## 1 Introduction  
Besides systemic chemotherapy, local treatments, such as radiation and hyperthermia treatments, are typically used for cancer treatment. In these methods, the level of cell death induction is used as an indicator of therapeutic effectiveness. Despite a wide range of possible methodological options, there is a lack of valid strategies, based not only on the effect of high temperatures, but with a valuable effect per se. Among these, ultrasound technology has emerged as a possible novel therapeutic approach, despite the need for proper validation. Shock waves are heterogeneous, discontinuous, rapid mechanical phenomena that have been observed in the laboratory and in nature, in microscopic as well as in macroscopic dimensions, and in all states of matter. In the management of solid cancer, the possible application of shock waves is ascribable to the pure mechanical effects on the cells. Differently, in addition to traditional surgery and chemotherapy, the use of high intensity focused ultrasound (HIFU) has been established as a noninvasive technique for tumor therapy. In particular, the method of laser-induced shockwave generation is able to permeabilize cell membrane and increase drug delivery. Laser-induced methods for shock wave generation are reproducible on the macroscopic level and they have proven to prevent lithotripter related side-effects, such as heating and cavitation [1]. The research on ultrasound (US) therapy is focused on interactions of ultrasound mechanical energy delivered to biological tissues and the related phenomena that cause temperature rises. In the field of diagnostics and therapy, in fact, several simplified models have been developed to estimate the variation in temperature, inertial and non-inertial cavitation [2], and their biological consequences. The use of US for cancer treatment relies on both thermal and non-thermal effects, i.e., hyperthermia and acoustic streaming/radiation force, respectively. US used in medicine can be divided into two main categories: US high intensity HIFU (high intensity focused ultrasound) and US low intensity LIU (low intensity ultrasound). The literature shows there is a limited value of the intensity from which the two types of ultrasounds are distinguished (Low: 0.5 MHz \(\leq\) f \(\leq\) 5 MHz, 0.1 MPa \(\leq\) P\({}_{\mathrm{a}}\)\(\leq\) 1.5 MPa; High: 0.8 MHz \(\leq\) f \(\leq\) 7 MHz, P\({}_{\mathrm{a}}\)\(>\) 10 MPa) [3]. Another classification of US is based on the intensity, ranging from 0.05-0.5 W/cm\({}^{2}\) for diagnostic imaging, to surgical applications with a range of 0.2-10 \(\times\) 10\({}^{3}\) W/cm, to therapeutic applications that can use both high and low intensities [4]. An essential feature that characterizes ultrasounds is that, with increasing frequency, the attenuation for dissipative effects is very pronounced and it is therefore necessary to determine the value of the energy lost in propagation. Among different US, high intensity focused ultrasound (HIFU) has been investigated extensively and found to be highly effective in treating different cancers via hyperthermia. The US has also been very effective in creating stroma in the cell membrane thus enhancing the drug intake. Tumor cells demonstrated the ability to acquire thermo-resistance due to repeated hyperthermia and the efficiency of hyperthermia-based treatments, hence, decreases with repeated use. Therefore, among magnetic and US based treatments, the latter demonstrated more effectiveness and strong application potential. Low intensity pulsed ultrasound (LIPUS) is a technology that can be used for therapeutic purposes. It exploits low intensity and pulsed mechanical waves to induce regenerative and anti-inflammatory effects on biological tissues, such as bone, cartilage, and tendons. Even if the real mechanism underlying its effectiveness has not been understood yet, it is plausible that the treatment relies on non-thermal phenomena, such as microbubbles and microjets induced by cavitation, acoustic streaming, and mechanical stimulation.