Supercontinuum laser-based gonio-scatterometer for in and out-of-plane spectral BRDF measurements.

The hyperspectral component of bidirectional reflectance measurements, namely from several hundred wavelengths upwards, is attracting growing interest for numerous applications in both optics and computer graphics. In this paper, we present a motorized hyperspectral bidirectional reflectance measurement bench that performs in-plane and out-of-plane measurements for isotropic materials using a supercontinuum laser covering the visible and near infrared range, with a sub-nanometer spectral accuracy. We describe the complete data processing chain, including a method for assessing the alignment error of the measurement bench.

Three-dimensional characterization of cortical bone microstructure by microcomputed tomography: validation with ultrasonic and microscopic measurements.

Background: The porosity of human cortical bone is one of the major parameters conditioning bone strength. The purpose of this study was to validate the characterization of human cortical bone microarchitecture using microcomputed tomography (microCT). To validate this microCT technique, the structural measurements were compared with other methods such as ultrasonic techniques and scanning electron microscopy (SEM).

Estimation of the 3D self-similarity parameter of trabecular bone from its 2D projection.

It has been shown that the analysis of two dimensional (2D) bone X-ray images based on the fractional Brownian motion (fBm) model is a good indicator for quantifying alterations in the three dimensional (3D) bone micro-architecture. However, this 2D measurement is not a direct assessment of the 3D bone properties. In this paper, we first show that S(3D), the self-similarity parameter of 3D fBm, is linked to S(2D), that of its 2D projection, by S(3D)=S(2D)-0.

A new anisotropy index on trabecular bone radiographic images using the fast Fourier transform.

Background: The degree of anisotropy (DA) on radiographs is related to bone structure, we present a new index to assess DA.

Methods: In a region of interest from calcaneus radiographs, we applied a Fast Fourier Transform (FFT). All the FFT spectra involve the horizontal and vertical components corresponding respectively to longitudinal and transversal trabeculae.

Anisotropy changes in post-menopausal osteoporosis: characterization by a new index applied to trabecular bone radiographic images.

Bone intrinsic strength is conditioned by several factors, including material property and trabecular micro-architecture. Bone mineral density (BMD) is a good surrogate for material property. Architectural anisotropy is of special interest in mechanics-architecture relations and characterizes the degree of directional organization of a material.