
Proceedings Paper
Geometry calibration for x-ray equipment in radiation treatment devices and estimation of remaining patient alignment errorsFormat | Member Price | Non-Member Price |
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Paper Abstract
Positioning a patient accurately in treatment devices is crucial for radiological treatment, especially if accuracy vantages
of particle beam treatment are exploited. To avoid sub-millimeter misalignments, X-ray images acquired from within the
device are compared to a CT to compute respective alignment corrections. Unfortunately, deviations of the underlying
geometry model for the imaging system degrade the achievable accuracy. We propose an automatic calibration routine,
which bases on the geometry of a phantom and its automatic detection in digital radiographs acquired for various
geometric device settings during the calibration. The results from the registration of the phantom's X-ray projections and
its known geometry are used to update the model of the respective beamlines, which is used to compute the patient
alignment correction. The geometric calibration of a beamline takes all nine relevant degrees of freedom into account,
including detector translations in three directions, detector tilt by three axes and three possible translations for the X-ray
tube. Introducing a stochastic model for the calibration we are able to predict the patient alignment deviations resulting
from inaccuracies inherent to the phantom design and the calibration. Comparisons of the alignment results for a
treatment device without calibrated imaging systems and a calibrated device show that an accurate calibration can
enhance alignment accuracy.
Paper Details
Date Published: 19 March 2008
PDF: 11 pages
Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 691355 (19 March 2008); doi: 10.1117/12.770294
Published in SPIE Proceedings Vol. 6913:
Medical Imaging 2008: Physics of Medical Imaging
Jiang Hsieh; Ehsan Samei, Editor(s)
PDF: 11 pages
Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 691355 (19 March 2008); doi: 10.1117/12.770294
Show Author Affiliations
Published in SPIE Proceedings Vol. 6913:
Medical Imaging 2008: Physics of Medical Imaging
Jiang Hsieh; Ehsan Samei, Editor(s)
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