title: Feasibility of single-isocenter, multi-arc non-coplanar volumetric modulated arc therapy for multiple brain tumors using a linear accelerator with a 160-leaf multileaf collimator: a phantom study.
abstract: The feasibility of single isocenter, multi-arc non-coplanar volumetric modulated arc therapy (VMAT) for multiple brain tumors was studied using an Elekta Synergy linear accelerator with an Agility multileaf collimator and a Monaco treatment planning system. Two VMAT radiosurgery plans consisting of a full arc and three half arcs were created with a prescribed dose of 20 Gy in a single fraction. After dose delivery to a phantom, ionization chambers and radiochromic films were used for dose measurement. The first VMAT radiosurgery plan had nine targets inside the phantom, and the doses were measured by the chambers at two different points and by the films on three sagittal and three coronal planes. The differences between the calculated dose and the dose measured by a Farmer ionization chamber and a pinpoint ionization chamber were <1.00% and <2.30%, respectively, and the average pass rates of gamma indices among the six planes under each of 3%/3 mm and 2%/2 mm criteria were 98.6% and 92.6%, respectively. The second VMAT radiosurgery plan was based on a clinical 14 brain metastases. Differences between calculated and film-measured doses were evaluated on two sagittal planes. The average pass rates of the gamma indices on the planes under each of 3%/3 mm and 2%/2 mm criteria were 97.8% and 88.8%, respectively. It was confirmed that single-isocenter, non-coplanar multi-arc VMAT radiosurgery for multiple brain metastases was feasible using Elekta Synergy with Agility and Monaco treatment planning systems. It was further shown that film dosimetry was accurately performed for a dose of up to nearly 25 Gy.
authors.affiliation: Research Physics, Elekta KK, 3-9-1 Shibaura, Minato-ku, Tokyo 108-0023, Japan yoshio.iwai@elekta.com.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Iwai
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical and Health Science, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Ozawa
authors.affiliation: Toshiba Medical Systems Corporation, 138 Shimoishigami, Otawara-shi, Tochigi 324-8550, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ageishi
authors.affiliation: Elekta, via Bernardo Rucellai 23, Milano IT-20126, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Pellegrini
authors.affiliation: Research Physics, Elekta KK, 3-9-1 Shibaura, Minato-ku, Tokyo 108-0023, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yoda
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary* / Q000601:surgery*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D006801:Humans; D010315:Particle Accelerators / Q000295:instrumentation*; D019047:Phantoms, Imaging; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation* / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods; D016896:Treatment Outcome
keywords: Agility; Monaco; VMAT; brain metastasis; film dosimetry; non-coplanar; radiosurgery; single isocenter