Mean glandular dose (MGD) is a quantity used to describe the absorbed dose of radiation to the

breast The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues. In females, it serves as the mammary gland, which produces and sec ...

mammography Mammography (also called mastography) is the process of using low-energy X-rays (usually around 30 kVp) to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer, typically through ...

. It is based on a measurement of air kerma and conversion factors. MGD can be calculated from measurements made with

PMMA PMMA may refer to: * para-Methoxymethamphetamine, a stimulant drug * Philippine Merchant Marine Academy * Poly(methyl methacrylate), a transparent thermoplastic often used as a glass substitute {{disambig ...

blocks. It is often used to compare typical doses to patients between different centres or internationally, and is the preferred measure of the potential risk from mammography.

Calculation

MGD can be calculated from a measured incident air kerma at the top of the breast,

K

, as follows:

D=Kgcs

g

converts from incident air kerma to MGD, with a glandularity of 50%, based on breast thickness and HVL.

c

corrects for glandularity other than 50%, depending on the breast thickness and HVL, with two versions for ages 50–64 and 40–49.

s

corrects for the x-ray spectra in use with a table of target/

filter Filter, filtering or filters may refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Filter (software), a computer program to process a data stream * Filter (video), a software component tha ...

combinations.

Applications

MGD is typically used to define limits on mammography exposures by national and international organisations such as the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...

and

International Atomic Energy Agency The International Atomic Energy Agency (IAEA) is an intergovernmental organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for any military purpose, including nuclear weapons. It was established in 195 ...

, at <2.5 milligray (mGy) per exposure to a standard breast (4.5 cm PMMA). In routine quality assurance testing of mammographic equipment, MGD measurements for a range of effective breast thicknesses with PMMA, and from real patient exposures, is widely recommended.

References

{{Radiation protection, state=uncollapsed Radiology Medical physics Radiation protection