Estimation of dose distributions in mammography into a tissue equivalent phantom

Abstract

Mammography is considered the most suitable technique for the identification, tracking and staging of breast diseases, especially cancer. However, the use of ionizing radiation carries a risk of inducing cancer in this kind of breast imaging procedure. In this way, it is important to know the dose distribution in typical mammography techniques. The aim of this work was to estimate the dose distributions in different positions parallel to the image plan and different depths of a tissue equivalent phantom using LiF thermoluminescent dosimeters (TLD). LiF TLDs pellets were positioned on the xy plan on a phantom BR12 at different depths. The set was irradiated in a GE Senographe DS System for a maximum field size. The dosimeters were irradiated using a Mo/Mo anode/ filter combination, 100 mAs, and different X-ray tube voltages (25, 28, 30 and 32 kVp). It was also used a fixed X-ray tube voltage (28 kVp), 100 mAs, and different anode/filter combinations (Mo/Mo, Mo/Rh and Rh/Rh). Dose variation in the y direction was more significant than in the x direction. It were observed variations up to 8% and 28.2% in x and y directions respectively. For the tube voltage 28 kVp, the maximum dose in the phantom surface in the y-axis was 16(1) mGy for Mo/Mo, and 15.0 (9) mGy for Mo/Rh and 12.8(6) for Rh/Rh.