Ultrasonic imaging method and apparatus

In a method for the non-invasive examination of objects such as body parts, the steps of

• insonifying at least a portion of the body part with a beam of broadband acoustic energy to produce echo signals from within the body,
• receiving echo signals from within the body and converting the same to electrical signals,
• passing the electrical signals through bandpass filter means having a variable filter transmission factor versus frequency characteristic, and
• time varying the filter transmission factor versus frequency characteristic of the bandpass filter in relationship with the depth from which the echo signals are received while receiving echo signals from over a range of depths within the body for compensating for depth dependent changes in the

In an ultrasonic system for the examination of the interior body parts, or the like, the combination comprising,

• means for recurrent pulse insonification of a body part under examination,
• means for receiving echo signals from discontinuities within said body part over a time period following pulse insonification, which signals have a spectral distribution dependent upon the depth within the body part from which the signal is received, and for converting received echo signals to electrical signals,
• bandpass filter means having variable operating characteristics through which said electrical signals are passed, and
• means for time varying operating characteristics of the bandpass filter means while passing said electrical signals therethrough for relating filter operating characteristics with the time varying spectral

In a method for the non-invasive examination of the interior of objects such as living organisms, or the like, the steps of,

• pulse insonifying at least a portion of an object to be examined with an acoustic energy beam to produce echo signals from discontinuities within the object,
• receiving over a time period following said pulse insonifying step echo signals from within the body, which echo signals have a spectral distribution dependent upon the depth from which the signal is received,
• converting the received echo signals to electrical signals,
• passing the electrical signals through bandpass filter means having a variable filter transmission factor versus frequency characteristic, and
• time varying the filter transmission factor versus frequency characteristic of said bandpass filter means while the electrical signals are passed therethrough to match the variable filter transmission factor versus frequency characteristic of said bandpass filter means with the time varying spectral distribution of the electrical signal for improving the