Development of a novel low-radiation-absorbent lok-bar to reduce X-ray scattering and absorption in RapidArc( ®) treatment planning and dose delivery.

Development of a novel low-radiation-absorbent lok-bar to reduce X-ray scattering and absorption in RapidArc(®) treatment planning and dose delivery. J Appl Clin Med Phys. 2017 Apr 06;: Authors: Monzen H, Kubo K, Tamura M, Hayakawa M, Nishimura Y Abstract We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok-bar (VL-bar) as a benchmark. CT images were obtained with or without lok-bar, and then each image was visually evaluated for artifacts. The attenuation rates for each lok-bar were measured using a farmer-type ionization chamber (PTW30013) and the I'mRT phantom (IBA Dosimetry GmbH). Measurement points were between gantry angles of 110 and 180°. The treatment apparatus was a NovalisTx (Brainlab AG); X-ray energies were set at 6 MV and 10 MV. In the presence of each lok-bar, the radiation dose was measured in accordance with 10 volumetric modulated arc therapy-stereotactic body radiation therapy (VMAT-SBRT) plans for lung cancer. Artifacts were seldom observed in the CT scans of the HM-bar. The attenuation rate of each lok-bar was higher when the X-ray energy was set at 6 MV than at 10 MV. The highest attenuation rate in the VL-bar was observed at a gantry angle of 11...
Source: Journal of Applied Clinical Medical Physics - Category: Physics Authors: Tags: J Appl Clin Med Phys Source Type: research