18 March 2015 Fluid-filled dynamic bowtie filter: a feasibility study
Author Affiliations +
Abstract
By varying its thickness to compensate for the different path length through the patient as a function of fan angle, a pre-patient bowtie filter modulates flux distribution to reduce patient dose, scatter, and detector dynamic range, and to improve image quality. A dynamic bowtie filter is superior to its traditional, static counterpart in its ability to adjust its thickness along different fan and view angles to suit a specific patient and task. Among the proposed dynamic bowtie designs, the piecewise-linear and the digital beam attenuators offer more flexibility than conventional filters, but rely on analog positioning of a limited number of wedges. In this work, we introduce a new approach with digital control, called the fluid-filled dynamic bowtie filter. It is a two-dimensional array of small binary elements (channels filled or unfilled with attenuating liquid) in which the cumulative thickness along the x-ray path contributes to the bowtie’s total attenuation. Using simulated data from a pelvic scan, the performance is compared with the piecewise-linear attenuator. The fluid-filled design better matches the desired target attenuation profile and delivers a 4.2x reduction in dynamic range. The variance of the reconstruction (or noise map) can also be more homogeneous. In minimizing peak variance, the fluid-filled attenuator shows a 3% improvement. From the initial simulation results, the proposed design has more control over the flux distribution as a function of both fan and view angles.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Picha Shunhavanich, Picha Shunhavanich, Scott S. Hsieh, Scott S. Hsieh, Norbert J. Pelc, Norbert J. Pelc, "Fluid-filled dynamic bowtie filter: a feasibility study", Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94121L (18 March 2015); doi: 10.1117/12.2081673; https://doi.org/10.1117/12.2081673
PROCEEDINGS
8 PAGES


SHARE
RELATED CONTENT

Fluid dynamic bowtie attenuators
Proceedings of SPIE (March 17 2015)
Implementation of a piecewise-linear dynamic attenuator
Proceedings of SPIE (March 08 2018)
Practical considerations for intensity modulated CT
Proceedings of SPIE (March 02 2012)
Watermarking for automatic quality monitoring
Proceedings of SPIE (April 28 2002)

Back to Top