Evaluation of PET Mainstream Scattering Correction Methods / 中国医疗器械杂志

OBJECTIVE@#Current mainstream PET scattering correction methods are introduced and evaluated horizontally, and finally, the existing problems and development direction of scattering correction are discussed.@*METHODS@#Based on NeuWise Pro PET/CT products of Neusoft Medical System Co. Ltd. , the simulation experiment is carried out to evaluate the influence of radionuclide distribution out of FOV (field of view) on the scattering estimation accuracy of each method.@*RESULTS@#The scattering events produced by radionuclide out of FOV have an obvious impact on the spatial distribution of scattering, which should be considered in the model. The scattering estimation accuracy of Monte Carlo method is higher than single scatter simulation (SSS).@*CONCLUSIONS@#Clinically, if the activity of the adjacent parts out of the FOV is high, such as brain, liver, kidney and bladder, it is likely to lead to the deviation of scattering estimation. Considering the Monte Carlo scattering estimation of the distribution of radionuclide out of FOV, it's helpful to improve the accuracy of scattering distribution estimation.

Aplicación forense de tecnología radiográfica dental portátil en Argentina: estado actual y perspectivas futuras / Forensic application of portable dental radiographic technology in Argentina: current status and future prospects

Objetivos: Mensurar los niveles de radiación de fuga y dispersión emanada a través de los blindajes y estructuras plomadas del tubo de rayos X de la unidad dental portátil NOMAD, controlando la retrodispersión con el uso del escudo protector de acrílico plomado adaptado en el extremo final del tubo localizador plomado. Se midieron las tasas de exposición dispersadas mediante un detector tipo Geiger-Müller y una cámara de ionización con respuesta en el rango de energías aportadas en diagnóstico por imágenes para la medición de la exposición directa y determinación posterior de las dosis. Se utilizó un fantomas diseñado para diagnóstico odontológico, sopesando la radiación en diferentes angulaciones de operación del equipo NOMAD, simulando los gestos posturales de odontólogos, radiólogos y sujetos a identificar. Se controlaron las tasas de exposición para determinar los valores de las dosis aportadas en las zonas significativas corporales más radiosensibles del operador del equipo. Se obtuvo como resultado que la retrodispersión en el cristalino del ojo del operador fue significativamente menor cuando el fantomas estaba acostado, mientras que a nivel de gónadas resultó más baja con el cuerpo sentado. La tasa de dosis máxima de radiación dispersa que impactó en los operadores fue de 350.8 micro Sieverts por hora (uSv/h) en la zona de gónadas, por cada radiografía tomada sin el uso del delantal de goma plomada, reduciéndose a 4.38 micro Sieverts por hora (uSv/h) al utilizarlo (AU)

Resonance light scattering spectroscopy can directly characterize protein solubility / 南方医科大学学报

OBJECTIVE@#To develop a fast, sensitive and cost-effective method based on resonance light scattering (RLS) for characterization of protein solubility to facilitate detection of changes in solubility of mutant proteins.@*METHODS@#We examined the response curve of RLS intensities to the protein concentrations in synchronous scanning mode. The curve intersection points were searched to predict the maximal concentrations of the protein in dispersion state, which defined the solubility of the protein in this given state. Bovine serum albumin (BSA, 0-50 g/L) was used as the model to investigate the influences of pH values (6.5, 7.0, and 7.4) and salt concentrations (0.05, 0.10, 0.15, and 0.20 mol/L) on the determined solubility. The solubility of glutathione S-transferase isoenzymes alpha (GSTA, 0-27.0 g/L) and Mμ (GSTM, 0-20.0 g/L) were estimated for comparison. The RLS-based method was used to determine the solubility of uricase (MGU, 0-0.4 g/L) to provide assistance in improving the solubility of its mutants.@*RESULTS@#We identified two intersection points in the RLS response curves of the tested proteins, among which the lower one represented an approximation of the maximal concentration (or the solubility of the protein) in single molecular dispersion, and the higher one the saturated concentration of the protein in multiple molecular aggregation. In HEPES buffer, the two intersection points of BSA (isoelectric point 4.6) both increased with the increase of pH (6.5-7.4), and their values were ~1.2 g/L and ~33 g/L at pH 7.4, respectively; the latter concentration approached the solubility of commercial BSA in the same buffer at the same pH. The addition of NaCl reduced the values of the two intersection points, and increasing salt ion concentration decreased the values of the lower intersection points. Further characterizations of GSTA and GSTM showed that the low concentration intersection points of the two proteins were ~0.7 g/L and ~0.8 g/L, and their high concentration intersection points were ~10 g/L and ~11 g/L, respectively, both lower than those of BSA, indicating the feasibility of the direct characterization of protein solubility by RLS. The two concentration intersection points of MGU were 0.24 g/L and 0.30 g/L, respectively, and the low concentration intersection point of its selected mutant was increased by 2 times.@*CONCLUSIONS@#RLS allows direct characterization of the solubility of macromolecular proteins. This method, which is simple and sensitive and needs only a small amount of proteins, has a unique advantage for rapid comparison of solubility of low-abundance protein mutants.

Comparison between charged aerosol detector and evaporative light scattering detector for analysis of sugar in Zhusheyong Yiqi Fumai and study on accuracy of methods / 中国中药杂志

Evaporative light scattering detector(ELSD) and charged aerosol detector(CAD) methods were established in this study for the content determination of four kinds of sugars in Zhusheyong Yiqi Fumai(YQFM), and the factors affecting the accuracy of CAD methods were discussed. HPLC-ELSD chromatographic separation was performed on a Shodex Asahipak NH2 P-50 column with acetonitrile-water(75∶25)as the mobile phase, with a flow rate of 0.8 mL·min~(-1), drift tube temperature of 80 ℃. The analysis by HPLC-CAD was performed on the same column with acetonitrile-water as mobile phase for gradient elution, with a flow rate of 0.8 mL·min~(-1), a neb temperature of 45 ℃, and power function(PF) of 1.3. The samples of YQFM were detected by ELSD and CAD respectively. It was found that YQFM was composed of fructose, glucose, sucrose and maltose. The linear relationship of the two methods was good, and the recoveries, reproducibility and stability of these four kinds of sugars measured by the two methods satisfied the requirements of methodology. Both CAD and ELSD detectors were accurate and reliable in detecting saccharides components in YQFM. In addition, it was revealed in this study for the first time that the PF parameter of CAD had an important influence on the accuracy of sugar determination and acted as the key parameter of CAD method. It was also found that for CAD, a non-linear detector, there was no significant difference between the results of linear regression and logarithmic regression.

Intraocular straylight before and after low myopic photorefractive keratectomy with and without mitomycin C / Dispersão de luz intraocular antes e depois da ceratectomia fotorrefrativa para baixa miopia com e sem mitomicina C

ABSTRACT Purpose: To evaluate ocular straylight before and after photorefractive keratectomy (PRK) for low myopia with and without topical mitomycin (MMC) treatment. Methods: Patients who underwent PRK for low myopia were enrolled into the study. PRK without MMC was performed in 21 eyes (12 patients), whereas PRK with topical 0.02% MMC was performed in 25 eyes (14 patients). Both groups were treated using the NIDEK EC5000 excimer laser. Measurements were performed using the C-Quant straylight meter preoperatively and at two and four months postoperatively. Results: The mean patient age was 30 ± 4 years, and the mean spherical equivalent refractive error was -2.2 ± 0.75 D. The mean preoperative intraocular straylight values were 1.07 ± 0.10 in the PRK without MMC group and 1.07 ± 0.11 log(s) in the PRK with topical MMC group. At two months after surgery, there was a decrease in mean intraocular straylight values in both groups. However, a significant difference was only reached in the PRK with MMC group [0.98 ± 0.09 log(s), p=0.002] compared with preoperative values, which was likely due to a greater scatter of measurements in the PRK without MMC group [1.03 ± 0.13 log(s), p=0.082]. At four months postoperatively, ocular straylight values were not significantly different compared with those at baseline in either the PRK without MMC group [1.02 ± 0.14 log(s), p=0.26] or in the PRK with topical MMC group [1.02 ± 0.11 log(s), p=0.13]. Conclusion: PRK for low myopia decreases ocular straylight, and MMC application further reduces straylight in the early postoperative period. However, ocular straylight values do not significantly differ at four months after surgery compared with those at baseline.

