RESUMO
The 10.3-h 165Er, decaying by electron capture to stable 165Ho, offers an excellent promise for use in diagnostic nuclear medicine, especially in conjunction with multiwire proportional-counter cameras. Using an ultra-high-resolution Si(Li) photon spectrometer, L and K x-ray photon yields in 165Er decay have been measured. The ratio PL/PK of electron-capture probalities in L and K shells is determined to be 0.196+/-0.030, in good agreement with theory. Estimates of Auger electron yields and yields of very-low-energy electrons from Coster-Kronig transitions are presented. Levels of 169Er and 171Er radioactive impurities in the reactor-produced 165Er sample are experimentally determined. Whole-body dose estimates for 165Er are given. These compare favorably with 99mTc dose.
