The sophistication and complexity of absorbed dose and treatment planning systems has increased significantly, particularly including three-dimensional (3D) treatment planning systems, and the use of conformal treatment planning and delivery techniques. This book led to the need for a comprehensive set of authentication in external radiotherapy, Brachytherapy and Proton therapy. The purpose of this thesis is to developing and implementing a comprehensive authentication but viable methods for modern radiotherapy treatment planning. The scope of the authentication needs for treatment planning is quite broad, encompassing image-based definition of patient anatomy, 3D beam descriptions for complex beams including multileaf collimator apertures, 3D dose calculation algorithms, and complex plan evaluation tools including dose volume histograms.