RESUMO Objetivo: Avaliar a dispersão de luz intraocular antes e depois da ceratectomia fotorrefrativa (PRK) para baixa miopia com e sem a aplicação tópica de mitomicina C. Métodos: Pacientes submetidos à PRK para baixa miopia foram selecionados para o estudo. PRK sem MMC foi realizado em 21 olhos (12 pacientes) e PRK com MMC tópica a 0,02% foi realizado em 25 olhos (25 pacientes). Ambos os grupos foram tratados com o excimer laser da Nidek EC5000. Avaliações foram realizadas usando o medidor de dispersão de luz C-Quant no pré-operatório e com 2 e 4 meses de pós-operatório. Resultados: A média de idade dos pacientes foi 30 ± 4 anos e a média do equivalente esférico foi -2,2 ± 0,75 D. As médias da dispersão de luz intraocular no pré-operatório foram 1,07 ± 0,10 no grupo PRK sem MMC e 1,07 ± 0,11 log(s) no grupo PRK com MMC tópica. Após 2 meses da cirurgia houve uma diminuição na média da dispersão de luz intraocular em ambos os grupos. Entretanto uma diferença estatisticamente significante, comparado com os valores pré-operatórios, foi observada apenas no grupo PRK com MMC (0,98 ± 0,09 log(s), p=0,002), provavelmente devido as medidas com maior espalhamento de luz no grupo sem MMC (1,03 ± 0,13 log(s), p=0,082). Após 4 meses de pós-operatório, os valores de dispersão de luz não apresentavam diferença estatisticamente significantes quando comparados com os valores iniciais, tanto no grupo sem MMC (1,02 ± 0,14 log(s), p=0,26) quanto no grupo com MMC tópica (1,02 ± 0,11 log(s), p=0,13). Conclusão: PRK para baixa miopia diminui a dispersão de luz ocular e a aplicação de MMC contribui para uma ainda menor dispersão de luz no período pós-operatório inicial. Entretanto, quatro meses após a cirurgia a dispersão de luz intraocular não é significantemente diferente das medidas pré-operatórias.

Impact of range straggling and multiple scattering on proton therapy of brain, using a slab head phantom

The advantages of proton beam in radiation therapy- like small lateral scattering as well as absence of exit dose tail in the organs which are after the tumor- make it capable of delivering more treatment doses to the target and much lesser to the critical tissues near it. In this study, the Monte Carlo MCNPX code has been used to simulate a slab head phantom irradiated by proton pencil beams. The simplified slab has tissue compositions of the ICRU 46, and the necessary data have been taken from adult male phantom of MIRD-ORNL family series. Suitable energy range of incident proton beams has been estimated in order to have the Bragg peaks inside the brain tissue. Energy straggling or, rather, range straggling, and multiple scattering which affect the lateral broadening of incident beams, have been investigated. The results show that the FWHM [Full Wide in Half Maximum] increases more than six times from 1.73 mm to 10.78 mm for the energy range of 50 - 135 MeV. The FWHM values of lateral dose profiles change from 1 mm in 50 MeV to 7.5 mm in 135 MeV, and it has been shown that when a pencil beam is used to irradiate a tissue, the absorbed dose in depth along the central axis does not show a Bragg peak pattern

