Susu Yan1, Hsiao-Ming Lu2, Jay Flanz2, Judith Adams2, Alexei Trofimov2, Thomas Bortfeld2. 1. Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts. Electronic address: syan5@mgh.harvard.edu. 2. Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts.
Abstract
PURPOSE: To retrospectively analyze the beam approaches used in gantry-based proton treatments, and to reassess the practical advantages of the gantry, compared with beam approaches that are achievable without a gantry, in the context of present-day technology. METHODS AND MATERIALS: We reviewed the proton therapy plans of 4332 patients treated on gantries at our hospital, delivered by the double scattering technique (n=4228) and, more recently, pencil beam scanning (PBS) (n=104). Beam approaches, relative to the patient frame, were analyzed individually to identify cases that could be treated without a gantry. Three treatment configurations were considered, with the patient in lying position, sitting position, or both. The FIXED geometry includes a fixed horizontal portal. The BEND geometry enables a limited vertical inflection of the beam by up to 20°. The MOVE geometry allows for flexibility of the patient head and body setup. RESULTS: The percentage of patients with head and neck tumors that could be treated without a gantry using double scattering was 44% in FIXED, 70% in 20° BEND, and 100% in 90° MOVE. For torso regions, 99% of patients could be treated in 20° BEND. Of 104 PBS treatments, all but 1 could be reproduced with FIXED geometry. The only exception would require a 10° BEND capability. Note here that the PBS treatments were applied to select anatomic sites, including only 2 patients with skull-base tumors. CONCLUSIONS: The majority of practical beam approaches can be realized with gantry-less delivery, aided by limited beam bending and patient movements. Practical limitations of the MOVE geometry, and treatments requiring a combination of lying and sitting positions, may lower the percentage of head and neck patients who could be treated without a gantry. Further investigation into planning, immobilization, and imaging is needed to remove the practical limitations and to facilitate proton treatment without a gantry.
PURPOSE: To retrospectively analyze the beam approaches used in gantry-based proton treatments, and to reassess the practical advantages of the gantry, compared with beam approaches that are achievable without a gantry, in the context of present-day technology. METHODS AND MATERIALS: We reviewed the proton therapy plans of 4332 patients treated on gantries at our hospital, delivered by the double scattering technique (n=4228) and, more recently, pencil beam scanning (PBS) (n=104). Beam approaches, relative to the patient frame, were analyzed individually to identify cases that could be treated without a gantry. Three treatment configurations were considered, with the patient in lying position, sitting position, or both. The FIXED geometry includes a fixed horizontal portal. The BEND geometry enables a limited vertical inflection of the beam by up to 20°. The MOVE geometry allows for flexibility of the patient head and body setup. RESULTS: The percentage of patients with head and neck tumors that could be treated without a gantry using double scattering was 44% in FIXED, 70% in 20° BEND, and 100% in 90° MOVE. For torso regions, 99% of patients could be treated in 20° BEND. Of 104 PBS treatments, all but 1 could be reproduced with FIXED geometry. The only exception would require a 10° BEND capability. Note here that the PBS treatments were applied to select anatomic sites, including only 2 patients with skull-base tumors. CONCLUSIONS: The majority of practical beam approaches can be realized with gantry-less delivery, aided by limited beam bending and patient movements. Practical limitations of the MOVE geometry, and treatments requiring a combination of lying and sitting positions, may lower the percentage of head and neck patients who could be treated without a gantry. Further investigation into planning, immobilization, and imaging is needed to remove the practical limitations and to facilitate proton treatment without a gantry.
Authors: Amanda J Deisher; Thomas J Whitaker; Chris J Beltran; Robert L Foote; Michael G Haddock; Anita Mahajan Journal: Int J Part Ther Date: 2020-02-21
Authors: Sarah Hegarty; Nicholas Hardcastle; James Korte; Tomas Kron; Sarah Everitt; Sulman Rahim; Fiona Hegi-Johnson; Rick Franich Journal: Front Oncol Date: 2022-03-03 Impact factor: 6.244
Authors: Omar A Zeidan; Ethan Pepmiller; Twyla Willoughby; Zhiqiu Li; James Burkavage; Brian Harper; Michael Fraser; Katie Moffatt; Sanford L Meeks; Naren Ramakrishna Journal: Int J Part Ther Date: 2022-07-01
Authors: Harald Paganetti; Chris Beltran; Stefan Both; Lei Dong; Jacob Flanz; Keith Furutani; Clemens Grassberger; David R Grosshans; Antje-Christin Knopf; Johannes A Langendijk; Hakan Nystrom; Katia Parodi; Bas W Raaymakers; Christian Richter; Gabriel O Sawakuchi; Marco Schippers; Simona F Shaitelman; B K Kevin Teo; Jan Unkelbach; Patrick Wohlfahrt; Tony Lomax Journal: Phys Med Biol Date: 2021-02-26 Impact factor: 4.174