title: Whole organ and islet of Langerhans dosimetry for calculation of absorbed doses resulting from imaging with radiolabeled exendin.
abstract: Radiolabeled exendin is used for non-invasive quantification of beta cells in the islets of Langerhans in vivo. High accumulation of radiolabeled exendin in the islets raised concerns about possible radiation-induced damage to these islets in man. In this work, islet absorbed doses resulting from exendin-imaging were calculated by combining whole organ dosimetry with small scale dosimetry for the islets. Our model contains the tissues with high accumulation of radiolabeled exendin: kidneys, pancreas and islets. As input for the model, data from a clinical study (radiolabeled exendin distribution in the human body) and from a preclinical study with Biobreeding Diabetes Prone (BBDP) rats (islet-to-exocrine uptake ratio, beta cell mass) were used. We simulated111In-exendin and68Ga-exendin absorbed doses in patients with differences in gender, islet size, beta cell mass and radiopharmaceutical uptake in the kidneys. In all simulated cases the islet absorbed dose was small, maximum 1.38 mGy for68Ga and 66.0 mGy for111In. The two sources mainly contributing to the islet absorbed dose are the kidneys (33-61%) and the islet self-dose (7.5-57%). In conclusion, all islet absorbed doses are low (<70 mGy), so even repeated imaging will hardly increase the risk on diabetes.
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Netherlands.
authors.forename: Inge
authors.initials: I
authors.lastname: van der Kroon
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Netherlands.
authors.forename: Wietske
authors.initials: W
authors.lastname: Woliner-van der Weg
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Brom
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Netherlands.
authors.forename: Lieke
authors.initials: L
authors.lastname: Joosten
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Netherlands.
authors.forename: Cathelijne
authors.initials: C
authors.lastname: Frielink
authors.affiliation: Department of Nuclear Medicine, Erasmus Medical Center, Rotterdam, Netherlands.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Konijnenberg
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Netherlands.
authors.forename: Eric P
authors.initials: EP
authors.lastname: Visser
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Netherlands.
authors.forename: Martin
authors.initials: M
authors.lastname: Gotthardt
mesh_terms: D000328:Adult; D000818:Animals; D002452:Cell Count; D003920:Diabetes Mellitus / Q000209:etiology / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D005710:Gallium Radioisotopes / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007205:Indium Radioisotopes / Q000737:chemistry / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects; D036341:Intercellular Signaling Peptides and Proteins; D007515:Islets of Langerhans / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects; D007668:Kidney / Q000378:metabolism* / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011827:Radiation; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000175:diagnosis*; D011874:Radiometry / Q000379:methods*; D051381:Rats; D011922:Rats, Mutant Strains; D055815:Young Adult
chemical_list: D005710:Gallium Radioisotopes; D007205:Indium Radioisotopes; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C043046:helospectin I; C000615430:Gallium-68; C000615551:Indium-111