PubMed · 14756176
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A Rimpler. 2003. Applications.. https://doi.org/10.1093/oxfordjournals.rpd.a006386
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Chemical mapping techniques using Raman microscopy are introduced, and using an example of a pharmaceutical tablet, the practical aspects of data collection and processing to produce a chemical image of the sample are detailed. Issues related to data processing, instrument standards, chemical image reportable errors, and the interpretation of chemical images are presented to encourage debate, develop solutions, and promote use in other challenging scientific applications. applications.
The EBT Gafchromic radiochromic film is a relatively new product designed specifically for dosimetry in radiation therapy. Due to the weak dependence of its response on the photon energy (variations are below 10% in the 50 kVp-10 MVp range), the film is ideal for dosimetry when the photon energy spectrum may be changing or unknown. In order to convert a map of optical densities into a map of absorbed radiation doses, a calibration curve constructed on the basis of standard calibration films is necessary. Our results have shown that, with the EBT Gafchromic film, one can use the same calibration curve for 6-MV X-ray fields of any size in the range from 5 x 5 cm(2) up to 40 x 40 cm(2). This is not the case for radiographic films, such as Kodak X-Omat V, whose response to the same dose varies approximately by 10% depending on the field size in this range. This insensitivity of the EBT Gafchromic film to size of the radiation field makes it possible to assess doses delivered by small radiation fields. With the help of this film, it was shown that the output factor for a 0.5 x 0.5 cm(2) field is 0.60+/-0.03 (2SD) relative to the 10 x 10 cm(2) field.
An ISO GUM measurement uncertainty estimation procedure was developed for a liquid-chromatographic drug quality control method-assay of simvastatin in drug formulation. In quantification of uncertainty components several practical approaches for including difficult-to-estimate uncertainty sources (such as uncertainty due to peak integration, uncertainty due to nonlinearity of the calibration curve, etc.) have been presented. Detailed analysis of contributions of the various uncertainty sources was carried out. The results were calculated based on different definitions of the measurand and it was demonstrated that unequivocal definition of the measurand is essential in order to get rigorous uncertainty estimate. Two different calibration methods - single-point (1P) and five-point (5P) - were used and the obtained uncertainties and uncertainty budgets were compared. Results calculated using 1P and 5P calibrations agree very well. The uncertainty estimate for 1P is only slightly larger than with 5P calibration.