A sensitivity study on the measurement of the CKM angle $ \gamma $ from $ \gamma $ decays is conducted using the D-meson reconstructed in the quasi flavour-specific modes $ \gamma $ , $ \gamma $ , and $ \gamma $ , as well as CP-eigenstate modes $ \gamma $ and $ \gamma $ , where the notation $ \gamma $ corresponds to a $ \gamma $ or $ \gamma $ meson. The LHCb experiment is presented as a use case. A statistical uncertainty of approximately $ \gamma $ can be achieved with the $ \gamma $ collision data collected in the LHCb experiment from 2011 to 2018. The sensitivity to $ \gamma $ should be of the order $ \gamma $ after accumulating 23 fb$^{-1}$ of $ \gamma $ collision data by 2025, whereas it is expected to improve further by 300 fb$^{-1}$ by the second half of the 2030 decade. The accuracy is dependent on the strong parameters $ \gamma $ and $ \gamma $ , which together with $ \gamma $ describe the interference between the leading amplitudes of the $ \gamma $ decays.