Given the prevalence and relatively low cost of ultrasound generation mechanisms, the premise of HIFU is that it is expected to be a non-invasive and low-cost therapy that can at least outperform care in the operating room.

The technology is different from that used in ultrasonic imaging, though lower frequencies and continuous, rather than pulsed, waves are used to achieve the necessary thermal doses.

HIFU is combined with other imaging techniques such as medical ultrasound or MRI to enable guidance of the treatment and monitoring.

In 2016, the US Food and Drug Administration (FDA) approved Insightec's Exablate system to treat essential tremor.

[14] During the treatment of metastasized liver cancer with HIFU, immune responses have been observed in locations that are distant from the focal region.

[19] HIFU beams are precisely focused on a small region of diseased tissue to locally deposit high levels of energy.

[20] Each sonication (individual ultrasound energy deposition) treats a precisely defined portion of the targeted tissue.

The entire therapeutic target is treated by using multiple sonications to create a volume of incompressible material, such as tap water.

The equations and methods described in this report are not intended to represent any clinical result, this is only an approach for thermal dose estimation in a incompressible material of just tap water; .

There are some reports that HIFU could be applied to cancers to disrupt the tumor microenvironment and trigger an immune response, as well as possibly enhance the efficacy of immunotherapy.

[26][27] At high enough acoustic intensities, cavitation (microbubbles forming and interacting with the ultrasound field) can occur.

Microbubbles produced in the field oscillate and grow (due to factors including rectified diffusion), and can eventually implode (inertial or transient cavitation).

During inertial cavitation, very high temperatures occur inside the bubbles, and the collapse during the rarefaction phase is associated with a shock wave and jets that can mechanically damage tissue.

[28] Stable cavitation creates microstreaming which induces high shear forces on cells and leads to apoptosis.

Strong streaming may cause cell damage but also reduces tissue temperature via convective heat loss.

The beam has the ability to pass through overlying tissues without harm and focus on a localized area with size limit of 2–3 mm, that is determined the clinical frequency of the ultrasound.

[1][34] MRgFUS is a 3D imaging technique which features high soft tissue contrast and provides information about temperature, thus allowing to monitor ablation.

However, low frame rate makes this technique perform poorly in real-time imaging and high costs represent a significant limitation to its use.

Another reason why ultrasound is ideal for image guidance is it verifies the acoustic window in real time since it is the same modality as the therapy.

[36] In addition, treatment outcomes can be estimated in real time through visual inspection of hyperechoic changes in standard B-mode images.