Digital radiography: an overview

Since the discovery of X-rays in 1895, film has been the primary medium for capturing, displaying, and storing radiographic images. It is a technology that dental practitioners are the most familiar and comfortable with in terms of technique and interpretation. Digital radiography is the latest advancement in dental imaging and is slowly being adopted by the dental profession. Digital imaging incorporates computer technology in the capture, display, enhancement, and storage of direct radiographic images. Digital imaging offers some distinct advantages over film, but like any emerging technology, it presents new and different challenges for the practitioner to overcome. This article presents an overview of digital imaging including basic terminology and comparisons with film-based imaging. The principles of direct and indirect digital imaging modalities, intraoral and extraoral applications, image processing, and diagnostic efficacy will be discussed. In addition, the article will provide a list of questions dentists should consider prior to purchasing digital imaging systems for their practice.     

Use of an inclined footrest for panoramic dental radiography.

An inclined footrest was evaluated as a positioning aid for dental panoramic radiography. Experimental and control groups of students were examined by a conventional panoramic technique, with and without the addition of an inclined footrest. All radiographs obtained were evaluated for six parameters in a single-blind fashion by three dentists. Results indicated that the inclined footrest reduced spinal-shadow artifacts and improved over-all image quality.     

Contracting with Children and Helmet Distribution in the Emergency Department to Improve Bicycle Helmet Use

OBJECTIVES: To determine whether injury prevention counseling and behavioral counseling delivered in the emergency department (ED) could result in increases in self-reported bicycle helmet use. METHODS: The authors undertook a trial of counseling in 222 children recruited in an urban ED between August 2000 and October 2001. All consenting patients in the ED aged 5 to 15 years who did not have life-threatening conditions were eligible. One hundred nine children were assigned to the control group on the basis of attendance on an odd-numbered day, and they received a photocopied photograph of the hospital. One hundred thirteen children were assigned to the intervention group, and they received a personal counseling session and signed a contract promising to wear their bicycle helmets. In addition, 57 of the intervention children were assigned (based on having an even-numbered birthday) to be fitted with helmets if they did not already own them. Parents were telephoned four weeks after the ED encounter for follow-up. RESULTS: Follow-up data were obtained for 148 children (67% follow-up rate), of whom only 69 reported riding a bicycle in the four weeks after their ED visit. Of the final sample of 69 children, 38 belonged to one of the intervention groups, and 25 of these (66%) reported always wearing a helmet while cycling during the four weeks after their ED visit, versus 13 of 31 (42%) in the control group (odds ratio, 2.66; p < 0.05). The effect of the intervention was independent of whether the children owned a helmet at baseline. CONCLUSIONS: Injury prevention counseling in the ED using "The Injury Prevention Program" (TIPP) sheet, behavioral contracting, and helmet distribution may have a significant effect on reports of subsequent bike helmet use.     

Sources of fatty acids stored in liver and secreted via lipoproteins in patients with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of excess liver triacylglycerol (TAG), inflammation, and liver damage. The goal of the present study was to directly quantify the biological sources of hepatic and plasma lipoprotein TAG in NAFLD. Patients (5 male and 4 female; 44 +/- 10 years of age) scheduled for a medically indicated liver biopsy were infused with and orally fed stable isotopes for 4 days to label and track serum nonesterified fatty acids (NEFAs), dietary fatty acids, and those derived from the de novo lipogenesis (DNL) pathway, present in liver tissue and lipoprotein TAG. Hepatic and lipoprotein TAG fatty acids were analyzed by gas chromatography/mass spectrometry. NAFLD patients were obese, with fasting hypertriglyceridemia and hyperinsulinemia. Of the TAG accounted for in liver, 59.0% +/- 9.9% of TAG arose from NEFAs; 26.1% +/- 6.7%, from DNL; and 14.9% +/- 7.0%, from the diet. The pattern of labeling in VLDL was similar to that in liver, and throughout the 4 days of labeling, the liver demonstrated reciprocal use of adipose and dietary fatty acids. DNL was elevated in the fasting state and demonstrated no diurnal variation. These quantitative metabolic data document that both elevated peripheral fatty acids and DNL contribute to the accumulation of hepatic and lipoprotein fat in NAFLD.     

Use of adenovirus protein IX (pIX) to display large polypeptides on the virion--generation of fluorescent virus through the incorporation of pIX-GFP.

The adenovirus (Ad) protein IX (pIX) is a minor component of the Ad capsid and associates with the hexons that make up the facets of the icosahedron. In this study, we investigated whether a large protein tag could be fused to pIX without compromising the Ad vector itself. As proof-of-principle, we generated a pIX-green fluorescent protein (GFP) fusion protein. We show that a virus encoding the pIX-GFP can be generated and that pIX-GFP fusion protein was incorporated into the Ad capsid as efficiently as native pIX. In tissue culture, translocation of Ad/pIX-GFP from the outside of the cell to the nucleus could be followed using fluorescence microscopy, and the timing of migration to the nucleus was similar to that previously reported for Ad. We also could track the virus after injection into the tibialis anterior muscle of mice. Shortly after injection, the majority of the Ad/pIX-GFP accumulated in pockets adjacent to the muscle fibers, with some migration of the virus between fibers. Our ability to attach GFP to the Ad virion, through fusion to pIX, provides a valuable tool for virus tracking in vitro and in vivo. Moreover, our data indicate that pIX can be used as a platform to anchor proteins to the Ad capsid, such as large ligands for cell-type-specific targeting of the vector.     

Visualization of B-scan transducer transverse cross-sectional beam patterns

A technique has been developed to "fool" a B-scanner into imaging the transverse cross-sectional beam pattern of its transducer. This technique can be easily used by clinical personnel to test in-house transducers under their normal conditions of use. The effects of various equipment parameters on the effective beam pattern and the image spatial resolution are demonstrated. It is shown that the technique may be used easily and accurately to measure transducer connector/acoustic axis misalignment.