Dictionary-based protoacoustic dose map imaging for proton range verification.

Area of Science:

• Medical Physics
• Radiation Oncology
• Acoustic Imaging

Background:

• Proton radiotherapy offers superior dose conformity but faces challenges due to uncertainties in proton range.
• Accurate in vivo verification of proton range is crucial for maximizing the clinical benefits of proton therapy.
• The radio-induced thermoacoustic effect generates acoustic waves, enabling protoacoustic range verification.

Purpose of the Study:

• To develop and evaluate a dictionary-based protoacoustic method for in vivo proton range verification.
• To utilize a priori dose distribution knowledge to create a dictionary of expected ultrasonic signals.
• To reconstruct the deposited dose by matching pre-calculated signals with online acquired data.

Main Methods:

• A dictionary of expected ultrasonic signals was created based on known proton dose distributions.
• Proton dose calculations were performed using the matRad treatment planning system.
• Acoustic wave propagation was simulated using k-Wave for signal analysis.
• The method's ability to detect range variations due to anatomical and beam position changes was assessed.

Main Results:

• The dictionary-based protoacoustic method successfully identified range variations caused by changes in tissue density and beam position.
• The average accuracy for detecting range shifts was 1.4 mm.
• The method demonstrated potential for real-time in vivo verification during proton therapy.

Conclusions:

• The proposed dictionary-based protoacoustic method offers a promising approach for in vivo proton range verification.
• This technique can help reduce uncertainty margins in proton therapy, improving treatment accuracy.
• Comparing measured acoustic signals with pre-calculated dictionary signals enables effective online monitoring.