sensor geometry
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The activity of radioactive pharmaceuticals administered to patients in nuclear medicine is usually determined using well-type high-pressure ionization chambers. For the Bqmeter chamber (Consortium BQM, Czech Republic) a Monte Carlo model was created using the MCNP4C2 code. Basic chamber characteristics for two sample containers of various geometry (a vial and an ampoule) were calculated and compared with measurements. As the pharmaceuticals are often measured in various syringes, the chamber response for samples in syringes was also studied.
- MeSH
- algoritmy MeSH
- artefakty MeSH
- dávka záření MeSH
- design s pomocí počítače MeSH
- kalibrace normy MeSH
- metoda Monte Carlo MeSH
- radiofarmaka analýza MeSH
- radiometrie metody normy přístrojové vybavení MeSH
- radionuklidy analýza MeSH
- referenční standardy MeSH
- reprodukovatelnost výsledků MeSH
- senzitivita a specificita MeSH
- software MeSH
- Publikační typ
- hodnotící studie MeSH
- Geografické názvy
- Česká republika MeSH
Affinity-based biosensing systems have become an important analytical tool for the detection and study of numerous biomolecules. The merging of these sensing technologies with microfluidic flow cells allows for faster detection times, increased sensitivities, and lower required sample volumes. In order to obtain a higher degree of performance from the sensor, it is important to know the effects of the flow cell geometry on the sensor sensitivity. In these sensors, the sensor sensitivity is related to the overall diffusive flux of analyte to the sensing surface; therefore increases in the analyte flux will be manifested as an increase in sensitivity, resulting in a lower limit of detection (LOD). Here we present a study pertaining to the effects of the flow cell height H on the analyte flux J, where for a common biosensor design we predict that the analyte flux will scale as J ≈ H(-2/3). We verify this scaling behavior via both numerical simulations as well as an experimental surface plasmon resonance (SPR) biosensor. We show the reduction of the flow cell height can have drastic effects on the sensor performance, where the LOD of our experimental system concerning the detection of ssDNA decreases by a factor of 4 when H is reduced from 47 μm to 7 μm. We utilize these results to discuss the applicability of this scaling behavior with respect to a generalized affinity-based biosensor.
PURPOSE OF THE STUDY Femoroacetabular impingement syndrome is a complex, often post-traumatically developing impairment of the hip joint, characterized by ambiguous symptomatology, which makes early diagnosis diffi cult, especially in the early stages. Experimental retrospective study was carried out to evaluate the usability of a triaxial gyroscopic sensor in routine practice as an additional indication criterion for operative versus conservative treatment procedures. MATERIAL AND METHODS 92 patients were included in the retrospective study, and 62 completed the investigation. All patients signed informed consent. A gyroscopic sensor was placed on the right side of the pelvis above the hip joint, and the patients walked approximately 15 steps. Furthermore, an evaluation of the data during stair climbing and a complete clinical examination of the dynamics and physiological movements in the joint was carried out. Data measured with a gyroscopic sensor were processed using differential geometry methods and then evaluated using spectral analysis and neural networks. The proposed technique of diagnosing FAI using gyroscope measurement is a fast, easy-to-perform method. RESULTS Our approach in processing gyroscopic signals used to detect the stage of arthrosis and post-traumatically developing FAI could lead to more accurate early detection and capture in the early stages. CONCLUSIONS The obtained data are easily evaluated, interpretable and benefi cial in diagnosing the early stages of FAI. The results of the conducted research showed this approach to more accurate early detection of arthrosis and post-traumatically developing FAI. Key words: wearable sensors; osteoarthritis; mathematical biophysics; telemedicine.
