A tomographic imaging system is disclosed in which the quantity of absorption or transmittance of a transmissive radiation by or through a certain tomographic cross-section of an object under consideration is detected and the distribution of radiation absorption or transmittance in the cross-section is reconstructed through a convolution operation. A weighting function used in the convolution operation is prepared with a predetermined one of its positive orders the value of which is an integration of the weighting function from the predetermined positive order to positive infinity and a predetermined one of its negative orders the value of which is in integration of the weighting function from the predetermined negative order to negative infinity.
