PURPOSE: This study introduced a novel 3D dosimetry system for radiotherapy in order to address the limitations of traditional quality assurance methods in precision radiotherapy techniques. METHODS: The research required the use of scintillation material, optical measurements, and a dose reconstruction algorithm. The scintillation material, which mimics human soft tissue characteristics, served as a both physical phantom and a radiation detector. The dose distribution inside the scintillator can be converted to light distributions, which were measured by optical cameras from different angles and manifested as pixel values. The proposed dose reconstruction algorithm, LASSO-TV, effectively reconstructed the dose distribution from pixel values, overcoming challenges such as limited projection directions and large-scale matrices. RESULTS: Various clinical plans were tested and validated, including a modified segment from the SBRT plan and IMRT clinical plan. The dosimetry system can execute full 3D dose determinations as a function of time with a spatial resolution of 1-2 mm, enabling high-resolution measurements for dynamic dose distribution. Comparative analysis with mainstream device MapCHECK2 confirmed the accuracy of the system, with a relative measurement error of within 5%. CONCLUSIONS: Testing and validation results demonstrated the dosimetry system's promising potential for dynamic treatment quality assurance.