Acoustic characterization of ultrasound fields able to induce sonodynamic activity in an in vitro cancer model

The corner stone of cancer management is by far chemotherapy, unfortunately toxicity and undesired side-effects of these antineoplastic approach often limit its usefulness. Recently it has been found that certain dye compounds non cytopathogenic per sé, in particular porphyrins, can achieve a cytopathogenic effect when the neoplastic site is subjected to ultrasounds irradiation, this technique is referred to as sonodynamic therapy (SDT). Despite the promising results, the poor reproducibility of the treatment, due to the poor investigation between the ultrasounds field parameters and the SDT activity, hampered the development of robust treatment protocol. Therefore the aim of this work has been the characterization of high intensity ultrasound fields needed to reach the SDT activity. First, by an ultrasound generator system, an in vitro sonodynamic treatment has been performed on HT-29 cell line, previously pre-incubated with 50 μg/mL of aminilevulinic acid, therefore a complete characterization of the ultrasound field in measurement conditions has been carried out. An ONDA type AIMS III scanning tank system with needle hydrophone ONDA type has been used and the real energy that hit the cellular culture in the burette has been evaluated. During insonation process the energy supplied to the cells has been about 5 10^-6 J introducing, for the first time in the sonodynamic field, a clear parameter of energy supplied to the cells.