The characteristic lines K-a, Ly-a and He-a X-ray source for diagnostics of the compressed state of laser plasma was proposed, and its optimal parameters were calculated under the conditions required for nuclear fusion [1]. Such a source operating in a pulsed regime can be used for determining the spatial distribution of laser- plasma density with high temporal resolution by means of multi-frame backlight imaging of the main target by X-ray pulses obtained by picosecond laser pulses irradiation of a secondary target. In the present report, we analyze the scheme with Ly-a/He-a line emission, found quantitative parameters of a multi-frame X-ray source for radiography of compressed state nuclear-fusion target, and describe images of the target in the case of spherically (elliptically) symmetric compression.