No abstract

It is demonstrated that the photoinduced gliding of the easy axis for nematics doped with various azo dyes on rubbed polyimide involves the formation of a second easy axis on the polyimide surface. While some azo dyes, such as disperse orange 3, do not exhibit large surface induced nonlinear effects, other dyes, such as methyl red, do. The amount of reorientation of the easy axis on rubbed polyimide is determined by the relative anchoring strengths of the easy axis formed from adsorbed dye and that formed from rubbing. One question of interest is what is the source of the anchoring strength? In this paper, we discuss the formation of easy axes via the photo-induced adsorption of azo dye. We will compare the anchoring strengths between dyed nematic liquid crystals and the easy axes formed by photoinduced adsorption of three isomers of the methyl red azo dye, ortho, meta, and para, as well as disperse orange 3. We will also discuss the impact of the carboxyl group position in the dye molecule on the anchoring strength.

The coronary artery calcium score (CACS) measures the buildup of calcium on the coronary artery wall and has been shown to be an important predictor of the risk of coronary artery diseases (CAD). Currently CACS is measured using CT, though the relatively high cost and high radiation dose has limited its adoption as a routine screening procedure. Digital Chest Tomosynthesis (DCT), a low dose and low cost alternative to CT, and has been shown to achieve 90% of sensitivity of CT in lung disease screening. However commercial DCT requires long scanning time and cannot be adapted for high resolution gated cardiac imaging, necessary for CACS. The stationary DCT system (s-DCT), developed in our lab, has the potential to significantly shorten the scanning time and enables high resolution cardiac gated imaging. Here we report the preliminary results of using s-DCT to estimate the CACS. A phantom heart model was developed and scanned by the s-DCT system and a clinical CT in a phantom model with realistic coronary calcifications. The adapted fan-beam volume reconstruction (AFVR) method, developed specifically for stationary tomosynthesis systems, is used to obtain high resolution tomosynthesis images. A trained cardiologist segmented out the calcifications and the CACS was obtained. We observed a strong correlation between the tomosynthesis derived CACS and CT CACS (r 2 = 0.88). Our results shows s-DCT imaging has the potential to estimate CACS, thus providing a possible low cost and low dose imaging protocol for screening and monitoring CAD.