Open AccessSimple quality assurance method of dynamic tumor tracking with the gimbaled linac system using a light field
Author(s) -
Miura Hideharu,
Ozawa Shuichi,
Hayata Masahiro,
Tsuda Shintaro,
Yamada Kiyoshi,
Nagata Yasushi
Publication year - 2016
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1120/jacmp.v17i5.6376
Subject(s) - quality assurance , linear particle accelerator , gimbal , tracking (education) , computer science , simple (philosophy) , field (mathematics) , medical physics , quality (philosophy) , optics , physics , mathematics , engineering , beam (structure) , aerospace engineering , operations management , psychology , pedagogy , external quality assessment , philosophy , epistemology , quantum mechanics , pure mathematics
We proposed a simple visual method for evaluating the dynamic tumor tracking (DTT) accuracy of a gimbal mechanism using a light field. A single photon beam was set with a field size of 30 × 30 mm 2at a gantry angle of 90°. The center of a cube phantom was set up at the isocenter of a motion table, and 4D modeling was performed based on the tumor and infrared (IR) marker motion. After 4D modeling, the cube phantom was replaced with a sheet of paper, which was placed perpendicularly, and a light field was projected on the sheet of paper. The light field was recorded using a web camera in a treatment room that was as dark as possible. Calculated images from each image obtained using the camera were summed to compose a total summation image. Sinusoidal motion sequences were produced by moving the phantom with a fixed amplitude of 20 mm and different breathing periods of 2, 4, 6, and 8 s. The light field was projected on the sheet of paper under three conditions: with the moving phantom and DTT based on the motion of the phantom, with the moving phantom and non‐DTT, and with a stationary phantom for comparison. The values of tracking errors using the light field were 1.12 ± 0.72 , 0.31 ± 0.19 , 0.27 ± 0.12 , and 0.15 ± 0.09 mm for breathing periods of 2, 4, 6, and 8 s, respectively. The tracking accuracy showed dependence on the breathing period. We proposed a simple quality assurance (QA) process for the tracking accuracy of a gimbal mechanism system using a light field and web camera. Our method can assess the tracking accuracy using a light field without irradiation and clearly visualize distributions like film dosimetry. PACS number(s): 87.56 Fc, 87.55.Qr