Effect of automatic kV selection on dose and contrast for a mammographic X-ray system.
The effect of automatic tube potential (kV) selection on breast dose and contrast has been assessed using a Philips MammoDiagnost 3000 mammography X-ray set. The performance of the X-ray set using automatic kV selection has been compared with that found using a fixed kV of 28. The AUTOKV mode selected 25 kV for breasts with thickness up to about 50 mm, which increased the contrast by 5-10%, and increased the mean glandular dose (MGD) per film by, on average, 30-40%. For large breasts with a compressed thickness of 70 mm and above, kVs up to 30 were selected so that the average MGD per film was reduced by 19% from 3.62 to 2.94 mGy, with an estimated loss in contrast of about 4-8%. For all breasts the mean MGD per film was 1.85 +/- 0.05 mGy where AUTOKV was used, and 1.74 +/- 0.08 mGy per film when 28 kV was used. The overall image quality of the mammograms was found to be higher when AUTOKV was used. Overall, the AUTOKV facility on this X-ray set generally worked well and resulted in slightly higher contrast and slightly better image quality at the price of a small increase in the average dose for this patient group when compared with the usual UK procedure of using a fixed 28 kV.
Young
K C
KC
Department of Medical Physics, Royal Surrey County Hospital, Guildford, UK.
Ramsdale
M L
ML
Rust
A
A
Cooke
J
J
D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000517:prevention & control; D004560:Electricity; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods*; D008403:Mass Screening / Q000379:methods; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D013679:Technology, Radiologic