Clinical Decision Support Systems (CDSS) assist clinicians in making clinical decisions by using experts' knowledge stored in the knowledge base. However, sharing and reusing the knowledge is a challenging task. Many systems are developed to facilitate sharing of medical knowledge and allow its reusability. These systems are compliant to standard approaches such as HL7 Arden Syntax and HL7 CDA (Clinical Document Architecture) to incorporate medical logic in standard format. The main drawback with these systems is the complicated procedure in the development of clinical knowledge by ordinary clinicians. The proposed research work is focusing on developing authoring tool that creates sharable clinical knowledge base using standards such as HL7 Arden Syntax, HL7 vMR and HL7 CDA. Moreover, the authoring tool provides user friendly GUI to facilitate clinicians in creating standard based executable clinical knowledge base. We are closely working with oncologists and clinicians of a prominent cancer hospital to deploy the tool for Head and Neck Cancer diagnosis and treatment recommendations.