Ponencia presentada en el XIX Congreso Internacional de Acústica (ICA2007), Madrid, 2-7 Sep 2007.-- PACS: Cs 43.35.Ud.To calculate the thermal dose in therapeutic ultrasound only the absorption phenomenon is considered. Nevertheless scattering can be non negligible, thus influencing global attenuation and consequently the thermal dose. This work proposes an experimental approach of the role scattering has in temperature generated by therapeutic ultrasound in biological phantoms. These phantoms mimic the acoustical and thermal properties of biological tissues. This study was conducted with continuous wave ultrasound at 1 and 3 MHz and 2 W/cm2. Five phantoms were used in the experiments. The first one composed of one single agar-gel based layer 85-mm thick. The others composed of two layers: one of 42-mm agar-gel and the other with 43-mm agar-gel mixed with graphite or PVC powder as scatterers. Seven thin thermocouples were inserted in the phantoms (two in the first layer and the others in the second one, 5 mm from each other) and connected to standard instrumentation. The phantoms were heated by ultrasound for 10 min. Preliminary results show that the layer with graphite powder reaches up to 4ºC more than the other phantoms at the same depth. Therefore, we have an initial indication how scattering can influence heating patterns and should be taken in consideration, at least in some scenarios.For elaboration of this work the support of the CYTED/CNPq (PULSETS) project and ALPHA N I-0343-FA-FCD-FI (PETRA II) program has been received.Peer reviewed