Glandular breast dose for monoenergetic and high-energy X-ray beams: Monte Carlo assessment.
OBJECTIVE
To extend the utility of normalized glandular dose (DgN) calculations to higher x-ray energies (up to 120 keV) and to provide the tools for investigators to calculate DgN values for arbitrary mammographic and x-ray spectra.


METHODS
Validated Monte Carlo methods were used to assess DgN values. One million x-ray photons (1-120 keV, in 1-keV increments) were input to a semicircular breast geometry of thicknesses from 2 to 12 cm and breast compositions from 0% to 100% glandular. DgN values for monoenergetic (1-120 keV) x-ray beams, polyenergetic (40-120 kV, tungsten anode) x-ray spectra, and polyenergetic mammographic spectra were computed. Skin thicknesses of 4-5 mm were used.


RESULTS
The calculated DgN values were in agreement within approximately 1%-6% with previously published data, depending on breast composition. DgN tables were constructed for a variety of x-ray tube anode-filter combinations, including molybdenum anode-molybdenum filter, molybdenum anode-rhodium filter, rhodium anode-rhodium filter, tungsten anode-rhodium filter, tungsten anode-palladium filter, and tungsten anode-silver filter. DgN values also were graphed for monoenergetic beams to 120 keV and for general diagnostic x-ray beams to 120 kV.


CONCLUSIONS
The tables and graphs may be useful for optimizing mammographic procedures. The higher energy data may be useful for investigations of the potential of dual-energy mammography or for calculation of dose in general diagnostic or computed tomographic procedures.
Boone
J M
JM
Department of Radiology, University of California, Davis, Medical Center, Sacramento 95817, USA. jmboone@ucdavis.edu
D001940:Breast / Q000033:anatomy & histology / Q000528:radiation effects*; D005260:Female; D005374:Filtration / Q000295:instrumentation; D006801:Humans; D008327:Mammography; D009010:Monte Carlo Method; D011829:Radiation Dosage; D014965:X-Rays