Microdosimetric analysis of radiation from a clinical mammography machine using realistic breast phantoms and a miniature proportional counter.
Phys Med Biol
; 41(11): 2295-306, 1996 Nov.
Article
em En
| MEDLINE
| ID: mdl-8938027
ABSTRACT
We have measured the microdosimetric spectra of a Senographe 600T mammography machine employing an Mo target with 0.8 mm Be inherent filtration and 0.03 mm Mo added filtration, giving a half-value layer of 0.35 mm A1 at 28 kVp. In all of our measurements a large collimator producing a 24 cm x 30 cm field at 65 cm was used. Two different phantom compositions differing in the ratio of adipose to fibroglandular tissue were compared, using simulated breast material from Nuclear Associates. Spectra were taken at various depths and locations in simulated breasts of 3.4 and 5 cm thickness. The detector used was a miniature proportional counter having outer dimensions of 5 cm x 1.8 cm diameter, with a sensitive volume 0.5 mm x 0.5 mm. The small dimensions of the counter and the cavity allowed total embedding in the breast material with minimal disturbance of the photon and secondary electron spectrum. Our results show that there can be changes in the radiation quality amounting to as much as 17% (as measured by the dose mean lineal energy. yD) between breasts of different thickness, at the same relative position within the breast. There is little difference due to breast composition.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Mamografia
/
Imagens de Fantasmas
Tipo de estudo:
Prognostic_studies
Limite:
Female
/
Humans
Idioma:
En
Revista:
Phys Med Biol
Ano de publicação:
1996
Tipo de documento:
Article