1. Medica Co., Ltd. (Upper Silesian School of Ultrasonography), 41-500 Chorzów, Poland
2. Collegium Medicum, Jan Kochanowski University, 25-317 Kielce, Poland
3. Municipal Hospital Co., Ltd., 41-703 Ruda Śląska, Poland
4. Collegium Medicum, WSB University, 41-300 Dąbrowa Górnicza, Poland
5. Department of Anaesthesiology and Critical Care, School of Medicine with the Division of Dentistry, Medical University of Silesia, 41-808 Zabrze, Poland