Differences in predicted and actually absorbed doses in peptide receptor radionuclide therapy

P. Kletting*, B. Muller, B. Erentok, J. Schmaljohann, F.F. Behrendt, S.N. Reske, F.M. Mottaghy, G. Glatting

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

PURPOSE: An important assumption in dosimetry prior to radionuclide therapy is the equivalence of pretherapeutic and therapeutic biodistribution. In this study the authors investigate if this assumption is justified in sst2-receptor targeting peptide therapy, as unequal amounts of peptide and different peptides for pretherapeutic measurements and therapy are commonly used. METHODS: Physiologically based pharmacokinetic models were developed. Gamma camera and serum measurements of ten patients with metastasizing neuroendocrine tumors were conducted using (111)In-DTPAOC. The most suitable model was selected using the corrected Akaike information criterion. Based on that model and the estimated individual parameters, predicted and measured (90)Y-DOTATATE excretions during therapy were compared. The residence times for the pretherapeutic (measured) and therapeutic scenarios (simulated) were calculated. RESULTS: Predicted and measured therapeutic excretion differed in three patients by 10%, 31%, and 7%. The measured pretherapeutic and therapeutic excretion differed by 53%, 56%, and 52%. The simulated therapeutic residence times of kidney and tumor were 3.1 +/- 0.6 and 2.5 +/- 1.2 fold higher than the measured pretherapeutic ones. CONCLUSIONS: To avoid the introduction of unnecessary inaccuracy in dosimetry, using the same substance along with the same amount for pretherapeutic measurements and therapy is recommended.
Original languageEnglish
Pages (from-to)5708-5717
Number of pages10
JournalMedical Physics
Volume39
Issue number9
DOIs
Publication statusPublished - Sep 2012

Keywords

  • PBPK modeling
  • PRRT
  • Y-90-DOTATATE
  • dosimetry
  • therapy planning
  • AKAIKE INFORMATION CRITERION
  • PHARMACOKINETIC MODEL
  • SOMATOSTATIN ANALOG
  • ANTI-CD45 ANTIBODY
  • MOLECULAR-SIZE
  • TUMOR UPTAKE
  • DOSIMETRY
  • BIODISTRIBUTION
  • RADIOIMMUNOTHERAPY
  • AFFINITY

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