Study on biosynthesis of silver nanoparticles using fagopyri dibotryis rhizoma extract and optimization of synthesis conditions / 中国中药杂志

Silver nanoparticles were synthesized from the extract of Fagopyri Dibotryis Rhizoma and the optimization of synthesis was studied. The absorbance of UV-visible spectroscopy was determined under the different influencing factors such as extracting time of Fagopyri Dibotryis Rhizoma powder, reation temperature of synthesis, volume of Fagopyri Dibotryis Rhizoma extract and concentration of AgNO3 to seek the optimization conditions. By means of FT-IR, TEM, DLS and XRD, the silver nanoparticles were characterized. The results showed that when the boiling time of Fagopyri Dibotryis Rhizoma powder was 5 min, resultant temperature was 25 degrees C, the volume ratio of 0.1 g x mL(-1) Fagopyri Dibotryis Rhizoma extract and 1 mmol x L(-1) AgNO3 was 1 to 10, and the reaction time was 3.5 h, the obtained silver nanoparticles had mean size about 27 nm and Zeta potential about -34.3 mV with good uniformity and dispersivity. Therefore, the green synthesis method of silver nanoparticles using extract of traditional Chinese medicine is stable and feasible.

Correlações entre straylight, aberrometria, opacidade e densitometria do cristalino em pacientes com catarata / Correlations of straylight, aberrometry, and lens scattering in cataract patients

Objetico: Correlacionar os níveis de straylight, de scattering, de opacidade do cristalino (LOCS III) e das aberrações ópticas intraoculares em pacientes com catarata nuclear. Métodos: Estudo observacional, prospectivo envolvendo 30 olhos de 30 pacientes com diagnóstico de catarata nuclear. A avaliação do straylight (espalhamento de luz) através do Log(s) foi realizada pelo C-Quant (Oculus, Wetzlar, Germany). A densitometria do cristalino (scattering) através do PNS (Pentacam Nucleus Staging) foi realizada pela tomografia de córnea e segmento anterior (Pentacam® - Oculus, Wetzlar, Germany) e a análise do tipo e graduação da opacidade do cristalino foi feito pelo Lens Opacities Classification System (LOCS III). O Ray tracing (iTrace, Vista, Tracy Technologies) foi utilizado para avaliação da aberrometria total e intraocular onde foi calculado com a integração da Topografia de Plácido. Os critérios de exclusão foram: doença corneana, doenças da retina e/ou nervo óptico e cirurgia ocular prévia. O Teste de Kolmogorov-Smirnov foi utilizado para avaliar a distribuição normal e o Teste de Spearman (não paramétrico) utilizado para as correlações entre as variáveis Log(s) x PNS; Log(s) x LOCS III; LOCS III x PNS; RMS IO x PNS; RMS IO x LOCS III e RMS IO x Log(s). Foi considerado como estatisticamente significante p≤ 0,05%. RESULTADOS: A média de idade dos pacientes foi de 72,3 anos (±8,9). As médias do PNS, do LOCS III, do Log(s) e da RMS IO, foram 2,7 (±1,14), 3,7 (±1,15), 1,49 (±0,38) e 1,23 (±0,5), respectivamente. As correlações de Spearman e o seu coeficiente de correlação (rho) foram p=0,270 (rho 0,20) entre Log(s) x PNS, um p=0,717 (rho 0,06) entre Log(s) x LOCS III, um p=0 (rho 0,76) entre LOCS III x PNS, um p=0,41 (rho -0,15) entre RMS IO x PNS, um p=0,39 (rho -0,15) entre RMS IO x LOCS III e um p=0,83 (rho 0.03) entre RMS IO x Log(s). CONCLUSÃO:A perda da qualidade de....

