Diagnostic ultrasound, a non‐invasive mode for imaging soft tissues, requires for its use an understanding of sound and sound‐tissue interaction physics. Ultrasound frequencies from 1.0 to 10.0 MHz are created by electrical stimulation of piezoelectric crystals. These crystals are housed within transducers, which, when applied to the body surface with a coupling agent will produce sound waves, referred to as the sound beam, which are propagated through the soft tissues of the body. When the sound beam encounters tissue interfaces of differing acoustic impedance, a portion of the sound beam is reflected back to the transducer which also acts as a receiver. Echoes returning from soft tissue acoustic interfaces are converted to electrical impulses and displayed on an oscilloscope screen as a cross section of the tissue. Lower frequency sound beams penetrate further into soft tissue, but have poorer resolving capabilities, than higher frequency sound beams.A, B, and M‐modes are the three basic forms of ultrasound used in soft tissue imaging. A‐mode ultrasonic imaging is a one‐dimensional display of echo amplitudes versus distance. B‐mode ultrasonic imaging produces an accurate two‐dime
📖 افتح في inklap 🔗 DOI 📮 اطلب بحثاً