A spherical rotational radiation therapy apparatus (SRRTA) with single spherical rotation center (SRC) is proposed. Referencing a combined X-Y-Z Cartesian and (r-α-β-γ) polar coordinates. The SRRTA includes a multi-axial gantry with rotatable proximal face around gantry bore; the proximal gantry face has at least one rotatable, along α-coordinate, pair of therapeutic level radiation-generating accelerator and image detector defining a therapeutic level radiation axis between the two; at least two arc-shaped sub-rails on the proximal gantry face; at least two rotationally slidable, against the arc-shaped sub-rails thus along α-coordinate, pairs of imaging level radiation-generating accelerators and image detectors defining an imaging level radiation axis between the two; the therapeutic level radiation axes and all imaging level radiation axes are configured to intersect at a single SRC along the longitudinal bore axis; an X-axis gantry pivoting driving mechanism is provided for driving the distal end of the multi-axial gantry.