Solid-state dosimeters: a new approach for mammography measurements

Area of Science:

• Medical Physics
• Radiological Dosimetry
• Diagnostic Imaging Technology

Background:

• Accurate dose assessment in mammography is crucial for patient safety and effective screening.
• Digital mammography units utilize various target/filter (TF) combinations, influencing radiation output.
• Solid-state dosimeters (SStDs) are increasingly used for mammography surveys, requiring validation against established methods.

Purpose of the Study:

• To compare the performance of commercially available SStDs from different manufacturers used in mammography surveys.
• To evaluate dose estimation differences between SStDs and ionization chambers (ICs) across various TF combinations.
• To review the scientific basis for mammography dose measurements using both traditional and SStD methods.

Main Methods:

• Evaluated SStDs from four manufacturers using two digital mammography units (GE Essential, Hologic Dimensions).
• Compared measurements for peak tube potential (kVp), half-value layer (HVL), and air kerma (AK) across multiple TF combinations (Mo/Mo, Mo/Rh, Rh/Rh, W/Rh, W/Ag, W/Al).
• Assessed relative average glandular doses (AGDs) and evaluated scatter effects from compression paddles by comparing SStD and IC measurements.

Main Results:

• SStDs demonstrated good accuracy for kVp measurements (within ±1.1 kVp) but showed greater discrepancies for HVL (-6.5% to +3.5%) and AK (-6% to +7%) compared to reference IC values.
• Relative AGDs calculated using SStD measurements generally underestimated doses compared to IC reference values (discrepancies up to -10%).
• Accounting for scatter radiation effects in AK measurements reduced discrepancies between SStD and IC AGD values.

Conclusions:

• SStDs exhibit good agreement with set kVp but poor agreement with HVL and AK measurements when compared to ICs.
• Discrepancies in AGD are partly due to differing responses to scattered radiation, with ICs typically yielding higher AGDs.
• Medical physicists should compare SStD results with traditional methods to identify and manage potential discrepancies in mammography dose assessments.