Patient-specific large-volume hyperthermia in the liver for ultrasound-enhanced drug delivery from thermosensitive carriers

Ultrasound-mediated mild hyperthermia in the range of 39C to 42C is a promising technique for noninvasive targeted release of thermally sensitive carriers in cancer therapy. The need to sustain a temperature rise of a few degrees evenly throughout a large volume currently limits this therapy to regions with a large accessible acoustic window. Furthermore, the need to continuously scan clinically available highly focused therapeutic ultrasound transducers typically used for ablation limits the volume that can be maintained at this temperature for tens of minutes, and greatly extends treatment time per unit volume. In addition, bone structures, such as the ribs, significantly restrict accessible target locations in areas such as the liver and play a significant role in preventing this therapy from entering into clinical practice. In order to overcome these limitations, we present a combined 3D full wave finite element modelling and experimental approach to design a sectored lens that can be placed on focused transducers to enable direct mild heating of a larger volume in the liver while accounting for patient-specific aberration in the prefocal path. [Work supported by the RCUK Digital Economy Programme, grant number EP/G036861/1 (Oxford Centre for Doctoral Training in Healthcare Innovation).]