1. A method for capturing data of a predetermined volume portion of an object under examination by an x-ray system, the x-ray system comprising an x-ray source and a detector, the method comprising: generating x-rays that emerge from the x-ray source, radiate through the predetermined volume portion, and after radiating through, impinge on the detector, the generating comprising activating the x-ray source; capturing the data of the predetermined volume, the capturing of the data comprising capturing pixel by pixel the x-rays impinging on the detector, wherein with the pixel-by-pixel capture, only a subset of all of the pixels of the detector are evaluated; and determining a rectangle in which the determined pixels are arranged, the determining of the rectangle being dependent on a trajectory of the x-ray source, wherein the subset of the pixels to be evaluated is determined dependently on the rectangle, and wherein only rows of the detector that run through the rectangle are read, such that rows that do not run through the rectangle are not read.