Method for determination of the mean fraction of glandular tissue in individual female breasts using mammography

Abstract

The nationwide breast cancer screening programme using mammography has been in full operation in the Netherlands since 1997. Quality control of the screening programme has been assigned to the National Expert and Training Centre for Breast Cancer Screening. Limits are set to the mean glandular dose and the centre monitors these for all facilities engaged in the screening programme. This procedure is restricted to the determination of the entrance dose on a 5 cm thick polymethylmethacrylate (PMMA) phantom. The mean glandular dose for a compressed breast is estimated from these data. Individual breasts may deviate largely from this 5 cm PMMA breast model. Not only may the compressed breast size vary from 2 to 10 cm, but breast composition varies also. The mean glandular dose is dependent on the fraction of glandular tissue (glandularity) of the breast. To estimate the risk related to individual mammograms requires the development of a method for determination of the glandularity of individual breasts. A method has been developed to derive the glandularity using the attenuation of mammography x-rays in the breast. The method was applied to a series of mammograms at a screening unit. The results, i.e., a glandularity of 93% within the range of 0 to 1, were comparable with data in the literature. The glandularity as a function of compressed breast thickness is similar to results from other investigators using differing methods.

Glandularity and mean glandular dose determined for individual women at four regional breast cancer screening units in The Netherlands

“…A method was used to derive glandularity of the individual compressed breasts using mammography by comparing measured attenuation in the actual compressed female breast during mammography and calculated attenuation in a breast model as a function of compressed breast thickness, glandularity and radiation quality (Jansen et al 2005).…”

“…The outer part of the compressed breast model is modelled using a 5 mm thick layer of adipose tissue. The overall breast thickness is varied and values of 11-110 mm have been used (Jansen et al 2005).…”

“…The methods for interpolation are presented by Jansen et al (2005). The average compositions of adipose and glandular tissues are used in the Monte Carlo calculations and it should be noted that individual tissue compositions can deviate.…”

Glandularity Estimation in Japanese Women by Using a Breast Model Made from Mammographic Findings of European Women

“…Additionally, SHI et al 21) reported breast skin thickness ranging from 0.87 to 2.34 mm (mean, 1.44 mm), which was lower compared to that of the breast model derived from the data of European women. In these previous studies, 4,20,21) the mammographic measurements of small, thin breasts were more affected than those of thicker breasts by the differences between the adipose layers of real breasts and the breast model. In addition, the thickness of skin of a real breast might be lower compared to that of the breast model.…”

“…DANCE et al 4) reported that, in younger women, the assumption of the presence of a 5-mm-thick adipose layer is unrealistic for very thin breasts (CBT < 25 mm), and it can lead to estimated glandularities > 100%. JANSEN et al 20) compared breast models composed of different layers, including a model with a 5-mm adipose layer, as proposed by DANCE et al, 4) as well as a two-component model with 3-mm-thick adipose tissue covered by 2-mm-thick skin tissue, at different values of CBT and reported that models with greater breast thicknesses exhibited relatively less attenuation because of increased beam hardening. Additionally, SHI et al 21) reported breast skin thickness ranging from 0.87 to 2.34 mm (mean, 1.44 mm), which was lower compared to that of the breast model derived from the data of European women.…”