Trade-off between breast dose and image quality using composite bismuth shields in computed tomography: A phantom...

Area of Science:

• Medical Physics
• Radiology
• Materials Science

Background:

• Bismuth composite shields (BCS) are proposed to reduce radiation dose in medical imaging.
• The impact of BCS on radiation dose reduction and image quality in chest CT is not fully understood.

Purpose of the Study:

• To evaluate the dose reduction efficiency of nano- and micro-bismuth composite shields (BCS).
• To assess the impact of these BCS on image quality during chest computed tomography (CT) scans.

Main Methods:

• Constructed BCS with varying bismuth oxide (Bi2O3) concentrations (15 wt%, 20 wt%) and thicknesses (1 mm, 1.5 mm).
• Assessed physical properties using SEM, XRD, and EDX.
• Measured breast radiation dose reduction using a PMMA phantom during chest CT.
• Evaluated image quality by analyzing signal and noise values.

Main Results:

• Dose reduction increased with shield thickness and bismuth weight percentage.
• Maximum dose reduction achieved with 20 wt% Bi2O3 nano-particles at 1.5 mm thickness.
• Mean image noise was higher with nano-particle BCS compared to micro-particle BCS.

Conclusions:

• Bismuth composite shields effectively reduce breast dose in chest CT.
• Particle size, bismuth concentration, and shield thickness are critical factors influencing dose reduction.
• The use of BCS can negatively impact diagnostic image quality, particularly with nano-particles.