DOSIS: a Monte Carlo simulation program for dose related studies in mammography

Area of Science:

• Medical Physics
• Radiological Sciences
• Computational Imaging

Background:

• Accurate mammography dosimetry is crucial for patient safety.
• Monte Carlo (MC) simulations offer a powerful tool for simulating radiation transport and dose distribution in mammography.
• Optimizing mammographic techniques requires detailed understanding of dose parameters.

Purpose of the Study:

• To develop and validate a Monte Carlo simulation program (DOSIS) for mammography dosimetry.
• To evaluate the impact of various mammographic technique parameters on breast dose.
• To compare the dosimetric performance of different mammographic target/filter combinations.

Main Methods:

• Development of a FORTRAN 90-based Monte Carlo simulation model (DOSIS) with a Visual Basic graphical user interface.
• Input of user-defined mammographic technique parameters (e.g., tube voltage, filtration).
• Simulation of radiation transport through water phantoms to assess surface dose, exposure at the detector plane, percentage depth dose, and isodose curves.

Main Results:

• Increased tube voltage (25 to 30 kVp) in Mo/Mo systems decreased surface dose by 42% for a 6 cm phantom, without affecting detector exposure.
• Using a W/Al system with 1.02 mm Al filter at 30 kVp reduced surface dose by 19.1% for a 5 cm phantom.
• W/Al systems demonstrated superior dosimetric performance, achieving up to a 65% reduction in surface dose compared to Mo/Mo systems at equivalent detector exposures.

Conclusions:

• The DOSIS program effectively simulates mammographic dosimetry and evaluates technique parameters.
• Tungsten/Aluminum (W/Al) anode/filter combinations offer significant dosimetric advantages over Molybdenum/Molybdenum (Mo/Mo) systems in mammography.
• Optimized filtration and target materials can substantially reduce breast surface dose, improving patient safety in mammography.