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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.
Kilovoltage X-Ray Units
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
The x-ray tube housing consists of a metal shield that encloses and protects the tube, providing shielding from unwanted x-rays. Permissible leakage levels through the shield at 1 m from the focal spot are 1 mGy h−1 and 10 mGy h−1 for equipment running up to 150 kVp and 300 kVp, respectively (IEC 2010). A filter holder and applicator mount are attached to the tube housing at the beam exit aperture. The filter holder usually contains one or more micro-switches to enable the system control unit to recognise coded external metal filters. For orthovoltage equipment with applicators of SSD above 40 cm, a radiation monitor should be provided to indicate the tube output rate (IEC 2010). This typically takes the form of a transmission ionisation chamber placed downstream of the filter holder (see Section 16.3.3). Such equipment can be calibrated to deliver the intended dose in terms of monitor units, rather like a linear accelerator (Gerig et al. 1994).
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.
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.
Importance of dosimetry protocol for cell irradiation on a low X-rays facility and consequences for the biological response
Published in International Journal of Radiation Biology, 2018
Morgane Dos Santos, Vincent Paget, Mariam Ben Kacem, François Trompier, Mohamed Amine Benadjaoud, Agnès François, Olivier Guipaud, Marc Benderitter, Fabien Milliat
All irradiations described in this article were performed at the Small Animal Radiation Research Platform (SARRP) from XSTRAHL (XSTRAHL Ltd., Camberley, UK) at IRSN (Fontenay-aux-Roses, France). SARRP is an image-guided micro irradiator composed of a Varian X-ray tube (NDI-225-22, NDI, Washington, DC) attached to a gantry that can be rotated between −180 and 180 degrees (Deng et al. 2007; Wong et al. 2008). The X-ray tube specifications are an inherent filtration of 0.8 mm of Beryllium, a large focal spot size about 3 mm, a high voltage (HV) range about 30–225 kV and a maximum current of the machine can reach 30 mA (depending on the HV applied). This device has been originally designed for small animal irradiation, but it could be also used for other applications, such as cell irradiations, even if its limited beam size is not optimum for that type of application. The irradiation field is limited to roughly 20 by 20 cm2 at the isocenter (Source-detector distance about 35 cm) including the penumbra region (see section Homogeneity of irradiation field). At IRSN, the SARRP is also used in routine for irradiation of cell culture at doses at HV below 100 kV. In this work, cells were irradiated at doses ranging from 0 to 4 Gy at 80 kV and at a dose rate of 0.63 Gy.min−1 in terms of Kair (using copper or aluminum additional filtration, named configurations 1 and 2, respectively).