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Differences in predicted and actually absorbed doses in peptide receptor radionuclide therapy
Author(s) -
Kletting Peter,
Müller Berthold,
Erentok Bahar,
Schmaljohann Jörn,
Behrendt Florian F.,
Reske Sven N.,
Mottaghy Felix M.,
Glatting Gerhard
Publication year - 2012
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4747266
Subject(s) - radionuclide therapy , dosimetry , peptide receptor , biodistribution , nuclear medicine , medicine , pharmacokinetics , radiation therapy , therapeutic effect , akaike information criterion , chemistry , receptor , mathematics , statistics , biochemistry , in vitro
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.