Purpose: To correlate straylight levels, lens scattering, lens opacity and intraocular aberrometry in patients with nuclear cataract. Methods: This is a prospective study. Thirty consecutive patients (30 eyes) were including. Ocular Straylight was evaluated using the C-Quant. Lens scattering was evaluated using Scheimpflug anterior segment tomography, using the new software PNS. Dilated slip lamp evaluation was performed and lens opacity was classified according to LOCS III scale. Total wavefront was measured by ray tracing (iTrace); intraocular aberrations were calculated by the integration of the Placido topography (Vista, Tracy Technologies. Exclusion criteria: corneal disease, retinal or optic nerves disease or previous ocular surgery. This is study analyzed was Kolmogorov-Smirnov for Normality. Spearman correlation test was performed. Results: The mean age from patients was 72,3 y (±8,9). The mean PNS was 2,7 (±1,14), the mean LOCS III was 3,7 (±1,15) and the mean Log(s) was 1,49(±0,38). The correlations between Log(s) x PNS, Log(s) x LOCS III and LOCS III x PNS obtained respectively p=0,270 (rho 0,20), p=0,717 (rho 0,06) e p=0 (rho 0,76). The mean RMS IO was 1,23 (+/- 0,5). The correlations between RMS IO x PNS was p=0, 41 (rho -0,15) and RMS IO x LOCS III was p=0,39 (rho -0.15) and between RMS IO x Log(s) was p=0,83 (rho 0,03). CONCLUSION: There is an association between the ...

new approach to scatter correction in SPECT images based on Klein_Nishina equation

Scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. Accurate estimation of scatter in projection data of SPECT is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. The objective of this paper is to develop and validate a scatter correction technique that use an accurate analytical model based on Klein_Nishina scatter equation and compare Klein_Nishina scatter estimation with triple energy window. In order to verify the proposed scattering model several cylindrical phantoms were simulated. The linear source in the cylindrical Phantoms was a hot rod filled with 99mTc. K factor defines as the ratio of scatter resulting from MC simulation to scatter estimated from Klein_Nishina formula. Also a SPECT/CT scan of the image quality phantom was acquired. Row data were transferred to a PC computer for scatter estimation and processing of the images using MLEM iterative algorithm in MATLAB software. The scatter and attenuation compensated images by the proposed model had better contrast than uncorrected and only attenuation corrected images. The K-factors that used in proposed model doesn't vary with different activities and diameters of linear source and they're just a function of depth and composition of pixels. Based on Mont Carlo simulation data, the K_N formula that used in this study demonstrates better estimation of scattered photons than TEW. Proposed scattered correction algorithm will improve 52.3% in the contrast of the attenuated corrected images of image quality phantom

Monte Carlo simulation of the divergent beam propagation in a semi-infinite bio-tissue / 生物医学工程学杂志

In order to study the light propagation in biological tissue, we analyzed the divergent beam propagation in turbid medium. We set up a Monte Carlo simulation model for simulating the divergent beam propagation in a semi-infinite bio-tissue. Using this model, we studied the absorbed photon density with different tissue parameters in the case of a divergent beam injecting the tissue. The simulation results showed that the rules of optical propagation in the tissue were found and further the results also suggested that the diagnosis and treatment of the light could refer to the rules of optical propagation.

Study on molecular characteristics of four components contained in Hedysari Radix polysaccharide by gel permeation chromatography-multiangle laser light scattering technology (GPC-MALLS) / 中国中药杂志

