Early detection system is extensively investigated to diagnose the condition of human body earlier. Currently, our research is focusing on the development of a non-invasive tomographic imaging system by utilizing a microwave imaging system to early detect tumor or cancer. It shows some advantages in comparison to the other tomography technologies, such as low health risk (non-ionization), low cost in implementation and operation, and ease of use. In the previous works, we have been developing a microwave imaging system. To evaluate the imaging system, simple numerical and physical phantoms are used to represent normal and abnormal tissue structure. Two dipole antennas are used for transmitting and receiving microwaves signals at 3 GHz. The data acquisition system uses translational and rotational method. From the scattering S21 parameters, are then used as the acquired data to generate a reconstructed image. In this paper, we investigate the effect of antenna position when the transmitting antenna is fixed at certain position to acquire the data prior to image reconstruction process by using simultaneous algebraic reconstruction technique (SART) algorithm. The results show that there is no significant degradation on the reconstructed images when the imaging system is applied in different acquisition system configuration.