Collimator and xenon-127 for ventilation studies

In comparison with xenon-133, the more energetic emissions from xenon-127 suffer less attenuation by tissues and should therefore provide images with better resolution in ventilation studies. However, the better resolution of the low-energy collimator used with xenon-133 may outweigh such advantages of the more energetic emission of xenon-127, which requires a medium or high-energy collimator.