X-ray detector
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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
Analýza databázy PubMed ukázala nedostatok informácií o rôntgenovej mikroanalýze (RtgMA) ľudskej sleziny. Vyšetrili sme slezinu pacienta postihnutého autoimúnnou trombocytopenickou purpurou. Na REM štúdium slezmy a na RtgMA sa pripravili vzorky fixované glutaraldehydom a pokovené meďou. Na RtgMA sme použili detektor QUANTUM a analyzátor DELTA-CLASS. V slezine fixovanej GA a pokrytej meďou sme okrem kremíka našli rôzne spektrálne čiary prvkov, ktoré sú obvykle prítomné v živočíšnych tkanivách. Biologický význam takého poznatku zostal pre nás zatiaľ nejasný.
There is a lack of information on x-ray microanalysis (XMA) of the human spleen. We have examined the spleen of a patient with autoimmune thrombocytopenic purpura. The specimens were fixed in glutaraldehyde and coated by copper. The XMA was performed by a Quantum detector Delta-Class analyzer. In addition to spectral lines of elements normally present m human tissues, we have hemonstrated silicon. The presence of silicon in human spleen may be a consequence of the organ's cleansing function.
Using dedicated contrast agents high-quality X-ray imaging of soft tissue structures with isotropic micrometre resolution has become feasible. This technique is frequently titled as virtual histology as it allows production of slices of tissue without destroying the sample. The use of contrast agents is, however, often an irreversible time-consuming procedure and despite the non-destructive principle of X-ray imaging, the sample is usually no longer usable for other research methods. In this work we present the application of recently developed large-area photon counting detector for high resolution X-ray micro-radiography and micro-tomography of whole ex-vivo ethanol-preserved mouse organs. The photon counting detectors provide dark-current-free quantum-counting operation enabling acquisition of data with virtually unlimited contrast-to-noise ratio (CNR). Thanks to the very high CNR even ethanol-only preserved soft-tissue samples without addition of any contrast agent can be visualized in great detail. As ethanol preservation is one of the standard steps of tissue fixation for histology, the presented method can open a way for widespread use of micro-CT with all its advantages for routine 3D non-destructive soft-tissue visualisation.
- MeSH
- ethanol chemie MeSH
- fotony * MeSH
- ledviny diagnostické zobrazování MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- plíce diagnostické zobrazování MeSH
- rentgenová mikrotomografie přístrojové vybavení metody MeSH
- srdce diagnostické zobrazování MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem 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
Spectral fluence of photoneutrons generated in the head of the radiotherapeutic linac Varian 2100 C/D was measured by means of the Bonner spheres spectrometer whose active detector of thermal neutrons was replaced by a track detector, i.e. a sandwich of four CR-39s with the boron radiator inserted between them. Measurements with different collimator settings showed that the fluence of photoneutrons was higher for the more open collimator.
The work was based on the identification and determination of selected elements in teas, plants and medicinal products for the treatment of anemia. To evaluate the quality of medicinal plants Urtica dioica L., Papaver somniferum, L., leguminous plant Lens culinaris, M. and also in medicaments Aktiferrin? gtt., Ferronat? retard pot.tbl and Sorbifer? Durulues? por. Tbl. Flm. was used nuclear analytical method Radionuclide X-ray Fluorescence Spectrometry. This method is suitable for the analysis of samples in the solid state and a liquid state. Solid samples were homogenized and compressed into tablets of defined shape and weight. Liquid samples were filtered through a chelating membrane 3M EmporeTM, which are used to selectively capture the polyvalent metal cations and are preconcentrating the elements from sample. Samples were analysed using radiation radionuclide 238 Pu and evaluated by means of a semiconductor detector and a multichannel analyser.
Multidetektorová CT angiografie věnčitých tepen využívá synchronizaci akvizice hrubých dat s EKG křivkou. K rekonstrukci obrazů se používá jen segment dat v diastolické fázi, dosahuje se tak časového rozlišení až 105 ms. Hodnotí se axiálni obrazy a na pracovní stanici jsou zhotovovány trojrozměrné rekonstrukce věnčitých tepen. Hlavní nevýhodou metody je relativně nízké časové rozlišení, které neumožňuje kvalitně zobrazit koronárni řečiště u osob s frekvencí vyšší než 85 za minutu i u pacientů s arytmiemi, také větve na laterální a spodní stěně srdce nejsou u všech pacientů kvalitně zobrazitehié. Ačkoliv má tato ojedinělá zobrazovací technika dosud limitace ve srovnání s katetrizační koronarografií, jde o první krok k neinvazivnímu zobrazení věnčitých tepen. V práci autoři hodnotí soubor 30 nemocných vyšetřených na šestnáctiřadém multidetektorovém přístroji Somatom Sensation 16 (Siemens, Forchheim, SRN).