- MeSH
- femoroacetabulární impingement * diagnóza chirurgie MeSH
- kyčelní kloub chirurgie MeSH
- lidé MeSH
- nemoci kloubů * MeSH
- neuronové sítě MeSH
- osteoartróza * MeSH
- retrospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Refractometric sensors utilizing surface plasmon resonance (SPR) should satisfy a series of performance metrics, bulk sensitivity, thin-film sensitivity, refractive-index resolution, and high-Q-factor resonance, as well as practical requirements such as manufacturability and the ability to separate optical and fluidic paths via reflection-mode sensing. While many geometries such as nanohole, nanoslit, and nanoparticles have been employed, it is nontrivial to engineer nanostructures to satisfy all of the aforementioned requirements. We combine gold nanohole arrays with a water-index-matched Cytop film to demonstrate reflection-mode, high-Q-factor (Qexp = 143) symmetric plasmonic sensor architecture. Using template stripping with a Cytop film, we can replicate a large number of index-symmetric nanohole arrays, which support sharp plasmonic resonances that can be probed by light reflected from their backside with a high extinction amplitude. The reflection geometry separates the optical and microfluidic paths without sacrificing sensor performance as is the case of standard (index-asymmetric) nanohole arrays. Furthermore, plasmon hybridization caused by the array refractive-index symmetry enables dual-mode detection that allows distinction of refractive-index changes occurring at different distances from the surface, making it possible to identify SPR response from differently sized particles or to distinguish binding events near the surface from bulk index changes. Due to the unique combination of a dual-mode reflection-configuration sensing, high-Q plasmonic modes, and template-stripping nanofabrication, this platform can extend the utility of nanohole SPR for sensing applications involving biomolecules, polymers, nanovesicles, and biomembranes.
- MeSH
- biosenzitivní techniky metody MeSH
- fosfatidylcholiny chemie MeSH
- limita detekce MeSH
- liposomy analýza chemie MeSH
- nanopóry * MeSH
- oxid hlinitý chemie MeSH
- povrchová plasmonová rezonance metody MeSH
- sérový albumin hovězí analýza MeSH
- skot MeSH
- zlato chemie MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
PURPOSE: To develop an assumption-free methodology for aligning the geometry of on-board imagers with the geometry of medical linear accelerators applied in image-guided radiotherapy (IGRT). MATERIAL: Alignment of the on-board imaging (OBI) system with respect to the accelerator system is achieved using a multi-modular phantom described elsewhere (Tabor et al., 2017), enabling the geometry of the linear accelerator to be specified without any pre-assumptions. METHODS: The placement of two isocentres (of the on-board imager and of the therapeutic system) and of three frames of reference (those of the on-board imager, of the therapeutic system, and of the treatment table) is formulated as an optimization problem. It is solved by analysing the images of fiducial points positioned in 3D space in phantom modules attached to the treatment table and to the collimator of the accelerator. Fiducials are projected onto an imaging plane of unknown characteristics from a virtual source of unknown coordinates. CONCLUSIONS: An analytical framework exploiting projection images of the proposed multi-modular phantom has been developed, enabling precise alignment of the reference frame related to the on-board imager with the reference frame related to the therapeutic system. Within the proposed framework, the necessary corrections of treatment table positioning prior to patient irradiation, are delivered in the treatment table coordinates.
The contribution deals with the first step in using proper wave-equation based ultrasound propagation model in image reconstruction from the ultrasonic computed tomography data. Particularly, it compares the transducer calibration results obtained via direct measurement of the empty image field and consequential data processing based on a simple direct-propagation model with the simulation results obtained via solving the single-frequency wave equation under proper border conditions reflecting the realistic measurement geometry. The results show a reasonable qualitative agreement when a certain degree of phase-shifted coupling from the transmitting transducer elements to the neighbouring elements of the transducer field is admitted.
