Initial application of a geometric QA tool for integrated MV and kV imaging systems on Trilogy, Synergy, and Vero

Weihua Mao, Michael Speiser, Paul Medin, Lech Papiez, Timothy Solberg, Lei Xing

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

Introduction: Several linacs with integrated kV imaging have been developed for delivery of image-guided Stereotactic Body Radiation Therapy (SBRT). High geometric accuracy and coincidence of kilovoltage (kV) imaging systems and MV beam delivery are essential for successful image guidance. A geometric QA tool is available of evaluating and characterizing geometric accuracy of kV and MV cone beam imaging systems. Materials and Methods: This geometric QA tool has been adapted as a routine QA tool for three different types of SBRT-dedicated linacs. They are a Varian Trilogy (Varian Medical Systems, Palo Alto, California, USA), Elekta Synergy (Elekta, Stockholm, Sweden), and Brainlab Vero (Brainlab AG, Feldkirchen, Germany). Both the Trilogy and Synergy linacs are equipped with a retractable kV x-ray tube and a flat panel detector. The Vero utilizes a rotating, rigid ring structure integrating a MV x-ray head mounted on orthogonal gimbals, an electronic portal imaging device (EPID), two kV xray tubes, and fixed two flat panel detectors. Two QA phantoms were built to suit different field sizes. Projection images of a QA phantom were acquired by MV and kV imaging systems at a series of gantry angles. In-house software was used to analyze projection images and calculate eight geometric parameters for each projection. Results: Over 4,300 individual projections have been acquired and analyzed. The Trilogy was calibrated 4 times over a six month period while the Synergy and the Vero were calibrated twice and once, respectively. Quantitative geometric parameters of both MV and kV imaging systems were successfully evaluated. Isocenter consistency of the imaging systems was evaluated. Additionally, the gimbal-based x-ray source positioning of the Vero was examined. Conclusion: Geometric accuracies of both MV and integrated kV imaging systems were quantitatively evaluated by this QA tool.

Original languageEnglish (US)
Title of host publicationWorld Congress on Medical Physics and Biomedical Engineering
Subtitle of host publicationRadiation Oncology
PublisherSpringer Verlag
Pages358-361
Number of pages4
Edition1
ISBN (Print)9783642034725
DOIs
StatePublished - 2009
EventWorld Congress on Medical Physics and Biomedical Engineering: Radiation Oncology - Munich, Germany
Duration: Sep 7 2009Sep 12 2009

Publication series

NameIFMBE Proceedings
Number1
Volume25
ISSN (Print)1680-0737

Other

OtherWorld Congress on Medical Physics and Biomedical Engineering: Radiation Oncology
Country/TerritoryGermany
CityMunich
Period9/7/099/12/09

Keywords

  • Geometric calibration
  • Image guidance
  • MV imaging
  • QA
  • kV imaging

ASJC Scopus subject areas

  • Bioengineering
  • Biomedical Engineering

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