Diffuse Optical Tomography (DOT) imaging technique has low spatial image resolution and low image quality. DOT studies have shown that image quality is more affected by the forward model problem equation numbers. Forward model problem is built with the source and detector couplings, frequency, and phase shift data in frequency domain DOT (FDDOT). To improve the image quality, source-detector match numbers or frequency-phase data are increased. In this study, increased number of frequency-shift data were added to the forward model. Since increasing the number of source-detector numbers and frequency-shift data will raise the computational cost, the optimum number of frequency-shift data was set in this work. 8 sources and 8 detectors were placed based on the back-reflection imaging geometry. Diffuse optic tomography technique has basically 3 different running principal mode which are continuous wave (CW), time resolved (TR), and frequency domain (FD). Geometrically DOT imaging modality has also three basic source-detector placement approaches. These are back-reflected, transmission-through and ring imaging modes. Ring geometric placement is the most appropriate for breast imaging. Back-reflected mode is also suitable for breast imaging, beside it is also convenient for other tissue and organ imaging. In this work, back-reflected geometric source-detector placement was used. 8 sources and 8 detectors were placed based on the back-reflected geometric shape and it generated 64 total number of source-detector couplings. Since frequency domain forward model was built, additional frequency-shift data was also added to the forward model problem. 100 MHz modulation frequency was used for light source. Tissue absorption coefficient ma is 0.2 cm− 1 and tissue scattering coefficient µs is 80 cm− 1. x, y, z cartesian grid coordinate system has 1 micrometer length in each direction for simulation tissue media. In this work, the effect of frequency-shift was observed to improve the reconstructed image quality. Image quality was assessed based on the adding number of frequency-shift data. The total number of 20 and 500 frequency-shifts were tested against each other case. 2 inclusions were embedded inside the imaging tissue simulation geometry. The case 1 which has 20 frequency-shifts and the case 2 which has 500 frequency-shifts were compared with each other. It was observed that case 2 is superior to the case 1. This is the first study to show the effect of increasing frequency-shift data to the forward model problem in DOT imaging modality.