error in modeled tumor positions. The mean deviation between modeled and measured tumor positions was 1.9 mm. The corresponding deviations for using the other surrogates were 2.0 mm (RDM), 2.8 mm (SDV), and 3.0 mm (TP). To produce a motion model that accurately models the tumor position over several fractions requires at least 10 simultaneous surrogate and image acquisitions over 1–2 minutes.