
Proceedings Paper
Noise correlation in CBCT projection data and its application for noise reduction in low-dose CBCTFormat | Member Price | Non-Member Price |
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Paper Abstract
There are growing interests in using cone-beam computed tomography (CBCT) for patient treatment position setup and
dose evaluation in radiation therapy. The repeated use of CBCT during the course of a treatment has raised concerns of
extra radiation dose delivered to patients. One way to reduce radiation dose delivered to patients during CBCT
procedure is to acquire CT projection data with a lower mAs level. However, the image quality of the projection image
and the reconstructed CBCT image will degrade due to excessive quantum noise as a result of low mAs protocol. In this
work, we first studied the noise properties of CBCT projection data from repeated scan and then improved low-dose
CBCT image quality by restoring CBCT projection images based on an improved noise model of CBCT projection data.
Analysis of repeated measurements show that noise is correlated among nearest neighbors in projection data, i.e.,
covariance matrix of projection data noise is non-diagonal. The covariance matrix of noise provides the knowledge of
second-order statistics of noise, which may lead to more accurate estimation for statistical image reconstruction and
restoration algorithm. We constructed the penalized weighted least-squares (PWLS) objective function by incorporating
the noise correlation of CBCT projection data. The optimal solution of the line integrals is then estimated by minimizing
the PWLS objective function. A quality assurance phantom was used to evaluate the presented algorithm for noise
reduction in low-dose CBCT.
Paper Details
Date Published: 13 March 2009
PDF: 8 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72582D (13 March 2009); doi: 10.1117/12.813891
Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)
PDF: 8 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72582D (13 March 2009); doi: 10.1117/12.813891
Show Author Affiliations
Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)
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