Document Type: Conference Proceedings
Department of Medical Radiation Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Introduction: the objectives of this research were determination of Mean Glandular Dose in film- screen and digital mammography examinations, estimation of accumulated effective dose in some of mammography centers in Tehran city and estimating cancer risk due to these examinations.
Materials and Methods: the clinical data were collected from the 1318 mammograms taken from 333 women who were referred to 4 mammography centers in Tehran. The mammography instruments in this study were one film-screen system, one DDR system and two CR system. An RTI dosimeter, piranha system version 3.1, was used for measurement of ESAK and HVL. Compressed breast thickness determined by the mammography systems which was calibrated by a millimeteric ruler. Dgn conversion factor was determined from a program written in C by Bouzarjomehri and et al. Height and weight patients were also measured.
Results: The mean ±SD results of MGD per film and per woman were respectively 2.04±0.75 mGy and 8.12 ± 2.75 mGy. The mean effective dose ± SD of patient was 0.4±0.13 m Sv. the number of patients referring to these four mammography centers estimated 8352 per year, so accumulated dose was 3.34 ±1.08 man. Sv
With considering of 8% per Sv cancer risk, according to BEIR VII report, the carcinogenic risk of the mammography examinations in these centers will be 0.26 women per year.
The MGD results showed a relatively linear correlation with CBT, but age, weight, BMI of the patients haven’t a correlation with MGD, r2<0.3.
Conclusion: The average MGD per mammogram of this study was higher than other references, which may be due to the higher average breast thickness of these women relative of the other references but the mean MGD of this study was lower than the RLs values reported by ICRP (3 mGy). The average MGD resulted in this study for the analogue mammography device was lower than the computed radiography (CR) and the direct digital radiography (DDR) devices of.