Mean glandular dose estimation using MCNPX for a digital breast tomosynthesis system with tungsten/aluminum and tungsten/ aluminum + silver x-ray anode-filter combinations

• Published in: Medical physics (Lancaster) 2008-12, Vol.35 (12), p.5278-5289
• Main Authors: Ma, Andy K. W., Darambara, Dimitra G., Stewart, Alexander, Gunn, Spencer, Bullard, Edward
• Format: Article
• Language: English
• Subjects: ALUMINIUM; aluminium compounds; Aluminum - pharmacology; Anisotropy; ANODES; BIOMEDICAL RADIOGRAPHY; Breast - pathology; breast imaging; Breast Neoplasms - diagnosis; Breast Neoplasms - radiotherapy; Cancer; Computed tomography; computerised tomography; COMPUTERIZED TOMOGRAPHY; diagnostic radiography; Digital tomosynthesis mammography; DOSIMETRY; Dosimetry/exposure assessment; Electrodes; Equipment Design; Female; FILTERS; Humans; IMAGE PROCESSING; Image sensors; MAMMARY GLANDS; Mammography; Mammography - methods; mean glandular dose; medical computing; medical image processing; Medical imaging; Monte Carlo; MONTE CARLO METHOD; Monte Carlo methods; NEOPLASMS; Phantoms, Imaging; Photons; Position sensitive detectors; POSITIONING; RADIATION DOSES; RADIOLOGY AND NUCLEAR MEDICINE; Radiometry; SCREENING; SILVER; Silver - pharmacology; tomosynthesis; TUNGSTEN; Tungsten - pharmacology; tungsten compounds; X RADIATION; X-Rays; X‐ray detectors
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.3002310

Breast cancer screening with x-ray mammography, using one or two projection images of the breast, is an indispensible tool in the early detection of breast cancer in women. Digital breast tomosynthesis (DBT) is a 3D imaging technique that promises higher sensitivity and specificity in breast cancer screening at a similar radiation dose to conventional two-view screening mammography. In DBT a 3D volume is reconstructed with anisotropic voxels from a limited number of x-ray projection images acquired over a limited angle. Although the benefit of early cancer detection through screening mammography outweighs the potential risks associated with radiation, the radiation dosage to women in terms of mean glandular dose (MGD) is carefully monitored. This work studies the MGD arising from a prototype DBT system under various parameters. Two anode/filter combinations ( W ∕ Al and W ∕ Al + Ag ) were investigated; the tube potential ranges from 20 to 50 kVp ; and the breast size varied between 4 and 10 cm chest wall-to-nipple distance and between 3 and 7 cm compressed breast thickness. The dosimetric effect of breast positioning with respect to the imaging detector was also reviewed. It was found that the position of the breast can affect the MGD by as much as 5% to 13% depending on the breast size.