Patient Dose in Digital versus Conventional Mammography

Abstract. Breast imaging techniques have received renewed attention as a proved means for earlier detection and diagnosis of breast cancer. Due to the extremely high image quality requirements in mammography, all aspects of the imaging process must be optimised. With this purpose new imaging systems have been incorporated. The aim of this paper is to present results of patient dose comparison in different digital and conventional imaging systems. The sample size was 240 patients (2 mammogram per patient) and 8 mammography units participated in the study: 3 G.E. Senographe. DMR, 2 G.E. Senographe 600T(with film-screen system Fuji UMMA HC/Agfa Detail R, HDR/Agfa Detail R, Agfa Mamoray HT/Agfa Detail R), 1 G. E. Senographe 500 T and 1 General Merate MSM with computed radiology system (Fuji FCR 5000 MA plus and Fuji IP / DI-HL photostimulable phosphor), and 1 G.E. Senographe 2000 d with flat-panel system. Radiographic technique (kVp, mAs, focus-image receptor distance, filter /anode combination and compress breast thickness) were recorded for each projection. By using the post exposure mAs (when was possible) and the output measured in the quality control programme, the entrance surface dose (ESD) was calculated. All results obtained (except in equipment num.7,MLO projection) were lower than ESD reference values, but mean values in digital modalities were higher than in conventional ones. However other aspects that contribute to the global patient dose, as the reject rate, were significantly lower in digital systems.