The Full Form of DRR is‍ Digitally Reconstructed Radiograph.

The generation of digitally reconstructed radiographs (DRRs) is a significant procedure in several medical imaging applications such as 2D/3D image registration. Also, digitally reconstructed radiographs play an important role in modern radiation therapy. They are planar X-rays that can be generated from the same data sets used for the planning CT scan, taken with the patient in the treatment position. To reduce the patient setup errors, image registration, such as 2D/2D, 2D/3D, 3D/3D image registration, was introduced. Essentially, 2D/3D registration is a procedure that the DRRs resulted from a 3D CT data set are to be matched with the real X-ray images by applying a rigid transformation. This means that we should look for a translation (expressed by three parameters tx, ty, tz) and a rotation (expressed with three parameters as well θx, θy, θz) in space. At last, a fast DRR generation technique, called three-dimension Bresenham line generation algorithm, with which satisfactory images are obtained would be proposed.