Recoil and conversion electron considerations of the 166Dy/ 166Ho in vivo generator

J. R. Zeevaart, Z. Szücs, S. Takács, N. Jarvi, D. Jansen

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The use of radionuclides as potential therapeutic radiopharmaceuticals is increasingly investigated. An important aspect is the delivery of the radionuclide to the target, i.e. the radionuclide is not lost from the chelating agent. For in vivo generators, it is not only the log K of complexation between the metal ion and the chelator that is important, but also whether the daughter radionuclide stays inside the chelator after decay of the parent radionuclide. In our previous work, we showed that the classical recoil effect is only applicable for decays with a Q value higher than 0.6 MeV (in the atomic mass range around 100). However, Zhernosekov et al. [1] published a result for 140Nd/ 140Pr (Q = 0.222 MeV) which indicated that > 95% of the daughter ( 140Pr) was lost by a DOTA chelator upon decay of 140Nd. The authors ascribed this to the "post-effect". Their experiment was repeated with the 166Dy/ 166Ho generator to ascertain whether our calculations were correct. It was found that 72% of the daughter ( 166Ho) was liberated from the DOTA chelator, indicating that the "post effect" does exist in contrast to our recoil calculations. Upon further investigation, we determined that one should not only consider recoil energy levels but also the mode of decay which was able to explain the partial recoil found for 166Dy/ 166Ho. It is concluded for the 166Dy/ 166Ho system that the low recoil energy of the daughter nucleus 166Ho is not a sufficient reason to rule out release of the nuclide from chelators. On the other hand, we found that the ratio of the 166Ho that gets released corresponds to the ratio of relaxation of Ho atoms via the Auger process.

Original languageEnglish
Pages (from-to)109-113
Number of pages5
JournalRadiochimica Acta
Volume100
Issue number2
DOIs
Publication statusPublished - Feb 2012

Fingerprint

Chelating Agents
radioactive isotopes
Radioisotopes
generators
Electrons
decay
electrons
atomic weights
nuclides
guy wires
Radiopharmaceuticals
Complexation
metal ions
delivery
Electron energy levels
energy levels
Isotopes
Metal ions
nuclei
Atoms

Keywords

  • Dy
  • Ho
  • DOTATOC
  • In vivo generators
  • Recoil

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Recoil and conversion electron considerations of the 166Dy/ 166Ho in vivo generator. / Zeevaart, J. R.; Szücs, Z.; Takács, S.; Jarvi, N.; Jansen, D.

In: Radiochimica Acta, Vol. 100, No. 2, 02.2012, p. 109-113.

Research output: Contribution to journalArticle

Zeevaart, J. R. ; Szücs, Z. ; Takács, S. ; Jarvi, N. ; Jansen, D. / Recoil and conversion electron considerations of the 166Dy/ 166Ho in vivo generator. In: Radiochimica Acta. 2012 ; Vol. 100, No. 2. pp. 109-113.
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