Fluence-Field Modulated X-ray CT using Multiple Aperture Devices.
We introduce a novel strategy for fluence field modulation (FFM) in x-ray CT using multiple aperture devices (MADs). MAD filters permit FFM by blocking or transmitting the x-ray beam on a fine (0.1-1 mm) scale. The filters have a number of potential advantages over other beam modulation strategies including the potential for a highly compact design, modest actuation speed and acceleration requirements, and spectrally neutral filtration due to their essentially binary action. In this work, we present the underlying MAD filtration concept including a design process to achieve a specific class of FFM patterns. A set of MAD filters is fabricated using a tungsten laser sintering process and integrated into an x-ray CT test bench. A characterization of the MAD filters is conducted and compared to traditional attenuating bowtie filters and the ability to flatten the fluence profile for a 32 cm acrylic phantom is demonstrated. MAD-filtered tomographic data was acquired on the CT test bench and reconstructed without artifacts associated with the MAD filter. These initial studies suggest that MAD-based FFM is appropriate for integration in clinical CT system to create patient-specific fluence field profile and reduce radiation exposures.
Biomedical Engineering, Johns Hopkins Univ., Baltimore, MD.
J Webster
JW
Stayman
Biomedical Engineering, Johns Hopkins Univ., Baltimore, MD.
Aswin
A
Mathews
Biomedical Engineering, Johns Hopkins Univ., Baltimore, MD.
Wojciech
W
Zbijewski
Biomedical Engineering, Johns Hopkins Univ., Baltimore, MD.
Grace
G
Gang
Biomedical Engineering, Johns Hopkins Univ., Baltimore, MD.
Jeffrey
J
Siewerdsen
Radiology, Johns Hopkins Univ., Baltimore, MD.
Satomi
S
Kawamoto
Philips Medical Systems, Haifa, Israel.
Ira
I
Blevis
Philips Medical Systems, Haifa, Israel.
Reuven
R
Levinson