Effect of source blur on digital breast tomosynthesis reconstruction

Area of Science:

• Medical Imaging
• Radiology
• Image Reconstruction

Background:

• Digital breast tomosynthesis (DBT) is a crucial imaging modality for breast cancer detection.
• Current DBT reconstruction methods often overlook the impact of x-ray focal spot characteristics, such as finite size and motion, on image quality.

Purpose of the Study:

• To investigate the effect of x-ray source blur on the spatial resolution of reconstructed DBT images.
• To compare the influence of varying blurred source sizes on image quality.

Main Methods:

• Analytical calculations and simulations were employed to model the point spread function (PSF) of source blur.
• Clinical DBT system parameters were used to estimate effective source sizes.
• Digital phantoms and the CatSim tool were utilized to simulate imaging with different source sizes.
• The impact of source blur on spatial resolution was analyzed by examining image contrasts.

Main Results:

• The point spread function (PSF) of source blur is highly shift-variant, complicating reconstruction.
• A stationary x-ray tube with a typical focal spot size (~0.3 mm) does not significantly impact resolution.
• X-ray tube motion during exposure can degrade image resolution, dependent on the effective source size in the direction of motion.
• Synchronous detector rotation with the source offers minimal reduction in source blur's influence.

Conclusions:

• X-ray tube motion during DBT acquisition substantially degrades reconstructed image resolution.
• Synchronous detector rotation does not effectively mitigate the resolution loss caused by source blur.
• Incorporating source blur modeling into reconstruction algorithms may enhance DBT image quality, particularly for continuous-motion acquisition.