Three-dimensional Scanning Technique Research Articles

Optical Three‐Dimensional Scanning Acquisition of the Position of Osseointegrated Implants: An in vitro Study to Determine Method Accuracy and Operational Feasibility

Manufacturing complex prosthetic framework on osseointegrated implants requires precision at every step of execution. The purpose of this study was to verify the possibility of applying the technology of image acquisition to determine the spatial position of osseointegrated implants. An optical three-dimensional scanning technique was employed: its measurement systematic error (bias) was calculated by comparing the results with the detection on a coordinates measuring machine. Measurements were carried out on master casts by doing an in vitro simulation of intraoral conditions. This study showed that the bias error value of the three-dimensional optical acquiring system was situated between 14 and 21 microm. As far as the accuracy is concerned, it seems possible to use the three-dimensional image acquisition technology as a valid alternative to traditional impression-making procedures. However, the bias levels obtained in this in vitro study will have to be confirmed in a clinical trial.

An experimental application of a 3D terrestrial laser scanner and acoustic techniques in assessing the quality of the stones used in monumental structures

This paper briefly describes the preliminary results of an experiment that aimed to test a new nondestructive methodology based on the integrated application of Three-Dimensional (3D) terrestrial laser scanning and acoustic techniques in the ultrasonic range (54 kHz) in evaluating the quality of stone materials. Our target is to evaluate the state of conservation of stone materials by correlating ultrasonic longitudinal pulse velocity and frequency spectra with the reflectivity or reflectance of the reflected 3D Laser Scanner (LS) beam pulse transmitted to a part of an investigated surface.

Clothing Air Gap Layers and Thermal Protective Performance in Single Layer Garment

A three-dimensional body scanning technique is used to measure the air gap layer distribution between different-sized protective garments and the body of a manikin used to evaluate garment thermal protective performance. The influence of fabric material and garment size on the manikin skin-clothing air gap layers existing in single layer thermally protective coveralls is analyzed. Protective performance of these garments is evaluated using the Manikin Thermal Protective Clothing Analysis System. Relationships between the burn patterns, measured on a flash fire manikin and measured manikin-garment air gap layers, are examined. The effects of thermally induced shrinkage as a result of flash fire exposure are discussed in comparisons between single layer protective coverall clothing made with heat resistant fabrics. An established numerical model is used to forecast the dimensions of skin-clothing air gap for optimum thermal protection.

Nanofluidics: Structural Forces, Density Anomalies, and the Pivotal Role of Nanoparticles

Cyclohexane is confined between two surfaces. Different types of confinement geometries are realized using different preparation protocols for mica surfaces. We profile thickness and refractive index of a nanometer-thin liquid film at high resolution with a newly developed three-dimensional scanning technique in the extended surface forces apparatus. We propose that the recently reported density anomalies in the thin liquid film are intimately coupled to the presence of local surface nonparallelism and nanoparticles that are produced during a widely used mica-cutting procedure. Measurements of cyclohexane confined between near parallel, nanoparticle-free mica surfaces contrast markedly with those reported in earlier studies.

Investigation and correlation of manikin and bench‐scale fire testing of clothing systems

AbstractThe US Army currently has five flame/thermal protective clothing systems to provide protection for soldiers against fire hazards. The protective performance of these clothing systems against burn injuries was investigated in full‐scale manikin tests. The protective performance of fabric layers of these clothing systems was also examined in bench‐scale tests. In addition, air gap thicknesses and distributions of the five clothing systems were determined by using a three‐dimensional laser scanning technique. In this paper, test conditions of the manikin and bench‐scale tests are compared, and the test results are correlated in light of the air gap measurements. The behavior of individual sensors on the manikin with similar test conditions to those of bench‐scale tests are compared with the bench‐scale tests. It is found that if the air gap distribution of a clothing system is known, bench‐scale tests could provide useful information for full‐scale performance, especially bench‐scale tests with zero air gap measurements. Published in 2002 by John Wiley & Sons, Ltd.

Three-dimensional work of fracture for mortar in compression

A high resolution three-dimensional scanning technique called X-ray microtomography was used to measure internal crack growth in small mortar cylinders loaded in uniaxial compression. Tomographic scans were made at different load increments in the same specimen. Three-dimensional image analysis was used to measure internal crack growth during each load increment. Load–deformation curves were used to measure the corresponding work of the external load on the specimen. Fracture energy was calculated using a linear elastic fracture mechanics approach, but using the actual surface area of internal cracks created. Preliminary results indicate fracture energies in the same range as those measured using traditional techniques.

Constitutive relationships of fabric, density, and elastic properties in cancellous bone architecture

The hypothesis that trabecular morphology can predict the elastic properties of cancellous bone has only partly been verified and no predictive analytical model is currently available. Such models are becoming increasingly relevant as the resolution levels of three-dimensional scanning techniques approach the size of trabeculae. This study took advantage of micro-finite-element methods and tested the aforementioned hypothesis in normal cancellous bone material collected at six anatomical locations from 56 individuals. Numerical analysis was based on high-resolution three-dimensional computer reconstructions of cancellous bone specimens from which the complete elastic characteristics and trabecular morphology, represented by three different fabric measures (the mean intercept length and two volume-based ones), were calculated. Each fabric measure was analyzed individually using the tensorial relationships derived by Cowin ( Mech Mater 4:137–147; 1985). Models for both stiffness and compliance entries were developed. The models based on stiffness entries could explain 93.4%–95.6% of the variance, whereas those based on compliance entries could explain 89.2%–89.4%. When using the former model, the MIL (mean intercept length measure) performed slightly better than the two volume-based measures, VO (volume orientation) and SVD (star volume distribution), with 23% less remaining variance. The high correlations found strongly support the hypothesis and increase the hope that, on the basis of information on trabecular morphology, it will be possible to obtain considerably better estimates of bone quality in vivo compared with the rough two-dimensional density measurements used today.

Energy-Microcrack Growth Measurments for Mortar Cylinders in Compression

ABSTRACTA high resolution three-dimensional scanning technique called x-ray microtomography was applied to measure internal damage and crack growth in small mortar cylinders loaded in compression. Tomographic scans were made at different load increments in the same specimen. Three-dimensional image analysis was used to measure internal crack growth during each load increment. Load-deformation curves were used to measure the work of the external load on the specimen. Non-recoverable work of load was related to measured crack growth to estimate work of fracture in three dimensions. Initial results indicate a roughly linear relationship between work of load and internal crack area.

Optimization of proton and heavy ion therapy using an adaptive inversion algorithm

In order to fully utilize the dose distributional advantages of pions, protons and heavy ions it is important to cover the target volume as well as possible by Bragg peaks and avoid irradiating surrounding organs at risk. The most general way to achieve this goal is by modulation of the range of the beam so that its Bragg peak falls exclusively in the target volume. This could only be achieved using a threedimensional scanning technique where an elementary pencil beam is scanned not only transverse to the central axis of the beam, but also along the longitudinal or depth axis which is approximately parallel to the central axis (cf. Fig. 1). The transverse scanning could be performed by an electromagnetic or mechanical scanning system whereas the longitudinal scanning could be done using variable energy extraction from the accelerator. Alternatively a variable beam energy absorber could be used in the treat-