The work presented is this thesis is an investigation of the spatial resolution of a Microstrip Gas Chamber (MSGC) as an imaging device for X-rays. Applications include digital radiology and experiments with synchrotron radiation. The investigation was done for X-ray energies around 20 keV, and the detector was evaluated for digital mammography. Both experiments and simulations were used for the evaluation of MSGCs. A series of experiments was performed at the Budker Institute of Nuclear Physics in Novosibirsk, Russia, using a parallel strip MSGC. It was shown that MSGCs have the potential to be used as imaging devices for medical applications. A simulation model, based on the Monte-Carlo program ITS, was developed to simulate the properties of MSGCs. The results of the simulation were in good agreement with the experimental data form Novosibirsk. More experiments were performed at UCL to test the model under different conditions, and were also simulated successfully. Having proved that the predictions of the simulation could be trusted the model was used to predict the performance of a keystone MSGC for digital mammography. The Line Spread Function (LSF) of the detector was simulated and the Modulation Transfer Function (MTF) was calculated.