Comparison of a personalized breast dosimetry method with standard dosimetry protocols

Abstract

Average glandular dose (AGD) in digital mammography crucially depends on the estimation of breast glandularity. In this study we compared three different methods of estimating glandularities according to Wu, Dance and Volpara with respect to resulting AGDs. Exposure data from 3050 patient images, acquired with a GE Senographe Essential constituted the study population of this work. We compared AGD (1) according to Dance et al . applying custom g, c, and s factors using HVL, breast thickness, patient age and incident air kerma (IAK) from the DICOM headers; (2) according to Wu et al . as determined by the GE system; and (3) AGD derived with the Dance model with personalized c factors using glandularity determined with the Volpara (Volpara Solutions, Wellington, New Zealand) software (Volpare AGD). The ratios of the resulting AGDs were analysed versus parameters influencing dose. The highest deviation between the resulting AGDs was found in the ratio of GE AGD to Volpara AGD for breast thicknesses between 20 and 40 mm (ratio: 0.80). For thicker breasts this ratio is close to one (1 ± 0.02 for breast thicknesses >60 mm). The Dance to Volpara ratio was between 0.86 (breast thickness 20–40 mm) and 0.99 (>80 mm), and Dance/GE AGD was between 1.07 (breast thickness 20–40 mm) and 0.98 (41–60, and >80 mm). Glandularities by Volpara were generally smaller than the one calculated with the Dance method. This effect is most pronounced for small breast thickness and older ages. Taking the considerable divergences between the AGDs from different methods into account, the selection of the method should by done carefully. As the Volpara method provides an analysis of the individual breast tissue, while the Wu and the Dance methods use look up tables and custom parameter sets, the Volpara method might be more appropriate if individual ADG values are sought. For regulatory purposes and comparison with diagnostic reference values, the method to be used needs to be defined exactly and clearly be stated. However, it should be accepted that dose values calculated with standardized models, like AGD and also effective dose, are afflicted with a considerable uncertainty budgets that need to be accounted for in the interpretation of these values.

Dosimetric evaluation of the mean glandular dose for mammography in Indian (North East) women.

“…To perform these calculations, a breast model needs to be defined . [5] Based on this study a 4cm thick( thickness of 4.5 cm breast is equivalent to 4 cm PMMA phantom) ,45% glandular and 55% adipose phantom would be more representative of this population. The study has some limitation.…”

“…Mean Glandular dose in digital mammography crucially depends on the estimation of individual breast glandularity. [5] It is generally accepted that the glandular tissue of breast is the most radiosensitive tissue [6].…”

Regression Analysis between the Different Breast Dose Quantities Reported in Digital Mammography and Patient Age, Breast Thickness, and Acquisition Parameters

“…Hence, it is only logical to assume that MGD accuracy depends on the method used for calculation. Salomon et al [ 13 ] conducted a study to compare between three different methods, including Wu et al [ 14 ] Dance et al [ 10 , 11 ] and Volpara [ 15 ]. While Volpara provided a tissue composition analysis allowing for a more accurate glandularity estimation, the Wu and Dance methods both used a reference table and customized conversion factors.…”

Breast Radiation Exposure of 3D Digital Breast Tomosynthesis Compared to Full-Field Digital Mammography in a Clinical Follow-Up Setting

“…To date, three different methods are applicable for MGD estimation, each of which has its limitations: (a) the Dance method [ 18 ], (b) commercial software solutions, and (c) the Wu method [ 19 ]. (a) Estimating MGD according to the Dance method relies on the formula where IAK stands for the incident air kerma (without backscatter), g is the conversion factor for a breast with a defined glandularity of 50% by weight, c is the correction factor for breast composition, and s is the correction factor for X-ray spectra different from Mo/Mo [ 20 ].…”

“…To date, three different methods are applicable for MGD estimation, each of which has its limitations: (a) the Dance method [18], (b) commercial software solutions, and (c) the Wu method [19].…”