Dokument: Novel Beam Optics of Achromatic Superconducting Gantries for Proton Therapy
| Titel: | Novel Beam Optics of Achromatic Superconducting Gantries for Proton Therapy | |||||||
| Weiterer Titel: | Neuartige Strahloptiken von achromatischen supraleitenden Gantries für die Protonentherapie | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=54774 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20201118-105226-2 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Huggins, Anthony [Autor] | |||||||
| Dateien: |
| |||||||
| Beitragende: | Prof. Dr. Lomax, Antony [Gutachter] Prof. Dr. Pretzler, Georg [Gutachter] | |||||||
| Stichwörter: | Proton Therapy, Accelerator Physics, Beam Optics, Achromatic Optics | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | Proton beam therapy can be advantageous for cancer treatment due to the depth dose curve of protons described by the Bragg peak. Because of the relatively large mass of protons, the equipment for proton therapy is, however, much larger and more expensive compared to conventional radiotherapy devices based on linear electron accelerators. Superconducting (SC) magnets have been identified to help reduce the size of proton therapy gantries for their high magnetic fields and small bend radii. Due to low thermal margins, one of the most challenging issues of SC magnets for their application in ion therapy beamlines is their inability to quickly ramp the magnetic field – usually an important requirement for therapeutic beam delivery. Two different designs of superconducting combined function magnets, the alternating gradient canted cosine theta magnet (AGCCT), and the so-called fixed-field magnet are studied with respect to their optical properties as local achromats, facilitating the transport of multiple beam energies without changes in field.
Based on the local achromat feature of the magnets a simplified and optimized gantry beamline for proton therapy is developed and discussed. Both magnets were optimized for their employment in the proposed gantry concept and use for therapeutic proton beam application addressing energy and emittance acceptance, focusing properties as well as weight, size and cryogen-free cooling considerations. The gantry optics of dipole and quadrupole fields were studied with a 1st order lattice code in Transport, while the higher order multipole fields of the achromats were developed and analyzed with the code COSY INFINITY based on transfer maps and differential algebra. The AGCCT is a curved version of the CCT design with additional winding layers to produce alternating quadrupole and sextupole fields. The results of 5th order tracking studies show that the AGCCT achieves a momentum acceptance of 16.5 % dp/p of proton beams with clinical properties regarding emittance and energy spread. The momentum acceptance is mainly limited by the radius of the warm bore of the magnet. Deviations from clinically acceptable beam properties were found with respect to focusing for large momentum deviations, leading to elliptical profiles, as well as positional shifts throughout the energy range. The feasibility of corrections of all unwanted effects by means of trim quadrupole coils is demonstrated. However, a comparison with clinical treatment energy range statistics revealed that the momentum acceptance of the AGCCT is insufficient to significantly alleviate ramping requirements, making the magnet less favorable for an application in a proton therapy gantry. The fixed-field magnet is a double-bend achromat of two straight racetrack coil designs with a c-shaped iron yoke and additional resistive quadrupoles. The two-dimensional field of the magnet facilitates a momentum acceptance over the entire clinical energy range from 70 to 225 MeV which is demonstrated with 7th order tracking. It is further shown that the beam properties at isocenter meet the clinical requirements throughout all energies. The feasibility of static field operation has significant economical and practical implications for conductor choice, cryostat design and operation of the magnet. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik | |||||||
| Dokument erstellt am: | 18.11.2020 | |||||||
| Dateien geändert am: | 18.11.2020 | |||||||
| Promotionsantrag am: | 15.10.2020 | |||||||
| Datum der Promotion: | 09.11.2020 |