Multi-row-detector CT angiography uses synchronized raw data acquisition with ECG curve. Only a part of data set in diastolic phase is used fo for reconstruction of images with temporal resolution up to 105 ms. The axial images and 3D-reconstructions of coronary vessels are evaluated. The most important disadvantage is a relativelly low temporal resolution, CTA couldn't be used for patients with the heart rate over 85 bpm and for patients with arythmia. Fine branches of coronary tree on lateral and lower wall isn't displayed very well in all patients. Although this unique method has a limitation in comparison to catheterization coronarography, it is the first step to noninvasive coronary imaging. Authors report about a group of 30 patients with different coronary vessel pathology who underwent examination on sixteen-row-detector equipment Somatom Sensation 16 (Siemens, Forchheim, Germany) using a rotation period of 420 ms.
In this work we present the application of X-ray fluorescence analysis (XRFA) in an investigation of the Land Register and the Register of the Court of the Kingdom of Bohemia and the manuscript of the Homiliary of the Opatovice Monastery from the 12th century. Radionuclide sources emitting radiation at an appropriate energy level and an X-ray tube were used to excite the characteristic radiation. A spectrometric Si(Li) detector and a Si-PIN detector with Peltier cooling were used to detect the excited characteristic radiation. Several types of pigments were identified and compositions of inks used within almost 5 centuries in the offices at the Prague Castle were determined.
- MeSH
- barvicí látky analýza MeSH
- dějiny středověku MeSH
- difrakce rentgenového záření metody MeSH
- rukopisy jako téma dějiny MeSH
- Check Tag
- dějiny středověku MeSH
- Publikační typ
- časopisecké články MeSH
- historické články MeSH
- Geografické názvy
- Česká republika MeSH
Hepatocelulámí karcinom je nejčastější primární maligní útvar jater. I když je jeho incidence v naší populaci relativně nízká, významný přínos má diferenciální diagnostika u nemocných s jatemí cirhózou a chronickou aktivní hepatitídou B a C. Dvoufázové helikální CT vyšetření má významný vliv na strategii léčby, především na posouzení možnosti chirurgického výkonu. Multidetektorová výpočetní tomografie ještě zvětšuje výhody dvoufázového vyšetření především jedinečným prostorovým rozlišením a možností trojrozměrného zobrazení cévní anatomie jater, patologické vaskularizace i cévní invaze nádoru. Autoři hodnotí soubor 14 nemocných s prokázaným hepatocelulárním karcinomem, z nichž čtyři nemocní byli vyšetřeni pomocí šestnáctidetektorového výpočetního tomografu.
Hepatocellular carcinoma (HCC) is the most frequent primary malignant liver tumor. Although its incidency in our population is relatively low, the improvement of di differential diagnosis is important in patients with liver cirrhosis and active hepatitis B and C. Biphasic helical computed tomography has strong infiuence in treatment strategy, especially in evaluation of possibility of surgical resection. Multi-detector-row CT improve the advantages of biphasic helical CT, especially by the unique spatial resolution in any plane direction. Three-dimensional CT angiograms help to asses not only the hepatic vascular anatomy, but also the pathologic vascularisation of HCC. Authors report a group of 14 patients with HCC diagnosed by helical CT; 4 of these patients underwent MDCT using sixteen-detector-row equipment.
- MeSH
- diferenciální diagnóza MeSH
- hepatitida C MeSH
- hepatocelulární karcinom MeSH
- lidé MeSH
- nádory jater MeSH
- počítačová rentgenová tomografie metody MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
OBJECTIVES: to assess the feasibility of CT with an integrated photon-counting-detector system (PC-CT) in the body imaging of clinical patients. METHODS: 120 examinations using photon counting detector CT were evaluated in six groups: 1/ a standard-dose lung, 2/ low-dose lung, 3/ ultra-high resolution (UHR) lung, 4/ standard-dose abdominal, 5/ lower-dose abdominal, 6/ UHR abdominal CTA. All CT examinations were performed on a single-source prototype device equipped with a photon counting detector covering a 50 cm scan field of view. Standard dose examinations were performed with the use of detector element size of 0.4 mm, ultra-high-resolution examinations with the detector element size of 0.2 mm, respectively. The stability of the system during imaging was tested. The diagnostic quality of the acquired images was assessed based on the imaging of key structures and the noise level in five-point scale, the effective dose equivalent, dose length product and noise level, and also relation to body mass index and body surface area were compared with three similar groups of CT images made with energy integrating high end scanner. The parameters were evaluated using Wilcoxon test for independent samples, the independence was tested using Kruskal-Wallis test. RESULTS: When PC-CT images radiation dose is compared with the similar imaging using energy integrating CT, the PC-CT shows lower dose in ultra-high resolution mode, the dose is significantly lower (p < 0.0001), the standard dose examinations were performed with the comparable radiation doses. PC-CT exhibited the significantly higher ratio between parenchyma signal and background noise both in lung and in abdominal imaging (p < 0.0001). CONCLUSIONS: PC-CT showed imaging stability and excellent diagnostic quality at dose values that are comparable or better to the quality of energy integrating CT, the better signal and improved resolution is most important advantage of photon counting detector CT over energy integrating detector CT.
- MeSH
- fantomy radiodiagnostické MeSH
- fotony * MeSH
- lidé MeSH
- plíce MeSH
- počítačová rentgenová tomografie * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
