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 (r2 = 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.
Digital chest tomosynthesis (DCT) is a 3D imaging modality which has been shown to approach the diagnostic capability of CT, but uses only one-tenth the radiation dose of CT. One limitation of current commercial DCT is the mechanical motion of the x-ray source which prolongs image acquisition time and introduces motion blurring in images. By using a carbon nanotube (CNT) x-ray source array, we have developed a stationary digital chest tomosynthesis (s- DCT) system which can acquire tomosynthesis images without mechanical motion, thus enhancing the image quality. The low dose and high quality 3D image makes the s-DCT system a viable imaging tool for monitoring cystic fibrosis (CF) patients. The low dose is especially important in pediatric patients who are both more radiosensitive and have a longer lifespan for radiation symptoms to develop. The purpose of this research is to evaluate the feasibility of using s-DCT as a faster, lower dose means for diagnosis and monitoring of CF in pediatric patients. We have created an imaging phantom by injecting a gelatinous mucus substitute into porcine lungs and imaging the lungs from within an anthropomorphic hollow chest phantom in order to mimic the human conditions of a CF patient in the laboratory setting. We have found that our s-DCT images show evidence of mucus plugging in the lungs and provide a clear picture of the airways in the lung, allowing for the possibility of using s- DCT to supplement or replace CT as the imaging modality for CF patients.
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.