title: Crypt cell dosimetry for 99Tcm-sestamibi in a new small intestinal dosimetry model.
abstract: The aim of the study was to calculate the absorbed dose to the crypt cells in the small intestine from (99)Tc(m)-sestamibi excreted through the intestinal tract. The absorbed dose was calculated taking into consideration the biodistribution of the radiopharmaceutical in the small intestinal wall and its contents, based on data gathered in rats. Absorbed dose calculations were performed using a new intestinal model in which S values for crypt cells are given both for the intestinal wall and for the intestinal contents as source organs. A maximum of 6% of the injected activity was found to be located in the intestinal wall at 30 minutes after injection and 13% in the intestinal contents at 2 h, resulting in an absorbed dose of 8.9 microGy/MBq to the crypt cells. Assuming the activity to be located only in the wall, we calculate an absorbed dose to the crypt cells 2.5 times higher than if all the activity is assumed to be present in the intestinal contents. Using the new intestinal dosimetry model, together with detailed biokinetic data for the radiopharmaceutical from animal studies, it is possible to calculate the absorbed dose to the crypt cells, which is not possible when using external imaging.
authors.affiliation: Department of Radiation Physics, The Jubileum Institute, Lund University, Lund University Hospital, Sweden. jonsson@radfys.lu.se
authors.forename: Lena
authors.initials: L
authors.lastname: Jönsson
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Liu
authors.forename: Bo-Anders
authors.initials: BA
authors.lastname: Jönsson
authors.forename: Michael
authors.initials: M
authors.lastname: Ljungberg
authors.forename: Sven-Erik
authors.initials: SE
authors.lastname: Strand
mesh_terms: D000818:Animals; D005260:Female; D007413:Intestinal Mucosa / Q000033:anatomy & histology; D007421:Intestine, Small / Q000033:anatomy & histology / Q000528:radiation effects*; D008297:Male; D008954:Models, Biological; D011829:Radiation Dosage; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D017256:Technetium Tc 99m Sestamibi / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi