The troubles arising in the introduction of the medical information system are mostly related to the requirement definition. The present study proposed the requirements definition method on radiation therapy information system (RTIS) by using business modeling. The interview was conducted with six medical professionals regarding the entire business in the radiotherapy department. These businesses were modeled using Diamond Mandala Matrix (DMM) and data flow diagram (DFD) methods. Subsequently, functional requirements on RTIS were defined based on these modeling. As a result, 21 DMMs and 129 DFDs were created and 120 functional requirements were defined. By defining the functional requirements of the users, mutual understanding with vendors will deepen, and avoid an expected trouble in introducing RTIS. DMM was effective as an initial modeling such as the interviews and the organization of businesses. DFD was also effective for the business improvement and the definition of system functional requirements.
Keywords: Diamond Mandala Matrix; business modeling; data flow diagram; radiation therapy information system; requirements definition.