General considerations on endosonographic equipment

摘要: Ultrasound imaging provides the physician with a great deal of information without risk to patient. Conventional ultrasound is well established in assessment diseases heart, abdominal and pelvic organs, soft tissues. However, visualization this approach limited some areas abdomen pelvis most mediastinum by obstacles sound wave propagation. Bone gas lungs alimentary canal are each responsible for extreme variations acoustic impedance, so that virtually all energy incident beam reflected rather than transmitted. Further, since attenuation related its frequency F as = 0 β (a coefficient at 1 MHz; ≈ 1), transcutaneous deep structures requires use low frequencies, which limits image resolution and, consequently, diagnostic capabilities.