As discussed in both CodeX RT and IHE-RO XRTS working groups, CodeX RT should model single treatment sessions to describe the progress of treatment and enable applications to show timelines of treatment dates. With CodeX RT 1.0.0, a cumulative progress is already available by creating a new updated plan summary after each session, However, to properly model what was newly delivered from each session (and treated fractions of plan in this session), separate Procedures for the delivery of all fractions should be added and grouped into treatment sessions (Encounter resource).