Delivering Volumetric Hyperthermia to Head and Neck Cancer Patient-Specific Models Using an Ultrasound Spherical...

Area of Science:

• Biomedical Engineering
• Oncology
• Medical Physics

Background:

• Hyperthermia (40-45 °C) is an effective adjuvant therapy for head and neck cancers, enhancing chemotherapy, radiation, and drug delivery.
• Current hyperthermia methods face challenges in uniformly and non-invasively treating large, deep tumors.

Purpose of the Study:

• To investigate the feasibility of a non-invasive ultrasound spherical random phased array transducer for targeted, uniform deep tissue hyperthermia.
• To assess the transducer's efficacy in patient-specific 3D models of thyroid and oropharyngeal cancers.

Main Methods:

• Simulations were performed using a 256-element, 1 MHz ultrasound transducer on 3D models of thyroid and oropharyngeal cancers.
• Various phasing schemes and power modulations were analyzed to determine isothermal volumes (40, 41, 43 °C) and heating depth.
• Temperature uniformity was evaluated using T10, T50, and T90 metrics, with intensity distributions and volumetric contours calculated.

Main Results:

• The array achieved controlled heating volumes ranging from 1-48 cm³ at 40 °C, 0.35-27 cm³ at 41 °C, and 0.1-8 cm³ at 43 °C.
• Heating depths varied from 7-39 mm (minimum) to 52-59 mm (maximum) from the skin's inner surface.
• Multifocal sonications improved heating homogeneity, reducing the length-to-diameter ratio by 38% compared to single-focus treatments.

Conclusions:

• The non-invasive ultrasound transducer effectively delivers targeted, uniform hyperthermia to deep tissues.
• This technology shows significant potential for treating various tumors, particularly challenging deep-seated oropharyngeal cancers, as an adjuvant therapy.