Open AccessClinical assessment and characterization of a dual‐tube kilovoltage X‐ray localization system in the radiotherapy treatment room
Author(s) -
Lee SungWoo,
Jin JianYue,
Guan Huaiqun,
Martin Flavious,
Kim Jae Ho,
Yin FangFang
Publication year - 2008
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.v9i1.2318
Subject(s) - image guided radiation therapy , repeatability , optical transfer function , nuclear medicine , linear particle accelerator , image resolution , linearity , image quality , optics , detector , imaging phantom , flat panel detector , flat panel , medicine , radiation therapy , medical physics , computer science , physics , mathematics , computer vision , radiology , image (mathematics) , beam (structure) , statistics , quantum mechanics
Although flat‐panel kilovoltage X‐ray imaging devices have been well tested for clinical use in diagnostic radiology, their use as a part of an image‐guided radiation therapy (IGRT) system in a treatment room is new and requires systematic assessment. We used the Novalis IGRT system (BrainLAB, Feldkirchen, Germany) for the present study. The system consists of two floor‐mounted kilovoltage X‐ray tubes projecting obliquely onto two flat‐panel detectors mounted on the ceiling. The system can automatically fuse two‐dimensional localization images with three‐dimensional simulation computed tomography images to provide positioning guidance. We evaluated these system parameters: Overall performance of the IGRT system, including isocenter correlation between the IGRT system and the linear accelerator (LINAC) Image quality of the system Exposure received by patients for a pair of images Linearity, uniformity, and repeatability of the systemThe Novalis system uses a daily isocenter calibration procedure to ensure consistency of isocenters between the IGRT and the LINAC systems. The localization accuracy was about 1 mm. We measured the relative modulation transfer function (RMTF) to quantify the spatial resolution of the imaging device, withf 50being 0.7 – 0.9 line pairs per millimeter. The maximal exposure of an image was 95 mR. We derived an empirical relationship between the exposure and the X‐ray technical settings. The other parameters of the system were quantitatively measured and generally met the requirements. The IGRT system is safe and reliable for clinical use as a target localization device. The measured data can be used as a benchmark for a quality assurance procedure. PACS number: 87.56‐v