A sharper ultrasound image
Image quality is one of the most difficult issues to resolve when it comes to ultrasound. Many variables go into creating and fine-tuning an image, and as service engineers, we need to be able to check the fundamentals to make sure the system is set up properly to produce the best image possible. Biomeds should be aware of how to optimize several major settings on an ultrasound system. My intent is to cover the basics, not to make you a clinical expert – that can take years.
One of the most common problems seen with image optimization is the position if the focal zone or transmit zone. This is where the system is electronically optimized to focus and is indicated by a “<” or some other symbol along the vertical scale of the image. This should be set at or below the area of interest.
The second item to verify is transmit or output power. The system’s acoustic output can be varied and you want to ensure that the power, with the customer’s approval, is set for sufficient output. Typically it is set for 100% or 0dB output except for obstetrical exams, where it can be reduced to 50% or -3dB.
Another item to verify is frequency. Is the transmit/receive frequency setting on the system correct for the preset the customer is using? Remember, as frequency increases, image quality also increases but penetration decreases and the inverse is true for decreasing the frequency. With contemporary ultrasound systems, a single probe may have up to 8 different settings.
All biomeds should be aware of the importance of system backups. During a backup, all of a customer’s presets are stored to that backup. A single preset may contain 50 – 75 different variables that tune the image for a particular body part and habitus. Now imagine that a system has 4 transducers, and 15 different customized presets and you can begin to see the challenges of restoring these manually. These settings listed above are a small fraction of what goes into a preset but can make a huge difference in overall image quality.