Er-165 is a radiolanthanide, usually in trivalent state. The ionic radius of Er3+ is 89 pm, i.e. just 3% larger than Lu3+, which explains that chelators suitable for Lu-177 can be directly employed for Er-165 too, in particular DOTA.
Er-165 decays by electron capture decay with a half-life of 10.36 hours to stable Ho-165.
Er-165 emits no gamma-rays, but X-rays, notably Kα at ≈47 keV (59.4(9) %) and Kβ at ≈54 keV (14.3(19) %). These energies make Er-165 suitable for SPECT-imaging.
The mean photon energy per decay is 37 keV and the mean electron energy emitted per decay is 5 keV . Most electrons are short-range Auger electrons with <1 µm and <26 µm respectively. Er-165 has therefore been proposed as therapeutic Auger electron emitter .
Er-165 is produced by proton irradiation of natural Ho carbonate targets at Hevesy Laboratory at DTU. A Ho/Er separation is performed by ion exchange chromatography.
Activity will be shipped from the PRISMAP facility Hevesy Laboratory (DTU, Risø, Denmark) to the users in form of Er3+ solution.
|Branching Ratio/Decay||100% EC|
|Purification||multi-step ion exchange|
|Chemical Form||Er3+ ion in 0.1 M HCl solution (1-2 ml)|
|Chemical Purity||Metal impurities determined by ICP-OES for each batch.|
|Identification||X-ray spectroscopy and half-life|
|Appearance||Clear colourless solution|
|Activity available||1 GBq (more to be discussed)|
|Grade||Research grade, n.c.a.|
|Other information||Bioburden and endotoxin burden can be analysed post release, upon request.|