PURPOSE: To provide a 3D dosimetric evaluation of a commercial portal dosimetry system using 2D/3D detectors under ideal conditions using VMAT. METHODS: A 2D ion chamber array, radiochromic film and gel dosimeter were utilised to provide a dosimetric evaluation of transit phantom and pre-treatment 'fluence' EPID back-projected dose distributions for a standard VMAT plan. In-house 2D and 3D gamma methods compared pass statistics relative to each dosimeter and TPS dose distributions. RESULTS: Fluence mode and transit EPID dose distributions back-projected onto phantom geometry produced 2D gamma pass rates in excess of 97% relative to other tested detectors and exported TPS dose planes when a 3%, 3 mm global gamma criterion was applied. Use of a gel dosimeter within a glass vial allowed comparison of measured 3D dose distributions versus EPID 3D dose and TPS calculated distributions. 3D gamma comparisons between modalities at 3%, 3 mm gave pass rates in excess of 92%. Use of fluence mode was indicative of transit results under ideal conditions with slightly reduced dose definition. CONCLUSIONS: 3D EPID back projected dose distributions were validated against detectors in both 2D and 3D. Cross validation of transit dose delivered to a patient is limited due to reasons of practicality and the tests presented are recommended as a guideline for 3D EPID dosimetry commissioning; allowing direct comparison between detector, TPS, fluence and transit modes. The results indicate achievable gamma scores for a complex VMAT plan in a homogenous phantom geometry and contributes to growing experience of 3D EPID dosimetry.

• MeSH
• bederní obratle účinky záření   MeSH
• celková dávka radioterapie MeSH
• fantomy radiodiagnostické MeSH
• lidé MeSH
• radiometrie přístrojové vybavení   metody   MeSH
• radioterapie s modulovanou intenzitou * metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• validační studie MeSH

Due to their attractive band gap properties and van der Waals structure, 2D binary chalcogenide materials have been widely investigated in the last decade, finding applications in several fields such as catalysis, spintronics, and optoelectronics. Ternary 2D chalcogenide materials are a subject of growing interest in materials science due to their superior chemical tunability which endows tailored properties to the devices prepared thereof. In the family of AIIBIII2XVI4, ordered ZnIn2S4-like based photocatalytic systems have been studied meticulously. In contrast, reports on disordered phases appear to a minor extent. Herein, a photoelectrochemical (PEC) detector based on the pseudo-binary MnIn2Se4 system is presented. A combination of optical measurements and DFT calculations confirmed that the nature of the bandgap in MnIn2Se4 is indirect. Its performance outclasses that of parent compounds, reaching responsivity values of 8.41 mA W-1. The role of the non-centrosymmetric crystal structure is briefly discussed as a possible cause of improved charge separation of the photogenerated charge carriers.

• Publikační typ
• časopisecké články MeSH

There are various different detectors, which can be used for radiotherapy measurements, and more are about to be adopted. Hybrid pixel detectors (HPD) have been originally developed for the high energy physics. However, over the last few years they also expanded in the medical physics. Novel 2D detector Pantherpix is a HPD designed specifically for the radiotherapy. In this article, its properties are characterised and an assessment of its use in radiotherapy photon beams is provided. Properties such as response stability, response linearity, angular dependence and energy dependence were studied. In order to prove sufficient clinical quality for relative dosimetry, further measurements were undertaken (i.e. dose profiles and collimator scatter factors). Acquired results were compared with ion chamber and gafchromic film results. Namely the applicability of PhPix for cobalt beam therapy, which is still widely used (and will be used in near future) in economically less developed countries, is considered.

• MeSH
• celková dávka radioterapie MeSH
• radiometrie * MeSH
• Publikační typ
• časopisecké články MeSH

A neutral marker of the EOF can gain a nonzero effective mobility because of its possible interaction with a charged complexing agent, such as a chiral selector in CE. We determined effective mobilities of four compounds often used as EOF markers (dimethyl sulfoxide, mesityl oxide, nitromethane, and thiourea) in the BGE-containing sulfated β-CD (60 g/L). All the compounds studied were measurably mobilized by their interaction with the selector. The highest effective mobility (-3.0·10(-9) m(2) s(-1) V(-1)) was observed for thiourea and the lowest (-1.5·10(-9) m(2) s(-1) V(-1)) for dimethyl sulfoxide and nitromethane. The mobilities were determined by a new two-detector pressure mobilization method (2d method), which we propose, and the results were confirmed by standard CE measurements. In the 2d method, one marker zone is situated in the BGE containing the charged selector, while the second marker zone is surrounded with a selector-free BGE, which prevents its complexation. The initial distance between the two marker zones equals the capillary length from the inlet to the first detector. After a brief voltage application, the final distance between the marker zones is determined based on known capillary length from the first to the second detector. The difference between these two distances determines the effective mobility.

