Volume 39, Issue 9 p. 5708-5717
Nuclear medicine physics

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

Peter Kletting

Peter Kletting

Klinik für Nuklearmedizin, Universität Ulm, Ulm 89081, Germany

Author to whom correspondence should be addressed. Electronic mail: [email protected]; Telephone: ++49 731 500 61371; Fax: ++49 731 500 61302.

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Berthold Müller

Berthold Müller

Klinik für Nuklearmedizin, Aachen University, RWTH, Aachen 52074, Germany

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Bahar Erentok

Bahar Erentok

Klinik für Nuklearmedizin, Universität Ulm, Ulm 89081, Germany

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Jörn Schmaljohann

Jörn Schmaljohann

Klinik für Nuklearmedizin, Aachen University, RWTH, Aachen 52074, Germany

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Florian F. Behrendt

Florian F. Behrendt

Klinik für Nuklearmedizin, Aachen University, RWTH, Aachen 52074, Germany

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Sven N. Reske

Sven N. Reske

Klinik für Nuklearmedizin, Universität Ulm, Ulm 89081, Germany

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Felix M. Mottaghy

Felix M. Mottaghy

Klinik für Nuklearmedizin, Aachen University, RWTH, Aachen 52074, Germany and Department of Nuclear Medicine, Maastricht University Medical Center (MUMC+), Maastricht 6229, The Netherlands

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Gerhard Glatting

Gerhard Glatting

Medical Radiation Physics/Radiation Protection, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim 68167, Germany

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First published: 30 August 2012
Citations: 40

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 using111In-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 90Y-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.