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Principles of Radiation Detection and Image Formation
Published in Ken Holmes, Marcus Elkington, Phil Harris, Clark's Essential Physics in Imaging for Radiographers, 2021
One technology that is very similar and is still being used clinically is the X-ray image intensifier (Figure 6.6). It only merits a brief description as this technology is slowly being phased out of production.
Image Intensifier System
Published in Robert J. Parelli, Principles of Fluoroscopic Image Intensification and Television Systems, 2020
When x-ray image intensifier tubes were first introduced, some means was needed to express their increased intensity. Because of the past familiarity with conventional fluoroscopic screens, it became commonplace to compare the image intensifier tube to the screen. The brightness gain, or “intensification gain” as it was called, was then expressed as the luminance of the output screen compared to the luminance of a standard Patterson fluoroscopic screen with the same incident radiation. The brightness gain is the ratio of the two illuminations:
Monte Carlo Simulation in Diagnostic Radiology
Published in Richard L. Morin, Monte Carlo Simulation in the Radiological Sciences, 2019
The radiation transmitted through the antiscatter device will be recorded by an x-ray receptor. In conventional radiography, x-ray intensifying screens in combination with a radiographic film are commonly used as the recording system. In computed tomography, solid-state detectors, xenon gas detectors, or a scintillation crystal-photodiode array are used. In digital radiography, an x-ray image intensifier coupled with a TV camera is often employed, although other x-ray receptors, such as a selenium plate, laser-stimulable storage phosphor screen, and photo-diode array, have also been examined.
Profiling of drug crystallization in the skin
Published in Expert Opinion on Drug Delivery, 2020
Choon Fu Goh, Ben J. Boyd, Duncan Q. M. Craig, Majella E. Lane
Both SAXS and WAXS were performed simultaneously at the BL40XU (High Flux Beamline) of the SPring-8 synchrotron station (Hyogo, Japan). A high-flux beam from a helical undulator (λ = 0.83 Å) was focused with two mirrors placed horizontally and vertically [13]. The X-ray energy was 15.0 keV with an energy bandwidth of about 3%. The X-ray microbeam was created by passing through a pinhole of 5 µm in diameter. The sample-to-detector distance was adjusted to approximately 2 m and 0.1 m for SAXS and WAXS, respectively. SAXS and WAXS profiles were recorded on a cooled CCD camera (1344 × 1024 pixels, ORCAII-ER, Hamamatsu Photonics Ltd., Hamamatsu, Japan) coupled with an X-ray image intensifier (V5445P, Hamamatsu Photonics Ltd., Japan) and an X-ray flat-panel imager (1032 × 1032 pixels, C9728DK, Hamamatsu Photonics Ltd., Hamamatsu, Japan), respectively. The reciprocal spacing, q, was calibrated with silver behenate and cerium oxide at room temperature, where q = 2π/d = 4π/λ sin(θ/2), θ is the scattering angle and d is the repeat distance. This setup gave the q range of 0.1 < q < 1.8 nm−1 for SAXS and 5 < q < 40 nm−1 (4º < θ < 30º) for WAXS. The exposure time of the X-ray microbeam for both SAXS and WAXS was 1 s. No radiation damage has been reported for both human [14] and porcine [15] skin samples for exposure times up to 15 min with a high-intensity X-ray (λ = 1.52 Å). All the experiments were performed at room temperature (25ºC). The data analysis was performed using FIT2D software (ESRF, Grenoble, France). The SAXS diffraction pattern was circular averaged to obtain a radial intensity profile. The WAXS scattering profile is presented as the XRD images generated.
A clinically oriented computer model for radiofrequency ablation of hepatic tissue with internally cooled wet electrode
Published in International Journal of Hyperthermia, 2018
E. Ewertowska, R. Quesada, A. Radosevic, A. Andaluz, X. Moll, F. García Arnas, E. Berjano, F. Burdío, M. Trujillo
The spatial distribution of the saline infused into the tissue by the boluses was analysed by means of an in vivo experimental study on two female pigs. The study was approved by the Animal and Human Experimentation Ethics Committee of the Universitat Autònoma de Barcelona (protocol numbers CEEAH 3336 and DMAH 8904). Both animals underwent a laparotomy to expose the liver for direct infusion. Iopamidol, a non-ionic contrast agent (G.E.S., Madrid, Spain), was added to the infused saline. The boluses were introduced into different sections of each lobe through the two expandable needles of an ICW electrode identical to that used in the clinical study. Six sets of infusions were made, each consisting of two 0.5 mL boluses injected at 0 s and 90 s, which gives 2 mL total volume injected per set. Each infusion took ∼15 s. The spatial distribution of infused saline was mapped by a GE OEC Fluorostar fixed X-ray image intensifier system (GE OEC Medical Systems, Salt Lake City, USA) without applying RF, since the aim was to determine the spatial distribution of the saline bolus just before RFA. The images were first preprocessed with Image J Software (open source available at https://imagej.net), adjusting brightness and contrast in order to reduce noise and enhance image quality. As the images from the first and second infusion of the same set were seen to have an almost identically shaped and sized distribution (see Results section for further details), they were overlapped to create a “generic distribution” for each set. The margins of the infused areas were then segmented by thresholding each 8-bit greyscale image [21], preceded by the background subtraction operation for increased effectiveness. The segmented margins were then merged with the original images, converted into binary format and mounted together to create one greyscale image in which each image made up 16.6% of the total greyscale intensity, so that 67% greyscale was considered as the “generic pattern” of saline infusion and hence was used to build the computer model.