<p><b>OBJECTIVE</b>To determine such molecular characteristic parameters as absolute molecular weight, molecular weight distribution, root-mean-square turning radius (Rg) and polydispersity index (Mw/Mn) of four components contained in Hedysari Radix polysaccharide 3 (HPS-3) and map weight-average molecular weight (Mw) with root-mean-square turning radius (Rg), in order to calculate conformations of the four components at solution state.</p><p><b>METHOD</b>The gel permeation chromatography-multi angle laser light scatting (GPC-MALLS) was adopted, with 0.1 mol x L(-1) NaNO3 contained 0.02% NaN3 as the mobilephase, Ultrahydrogel 1000 connected in series with Ultrahydrogel500.</p><p><b>RESULT</b>Among the four components of HPS-3, HPS-3-C showed the highest weight average molecular weight of 1.986 x 10(5) g x mol(-1), followed by HPS-3-B 1.113 x 10(5) g x mol(-1) and HPS-3-D 8.457 x 10(4) g x mol(-1) HPS-3-A showed the lowest weight average molecular weight of 1. 223 x 10(4) g x mol(-1) but the highest square radius of gyration, that is 55.5 nm. HPS-3-D had the widest range of molecular weight distribution in four components, with the polydispersity index (Mw/Mn) of 2.543. In the mobile phase, HPS-3-A was globular structure, HPS-3-C was random coil, HPS-3-B and HPS-3-D were both highly branched structure.</p><p><b>CONCLUSION</b>The results provided necessary basis for further studies on molecular characteristics of the four components contained in HPS-3 and their relationship with bioactivity.</p>

The influence of energy on X-ray voxel Monte Carlo algorithm based on kilovoltage cone beam computed tomography images for dose calculation / 生物医学工程学杂志

This paper is to investigate how the different energy impact the accuracy of X-ray Voxel Monte Carlo (XVMC) algorithm when it is applied for dose calculation in Kilovoltage cone beam CT(kv-CBCT) images. The CIRS model 062 was used to calibrate the CT numbers-relative electron density table of CT and CBCT images. CT and CBCT scans were performed when simulation model of human head-and-neck placed in same position to simulate locally advanced nasopharyngeal carcinoma. 6MV and 15MV photon were selected in Monaco TPS to design intensity-modulated radiotherapy (IMRT) plans. XVMC algorithm was selected for dose calculation then the calculation results were compared and the impact of energy on the calculation accuracy was analyzed. The comparison results of dose volume histograms (DVHs), dose received by targets, organs at risk, conform index and uniform index of targets indicate a high agreement between CT based and CBCT based plans. More evaluation indicators show higher accuracy when 15MV photon was selected for dose calculation. gamma index analysis with the criterion of 2mm/2% and threshold of 10% was used for comparison of dose distribution. The average pass rate of each plane was 99.3% +/- 0.47% on the base of 6MV and 99.4% +/- 0.44% on the base of 15MV. CBCT images after calibration has high accuracy of dose calculation and has higher accuracy when 15MV photon was selected.

HILIC-eLSD determination of five oligosaccharides contained in Morinda officinalis / 中国中药杂志

<p><b>OBJECTIVE</b>To determine determinate five oligosaccharides, namely sucrose, 1-kestose, nystose, 1F-fructofurano-syinystose, bajijiasu contained in Morinda officinalis with an HILIC-ELSDI) method.</p><p><b>METHOD</b>Waters XBridge Amide (4.6 mm x 150 mm, 3.5 microm) hilic column was adopted for gradient elution, with acetonitrile (A) and 0.2% triethylamine (B) as the mobile phase. The column temperature was set at 40 degrees C, with the flow rate of 0.8 mL x min. Waters 2424 evaporative light scattering detector (ESLD) was used as detector, with the gas flow of 275.79 kPa and drift tube temperature of 90 degrees C.</p><p><b>RESULT</b>The detection range for the five oligosaccharides were 2.128-21.28 microg for sucrose (r = 0.999 3), 1.864-18.64 microg for 1-kestose (r = 0.999 6), 1.92-19.2 microg for nystose (r = 0.999 8), 1.912-19. 12 microg for 1F-fructofuranosyinystose (r = 0.999 5), 2.368-23.68 microg for bajijiasu (r = 0.999 4), respectively. The recovery of the five oligosaccharides ranged between 92.81%-102.8% (n = 6).</p><p><b>CONCLUSION</b>The method is so simple, accurate and highly reproducible that it can be used as an analytical method for effective evaluation of the quality of M. officinalis herbs.</p>

Methods for grain size analysis of nanomedicines / 药学学报

As nanomedicines are developing fast in both academic and market areas, building up suitable methods for nanomedicine analysis with proper techniques is an important subject, requiring further research. The techniques, which could be employed for grain size analysis of nanomedicines, were reviewed. Several key techniques were discussed with their principles, scope of applications, advantages and defects. Their applications to nanomedine analysis were discussed according to the properties of different nanomedicines, with the purpose of providing some suggestions for the control and administration of nanomedicines.

