**5. Conclusions**

It should be noted that a complete quality control programme requires some hours of machine time for acquisition only.

However, due to the very high number of ultrasound exams performed worldwide, we recommend at least a complete annual check for each piece of equipment, reserving the right to decide to carry out any simple checks at higher frequencies, which require little waste of time, and in any case whenever the radiologist deems it necessary.

Planning a quality control programme can reduce the number of repeated investigations, make the diagnosis more accurate and limit patient referral to other methods for diagnostic completion, making each ultrasound examination more accurate and informative.

It concerns real-time B-mode ultrasound and Doppler velocimetry, both spectral and colour mode.

It should follow a protocol that contains the parameters to be evaluated, the phantoms to be used, the measurement methods, the frequencies of the evaluations and, possibly, the tolerance limits.

A set of controls both for B-mode and Doppler are proposed. The parameters investigated were chosen following their clinical relevance and in the cases was possible, limits of tolerance suggested.

The tests were all used in commercial or homemade phantoms and the problems and general results were discussed. This can be a simple way to approach the physics of quality control in ultrasound. If someone wants to go into detail some useful reference is suggested. With the very high number of exams worldwide performed, it is mandatory to follow a QA programme like in the case of X-rays.
