Apparatus and method for acoustic imaging using inverse scattering techniques

A method of producing an image of an object from acoustic energy that has been transmitted through and scattered by the object, said image comprising a high and acoustic absorption at all points within the object, and said method comprising the steps of:

• electronically transmitting an electric signal at multiple frequencies and transducing said electric signal at each said frequency into acoustic energy propagated toward said object from a plurality of transducer transmitter positions;
• electronically processing said electrical signal to determine from said transmitter positions an incident field corresponding to said propagated acoustic energy, said incident field being stored in the memory of a central processing unit (CPU) in the form of digitized electric signals;
• detecting at a plurality of transducer receiver positions said acoustic energy transmitted through and scattered by said object;
• electronically processing said detected acoustic energy so as to transform said detected energy into a plurality of digitized electric signals stored in said memory of said CPU and corresponding to a scattered field detected at said transducer receiver positions;
• said CPU preparing an initial estimate of the scattering potential for said object and an initial estimate of the internal field of said object at each pixel of a display screen on which said acoustic image is to be displayed and storing each said estimate in said memory;
• said CPU determining at each said frequency and storing in said memory a scattered field derived at said frequency from said initial estimates of the scattering potential and internal field, and thereafter comparing at said frequency said scattered field detected at said receiver positions to said scattered field determined by said CPU;
• said CPU determining at each said frequency and storing in said memory a new estimate of said internal field at each said pixel derived from said incident field, the last estimate of the internal field at each said pixel, and the last estimate of said scattering potential at each said pixel, said new estimate of the internal field at said frequency comprising all orders of scattering;
• said CPU determining and storing in said memory a new estimate of said scattering potential derived from said new estimate of said internal field and said scattered field detected at said receiver positions;
• said CPU continuing to update the estimate for said internal field and scattering potential until said scattered field determined by said CPU approximates said scattered field detected at said receiver positions within a selected range of tolerance;
• and
• said CPU thereafter using the determined scattering potential to reconstruct and store said image in said CPU memory.