In this paper, we have examined the possibility of incorporating pulse
compression techniques into a conventional medical B-scan imaging sch
eme. Linear frequency modulation fm, one form of pulse coding among ma
ny others, has been used in this study. With this approach, one can ov
ercome current peak intensity limitations. A theoretical framework tha
t includes medium propagation effects, transducer bandwidth and diffra
ction effects is presented, which could be used to examine the system
point spread function under this imaging scheme. A prototype experimen
tal set-up and signal processing are described and used for simple ima
ging tasks in attenuating and nonattenuating media. Analysis of the ex
perimental point spread functions shows that resolution similar to con
ventional short pulse imaging can be achieved. However, the existence
of large range side lobe levels usually associated with pulse compress
ion processing can degrade contrast resolution in medical ultrasound.
We have considered various different factors that can affect the range
side lobe levels and examined their effect either experimentally or t
hrough simulations. The technique has the potential for improving sign
al-to-noise ratio (SNR), maximum penetration depth and resolution with
out exceeding peak intensity limitations. Some possible applications a
re discussed that merit further evaluation. Our work demonstrates the
feasibility of this technique and presents a theoretical framework tha
t can be used in future studies aimed at evaluating image quality, sys
tem performance, and possible artifacts under such an imaging scheme.
(C) 1995 Academic Press, Inc.