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Electron-Beam Treatment Planning Techniques
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Alan McKenzie, David Thwaites, W. P. M. Mayles
The basic physics of electron beams used in clinical practice has been described in Chapter 24. The present chapter discusses how these principles may be applied to techniques and problem-solving in electron treatment planning. In the following discussion, the term treatment planning is taken to include treatment using single beams; indeed, such treatments constitute the bulk of electron therapy in clinical practice.
Cherenkov and Scintillation Imaging Dosimetry
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
Rachael L. Hachadorian, Irwin I. Tendler, Brian W. Pogue
Limited to MV Photon and Electron Therapy Beams: While photons and electrons constitute the majority of radiotherapy treatments currently, it neglects proton and heavy ion beams. Although the origin of Cherenkov comes from a relativistic charged particle, the observable effect for proton beams was substantially diminished by comparison to photon and electron beams. Darafsheh et al. demonstrated that the visible signal responsible for proton therapy dosimetry using bare optical fibers is not Cherenkov radiation, yet still the value of beam range finding in this application is compelling [42, 43].
Solid-State Dosimeters
Published in Gad Shani, Radiation Dosimetry, 2017
A direct-reading semiconductor dosimeter has been investigated by Soubra et al. [13] as a radiation detector for photon and electron therapy beams of various energies. The operation of this device is based on the measurement of the threshold voltage shift in a custom-built metal oxide-silicon semiconductor field effect transistor (MOSFET). This voltage is a linear function of absorbed dose. The extent of thelinearity region is dependent on the voltage-controlled operation during irradiation. Operating two MOSFETS at two different biases simultaneously during irradiation will result in sensitivity (V/Gy) reproducibility better than ±3% over a range in dose of 100 Gy and at a dose per fraction greater than 20 × 10-2 Gy. The modes of operation give this device many advantages, such as continuous monitoring during irradiation, immediate reading, and permanent storage of total dose after irradiation.
Clinical and dosimetric evaluation of recurrent breast cancer patients treated with hyperthermia and radiation
Published in International Journal of Hyperthermia, 2019
Sharvari Dharmaiah, Johnathan Zeng, Vinay S. Rao, Ouyang Zi, Tianjun Ma, Kevin Yu, Heeruk Bhatt, Chirag Shah, Andrew Godley, Ping Xia, Jennifer S. Yu
Twelve patients received intensity-modulated radiation therapy (IMRT), 13 patients received electron therapy, and 11 patients received conventional photons with opposed tangents with or without regional nodal irradiation. Patients who received IMRT had larger treatment volumes (median 2352.4 cc, range 247.0–3619.7 cc) compared with patients who received conventional photon radiation (median 260.6 cc, range 11.7–1548.0 cc) or electrons (median 47.0 cc, range 30.8–601.0 cc) (Figure 2(A)). Because patients receiving IMRT had large volumes of disease, their total mean lung dose was higher than those patients who received either electron or conventional photon techniques (p < .0001 for both) (Figure 2(B)). The difference in total mean lung dose between conventional photon and electron techniques was not significant (p = .16). Similarly, the percent of ipsilateral lung volume receiving greater than 5 Gy (V5) for patients receiving IMRT was higher than that of patients receiving electron therapy or conventional photon radiotherapy (p < .0001 for both) (Figure 2(C)). Mean heart dose irrespective of laterality of treatment was 1.71 Gy conventional photons (n = 9) and 11.44 Gy for IMRT (n = 10) (Figure 2(D)). For left-sided treatments, mean heart dose was 1.41 Gy for electrons (n = 6) (Figure 2(E)), 2.37 Gy for conventional photons (n = 6) and 12.28 Gy for IMRT (n = 4). For right-sided IMRT cases, mean liver dose was 12.72 Gy (n = 5).
The effect of 111In radionuclide distance and auger electron energy on direct induction of DNA double-strand breaks: a Monte Carlo study using Geant4 toolkit
Published in International Journal of Radiation Biology, 2018
Behnaz Piroozfar, Gholamreza Raisali, Behrouz Alirezapour, Mohammad Mirzaii
More than half of radionuclides which decay by electron capture and/or internal conversion, emit Auger electrons with energies ranging from few eV to few keV. The Auger electrons’ range in water changes from a nanometer to several micrometers comparable with subcellular scale (Kassis 2003, 2004; Boswell and Brechbiel 2005; Nikjoo et al. 2008). The emitted Auger electrons lead to highly localized energy deposition (106–109 cGy) in an extremely small volume in the proximity of the decaying nucleus (Boswell and Brechbiel 2005; Balagurumoorthy et al. 2012). For many years, because of low energies and short range of Auger electrons, their biological effects and therapeutic applications were neglected (Kassis 2003, 2004), but based on the recent investigations and observed biological effects, Auger electron therapy and its therapeutic potential have increasingly been considered (Buchegger et al. 2006; Cai et al. 2010; Tavares and Tavares 2010; Pszona et al. 2012). In contrast to α and β-particles, Auger electrons with high linear energy transfer are much less radiotoxic to healthy cell while travelling in blood or bone marrow, and become highly efficient when incorporated into DNA of target cells (Buchegger et al. 2006; Emfietzoglou et al. 2008).
Peptide receptor radionuclide therapy in neuroendocrine neoplasms and related tumors: from fundamentals to personalization and the newer experimental approaches
Published in Expert Review of Precision Medicine and Drug Development, 2023
b) Auger electrons with minimum tissue penetration range with a potent cytotoxic effect have been tried in PRRT using 111In but the use lagged when powerful agents like 90Y got introduced. The major problem with auger electron therapy is the requirement of delivery system/internalization so radionuclide comes closest to the nucleus and problems in dosimetric estimations. But the approach is again getting into interest with the advent of newer delivery systems, cheap production methods, and computerized dosimetric models.