3D-specific absorption rate estimation from high-intensity focused ultrasound sonications using the Green's function...

Area of Science:

• Medical Physics
• Biomedical Engineering
• Ultrasound Therapy

Background:

• Accurate dosimetry is crucial for high-intensity focused ultrasound (HIFU) treatments.
• Specific absorption rates (SARs) quantify energy deposition, guiding treatment efficacy and safety.
• Current methods for SAR derivation can be computationally intensive or lack accuracy.

Purpose of the Study:

• To evaluate a novel numerical inverse Green's function method for deriving SARs.
• To utilize 3D magnetic resonance imaging (MRI) temperature measurements and tissue properties.
• To assess the method's performance against simulations and experimental phantom data.

Main Methods:

• A numerical inverse Green's function approach was developed to estimate SARs from simulated and MR-measured temperature data.
• Simulations involved calculating a 'true' SAR and using the Pennes bioheat transfer equation (PBTE) to generate temperature maps.
• Noise was added to simulate in vivo conditions, and the method was compared to linear and analytical approaches.

Main Results:

• The numerical method accurately estimated SAR distributions (within 10% of true SAR in noise-free simulations).
• Temperature maps derived using the estimated SAR showed high accuracy (RMSE <0.2°C in simulations).
• Despite noise amplification, the method maintained accurate temperature predictions and was significantly faster than existing methods.

Conclusions:

• The numerical inverse Green's function method provides a computationally efficient and accurate means of SAR estimation.
• The method demonstrates high accuracy in generating temperature maps, even with amplified noise.
• This approach holds potential for improving HIFU treatment monitoring and planning.