Simultaneous determination of trillin and desgalactotigonin contents in Solanum lyratum by HPLC-ELSD / 中国中药杂志

<p><b>OBJECTIVE</b>To establish a HPLC-ELSD method for simultaneous determination of trillin and desgalactotigonin contents in Solanum lyratum.</p><p><b>METHOD</b>A Diamonsil C18 column (4.6 mm x 250 mm, 5 microm) was adopted, with the mobile phase consisting of acetonitrile-10 mmol x L(-1) ammonium acetate (52: 48). The temperature was 25 degrees C, the flow rate was set at 0.6 mL x min(-1), and the sample size is 20 microL. The temperature of drift tubes and gas flow rate of the detector were set at 95 degrees C and 2.3 L x min(-1), respectively.</p><p><b>RESULT</b>With in the linear ranges of 20-200 mg x L(-1) and 10-100 mg x L(-1), trillin and desgalactotigonin show a good linear relationship. The average recovery was 99.4% (RSD 0.90%) for trillin and 100.3% (RSD 1.1%) for desgalactotigonin.</p><p><b>CONCLUSION</b>The method is so accurate and easily reproducible that it is suitable for the quality control of S. lyratum medicinal materials.</p>

HPLC-ELSD fingerprint of Marsdenia tenacissima from different habitats / 中国中药杂志

<p><b>OBJECTIVE</b>To establish a HPLC-ELSD fingerprint of Marsdenia tenacissima from different habitats, in order to provide a reliable method for scientific assessment and effective quality control.</p><p><b>METHOD</b>HPLC-ELSD was adopted to determine 25 baches of M. tenacissima herbs from different habitats. Traditional Chinese medicine chromatographic fingerprint similarity software assessment system 2004 developed by China Pharmacopoeia Committee was adopted to establish a common mode chart and assess chromatographic similarity based on the degree of correlation.</p><p><b>RESULT</b>The common mode for M. tenacissima herb C21 steroidal fingerprint was established, including 11 common characteristic peaks. Among them, 10 were identified. According to the assessment on the similarity of 25 batches of samples, 80% of them showed a similarity of over 0.80 in steroidal HPLC-ELSD fingerprint.</p><p><b>CONCLUSION</b>The method can be used to assess the quality of M. tenacissima.</p>

effect of energy and field size on determination of virtual source of the linear accelerator varian 2100 CD

In dosimetric calculation, it is desirable to represent the actual electron beam as originating from a virtual point source in vacuum so that the inverse square law can be applied. Therefore in this research with dosimetry of different treatment fields for different energy of electron beams the position of virtual source for electron beams is determined and one can use the inverse square rule for this electrons as the photons. In this work, the source position of electron beams [s[vir]] from a Varian clinac 2100 CD for different field sizes at different energies was determined by use of elastic scattering theory and dosimetry data. With a parallel plate chamber PPC40 in a 50x50x50cm[3], phantom and Omini-pro accept software the depth dose profiles of 6x6, 10x10, 15x15, 20x20 and 25x25 cm[2] applicators in different energies [6,9,12 and 15 Mev] for treatment electron beams determined. From the dose profile of maximum depth and multiple scattering rules of electrons from the target the position of virtual source of electron beams for each applicator in different energy were obtained. The obtained results from this method showed a dependence on energy and field size for S[vir]. The position of S[vir] is a function of dimension of treatment field and energy. In larger treatment fields and higher energies this distance is longer

effects of low level 660nm laser irradiation on pain and teeth hypersensitivity after periodontal surgery

