The effect of energy window on cardiac ejection fraction

S. L. Bacharach, M. V. Green, R. O. Bonow, S. L. Findley, M. E. Daube-Witherspoon, S. M. Larson

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


ECG gated gamma-ray energy spectra from the left ventricle were created each 50 msec during the cardiac cycle. Nine of ten subjects were studied with a nonimaging Nal probe, and the tenth with a high-resolution Germanium detector. Placing multiple energy windows over the energy spectra, EF was found to vary with the energy window selected. Moving a 20% window across the photopeak produced a roughly linear increase in EF with energy (2.3 EF units per 10 keV increase in energy) in eight of the ten subjects. Dividing the photopeak into a low (126-140 keV) and high-energy (140-154 keV) portion gave significantly different EFs (high energy exceeding low energy by 17%). Increasing the width of a narrow window centered about the photopeak produced negligible change in EF. Examining the energy spectra showed that the small-angle scattered radiation (126-139 keV) was proportionately greater at end systole than at end diastole, after normalizing the spectra to the same photopeak area.

Original languageEnglish (US)
Pages (from-to)385-391
Number of pages7
JournalJournal of Nuclear Medicine
Issue number3
StatePublished - Jan 1 1988

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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