Normalized average glandular dose in magnification mammography.
OBJECTIVE
To evaluate the normalized average glandular dose (the average glandular dose per unit entrance skin exposure) in magnification mammography.


METHODS
Photon transport in the breast was simulated by using Monte Carlo methods. A semielliptical cylinder containing glandular and adipose tissue was used to simulate the breast. Measured mammography spectra for a molybdenum target-molybdenum filter unit were utilized. The normalized average glandular dose was calculated as a function of half-value layer, tube voltage, breast thickness, and breast composition for typical magnification geometries.


RESULTS
The normalized average glandular dose in magnification mammography is 7%-25% lower than that with the contact (nonmagnification) technique because of the effects of partial irradiation, smaller field size, and greater percentage depth dose gradient at the reduced source-to-skin distance.


CONCLUSIONS
The normalized average glandular dose in magnification mammography is lower than that in contact mammography. The average glandular dose in magnification mammography, however, is still substantially greater due to the two to three times greater entrance skin exposure.
Liu
B
B
Department of Radiology, University of Michigan, Ann Arbor 48105, USA.
Goodsitt
M
M
Chan
H P
HP
D005260:Female; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data; D008954:Models, Biological; D009010:Monte Carlo Method; D011829:Radiation Dosage