title: Evaluation of the Positional Accuracy and Dosimetric Properties of a Three-dimensional Printed Device for Head and Neck Immobilization.
abstract: Our aim was to investigate the feasibility of a three-dimensional (3D) -printed head-and-neck (HN) immobilization device by comparing its positional accuracy and dosimetric properties with those of a conventional immobilization device (CID). We prepared a 3D-printed immobilization device (3DID) consisting of a mask and headrest with acrylonitrile-butadiene-styrene resin developed from the computed tomography data obtained by imaging a HN phantom. For comparison, a CID comprising a thermoplastic mask and headrest was prepared using the same HN phantom. We measured the setup error using the ExacTrac X-ray image system. Furthermore, using the ionization chamber and the water-equivalent phantom, we measured the changes in the dose due to the difference in the immobilization device material from the photon of 4 MV and 6 MV. The positional accuracy of the two devices were almost similar in each direction except in the vertical, lateral, and pitch directions (t-test, p<0.0001), and the maximum difference was 1 mm, and 1°. The standard deviations were not statistically different in each direction except in the longitudinal (F-test, p=0.034) and roll directions (F-test, p<0.0001). When the thickness was the same, the dose difference was almost similar at a 50 mm depth. At a 1 mm depth, the 3DID-plate had a 2.9-4.2% lower dose than the CID-plate. This study suggested that the positional accuracy and dosimetric properties of 3DID were almost similar to those of CID.
authors.affiliation: Radiation Technology, Tohoku University Hospital.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Sato
authors.forename: Ken
authors.initials: K
authors.lastname: Takeda
authors.forename: Suguru
authors.initials: S
authors.lastname: Dobashi
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kadoya
authors.forename: Kengo
authors.initials: K
authors.lastname: Ito
authors.forename: Mizuki
authors.initials: M
authors.lastname: Chiba
authors.forename: Kazuma
authors.initials: K
authors.lastname: Kishi
authors.forename: Isao
authors.initials: I
authors.lastname: Yanagawa
authors.forename: Keiichi
authors.initials: K
authors.lastname: Jingu
mesh_terms: D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D009333:Neck / Q000000981:diagnostic imaging*; D056888:Patient Positioning; D066330:Printing, Three-Dimensional / Q000295:instrumentation; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results