Tooth pain and sensitization are the two main causes of discomfort after periodontal flap surgery. Effects of low level laser therapy for reducing pain have already been established; these kinds of lasers have been used for tooth desensitization as well. This controlled blind study sought to compare tooth pain and sensitization after 660nm laser irradiation in a split mouth and also in a control group after periodontal flap surgery. Forty patients were enrolled in this study. In these entire patients periodontal flap surgery was done in the upper anterior segment. In the test group, by tossing of a coin the left or right side was determined for laser irradiation, so central incisor, lateral incisor and canine were irradiated by swiping motion of 660nm laser [AZOR, Russia] 25mW, 4.5 J, and 3 min every other day starting one day after surgery; and in collateral segment a placebo probe was put to blind the patients. In the control group, dressing was used after surgery. One, 3, 5 and 7 days after surgery for both groups visual analog score [VAS] for tooth pain and sensitization were recorded for both sides in each patient. In the laser group, both sides had lower VAS for pain than the control group [P< 0.05] after the first day. There was no statistical difference in the laser group between laser irradiated, or non-irradiated segment and for sensitization between groups. Pain can be reduced after periodontal surgery by using low level 660nm laser therapy. Lower pain in both sides in the laser group may be the result of the spread of mediators and neurotransmitters secreted after laser irradiation, or may be because of scattered radiation in the collateral part

propagation of laser light in skin by Monte Carlo- diffusion method: a fast and accurate method to simulate photon migration in biological tissues

Due to the importance of laser light penetration and propagation in biological tissues, many researchers have proposed several numerical methods such as Monte Carlo, finite element and green function methods. Among them, the Monte Carlo method is an accurate method which can be applied for different tissues. However, because of its statistical nature, Monte Carlo simulation requires a large number of photon pockets to be traced, so it is computationally expensive and time consuming. Although other numerical methods based on the diffusion method are fast, they have two important limitations: first, they are not valid near the bounder of sample and source, and second, their accuracy is less than Monte Carlo method. In this study, we combine the accuracy of Monte Carlo method and speed of the diffusion method. This hybrid method is faster than Monte Carlo Method and its accuracy is higher than the diffusion method. We first evaluate this hybrid model and the reflectance of a biological phantom is calculated by Monte Carlo method and this hybrid model. Then the propagation of laser light in the skin tissue has been studied. In this study, a combined method based on the Monte Carlo method and the diffuse equation is introduced. This hybrid method is five times faster than Monte Carlo Method, and its accuracy is higher than the diffusion method. The propagation of laser light in skin has also been studied by this hybrid method and its accuracy shows that it can be applied for laser penetration in biological tissues. It seems that this method is good for photo dynamic therapy [PDT] and optical imaging

Mechanisms of laser-tissue interaction: I. optical properties of tissue

Today, lasers are widely used in biology and medicine, and the majority of health centers and hospitals utilize modern laser systems for diagnosis and therapy applications. Researchers have introduced different medical applications for different lasers used in surgeries and other medical treatments. Medical lasers can be categorized in both diagnosis and therapy branches. Main difference between diagnosis and therapy applications is the type of laser-tissue interactions. In diagnosis, one tries to arrange a noninvasive method to study the normal behavior of tissue without any damage or clear effect on tissue. But in therapy, such as surgery, a surgeon uses laser as a knife or for affecting a specific region. So, the medical laser applications are defined by the interaction type between laser light and tissues. The knowledge of laser-tissue interaction can help doctors or surgeons to select the optimal laser systems and modify the type of their therapy. Therefore, we seek to review the mechanisms of laser- tissue interaction. In this paper, the optical properties of biological tissue such as absorption, scattering, penetration and fluorescence are reviewed. Also, the effects of these properties on laser penetration in tissue have been explained