The invention relates to a CT imaging apparatus and a method for generating sectional images of an object such as a patient on a patient table. According to one embodiment, first projections (P) are generated along a first helical scanning path (Tr1) of a first X-ray source according to a sparse angular sampling scheme. Additional projections (Q1, Q2, R1) may dynamically be introduced along said first helical scanning path (Tr1) and/or along a second helical scanning path (Tr2) of an additional X-ray source based on the evaluation of previous projections (P1).