1. A medical image processing apparatus, comprising: an imaging unit configured to image an affected area in two directions using X-rays; a mask image generating unit configured to image the affected area before a device for treating the affected area is brought closer to the affected area, to thereby generate first and second mask images corresponding to the two directions; a subtraction processing unit configured to image the affected area while bringing the device closer to the affected area, to thereby generate first and second X-ray fluoroscopic images corresponding to the two directions, and to subtract the first and second mask images from the generated first and second X-ray fluoroscopic images, to thereby generate first and second treatment device images on which movement of the device is extracted; a reconstructing unit configured to reconstruct images of the device as three-dimensional data on a basis of the first and second treatment device images, to thereby generate three-dimensional device image data; a first rendering image generating unit configured to project the three-dimensional device image data in two directions according to a second X-ray geometry that is different from a first X-ray geometry used for imaging the first and second X-ray fluoroscopic images, to thereby generate first and second device rendering images; a second rendering image generating unit configured to project the affected area contained in three-dimensional image data acquired in advance, in two directions according to the second X-ray geometry, to thereby generate first and second affected area rendering images; and an image combining unit configured to combine the first and second device rendering images with the first and second affected area rendering images for each corresponding direction, to thereby generate combined parallax images in two parallax directions corresponding to the two directions, and to output the two generated combined parallax images.