Mammographic oblique views 45° versus 60° : breast thickness, breast exposure and image quality

Abstract

Background. Standard screening mammography includes two views: craniocaudal and mediolateral oblique. In the mediolateral oblique projection a central beam angle can varies between 30° and 60°.

Patients and methods. We compare the thickness of the compressed breast, time-current product, exposures and image quality in two different mammographic oblique views: 45°versus 60°. Our study population consisted of 33 women in whom additional 60°-films after standard 45°-films were obtained for the objective diagnostic reasons.

Results. The mean thickness of the compressed breast was significantly lower with an angle of 60° than with an angle of 45° (47.8 vs. 50.7 mm, p<0.01); the mean time-current product and the mean breast exposure were significantly lower with an angle of 60° than with an angle of 45° (42.6 vs. 46.7 mAs, p<0.01; 0.67 vs. 0.78 mGy, p<0.01). The difference in the image quality has not reached statistical significance (but it exists!).

Conclusions. By introducing 60°-films instead of commonly used 45°-films, mammograms of at least the same quality can be obtained with lower radiation dose, which is of great importance when we remind the great radiosensitivity of glandular breast tissue.