Abstract: A medical treatment planning system which enables multiple collaborators in different locations to interactively view and manipulate data for use in, for example, preparing a treatment plan while also interacting with each other. Interactive medical treatment planning involving multiple participants using multiple treatment planning stations includes establishing one of the treatment planning stations as a session controller and launching treatment planning software thereon; establishing a communication connection between the session controller planning station and all of the treatment planning stations participating in a planning session; and displaying, on all participating treatment planning stations, treatment plan information being displayed on the session controller treatment planning station.