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Proton Therapy
Published in Harald Paganetti, Proton Therapy Physics, 2018
Proton therapy paved the way for many other advances in radiation therapy. The proton therapy group at MGH developed the first computerized treatment planning program in the early 1980s, which was subsequently used clinically [76–79]. Other developments included the innovative concepts of beam’s eye view and dose–volume histograms, the features that have become standard in radiation therapy. Sophisticated patient positioning was developed first in proton therapy because the finite range of proton beams required a more precise setup than in photon therapy [80].
3D liquid scintillation dosimetry for photons and protons
Published in Sam Beddar, Luc Beaulieu, Scintillation Dosimetry, 2018
The second helpful consideration is the fact that the projections are not limited to axial directions, as is the case in most medical imaging modalities. It is possible to acquire a beam’s-eye view in addition to axial views of the radiation beam. This beam’s-eye-view adds a great deal of independent information that is complementary to the axial views.
Beam’s eye view imaging with low atomic number linear accelerator targets
Published in Ross I. Berbeco, Beam’s Eye View Imaging in Radiation Oncology, 2017
Beam’s eye view (BEV) imaging has been applied to guidance of radiation therapy for decades (Rabinowitz et al. 1985; Rosenthal et al. 1992) and provides arguably the most useful view possible, that is, that of the tumor volume relative to the collimation of the treatment beam. However, since its inception, BEV imaging has been fundamentally limited by the beam’s energy characteristics. Linear accelerator (LINAC) photon beams were designed specifically for therapeutic purposes (Podgorsak et al. 1975), providing appropriate depth-dose characteristics for typical patient geometries. Therapeutic energy spectra, for example, for a 6 MV beam, contain less than 0.5% of photons in the diagnostic energy range (Orton and Robar 2009). When applied to the task of radiographic imaging, this attribute presents two key disadvantages. First, the predominant interaction for the majority of primary photons in tissue is Compton scatter, the mass coefficient of which shows no dependence on the effective atomic number of the medium being imaged. A near absence of primary photons in the diagnostic energy range limits the proportion of photoelectric absorption occurring in the patient, and thus the strong dependence on atomic number (with a mass coefficient varying approximately with Z3) of this interaction cannot be leveraged in producing differential attenuation between tissues, that is, subject contrast. The second limitation is the low efficiency of common detectors used for BEV imaging when used to detect therapeutic beams. For example, a typical Gd2O2S detector provides approximately 1% zero-frequency detective quantum efficiency (DQE) (Munro and Bouius 1998).
Heart sparing breast cancer radiotherapy using continuous positive airway pressure (CPAP) and conventional supine tangential fields: an alternative method for patients with limited accessibility to advanced radiotherapy techniques
Published in Acta Oncologica, 2019
Whoon Jong Kil, Tabitha Pham, Kyubo Kim
Planning target volumes (PTVs) and organs at risk (OARs) were contoured on both CT-CPAP and CT-FB scans for RT planning (ipsilateral-RT plan) according to RTOG 1304. Contralateral side whole breast or chest wall were also contoured on both CT-CPAP and CT-FB to create contralateral-RT plans for dosimetric comparison for all patients. Prescription was 50 Gy in 25 fractions without boost for all RT plans in this study. Eclipse RT planning system (version 10.0, Varian Medical System, Palo Alto, CA, USA) was used with a Varian Trilogy linear accelerator using 6-MV photons. Treatment planning aimed to reduce dose to OARs as much as possible without compromising the coverage of the PTVs. All RT plans were created using 3DCRT technique for this study. Ipsilateral-postmastectomy RT plans comprised the 4-field photon only fields consisted of two tangential fields covering PTV-chest wall and IMN, and anterior-posterior fields covering PTV-supraclavicular node. For ipsilateral-breast RT and all contralateral-RT plans, two tangential fields covering PTV-whole breast or chest wall only were used. The beam’s-eye view was used to shape multi-leaf collimators to block OARs. Field-in-field technique was used to maximize dose homogeneity.
Stereotactic Ablative Body Radiotherapy for Primary Non-Small-Cell Lung Cancer: Achieving Local Control with a Lower Biologically Effective Dose
Published in Cancer Investigation, 2018
Simeng Zhu, Judith L. Lightsey, Bradford S. Hoppe, Paul Okunieff, Priya K. Gopalan, Frederic J. Kaye, Christopher G. Morris, Anamaria R. Yeung
Dynamic conformal arc therapy was the most common technique used, with the beam apertures specified to mimic the projection of the PTV in the beam’s eye view through each arc angle. The arc angles and spans were selected to minimize exposure of critical normal tissues and optimized to maximize target coverage and conformality as well as achieve the steepest possible dose gradient beyond the PTV. The dose was prescribed to a minimum coverage of 95% of the gross target volume with the 100% isodose line; the 80% isodose line covered a minimum 95% of the PTV. When dynamic arcs were not used, either volumetric-modulated arc therapy or multiple fixed coplanar beams shaped with multileaf collimators was used. Stereotactic localization was performed with daily on-board image guidance using cone-beam CT for all fractions for each individual target.
Investigating particle track topology for range telescopes in particle radiography using convolutional neural networks
Published in Acta Oncologica, 2021
Helge Egil Seime Pettersen, Max Aehle, Johan Alme, Gergely Gábor Barnaföldi, Vyacheslav Borshchov, Anthony van den Brink, Mamdouh Chaar, Viljar Eikeland, Grigory Feofilov, Christoph Garth, Nicolas R. Gauger, Georgi Genov, Ola Grøttvik, Håvard Helstrup, Sergey Igolkin, Ralf Keidel, Chinorat Kobdaj, Tobias Kortus, Viktor Leonhardt, Shruti Mehendale, Raju Ningappa Mulawade, Odd Harald Odland, Gábor Papp, Thomas Peitzmann, Pierluigi Piersimoni, Maksym Protsenko, Attiq Ur Rehman, Matthias Richter, Joshua Santana, Alexander Schilling, Joao Seco, Arnon Songmoolnak, Jarle Rambo Sølie, Ganesh Tambave, Ihor Tymchuk, Kjetil Ullaland, Monika Varga-Kofarago, Lennart Volz, Boris Wagner, Steffen Wendzel, Alexander Wiebel, RenZheng Xiao, Shiming Yang, Hiroki Yokoyama, Sebastian Zillien, Dieter Röhrich
One of the proposed modalities that could increase the PT treatment accuracy is proton CT (pCT)/proton radiography (pRad). pCT has been shown to reduce the systematic errors of the relative stopping power (RSP) needed for treatment planning [3,4]. Furthermore, a sufficiently quick pRad system could be used as beam’s eye view imaging prior to treatment for accurate range verification through the Water Equivalent Path Length (WEPL) map [5].