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Introduction
Published in Gavin Poludniowski, Artur Omar, Pedro Andreo, Calculating X-ray Tube Spectra, 2022
Gavin Poludniowski, Artur Omar, Pedro Andreo
X-ray tubes are used in a variety of fields, including medical imaging, low- and medium energy x-ray radiotherapy, material science, and industrial testing. The optimal characteristics of an x-ray beam can vary widely from application to application and hence x-ray tube design does also. Even for a given x-ray tube, there are adjustable parameters such as the tube potential, exposure setting, and filtration that considerably affect the properties of the beam.
Computed Tomography Imaging in Radiotherapy
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
CT imaging is based on the measurement of photon attenuation profiles during the rotation of an x-ray tube located in the CT gantry. The x-ray tube operates at voltages between 80 kV and 140 kV and with high currents (up to 500 mA to 800 mA). At the output of the tube, a physical filtering system provides beam attenuation compensation (head/body) and beam hardening. A collimating slit is used to block the x-ray beam in the longitudinal direction so as to define a slice of a specified thickness. After traversing the patient, this fan-beam is intercepted by a series of 700 to 1000 detector elements in an arc-shaped row in the transverse plane of the patient. A focused anti-scatter grid is used to improve the image quality by eliminating most of the scattered radiation.
Diagnostic Imaging Using X-rays
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Debbie Peet, Richard Farley, Elizabeth Davies
All diagnostic X-ray imaging systems generate X-rays using an X-ray tube, as shown in Figure 4.1. The X-ray tube uses a high voltage to accelerate electrons produced by thermionic emission across a vacuum tube.
A trial to visualize perforators images from CTA with a tablet device: experience of operating on minipigs
Published in Computer Assisted Surgery, 2022
Hisato Konoeda, Miyuki Uematsu, Nie Jumxiao, Ken Masamune, Hiroyuki Sakurai
Following catheterization of the left jugular vein and the attachment of. CT scanner skin markers (IZI Medical Products Inc., MD, USA), which were placed onto the surface of the skin at 50-mm intervals prior to image acquisition, CTA and the surgical procedure were conducted with the animal in the prone position. CTA was performed using a 16-detector-row CT scanner (BrightSpeed Elite; General Electric, Milwaukee, WI, USA). The scans were performed using the following parameters: 0.37-s gantry rotation speed, 0.50-mm collimator width slice thickness, and 1.37 helical detector pitch. The X-ray tube voltage was 120 kV, and the tube current ranged from 118 to 151 mA. All scanning procedures were performed after intravenous administration of 200 ml of nonionic iodinated contrast medium at a concentration of 370 mg/ml (Iopamilon 370; Bayel, Tokyo, Japan). The contrast material was injected at a rate of 4 ml/s via an 18-g intravenous catheter inserted into the left jugular vein. The scanning delay was 10 s.
Fabrication of hesperidin nanoparticles loaded by poly lactic co-Glycolic acid for improved therapeutic efficiency and cytotoxicity
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Saja H. Ali, Ghassan M. Sulaiman, Mohammad M. F. Al-Halbosiy, Majid S. Jabir, Anaheed H. Hameed
After this step, the pellet was re-dispersed in 20 mL of deionized distilled water for further assessments. The crystalline state of the samples was estimated with an X-ray diffractometer (XRD-6000, Shimadzu, Japan). The diffraction pattern was obtained using a Cu Kα incident beam (λ = 1.542 A°) at 2θ = 0°–65°. The voltage and current of X-ray tubes were 45 kV and 30 mA, respectively. FTIR analysis was carried out with an FTIR spectrometer (8400S, Shimadzu, Japan) in attenuated total reflection mode and spectral range of 4000–400 cm−1 with a resolution of 4 cm−1. Particle size was determined by photon correlation spectroscopy (PCS) by using a Zetasizer 5000 (Malvern Instruments Ltd., UK). Finally, the morphology and the uniformity of hesperidin nanoparticles were confirmed via scanning electron microscopy assay (Shimadzu AA-7000, Japan).
Radiation therapy techniques in the treatment of skin cancer: an overview of the current status and outlook
Published in Journal of Dermatological Treatment, 2019
Ali Pashazadeh, Axel Boese, Michael Friebe
While useful in the management of skin cancers, it should be noticed that electron beam therapy has its challenges. It has complicated dosimetry. In the treatment of small lesions, which is the case in most of NMSCs, it is associated with some degree of uncertainty in dose calculation (26). Percent depth dose (PDD) and output factors can change significantly in small-field treatments, typically less than 10 mm in diameter, which should be considered during electron dosimetry (33). Compared to the X-ray therapy that has a sharp edge of the radiation field, the edge of the electron beam field is blurry. The lead cutouts used for dose collimation and better dose coverage on the skin are usually messy in terms of construction and may be uncomfortable for patients (33). There is also uncertainty in the amount of bolus needed for each patient. In electron beam therapy of skin tumor, a relatively large safety margin of 10–20 mm is usually required (34). In contrast to X-ray photons that can be produced with Co-60, X-ray tubes and linear accelerators, high-energy electrons used in electron beam therapy are mainly produced by a linear accelerator. Therefore, production of the electron beam is always expensive and the treatments are costly (30). For tumors located in the anatomically challenging areas and irregular anatomies, dosimetry of electron beam therapy will be difficult and subject to error in calculation.