Application of dual energy x-ray absorptiometry
R. C. Richard Davison, Paul M. Smith, James Hopker, Michael J. Price, Florentina Hettinga, Garry Tew, Lindsay Bottoms in Sport and Exercise Physiology Testing Guidelines: Volume I – Sport Testing, 2022
In sport and exercise sciences, follow-up DXA scans are valuable for examining the effects of a training programme, injury rehabilitation, a competitive season or exercise or nutrition intervention on bone and body composition. To interpret change accurately, it is important to ensure the following: Standardised protocols are established and followed at each time point for consistency.Height and body mass are measured and updated at each time point.Consistent application of reference data.Careful inspection of scan images from each time point to ensure correct and consistent placement of ROIs.Knowledge and application of precision and least significant change (see later).To ensure consistency, one should always use the same densitometer. If this is not possible, one must perform a cross-calibration procedure (see later).
Film Dosimetry
Gad Shani in Radiation Dosimetry, 2017
To minimize possible variations due to film-processing conditions, a Kodak X-Omat RP processor was used by Robar and Clark for which the throughput is very high and quality assurance is performed daily. Developer temperature fluctuated by less than ±0.5°F between processing sessions. Optical density was measured using a scanning densitometer. Base-plus-fog optical density was subtracted from scanned optical densities for each film.
Physics and characteristics of radiochromic films
Indra J. Das in Radiochromic Film, 2017
It is clearly obvious from Figures 3.1–3.11 that with varying absorption and transmission spectra, a reader should be sensitive enough to provide high fidelity and accurate reading needed for dose measurements. Selection of the scanner or densitometer is discussed in Chapter 4.
Supplementation with macular carotenoids reduces psychological stress, serum cortisol, and sub-optimal symptoms of physical and emotional health in young adults
Published in Nutritional Neuroscience, 2018
Nicole Tressa Stringham, Philip V. Holmes, James M. Stringham
The concentration of MCs in the central retina (MPOD) was assessed with a non-invasive, perceptual task called heterochromatic flicker photometry (HFP). A densitometer (Macular Metrics Corp., Rehoboth, MA) described by Wooten et al.40 was used for this purpose. The densitometer, detailed measurement procedures, and the principle of HFP have been fully described in earlier publications.41,42 Briefly, subjects are presented with two superimposed lights that are temporally alternated in square-wave counterphase. This gives the subject an impression on a flickering disc of light. The peak (550 nm) of the spectral composition of one of the lights is chosen to bypass the absorption of MP, and the other (460 nm) is strongly absorbed by MP. The subject's task is to adjust the relative radiance of the two lights until a percept of no flicker is achieved. All other factors being equal, a subject that requires more short-wave (i.e. 460 nm) relative to middle-wave (i.e. 550 nm) light to achieve null flicker has higher MPOD. This task is performed for the locations of interest within the fovea, which presumably contain MP, and for a reference location in the parafovea that does not (about 7° eccentricity). To obtain a measure of MPOD at a given test locus, the logarithmic ratio of short- to middle-wave radiance (for null flicker) at the reference location is subtracted from the corresponding logarithmic ratio found at the test locus.
Enabling faster subcutaneous delivery of larger volume, high viscosity fluids
Published in Expert Opinion on Drug Delivery, 2022
Christopher J. Rini, Bruce C. Roberts, Aishwarya Vaidyanathan, Aojun Li, Rick Klug, Douglas B. Sherman, Ronald J. Pettis
Commercial radiographic contrast media without formulation modification were used to investigate lower range viscosity solutions at nominal viscosities of 2.3 cP, 5.8 cP, 11.8 cP, and 20.4 cP at 20°C (Omnipaque™ 140 mg, 240 mg, 300 mg, and 350 mg iodine/mL, respectively; GE Healthcare, Oslo, Norway). Custom contrast injection solutions were formulated to examine higher injectate viscosities (30 cP, 40 cP, and 50 cP) using iohexol contrast (reagent grade, Sigma-Aldrich Histodenz™) with dextran (Dextran 40 MW 40,000, pharmaceutical grade, Pharmacosmos, Holbaek, Denmark) as a viscosity modifier. Rheological characterization of solution viscosity across shear rates was completed by Brookfield LVDV III+ rheometer (AMATEK Brookfield, Middleborough, MA, USA) at 20°C using a CPE-40 spindle; actual measured viscosities reported (Table 2). Solution density measurements were completed using a DMA 4500 M densitometer (Anton Paar, Graz, Austria) at 20°C. Syringes were manually filled with 2.0-mL contrast solution by positive displacement pipette, vacuum stoppered, and evaluated using a visual gauge to confirm a ± 5% fill accuracy.
Optimization and development of antidiabetic phytosomes by the Box–Behnken design
Published in Journal of Liposome Research, 2018
The experiments were performed at a temperature of 22 °C and 55% humidity in controlled conditions. Precoated silica gel HPTLC plates (E-Merck, Darmstadt, Germany) were used for chromatographic separation. Five microliters of extract was spotted with the help of the auto sampler. The chromatogram was run using solvent system of ethyl acetate:formic acid:glacial acetic acid:water (100:11:11:26). The resulted plates were air dried and scanned. A spectro-densitometer (Scanner 3, CAMAG) was employed for the densitometry measurements, spectra recording and data processing. The chromatograms were recorded at the wavelength of 254 and 366 nm. The retention factor (Rf) value of each compound separated on plate and data of peak area of each band were documented.
Related Knowledge Centers
- Solar Cell
- Spectrophotometry
- Instrumentation
- Nucleic Acid Methods
- Microdensitometer