Mammograms obtained with rhodium vs molybdenum anodes: contrast and dose differences.
OBJECTIVE
A mammography unit with both a molybdenum anode and a rhodium anode, filtered with molybdenum and rhodium, respectively, was evaluated to determine which types of women would benefit from the dose savings of the rhodium combination despite some loss of contrast.


METHODS
In 100 women, the molybdenum anode and molybdenum filtration (Mo/Mo) were used to obtain mammograms of the right breast, and the rhodium anode and rhodium filtration (Rh/Rh) were used for mammograms of the left breast. All mammograms were obtained at 26 kVp. All milliampere-second values used to radiograph the breasts of these women were recorded. Mammograms of 54 women (30 with previous mammograms available), representing the four types of breasts as defined by the American College of Radiology, were interpreted by three radiologists. Each mammogram was assigned a grade for breast type, preference (Rh/Rh, Mo/Mo, or previous mammograms), contrast, and sharpness.


RESULTS
Overall, mammograms obtained by using the Mo/Mo combination were preferred. However, for images of types 3 and 4 breasts, Rh/Rh was preferred twice as often as it had been for mammograms of types 1 and 2 breasts. The mean glandular dose for all breast types when the Rh/Rh combination was used was 42% of the dose used for the Mo/Mo combination. For a 6-cm-thick dense breast, the Rh/Rh combination required 40% of the dose required for the Mo/Mo combination.


CONCLUSIONS
Mammograms obtained with the Rh/Rh combination carried an overall decrease in contrast and mean glandular dose. However, for young women and some women with large dense breasts, the Rh/Rh mammograms were equivalent to or better than the mammograms obtained with the Mo/Mo combination. Effective use of Rh/Rh units requires careful selection of women based on age or the amount of glandular tissue seen on previous mammograms.
Kimme-Smith
C
C
Iris Cantor Center for Breast Imaging, University of California, School of Medicine, Los Angeles 90024.
Wang
J
J
DeBruhl
N
N
Basic
M
M
Bassett
L W
LW
D001940:Breast / Q000528:radiation effects; D004566:Electrodes; D005260:Female; D006801:Humans; D008327:Mammography / Q000295:instrumentation* / Q000379:methods; D008982:Molybdenum; D011829:Radiation Dosage; D011835:Radiation Protection; D012238:Rhodium; D014963:X-Ray Intensifying Screens
D008982:Molybdenum; D012238:Rhodium