Clinical assessment and characterization of a dual tube kilovoltage X-ray localization system in the radiotherapy treatment room

Sung Woo Lee, Jian Yue Jin, Huaiqun Guan, Flavious Martin, Jae Ho Kim, Fang Fang Yin

Research output: Contribution to journalArticle

10 Scopus citations


INTRODUCTION: Although flat-panel based X-ray imaging has been well tested in diagnostic radiology, its use as an image-guided-radiotherapy (IGRT) system in a treatment room is new and requires systematic assessment. MATERIALS AND METHODS: BrainLab Novalis IGRT system was used for this study. It consists of two floor mounted kV X-ray tubes projecting obliquely into two flat-panel detectors mounted on the ceiling. The system automatically fuses the 2D localization images with 3D simulation CT image to provide positioning guidance. The following characteristics of the system were studied: (1) Coincidence of the isocenters between the IGRT and Linac; (2) Image quality; (3) Exposure; (4) Linearity, uniformity and repeatability. RESULTS: (1) Localization accuracy and coincidence of the isocenters between the IGRT and Linac was better than 1-mm. (2) The spatial resolution was quantified using the relative modulation-transfer-function with f50=0.7-0.9 lp/mm. The variation of contrast-noise-ratio with technical settings was measured. (3) The maximal exposure of an image was less than 95 mR. An empirical relation between the exposure and the X-ray technical setting was derived. (4) The linearity, uniformity and repeatability of the system generally meet the requirements. CONCLUSION: The system can be safely and reliably used as a target localization device.

Original languageEnglish (US)
Pages (from-to)1-15
Number of pages15
JournalJournal of Applied Clinical Medical Physics
Issue number1
Publication statusPublished - Jan 13 2008


ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Instrumentation

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