Evaluation of The Mean Glandular Doses by Estimation and Measurement with Ionization Chamber in Mammogrpahy Examinations in Southwest Nigeria

Abstract

Mammography is the primary imaging modality utilizes low energy characteristics radiation for detection of abnormal growth in breasts; and its effectiveness in breast cancer diagnosis has been widely reported. Most manufacturers of mammography machine do rely on the dance formular for calculating the Mean Glandular Dose (MGD) values on the Digital Information for Communication (DICOM) header of mammography machines. The aim of this study was to check the reliability of the MGD values estimated using the Dance formula using an ionization chamber. Five mammography machines from five tertiaries medical centres within Southwest Nigeria were considered for this research work. Direct measurement was carried out using the Ionization Chamber of the RadCal Accu-gold detector. The entrance surface dose was measured and thereafter converted to MGD using the recommendation of the American College of Radiology. The Ionization chamber recorded higher values for MGD per patients, ranging from 2.49±1.32 mGy to 6.99±3.88 mGy for CC and MLO views respectively. The MGD values per patient estimated by the detector ranged from 1.98±0.84 mGy to 5.94±2.78 mGy for CC and MLO views respectively. The MGD values measured by the Accu-Gold Ionization chamber were relatively higher when compare to the estimated MGD values from the DICOM header of the mammography machines. This may be due to the fact that some exposure factors like the compression contributed to the low dose recorded by the mammogram machine in the DICOM header. The study established the reliability of the MGD values estimated using the Dance formula