Abstract:
Quality control tests have been undertaken on thirteen mammography systems with the aim of optimizing procedures and patient radiation protection, establishing diagnostic reference levels (DRLs) and establishing quality control (QC) baseline data for the diagnostic mammography practice in Ghana. Quantitative image quality analysis was performed with “ImageJ” software using the “Rose Model” while all other tests were performed using internationally accepted protocols. Results from tube voltage accuracy and repeatability, output linearity and repeatability and half value layer measurements indicated satisfactory performance of all the systems. Results from the mammography units’ assembly evaluation, compression plate assessment and short term automatic exposure control (AEC) test showed in some systems malfunctioning of compression paddles, misalignment of the compression plate and faulty AEC systems. Estimated parameters of signal-to-noise ratio (SNR) indicate that all images were not of standard quality. Results from mean glandular dose (MGD) measurements show that doses being received are within the acceptable levels with the exception of two systems whose MGD estimates exceeded the limit by 17.07% and 3.92% for the 60 mm and 75 mm equivalent breast thicknesses (EBT) respectively. Another system also exceeded the limit by 9.52% for the 75 mm EBT. DRLs based on phantom measurements have been established. Data from measurements undertaken was used to develop a model using MINITAB application software that predicts the exposure parameters, mean glandular dose and image quality before exposure is taken. Results from modelled equations proved to aid the mammography process.
