Studies on Lattice radiotherapy (LRT) for breast cancer have been largely lacking. This study investigates the dosimetric feasibility of using Gamma Pod, a stereotactic radiotherapy apparatus originally designed for breast SBRT, to deliver LRT to large, bulky breast tumor as a noninvasive treatment option. The GammaPod-based LRT was simulated using Geant4 Gate Monte Carlo software. The simulated GammaPod was equipped with 5mm diameter non-coplanar circular beams that span 28° latitudinally from 18° to 43° off the horizontal plane. Two degrees longitudinal intervals were used to simulate rotating sources. To simulate the treatments to different breast sizes, three water-equivalent hemisphere volumes with diameters of 10, 15, and 20cm were analyzed. The lattice was planned by spacing focal points 2cm apart in the transverse and sagittal planes and 2.5cm in the coronal plane. This resulted in 22-172 shots for full breast treatment. The maximum dose for each individual shot was 20Gy. The peak-to-valley dose differences and skin dose were analyzed. To verify the feasibility of delivering LRT, a test plan was created and delivered to a commercial diode array dose verification device using a clinical GammaPod system with 15mm collimators. The dose profiles showed the average peak-to-valley dose percent differences of 94.10% in the 10cm hemispherical volume, 88.95% in the 15cm hemispherical volume, and 83.60% in the 20cm hemispherical volume. Average skin dose was 1.27, 1.72, and 2.13Gy for the 10, 15, and 20cm irradiation volumes, respectively. The LRT plan delivered using a clinical GammaPod system with larger collimators verified the feasibility of LRT plan delivery. GammaPod-based lattice radiotherapy is a viable treatment option and its application can be extended to treating large bulky breast tumors.