The X-radiation from relativistic channeled electrons at the Bragg angles – Parametric X-Radiation at Channeling (PXRC) – is studied both experimentally and theoretically. The experiment was carried out using a 255MeV electron beam from a Linac at newly constructed beam line for the study of interactions between a relativistic electron beam and crystals at the SAGA Light Source. The observed asymmetry of PXRC angular distribution at (220) planar channeling in a 20μm Si is explained taking account of two quantum effects: initial populations and transverse form-factors of the quantum states of planar channeled electrons. Further perspectives for PXRC studies at SAGA-LS are analyzed.