- MeSH
- algoritmy MeSH
- financování organizované MeSH
- interpretace obrazu počítačem metody normy MeSH
- kalibrace MeSH
- měniče MeSH
- radiační rozptyl MeSH
- reprodukovatelnost výsledků MeSH
- senzitivita a specificita MeSH
- ultrasonografie normy přístrojové vybavení MeSH
- vylepšení obrazu metody normy MeSH
- Publikační typ
- hodnotící studie MeSH
- srovnávací studie MeSH
- validační studie MeSH
- Geografické názvy
- Česká republika MeSH
For experiments with dispersed radioactive aerosols in a radon-aerosol chamber (RAC), it is desirable to know the activity of the radioactive aerosols applied in the RAC. A COLIBRI TTC survey metre with an SABG-15+ probe (Canberra, USA) was purchased for this purpose. The probe is designed for surface contamination measurements, and it is intended to measure the activity of aerosols deposited on the filters during experiments in the RAC. Since the probe is calibrated in a different geometry, its response in the authors' experimental geometry was simulated by a Monte Carlo method. The authors present a Monte Carlo model using MCNPX and an experimental verification of this probe model.
- MeSH
- aerosoly analýza MeSH
- alfa částice MeSH
- design vybavení MeSH
- kalibrace MeSH
- metoda Monte Carlo MeSH
- monitorování radiace přístrojové vybavení MeSH
- počítačová simulace MeSH
- radioaktivní látky znečišťující vzduch analýza MeSH
- radiometrie přístrojové vybavení metody MeSH
- radionuklidy analýza MeSH
- teoretické modely MeSH
- záření gama MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Úvod: Byla provedena křížová kalibrace tomografické citlivosti SPECT/CT kamery GE Discovery 670 vůči lokálnímu měřiči aktivity BQMetr4. Materiál a metoda: Chyba kalibračního koeficientu byla odhadnuta na 5,1 % v laboratorních podmínkách. Výsledná kalibrace byla ověřena sérií měření na fantomu Jaszczak bez vnitřních struktur a s horkými ložisky v různých geometriích a pro různé korekce. Výsledky: Nejvyšší přesnost v nesymetricky rozptylujícím a pohlcujícím prostředí vykazuje pro objekty velikosti 25 mm kombinace korekcí na rozptyl akvizicí ve dvou energetických oknech a zeslabení pomocí CT 7,2 (± 2,9stat ± 10,3sys) % pro manuální segmentaci a 7,9 (± 1,5stat ± 8,2sys) % pro segmentaci založenou na hledání maximálního průměru oblasti pevné velikosti. V případě automatické segmentace je vhodné k těmto korekcím připojit i algoritmus resolution recovery, takže celková přesnost dosáhla 0,5 (± 0,9stat ± 7,9sys) %. Závěr: Přesnost hodnot SUV je dána přesností křížové kalibrace, systematická chyba je oproti kalibraci zvýšená nepřesností měřiče aplikované aktivity a byla odhadnuta na nejvíce 7,1 % pro korekci na zeslabení a rozptyl a pro všechny uvažované metody segmentace.
Introduction: A cross-calibration of tomographic sensitivity of SPECT/CT camera GE Discovery 670 against the local dose calibrator BQMetr4 was done. Material and methods: The error of the calibration coefficient was estimated to be 5,1 % in laboratory conditions. The calibration was confirmed by a series of measurements with the Jaszczak phantom with no inside structures and with hot lesions in various geometries and for different corrections. Results: The highest precision in a non-symmetrically scattering and attenuating environment for objects of size 25 mm was achieved for the combination of scatter correction by acquisition in two energy windows and CT-based attenuation correction 7,2 (± 2,9stat ± 10,3sys) % for manual segmentation and 7,9 (± 1,5stat ± 8,2sys) % for segmentation based on searching the maximal average in a region of fixed size. For automated segmentation using thresholding it is desirable to implement the resolution recovery algorithm and the final precision reached 0,5 (± 0,9stat ± 7,9sys) %. Conclusion: The precision of SUV is determined by the precision of the cross-calibration. The systematic error of SUV is higher than the systematic error of the calibration due to imprecision of the dose calibrator and was estimated to 7,1 % at most for attenuation and scatter corrections for any segmentation method studied.
