Radiation physics has been an important subject for researchers as it is used especially in medical fields for different purposes and also due to its hazardous effects. This study is aimed to investigate the mass attenuation coefficient of some organs and the radiation absorption effects of adipose tissue on computed tomography scan in different radiological energies using MCNPX (version 2.6.0) general purpose Monte Carlo code. This simulation was done by selecting organs from the cranium, thorax and abdominal anatomical regions. Additionally, the mass attenuation coefficient of adipose tissue was calculated to determine the relationship between radiation reduction rates of anatomical regions and adipose tissue thickness. On the other hand, the radiation attenuation quantities of the selected computed tomography regions were calculated, showing the effect of adipose tissue on these measurements. The MCNPX simulations were compared with the results obtained by XCOM data to ensure validation of this simulation geometry and a good agreement was observed.