Parametrization of mammography normalized average glandular dose tables

Abstract

Data from existing tables of normalized glandular doses in mammography were parametrized to determine analytical expressions that match tabulated results within known uncertainties. The parametrization was performed for three different target/filter combinations (molybdenum target-molybdenum filter, molybdenum target-rhodium filter, and rhodium target-rhodium filter) and three different breast compositions (100% adipose, 50% adipose-50% glandular, and 100% glandular). The analytical expressions provide the normalized glandular dose for any breast composition within stated ranges of tabulated input parameters (kVp, half-value layer, and breast thickness). The maximum difference between tabulated and parametrized data is 1.29%, which is smaller than the stated 2% uncertainty in tabulated dose data due to uncertainties in the x-ray spectra models used to generate the tables. Analytical expressions are easily coded to create custom functions that return the normalized glandular dose for the set of input parameters. Examples of implementation are presented in Microsoft Visual Basic for Applications (VBA).

Mean glandular dose in digital mammography: a dose calculation method comparison

“…This method was applied using the paper published by Sobol and Wu, 15 which provides parameterization equations to calculate DgN for different anode/ filter combinations and different glandularities. The parameterization equations were implemented into our excel workbook using 50% glandularity.…”

“…MGD is calculated using conversion factors established by Monte-Carlo simulations. Dance et al, [12][13][14] Sobol and Wu, 15 Wu et al, 16 and Boone et al [17][18][19] have established conversion factors that are widely used to estimate MGD. The three models differ slightly in the simulation method, but all reported conversion factors dependent on breast thickness, glandularity, x-ray spectra, and beam quality.…”

An Analysis of Application of Mean Glandular Dose and Factors on Which It Depends to Patients of Various Age Groups

“…A study conducted in Iran included 246 patients (Bouzarjomehri et al, 2006) and showed that an obtained MGD dose for a 141 complete mammographic examination in that country was 5,57 mGy, which is significantly more in regard to this study and which, most probably, is a consequence of a quality control system which was established late and differences in compressed breast thickness. The mentioned studies did not use conversion factors according to Dance (which are used in this study), but in Austra, Korea and Malaysia one used conversion factors according to Wu (Wu et al, 1991), in Sweden according to Rosenstein and in Iran according to Sobol (Sobol & Wu, 1997). Values of MGD dose for a complete mammographic examination in Bosnia and Herzegovina are 5,0 % higher in regard to results obtained from 300 patients in Malaysia (Jamal et al, 2003) and 7,8 % higher in regard to the most complete study (Young & Burch, 2000) conducted in the Great Britain which included 8745 patients.…”

Clinical and Technical Evaluation of Full-Field Digital Mammography

“…We used the parametrization of normalized average glandular dose tables by Sobol and Wu to determine technique factors that provide equal average glandular doses for different digital techniques. [4].…”