The X-ray fluorescence measurement method in which the presence of fluorescent target particles is detected in the object 1 to be inspected and the existing target particles are localized in the object 1 is performed by (a) the source device 10 in the first projection direction. Generating an X-ray beam 2 extending through the object 1 in a parallel X-ray beam direction, (b) the source device 20 by moving the source device and the object 1 relative to each other； Irradiating the object 1 with the X-ray beam 2 at a plurality of scan positions in the first projection plane, set by (c), (c) being firmly connected to the source device 10, A plurality of spectral selective detector elements 31 arranged to detect X-ray radiation in the spatial direction of and detector elements from the X-ray radiation scattered in the object 1 extending radially with respect to the X-ray beam direction； 31) and the detector element 31 is Multiple spaces at each scan position using a detector array device 30 comprising a plurality of screen lamellas 32 arranged in a manner capable of detecting X-ray radiation from all positions in the volume of the ray beam. Detecting the X-ray radiation emitted from the object 1 in the direction, and (d) detecting the X-ray fluorescence of the target particle in the detected X-ray radiation, and detecting the X-ray fluorescence when the X-ray fluorescence is detected. Processing the detector signal of the detector element to localize the target particle in 1). For each of the plurality of predetermined scan positions, the energy spectrum of the X-ray radiation coming from the object is measured with each detector element and a subset of significant detector elements 31 is searched so that the detector signal of the detector element is Increased statistical significance compared to the detector element 31 facilitates the detection of X-ray fluorescence of the target particle, and if a significant detector element 31 is found at at least one scan position,
