We developed an automatic method for measurement of vertebral bone density based on QCT with the use of internal references(muscle and subcutaneous fat) instead of traditional external phantom.
The automatic multistep approach starts with segmentation of periosteal and endosteal surfaces of spine to define ellipse
ROI in cancellous bone followed by segmentation of muscle and subcutaneous fat in the spine image and a subsequent calculation of bone mineral density in ellipse ROI and segmentation trabecular and cortical bone ROI using muscle and subcutaneous fat as internal references. The segmentation approach used a hybrid region-growing method which used local adaptive threshold and morphological operation.
We conducted with-phantom and without-phantom measurements by using 94 clinical cases. The doctor manually defined the ellipse ROI in the with-phantom measurement. As for the without-phantom measurement, we use our method to automatically gain the BMD. The Interaclass Correlation Coefficient (ICC) is 0.93. We removed the points whose muscle and fat values are 2 times deviated from the standard deviation. And the calibrated ICC value is 0.999.
The without-phantom measurement method is not fit for the patients whose muscle and fat are seriously deviated from the average value. The without-phantom measurement method proposed in this paper can automatically measure the BMD of spine. By accurately segmenting cortical bone and trabecular bone, determining ROI and removing
inappropriate data, it is proved that the BMD measurement result by this method is highly consistent with that by with-phantom method.
The different composition in 42Sn58Bi and 96.5Sn3.5Ag system has been studied. The reflow conditions of various composition pastes were studied, and a suitable adding of Sn-Ag paste could raise the soldering temperature of paste. It was found that the shear tensile strength of solder joint could be improved after adding suitable Sn-Ag to Sn-Bi paste by testing the solder joint tension. The thermal fatigue properties were studied through performed thermal annealing and thermal shocking. The shear tensile strength of solder joints for adding suitable Sn-Ag is higher than the pure Sn- Bi after thermal shocking. The solder property, mechanical and fatigue failure properties of solder joint for adding suitable Sn-Ag could be improved. It was found that suitable Sn-Ag could decrease the porosity in Sn-Bi solder joint thought X-ray and SEM analysis.
In this paper, a new of oxygen sensor using the electrochemical oxygen pump of ZrO<SUB>2</SUB>-8Y<SUB>2</SUB>O<SUB>3</SUB> zirconia electrolyte the artificial oxygen diffusion overpotential behavior has been investigated from the theoretical and practical viewpoints. The factors influencing the limiting current in the normal diffusion region. That is the oxygen molar fraction, gaseous diffusion coefficient, the temperature, the pressure, and the two geometric quantities (area and length). But the limiting current-type zirconia oxygen sensor shows an abnormal output in an exhaust gas at low excess air ratio. The influence of components of the exhaust gas and the mechanism of generation of the abnormal output are reported.