Mean Glandular Dose (Mammography)

Dance/Skinner formalism: convert incident air kerma to MGD per breast view

Exposure parameters

Incident air kerma K (mGy)

Air kerma at the upper surface of the breast (without backscatter).

Compressed breast thickness (mm)

Glandularity (%)

Use Dance 2000 average for given thickness (auto) or override based on age/density.

Anode / filter

HVL (mm Al)

Acquisition mode

MGD per view

—

mGy

Formula

\( \text{MGD} = K \times g \times c \times s \times T \)

K — incident air kerma · g — glandularity & thickness factor (Dance 1990) · c — actual vs 50 percent glandularity correction (Dance 2000) · s — spectrum/anode-filter correction (Dance 2000) · T — tomosynthesis sweep correction (Dance 2011, T = 1.0 for 2D)

Spectrum factor s (Dance 2000)

Anode / filter	s
Mo / Mo	1.000
Mo / Rh	1.017
Rh / Rh	1.061
W / Rh	1.042
W / Ag	1.042
W / Al	1.050

Reference / acceptance limits

Compressed thickness	Acceptable MGD	Achievable
20 mm	< 0.6 mGy	< 0.4 mGy
40 mm	< 1.5 mGy	< 1.0 mGy
50 mm	< 2.0 mGy	< 1.6 mGy
60 mm	< 3.0 mGy	< 2.4 mGy
70 mm	< 4.5 mGy	< 3.6 mGy
80 mm	< 6.5 mGy	< 5.1 mGy

European Guidelines for Quality Assurance in Breast Cancer Screening, 4th ed. (2006), Chapter 2b.

Sources

Dance DR. Monte Carlo calculation of conversion factors for the estimation of mean glandular breast dose. Phys Med Biol 1990;35:1211-1219. doi:10.1088/0031-9155/35/9/002
Dance DR et al. Additional factors for the estimation of mean glandular breast dose using the UK mammography dosimetry protocol. Phys Med Biol 2000;45:3225-3240. doi:10.1088/0031-9155/45/11/308
Dance DR et al. Estimation of mean glandular dose for breast tomosynthesis: factors for use with the UK, European and IAEA dosimetry protocols. Phys Med Biol 2011;56:453-471. doi:10.1088/0031-9155/56/2/011
EUREF European Guidelines for Quality Assurance in Breast Cancer Screening, 4th ed. (2006).