• MeSH
• aceton chemie   MeSH
• beta-cyklodextriny chemie   MeSH
• chemické modely * MeSH
• dimethylsulfoxid chemie   MeSH
• elektroforéza kapilární metody   MeSH
• elektrolyty chemie   MeSH
• elektroosmóza metody   MeSH
• hexanony chemie   MeSH
• methan analogy a deriváty   chemie   MeSH
• nitroparafiny chemie   MeSH
• thiomočovina chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This work proposes a new method for pseudo-3D verification of intensity-modulated radiation therapy (IMRT) dose distributions. Unlike commercial solutions, it uses measured doses only for gamma evaluation. Its resolution is far better than with electronic detectors within the measured plane and comparable in other directions. It is readily available at clinics because it uses existing resources-a slab phantom and EBT3 films. The method was tested on six IMRT clinical cases. An in-house code for 2D and pseudo-3D gamma analysis was written in MATLAB and compared to OmniPro I'mRT.

• MeSH
• celková dávka radioterapie MeSH
• fantomy radiodiagnostické * MeSH
• filmová dozimetrie přístrojové vybavení   metody   MeSH
• lidé MeSH
• nádory prostaty radioterapie   MeSH
• plánování radioterapie pomocí počítače přístrojové vybavení   metody   MeSH
• radioterapie s modulovanou intenzitou přístrojové vybavení   metody   MeSH
• záření gama MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

• MeSH
• interpretace obrazu počítačem MeSH

• Konspekt
• Lékařské vědy. Lékařství
• NLK Obory
• lékařská informatika

Three dimensions of chromatographic separation, using split-flow two-dimensional liquid chromatography (SF-2D-LC) with two parallel second dimensions, LC × 2LC, combined with quadruple parallel mass spectrometry (LC3MS4) is demonstrated for analysis of NIST SRM 1849a adult/infant formula. The first dimension, 1D, was a conventional non-aqueous reversed-phase (NARP) HPLC separation using two C18 columns in series, followed by detection using an ultraviolet (UV) detector, a fluorescence detector (FLD), with flow then split to a corona charged aerosol detector (CAD), and then dual parallel mass spectrometry (MS), conducted in atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) modes. The first second dimension, 2D(1), UHPLC was conducted on a 50.0 mm C30 column using a NARP-UHPLC parallel gradient for separation of short-chain triacylglycerols (TAGs) from long-chain TAGs, with detection by UV and ESI-MS. The second dimension, 2D(2), UHPLC was conducted using a 100.0 mm C30 column with a NARP-UHPLC parallel gradient for improved separation of TAG isomers, with detection by UV, an evaporative light scattering detector, and high-resolution, accurate-mass (HRAM) ESI-MS. Transferred eluent dilution was used to refocus peaks and keep them sharp during elution in both 2Ds. The separation space in the 2D(2) was optimized using multi-cycle (aka, "constructive wraparound") elution, which employed flow rate programming. In the 1D, calibration lines for quantification of fat-soluble vitamins were constructed. A lipidomics approach to TAG identification and quantification by HRAM-ESI-MS was applied to the 2D(2). These experiments can be represented: LC1MS2 × (LC1MS1 + LC1MS1) = LC3MS4, or three-dimensional liquid chromatography with quadruple parallel mass spectrometry.

• MeSH
• dospělí MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací * MeSH
• lidé MeSH
• náhražky mateřského mléka * MeSH
• triglyceridy MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Zobrazovací systémy rentgenové výpočetní tomografie (CT RTG) byly zavedeny v polovině sedmdesátých let. První desetiletí vývoje bylo hlavní úsilí soustředěno na dosazení vyššího prostorového rozlišení a rychlejšího sběru obrazových dat (skenování). Tyto systémy lze označit jako konvenční CTRTG. Další vývoj vedl k zavedení „slip-ring" technologie a „helical" („spiral") akvizice (Helical X-ray CT), CT RTG fluoroskopie (Real-time CT) a mimořádně rychlých - subsekundových systémů (Super-high-speed CT). Hlavní úsilí je v současné době soustředěno na vývoj systémů, které by umožňovaly v co nejkratším čase sejmout velký objem snímané scény v co nejtenčích tomografických řezech. Slibnou cestou se jeví kombinace „helical" a vícevrstvé akvizice (Multi-slice CT). Konečným cílem je vývoj rychlých 3D CTRTG systémů (High-speed 3D CT).

X-ray computed tomography was introduced in the mid 1970s, and significant improvements have been made in performance over the past 25 years. For the first 10 years or so, development work focused on achieving higher resolution in the axial plane and faster scannng. Then, around the end of the 1980s, Helical Scan permit continuous volume scanning was developed. New clinical applications using real time image reconstruction have also been developed. CT fluorographic guidance for biopsy procedures is one example. In 1998, a super-high-speed CT scanner was introduced; it permits 0.5-s rotation and expands the range of applications to include the cardiovascular systém. Efforts are being made to develop a new type of CT system that can scan volumes over a large range within a short time with thin slice images. The combination of helical scanning with multi-slice CT-involving several detector arrays stacked in the z direction (lengthways axis of the patient) - is one of the most promising approaches. The pursuit of faster scanning and higher resolution in olume scanning made possible by helical CT, and have been engaged in development of high-speed 3D scanner in which the detectors are extended in the longitudinal direction to create a (larger-area detectors to permit the acquisition of 3D images over a wide longitudinal range in a single rotation) 2D detector array. Multislice CT is considered to be the first step in realisation of such a high-speed scanner.

