Dosimetry in Digital Breast Tomosynthesis Evaluated by Monte Carlo Technique

Area of Science:

• Medical Physics
• Radiological Imaging
• Radiation Dosimetry

Background:

• The impact of tube angular deviation during digital breast tomosynthesis (DBT) on radiation dose is not well understood.
• Accurate dose assessment is crucial for optimizing patient safety in breast imaging.
• Understanding dose distribution is essential for evaluating potential risks associated with varying acquisition parameters.

Purpose of the Study:

• To investigate the influence of tube angular deviation in DBT on absorbed dose in the breast and other organs.
• To compare radiation dose metrics between DBT and digital mammography (DM) under varying angular conditions.
• To quantify dose coefficients and relative organ doses for different tomosynthesis acquisition parameters.

Main Methods:

• Employed Monte Carlo simulations utilizing an adult female anthropomorphic phantom (FSTA_M50_H50).
• Simulated tomosynthesis equipment with Mo/Mo, Mo/Rh, and W/Rh target/filter combinations at 28 kV.
• Calculated absorbed dose coefficients (DT/Kair) for the breast and relative organ doses (ROD) for other organs.

Main Results:

• DBT parameters resulted in absorbed dose coefficients up to 24 times higher than DM parameters for the examined breast.
• A specific DBT exam yielded a DT/Kair of 0.97 × 10-1 mGy/mGy for the right breast.
• Highest relative organ doses were observed in the thyroid, eyes, liver, and eye lenses, with variations noted for all non-zero degree projections.

Conclusions:

• Angular deviation of the X-ray tube during DBT acquisition significantly increases breast radiation dose compared to DM.
• Specific organs like the thyroid and eyes receive notable doses during DBT, necessitating careful consideration of acquisition parameters.
• The findings underscore the importance of optimizing DBT protocols to minimize radiation exposure while maintaining diagnostic image quality.