A Structure Design Method for Reduction of MRI Acoustic Noise

Area of Science:

• Medical Physics
• Acoustics Engineering
• Biomedical Engineering

Background:

• Acoustic noise from split gradient coils is a significant challenge in MRI-LINAC systems.
• This noise can impact patient comfort and potentially affect treatment precision.
• Existing noise reduction methods may have limitations or interfere with system functionality.

Purpose of the Study:

• To develop and evaluate an effective acoustic noise reduction scheme for split gradient coils in MRI-LINAC systems.
• To minimize acoustic noise without compromising the performance of the MRI-LINAC system.
• To provide a quantitative assessment of the proposed noise reduction strategies.

Main Methods:

• Design of a split gradient assembly with an asymmetric configuration to prevent resonant vibrations.
• Incorporation of horn structures at the outer ends of the split main magnet to redirect acoustic fields.
• Utilization of the finite element method (FEM) for quantitative simulation and evaluation of noise reduction effectiveness.

Main Results:

• Increasing one gradient assembly cylinder length by 20 cm reduced noise by up to 6.9 dB (inside) and 5.6 dB (outside) the central gap.
• Optimized horn structures (55 cm length) achieved noise reductions of up to 7.4 dB (inside) and 5.4 dB (outside) the central gap.
• The proposed design effectively reduces acoustic noise without interfering with other noise reduction techniques.

Conclusions:

• The developed asymmetric split gradient assembly and horn structures offer a viable solution for mitigating acoustic noise in MRI-LINAC systems.
• The finite element method simulations confirm significant noise level reductions achievable with the proposed modifications.
• This approach provides an effective and compatible method for enhancing MRI-LINAC system acoustics.