Читать книгу Point-of-Care Ultrasound Techniques for the Small Animal Practitioner - Группа авторов - Страница 88

The ultrasound beam has a focus position where the beams narrow to give a more detailed image at a certain depth. The beams do not converge, as we may think of light focusing on the retina, because they will again diverge beyond the focal position. The physics of this can be found in additional references (Nyland et al. 2002). Both the focus position and number of focal points can be set and adjusted by the sonographer. However, the processor can only handle a certain amount of information and by asking it to do more, it will reduce other items, normally the frame rate or how many times/second the image is refreshed. High frame rates make for a smooth image but take a lot of processing power. Low frame rates give a choppy image. Ask the processor to do more and it will respond by giving you a lower frame rate, a choppier image.

Pearl: For the POCUS and FAST scans, generally keep the focal point number at 1, and set the focal point's position at, or just deep to, the area of interest.