An apparatus to deliver conformal radiotherapy using external beam Cobalt 60 source is disclosed. The apparatus comprises an enclosed circular gantry placed above the bearings along with an integrated in house X-ray unit with the X-ray detector, source head and beam stopper. The X-ray unit along with the X-ray detector of the enclosed circular gantry are aligned to the radiation beam plane such that 3-D image of the tumour can be constructed using a cone beam computed tomography (CBCT) and radiation treatment is delivered by beam limiting device, without moving the patient from one patients treatment couch to other thus reducing the inconvenience to the patient achieving high tumour positioning accuracy and for alignment of X-ray and radiation beams.