Carrageenan Biopolymer for Medical Ultrasonography using Phantom CIRS Anak Agung Aris Diartama, Suryono Suryono, Sugiyanto Sugiyanto, Putu Irma Wulandari, I Putu Eka Juliantara and Kadek Yuda Astina E3S Web Conf., 202 (2020) 12001 Published online: 10 November 2020 DOI: 10.1051/e3sconf/202020212001