Air gap technique (mammography)
The air gap technique is utilised for the magnification mammography view.
Magnification mammography is a high dose imaging technique which is generally utilised as a follow-up to a standard mammogram image series when a focal area needs to be more clearly examined 1. The air gap technique is utilised in magnification mammography to aid in the visualisation of microcalcifications that may not be clearly distinguished otherwise.
The addition of an air gap between the imaged breast tissue and the image receptor effectively reduces the focal area imaged, and therefore increases the magnification and spatial resolution. The magnification and spatial resolution increase allows small lesions and microcalcifications to be well visualised 2.
Anti-scatter grids are generally not used due to the air gap being utilised as both a magnification and scatter reduction tool. The presence of the grid would increase the radiation dose even further.
- 1. Hariqbal Singh, Amol Sasane, Roshan Lodha. Textbook of Radiology Physics. ISBN: 9385891308
- 2. Whitman, G. J. and Haygood, T. M., Eds.: Digital Mammography: A Practical Approach, Cambridge University Press, Cambridge., 2012.