• MeSH
• technologie MeSH
• tomografie metody   přístrojové vybavení   trendy   MeSH
• tomografy rentgenové počítačové MeSH
• Publikační typ
• přehledy MeSH

Zobrazovací systémy rentgenové výpočetní tomografie (CT RTG) byly zavedeny v polovině sedmdesátých let. V prvním desetiletí vývoje bylo hlavní úsilí soustředěno na dosažení vyššího prostorového rozlišení a rychlejší sběr obrazových dat (skenování). Tyto systémy lze označit jako konvenční CTRTG. Další vývoj vedl k zavedení „slip-ring" technologie a „helical" akvizice (Helical X-ray CT), CT RTG fiuoroskopie (Real-time CT) a mimořádné rychlých- subsekundových systémů (Super-high-speed CT). Hlavní úsilí je v současné době soustředěno na vývoj systémů, které by umožňovaly V CO nejkratším čase sejmout velký objem snímané scény v co nejtenčích tomografických řezech. Slibnou cestou se jeví kombinace „helical" a vícevrstvé akvizice (Multi-slice CT). Konečným cílem je vývoj rychlých 3D CTRTG systémů (High-speed 3D CT).

X-ray computed tomography was introduced in the mid 1970s, and significant improvements have been made in performance over the past 25 years. For the first 10 years or so, development work focused on achieving higher resolution in the axial plane and faster scanning. Then, around the end of the 1980s, Helical Scan permitting continuous volume scanning was developed. New clinical applications using real time image reconstructions have also been developed-among these CT fluorographic guidance for biopsy procedures. In 1998, a super-high-speed CT scanner was introduced, permitting 0.5-s rotation and expanding the range of applications to include the cardiovascular system. Efforts are being made to develop a new type ofCTsystem being able to scan volumes over a large range within a short time with thin slice images. The combination of helical scanning with multi-slice CT involving several detector arrays stacked in the z direction (length-ways axis of the patient) is one of the most promissing approaches. The pursuit of faster scanning and higher resolution in volume scanning made possible by helical CT, and have been engaged in development of high-speed 3D scanner in which the detectors are extended in the longitudinal direction to create a (larger-area detectors to permit the acquisition of 3D images over a wide longitudinal range in a single rotation) 2D detector array. Multislice CT is considered to be the first step in realisation of such a high-speed scanner.

• MeSH
• počítačová rentgenová tomografie metody   přístrojové vybavení   MeSH
• Publikační typ
• přehledy MeSH

OBJECTIVE: Multidetector-row CT (MDCT) and contrast-enhanced echocardiography (CEE) are being increasingly used for assessment of left ventricular (LV) function. Excellent spatial and contrast resolution of MDCT allows this evaluation along with coronary angiography. CEE improves the accuracy of 2D echocardiography. Data on side-by-side comparison of both techniques for assessment of LV size and function in subjects with a non-dilated or dilated left ventricle are limited. METHODS AND RESULTS: Our study population included 64 patients. Group I included 31 patients with an implanted pacemaker who had a non-dilated left ventricle with preserved systolic function. Group II comprised 33 patients with dilated cardiomyopathy and severe systolic LV dysfunction. LV end-diastolic and end-systolic volumes (LVEDV, LVESV) and ejection fraction (LVEF) were assessed using both CEE and short-axis MDCT. The results obtained by both techniques were compared by linear regression and Bland-Altman analysis. Additionally, intra- and interobserver reproducibility was assessed. Both CEE and MDCT measurements highly correlated (r = 0.61-0.94). However, CEE significantly underestimated LVEDV and LVESV, and this bias was higher with enlarged LV volumes. LVEF was overestimated by CEE in both groups with a higher bias in the group with preserved systolic function. Both intra- and interobserver reproducibility was significantly better for MDCT, the worst reproducibility was observed for CEE in group I. CONCLUSION: Despite a high correlation between MDCT and CEE measurements, CEE provides consistently lower volumes and higher LVEF. This suggests that both methods are not completely interchangeable. Reproducibility of CEE is inferior to reproducibility of MDCT, especially in non-dilated left ventricles with preserved function.

• MeSH
• dilatační kardiomyopatie patofyziologie   ultrasonografie   MeSH
• funkce levé komory srdeční MeSH
• koronární angiografie metody   MeSH
• lidé středního věku MeSH
• lidé MeSH
• počítačová rentgenová tomografie metody   MeSH
• reprodukovatelnost výsledků MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• srdeční komory ultrasonografie   MeSH
• tepový objem MeSH
• vylepšení obrazu MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• práce podpořená grantem MeSH
• srovnávací studie MeSH