Normalized glandular dose (DgN) coefficients from experimental mammographic x-ray spectra

Area of Science:

• Medical Physics
• Radiological Dosimetry

Background:

• Mean glandular dose (DgN) is crucial for mammography dosimetry.
• It depends on breast characteristics and X-ray spectrum.
• Accurate DgN estimation is vital for patient safety and effective screening.

Purpose of the Study:

• To develop and validate an experimental method for deriving polyenergetic normalized glandular dose coefficients (DgN_p).
• To compare DgN_p values obtained through this method with existing techniques and patient data.
• To evaluate the depth-dependent DgN_p (depth-DgN_p) within breast phantoms.

Main Methods:

• Utilized breast phantoms with varying glandular/adipose proportions (30/70, 50/50) and thicknesses up to 4.5 cm.
• Measured X-ray spectra incident and transmitted through phantoms using a Mammomat 3000 Nova system (Mo/Mo, Mo/Rh, W/Rh spectra at 26-28 kVp).
• Compared experimental DgN_p with results from Boone's method, DICOM Organ Dose, and VolparaDose calculations; assessed depth-DgN_p using X-ray spectra and TLDs.

Main Results:

• The experimental method showed maximum differences of 11% compared to Boone's method and up to 8.0% compared to patient image data.
• Depth-DgN_p estimations using incident-transmitted spectra differed by up to 5.2% from whole-phantom calculations.
• TLD-based depth-DgN_p distributions were consistent with experimental spectra, with a maximum difference of 3.9%.

Conclusions:

• Polyenergetic X-ray spectrometry is a viable tool for mammography dosimetry research, enabling spectral characterization.
• This experimental approach aids in understanding the impact of X-ray spectra on glandular dose.
• The validated method provides a reliable basis for further investigations in mammography dose assessment.