Production and use of ultrasound — common mistakes

Remember that a large impedance difference is key to forming an image (you need echoes!), but too large a difference (like between tissue and air) will block the ultrasound from entering the body at all.

Audible sound waves have much longer wavelengths than ultrasound. To resolve fine details in the body (like organs or foetuses), a shorter wavelength is needed to produce clear images. Ultrasound's high frequency and short wavelength allow for this high resolution, which audible sound cannot provide.

Axial resolution refers to the ability of the ultrasound system to distinguish between two objects located along the path of the ultrasound beam. Short pulses, achieved through damping in the transducer, are essential for high axial resolution, allowing closely spaced structures to be seen as separate.

Medical ultrasound is generally considered very safe, as it uses non-ionizing radiation (unlike X-rays) and doesn't significantly heat tissues when used diagnostically. The energy levels are low, and the technique has been widely used for decades without known long-term harmful effects, making it a preferred imaging method for sensitive applications like pregnancy scans.