Mean glandular doses for women undergoing mammographic breast screening in Oyo state, Nigeria

Abstract 

In this work, thermoluminescent dosimeters have been used to measure entrance surface doses (ESDs) of patients undergoing mammographic screening at the University College Hospital, Ibadan, Oyo state. The mean glandular doses (MGDs) were also calculated using the measured ESDs. The results showed that the ESDs ranged from 0.26mGy to 21.26mGy for the mediolateral oblique (MLO) views and 0.08mGy to 5.36mGy for the craniocaudal (CC) views. The calculated MGD ranged from 0.07mGy to 3.57mGy for the MLO views and 0.02mGy to 0.98mGy for the CC views. The possible reasons for the large variations in the individual ESD values and MGD values for both views are discussed using patients' data, equipment specific data and the technical parameters used for the examinations. Comparison showed that the mean ESD values and MGD values reported in this work are below published values. The mean of the calculated MGD values is also found to be lower than the recommended guidance level of 3.0mGy when using grid. 92.5% of the patients had MGD values that are less than 2.5mGy, hence a national reference MGD value of 2.5mGy is proposed for Nigeria. Implementation of a dose reduction program in mammographic screening is also suggested because of the observed large variations in patients MGD values.

PACS:: 87.59.eg, 87.57.uq

Keywords:: Thermoluminescent dosimeter, Entrance surface dose, Mediolateral oblique, Craniocaudal