Effect of reconstruction filters on ultrasound computed tomography image quality in two different detector arrangements: a preliminary simulation study

Purpose: In soft tissues, tumors have generally different sound speeds than normal
tissues, so that sound speed images could be used to characterize breast cancer and
to study the tumor invasion process. Ultrasound Computed Tomography (UCT) has a
great potential to provide quantitative estimations of physical properties of normal and
abnormal tissues that provides accurate characterization capability for breast cancer.
The goal of this study is a comparison of two different detector arrangement and image
reconstruction filters on image quality parameters in fan-beam back projection method
to introduce the modified arrangement and filter to achieve high-quality USCT images.
Materials and Methods: Two USCT systems with two different detector
arrangement of the ultrasound array, ring-shape and parallel shape, have been
simulated and Point Spread Function (PSF), Modulate Transform Function (MTF)
and spatial resolution are three image quality parameters, have been investigated in
both systems. In this study, a modified filter introduced that apply on the sinogram
in two dimensions in spite of the Ram-Lak that apply on sinogram in one dimension.
Results: These study results show that the spatial resolution affected by not only
detector arrangement but also reconstruction filters. In addition, applying the modified
filter improves the resolution of the ring-shaped system and destroy the resolution of
the line one and we have higher resolution in the modified filter than Ram-Lak.
Conclusion: The result suggests that to have high-resolution USCT images, the
difference filters specially modified filter can be used and ring-shaped system has
higher resolution images than line one.