Raman scattering spectra of single crystalline Y12xCaxTiO3 (x=0, 0.10, 0.30, 0.37, 0.38, and 0.41) have been systematically studied in the temperature region from 298 to 8 K. The structural transition from the orthorhombic phase to the monoclinic one occurs below 200 K in x<0.38. The intensity increase, related to the metal-insulator transition, has been observed below 100 K in Y0.62Ca0.38TiO3 . The phase separation from the monoclinic phase to the metallic orthorhombic and insulating monoclinic phase occurs below the metalinsulator transition temperature (TMI) in Y0.62Ca0.38TiO3 . The intensity-increase is explained by the appearance of the orthorhombic structure below TMI and its anisotropic appearance is related to the random orientation of the principle axes of the orthorhombic grain.