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Solid-State Dose Measuring Devices
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Different authors (Soubra et al. 1994; Chuang et al. 2002; Scalchi and Francescon 1998) report a MOSFET reproducibility of approximately 3% (k = 1)* for standard dosimeters connected to a bias box. In fact, it can differ depending on the type of detector and associated mode (Scalchi et al. 2010), on the readout device, on the state of the dosimeter (new or previously used), etc. These characteristics should be evaluated in practical conditions, and the dosimeters should be regularly re-calibrated.
Radiation Safety
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Debbie Peet, Elizabeth Davies, Richard Raynor, Alimul Chowdhury
Such reviews require knowledge of the work carried out as well as the properties of the dosimeters in use. Although there are relatively few individuals recording higher doses it is important to ensure that these individuals are not recording significantly higher doses than colleagues doing the same work as this would indicate that best practice is not being followed.
Film Dosimetry
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
Sina Mossahebi, Nazanin Hoshyar, Rao Khan, Arash Darafsheh
Film dosimeters provide two-dimensional (2D) measurement with high spatial resolution over a large area. There are in general two types of films used as dosimeters: radiographic and radiochromic. Radiographic films have been phased out of most of radiotherapy clinics in the United States and Canada; they have been replaced by 2D flat panel imagers and radiochromic films. Radiochromic films are now widely used in radiation therapy dosimetry and particularly in quality assurance (QA), especially for planar dose distribution comparisons. These films have been very useful for in vivo measurements, small field dosimetry as well as dose distribution evaluation of high dose-gradient regions because of their high spatial resolution, water equivalency, and ease of handling [1–6].
Dosimetry and uncertainty approaches for the million person study of low-dose radiation health effects: overview of the recommendations in NCRP Report No. 178
Published in International Journal of Radiation Biology, 2022
Lawrence T. Dauer, André Bouville, Richard E. Toohey, John D. Boice, Harold L. Beck, Keith F. Eckerman, Derek Hagemeyer, Richard W. Leggett, Michael T. Mumma, Bruce Napier, Kathy H. Pryor, Marvin Rosenstein, David A. Schauer, Sami Sherbini, Daniel O. Stram, James L. Thompson, John E. Till, R. Craig Yoder, Cary Zeitlin
The Report provides several dose coefficients [relating Hp(10) and organ dose] that could be applicable to various external exposure scenarios and geometries for the MPS populations where personal dosimeter data were available. Figure 3 provides an example of dose coefficients for AP exposure geometry. The use of dose coefficients typically assumes uniform irradiation of the body from a designated angle of incidence, particularly for the torso where most of the radiosensitive organs reside. Some exposure scenarios and radiation environments do not result in relative uniform irradiation of the torso and head. In these situations, the estimate of Hp(10) may need to be modified to reflect the nonuniform irradiation of different regions of the body. In the absence of detailed information on the irradiation geometry related to work activities, it is recommended to assume typical or representative geometries such as 100% AP or 50% AP plus 50% ROT (NCRP, 2009b), or 50% AP plus 50% isotropic (Thierry-Chef et al. 2007). In some facilities, multiple personal monitoring dosimeters may have been used by a single person during conditions of very nonuniform irradiation of the body. In such cases, the estimate of Hp(10) from the dosimeter located nearest the organ of interest should be used. ANSI/HPS (2011) prescribes a procedure in which the body is divided into compartments for which a separate compartment-weighted Hp(10) value is assessed from a dosimeter located nearest that compartment.
RENEB/EURADOS field exercise 2019: robust dose estimation under outdoor conditions based on the dicentric chromosome assay
Published in International Journal of Radiation Biology, 2021
David Endesfelder, Ursula Oestreicher, Ulrike Kulka, Elizabeth A. Ainsbury, Jayne Moquet, Stephen Barnard, Eric Gregoire, Juan S. Martinez, François Trompier, Yoann Ristic, Clemens Woda, Lovisa Waldner, Christina Beinke, Anne Vral, Joan-Francesc Barquinero, Alfredo Hernandez, Sylwester Sommer, Katalin Lumniczky, Rita Hargitai, Alegría Montoro, Mirta Milic, Octávia Monteiro Gil, Marco Valente, Laure Bobyk, Olga Sevriukova, Laure Sabatier, María Jesús Prieto, Mercedes Moreno Domene, Antonella Testa, Clarice Patrono, Georgia Terzoudi, Sotiria Triantopoulou, Rositsa Histova, Andrzej Wojcik
A detailed description of the RPL glass dosimeters used for this field test can be found in (Waldner et al. 2021). For the purpose of biological dosimetry, RPL glass dosimeters were placed in a sealed vinyl bag for the measurements performed inside thermos flasks filled with warm water and on the external surface of the thermos flasks. Inside the thermos flasks, three dosimeters were placed on each blood tube at the surface facing the source along the vertical axis, namely at the top, center and bottom of the tube. The blood height in each tube was approximately 6 cm. The dosimeters were placed in this way to evaluate a possible dose gradient on the vertical axis and also to estimate the doses received by the samples. To evaluate a possible problem of the positioning of the water container, for samples analyzed by the RENEB participants, additional dosimeters were placed in the horizontal plane around the outside of the flask at half height. Dose estimates from 1–4 dosimeters (blue circles in Figure 1(E,F)) were available for the analysis. This also aims to evaluate any possible perturbation caused by the phantom on which the containers were attached.
Current utilization and future directions of robotic-assisted endovascular surgery
Published in Expert Review of Medical Devices, 2020
Peter Legeza, Gavin W. Britz, Thomas Loh, Alan Lumsden
By following the ALARA (as low as reasonably achievable) principles [8], operators should pursue the limitation of radiation exposure for the patient, physicians, and staff. In addition to patient specific case planning, preoperative selection of optimal C-arm angulations, commercially available imaging systems include several features to reduce radiation exposure, such as low-dose settings, pulse mode, collimation, digital image magnification, and imaging fusion [9–11] Personal protective equipment (PPE) is also mandatory to use for all staff, who are exposed to radiation during interventional procedures. These include lead aprons, thyroid protection, lead caps, and leaded glasses. Dosimeters provide data on radiation exposure, which also enhances the awareness of radiation exposure, and enables to compare radiation information between different centers. With the techniques mentioned above, improvement was achieved in the radiation exposure for the patients and the interventional physicians as well.