The paper reports experimental results demonstrating some properties of microfocus radiation generated in narrow internal silicon (Si) and tantalum (Ta) targets of the B-18 betatron with electron energy of 18 MeV. The targets were 50-μm- and 8-μm-thick Si crystals and a 13-μm-thick Ta foil oriented with a goniometer along the inner electron beam. The results showed strong dependence of the radiation beam shape on the orientation of the target relative to the electron beam, and on the target material. The resolution and contrast dependences of the Duplex IQI standard wire pair images on the position of the pairs in the radiation beam and on the target material are shown. The obtained results revealed the role of absorption and refraction of radiation in generation of magnified images of plastic and metal plate edges. Radiation generated in the Ta target showed high detection sensitivity for narrow gaps and thin inclusions in steel thickness.