Please refer: https://en.wikipedia.org/wiki/Linear_energy_transfer

Both Gamma and X-rays are photons and have similar interactions. Please follow this and offer your comments-

Gamma rays are photons, whose absorption cannot be described by LET. When a gamma quantum passes through matter, it may be absorbed in a single process (photoelectric effect, Compton effect or pair production), or it continues unchanged on its path. (Only in the case of the Compton effect, another gamma quantum of lower energy proceeds). Gamma ray absorption therefore obeys an exponential law (see Gamma rays); the absorption is described by the absorption coefficient or by the half-value thickness.

LET has therefore no meaning when applied to photons. However, many authors speak of "gamma LET" anyway,[6] where they are actually referring to the LET of the secondary electrons, i.e., mainly Compton electrons, produced by the gamma radiation.[7] The secondary electrons will ionize far more atoms than the primary photon. This gamma LET has little relation to the attenuation rate of the beam, but it may have some correlation to the microscopic defects produced in the absorber. It must be noted that even a monoenergetic gamma beam will produce a spectrum of electrons, and each secondary electron will have a variable LET as it slows down, as discussed above. The "gamma LET" is therefore an average.

The transfer of energy from an uncharged primary particle to charged secondary particles can also be described by using the mass energy-transfer coefficient.[1]