Recent experiments in serial femtosecond
crystallography (SFX) have demonstrated the feasibility of obtaining structural
information from nanoscale crystals using X-ray free-electron lasers (XFELs).
However, due to difference in the sizes, orientations and intensities of the
XFEL pulses during experiments, the Monte-Carlo integration method used in SFX requires
great numbers of patterns in order to determine a reliable crystal structure. Here,
an improved integration algorithm for SFX data processing is reported. By
evaluating the dimensions of each crystal and correcting for the geometric
factors of single patterns, the effective diffraction intensities, as opposed
to the directly measured single-shot pattern diffraction intensities, can be merged
to acquire more accurate integrated intensities which can be used for structure
determination. This improvement enhances the quality of electron-density maps
and decreases the number of diffraction patterns that are needed to solve the crystal
structure in SFX experiments.