X-ray diagnostic system. The system includes a source of x-rays which communicates with an x-ray beam concentrator spaced apart from the x-ray source and disposed for receiving x-rays from the x-ray source. An x-ray spectrometer is disposed for receiving x-rays from the concentrator. In a preferred embodiment, the concentrator is formed of a cylindrical spiral of a metal-coated plastic material having a surface for reflecting x-rays. In another embodiment, the concentrator includes a plurality of concentric nested cylinders of a metal-coated plastic material for reflecting x-rays. In yet another embodiment, the concentrator is a glass capillary bundle. The concentrator allows the spectrometer to be spaced away from the source of x-rays such as scanning electron microscope.