Evaluation of the effect of respiratory movements of the organs on the resolution index.

The motions of the respiratory movement of the diaphragms were filmed and the character of the motion was evaluated. The line-spread function of a motionless line source was compared with that of a moving source (for two kinds of motion: regular and harmonic). Similar calculations were made for increasing the motion amplitudes of the source and for different values of static resolution. The final dynamic resolution was calculated. The results show that when respiratory motion exceeds 13 mm (which happens in about 50% of clinical examinations) the resolution decreases by more than 25% so that it is necessary to use special methods of eliminating these artefacts.