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61.
Willem M. Star Hans P. A. Marijnissen Harald Jansen Marleen Keijzer Martin J. C. VAN Gemert 《Photochemistry and photobiology》1987,46(5):619-624
Abstract In Photodynamic Therapy (PDT) there is a need for accurate quantitative light dosimetry. This has become particularly apparent in the treatment of superficial bladder cancer, either by focal or by whole bladder wall irradiation. We have studied this problem using a spherical model of the bladder, consisting of two concentric thin-walled plastic spheres, 8 and 10 cm in diameter. The inner sphere was filled with water or with a light-scattering medium. The space between the spheres was filled with an optically tissue equivalent liquid. An isotropic light source was placed at the center of the spheres. Light energy fluence rates (light "dose rates") during PDT of the bladder simulated in this manner, were measured using a specially developed miniature light detector and were also calculated using a mathematical model. These data were confirmed by measurements in vivo (dog bladder). In the case of focal irradiation at a wavelength of 630 nm, the ratio (R) between the true light fluence rate at the bladder surface and the fluence rate due to the primary light beam is somewhat larger than 1, depending on the diameter of the primary beam. The maximum ratio is 2, for a beam diameter of several centimeters. In the case of whole bladder wall PDT, R is larger than 5. This is due to the strong scattering of (red) light by tissue and indicates that the intensity of the primary beam, which is usually reported, is not a good measure of the true fluence rate for whole bladder wall PDT. When the light source is moved away from the center of the spheres, the rate of change of the fluence rate at the bladder wall is more than a factor of 2 larger when the bladder cavity is filled with a light-scattering suspension, as compared with water. The use of a light-scattering medium may therefore not be advantageous to achieve a uniform light distribution across the bladder wall. 相似文献
62.
Viviane Van Hoof Hugo Cluckers Vera Verhaeghe Marleen Truyens An Hennebel 《Accreditation and quality assurance》2004,10(1-2):20-26
The automation of test validation procedures in a routine clinical laboratory by integrating artificial intelligence with the lab information system (LIS) is the focus of this study. Test validation consists of three layers: (1) acceptance of patient results based on technical criteria (technical validation), (2) acceptance of patient results based on internal quality control (QC) results (QC validation) and (3) medical validation of the patient protocol. The emphasis here is put on QC validation. General concepts regarding the setting of performance limits for internal QC results are briefly reviewed. As a practical example, we describe how the different layers of test validation were integrated with Molis, a LIS (Sysmex, Barchon, Belgium) used in a routine clinical biochemistry lab. PGP5 software (PGP, Brussels, Belgium) is used for technical validation and is installed on a Linx work-cell (Thermo Clinical Labsystems, Vantaa, Finland). The latter integrates four different Vitros instruments (OCD, Beerse, Belgium). QC validation and medical validation are performed with QC-Today (IL, Zaventem, Belgium) and VALAB (Erim, Toulouse, France), respectively. Both programs are bi-directionally coupled with the LIS. After 2 years of experience with this integrated system, it is clear that automation of validation rules and procedures has enhanced efficiency and overall quality of patient results.Presented at the Ninth Conference on Quality in the Spotlight, 18–19 March 2004, Antwerp, Belgium. 相似文献
63.
64.
Mol HG Rooseboom A van Dam R Roding M Arondeus K Sunarto S 《Analytical and bioanalytical chemistry》2007,389(6):1715-1754
The ethyl acetate-based multi-residue method for determination of pesticide residues in produce has been modified for gas
chromatographic (GC) analysis by implementation of dispersive solid-phase extraction (using primary–secondary amine and graphitized
carbon black) and large-volume (20 μL) injection. The same extract, before clean-up and after a change of solvent, was also
analyzed by liquid chromatography with tandem mass spectrometry (LC–MS–MS). All aspects related to sample preparation were
re-assessed with regard to ease and speed of the analysis. The principle of the extraction procedure (solvent, salt) was not
changed, to avoid the possibility invalidating data acquired over past decades. The modifications were made with techniques
currently commonly applied in routine laboratories, GC–MS and LC–MS–MS, in mind. The modified method enables processing (from
homogenization until final extracts for both GC and LC) of 30 samples per eight hours per person. Limits of quantification
(LOQs) of 0.01 mg kg−1 were achieved with both GC–MS (full-scan acquisition, 10 mg matrix equivalent injected) and LC–MS–MS (2 mg injected) for
most of the pesticides. Validation data for 341 pesticides and degradation products are presented. A compilation of analytical
quality-control data for pesticides routinely analyzed by GC–MS (135 compounds) and LC–MS–MS (136 compounds) in over 100 different
matrices, obtained over a period of 15 months, are also presented and discussed. At the 0.05 mg kg−1 level acceptable recoveries were obtained for 93% (GC–MS) and 92% (LC–MS–MS) of pesticide–matrix combinations. 相似文献
65.
Mai Z Hanel R Batenburg J Verhoye M Scheunders P Sijbers J 《Magnetic resonance imaging》2011,29(4):536-545
Bias field reduction is a common problem in medical imaging. A bias field usually manifests itself as a smooth intensity variation across the image. The resulting image inhomogeneity is a severe problem for posterior image processing and analysis techniques such as registration or segmentation. In this article, we present a novel debiasing technique based on localized Lloyd-Max quantization (LMQ). The local bias is modeled as a multiplicative field and is assumed to be slowly varying. The method is based on the assumption that the global, undegraded histogram is characterized by a limited number of gray values. The goal is then to find the discrete intensity values such that spreading those values according to the local bias field reproduces the global histogram as good as possible. We show that our method is capable of efficiently reducing (even strong) bias fields in 3D volumes. 相似文献
66.
Inside Cover: Red Blood Cells Polarize Green Laser Light Revealing Hemoglobin′s Enhanced Non‐Fundamental Raman Modes (ChemPhysChem 18/2014)
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67.
Wood M Laloup M Samyn N del Mar Ramirez Fernandez M de Bruijn EA Maes RA De Boeck G 《Journal of chromatography. A》2006,1130(1):3-15
Recent years have seen the development of powerful technologies that have provided forensic scientists with new analytical capabilities, unimaginable only a few years ago. With liquid chromatography-mass spectrometry (LC-MS) in particular, there has been an explosion in the range of new products available for solving many analytical problems, especially for those applications in which non-volatile, labile and/or high molecular weight compounds are being analysed. The aim of this article is to present an overview of some of the most recent applications of LC-MS (/MS) to forensic analysis. To this end, our survey encompasses the period from 2002 to 2005 and focuses on trace analysis (including chemical warfare agents, explosives and dyes), the use of alternative specimens for monitoring drugs of abuse, systematic toxicological analysis and high-throughput analysis. It is not the intention to provide an exhaustive review of the literature but rather to provide the reader with a 'flavour' of the versatility and utility of the technique within the forensic sciences. 相似文献