Development of an adaptive safety parameter model for diagnostic ultrasond and improvement of image quality

Diagnostic ultrasound as an imaging tool in medicine has been used for nearly half a century. Diagnostic ultrasound has been used to obtain information about the structure and function of tissues and organs. However, as acoustic energy transmitting into the body, DUS has potential effects on living tissues, namely, thermal and mechanical bioeffects. The bioeffects caused by diagnostic ultrasound, under certain exposure conditions, are considered harmful. In this thesis, it is proposed a safety parameter for thermal and mechanical bioeffects of diagnostic ultrasound; that is, SUT (safe use time). The SUT model is constructed to determine how long one piece of tissue can be insonated safely according to a threshold exposure. This study suggests that an increase in acoustic intensity beyond the current U.S. Food and Drug Administration (FDA) limit of intensity can be theoretically possible by using SUT model while staying within the safe limit.Using the proposed SUT model, high power ultrasound can be applied for a short time so that the user can improve imaging performance while staying within safe limits. The present study was motivated particularly by the goals of higher resolution and/or deeper penetration by using the SUT model. The results presented here suggest that the safe use of higher ultrasound output levels than currently allowed by FDA may be possible for obtaining substantial improvements in penetration depth and/or resolution. Also, the study reveals that image quality may change as a function of exposure time in addition to acoustic energy and frequency.