Abstarct: Today, a significant percentage of cancer deaths among women worldwide are caused by breast cancer, but studies show that if this cancer is detected in the early stages, the chances of its treatment increase greatly. One of the best ways to diagnose breast cancer is mammography with X-rays. Exposure to ionizing radiation can cause biological risks to body tissues. The aim of the current research is to determine the absorbed dose in sensitive body organs during mammography. n the present study, the desired phantom and mammography system are simulated using Gate simulation code, which is a suitable tool for simulating DM mammography. The work steps in this thesis include three main steps. In the first step, an X-ray tube was created to create suitable energy spectra for mammography and the resulting spectra were compared with the IPEM report No. 78. After that, a quality control phantom was designed to check image quality baxsed on standard criteria.And finally, a phantom was simulated according to the dimensions of the reference phantom ORNL adult phantom and the required organs, as well as the geometry of a digital mammography device including a breast support baxse, a compressor pedal and a detector, to calculate the dose in the organs. And this was done in two main mammography views (CC and MLO). The distribution of the dose in the patient's body was very wide and all the examined organs receive the dose, however small. After the examined breast and the tumor, the highest dose is received by the contralateral breast at an average of 2735/5 μGy and in the lungs at 48/9 μGy and the amount The average dose of the uterus is 0/022 μGy .In the examination of the image quality, it was found that the amount of resolution in all target and filter combinations and different energies shows a constant value of 15 LP⁄mm. The amount of contrast to noise in the range of our study (50 ٪ of the gland) with a very small percentage difference in the energy of 25 KeV and in W-Rh composition. Also, the result of examining the dose in the target and filter combinations and different energies shows that the lowest amount of dose in Mo-Mo combination and in 25 KeV energy and the highest amount in the combination W-Rh and obtained at 30 KeV energy. In the tumor, the lowest amount of dose was obtained in W-Rh combination and at 25 KeV energy and the highest amount was obtained in Mo-Mo combination and at 30 KeV energy. According to all the obtained results, in our study, 25 KeV energy is introduced as the optimal energy, but in order to choose the appropriate filter and target combination,Establish a balance between dose and image quality.