Abstract: Objective To propose a new computer software-based medical image processing technique with high resolution digital scanner for radiotherapy verification. Methods Under the platform of Windows 2000, the software, programmed with Visual C++.NET, was developed according to modular design. All data of the films and the treatment planning system could be processed as images or dose curves for a robust result. Results Many functions such as data acquisition, automatic analysis and computation and image processing were integrated in the system. Both geometric and dosimetric errors could be calculated at the same time to verify the radiotherapy accuracy. Conclusion This system has good accuracy and stability for cost-effective radiotherapy verification.