Abstract ID: 225 Development of adjustable model breast using mammographic information for Monte Carlo simulation in nuclear medicine — Impact on dosimetry

For accurate estimation of the breast dose in nuclear medicine examinations, the development of an adjustable sizes model breast for Monte Carlo simulation is important. The development of the model breast for nuclear medicine studies is difficult because the size of the breast must be known. The purpose of this study is to develop the adjustable sizes model breast using mammographic information for Monte Carlo simulation in nuclear medicine and to investigate its impact on dosimetry using the SimDOSE simulation code [1] . This study constructed two sizes of ORNL phantoms with two radionuclides: 18 F and 99m Tc. The dimension of a breast phantom, a semi-oblate spheroid model, was established from the collected breast parameters of a cohort of patients in mammography [2] to provide a model breast allowing for changing sizes. Breast phantoms with various breast sizes, shapes, compositions, and the glandular distribution were created. The preliminary results showed the ratios of S-values of the breast ranged from 0.94 to 1.01 and the difference caused by breast shapes was insignificant. The organ dose of left and right breast may be considered separately due to in the dose difference between left and right breast. For different glandular distributions, the differences in S-values of the gland self-absorbed dose is about 5–8%. We conclude that the breast size has significant impacts and the glandular distribution has moderate impacts on the S-values of the breast, while the breast shape and compositions cause minor changes in the S-value. Therefore, this study provided the new method to assess the breast dose in Nuclear Medicine.