Collimator and xenon-127 for ventilation studies.

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