Microscopic Spatial Inhomogeneity of Radiopharmaceutical Deposition in Mammalian Tissues: Dosimetry at the Cellular Level and Comparison with Conventional Dosimetry
| Autor: | G. M. Makrigiorgos, A. D. Van Den Abbeele, Janina Baranowska-Kortylewicz, D. W. Vinter, S. Ito, Amin I. Kassis, Stephen Adelstein |
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| Rok vydání: | 1990 |
| Předmět: |
Radiation
Materials science Radiological and Ultrasound Technology business.industry Public Health Environmental and Occupational Health General Medicine Cellular level Subcellular distribution Deposition (phase transition) Dosimetry Radiology Nuclear Medicine and imaging Nuclear medicine business Biomedical engineering |
| Zdroj: | Radiation Protection Dosimetry. 31:319-324 |
| ISSN: | 1742-3406 0144-8420 |
| DOI: | 10.1093/oxfordjournals.rpd.a080689 |
| Popis: | An experimental and a theoretical examination of the validity of the dosimetric assumptions of conventional internal dosimetry at the cellular level has been performed. Conventional dosimetry assumes a homogeneous distribution of radioactivity over the organ of interest. Experiments were carried out to derive in a quantitative manner the distribution of intravenously injected 99Tcm-labelled albumin colloid (Microlite) in mouse spleen and lung. Using tritium autoradiography, Microlite was found to concentrate highly and nearly exclusively in the macrophages of the reticloendothelial system in the organs examined. These cells comprise about 1 to 2% of the spleen volume and about 0.1 to 1% of the lung volume. The intracellular-to-extracellular radionuclide concentration was measured using a quantitative videodensitometer, and the fraction of the mouse organ volume occupied by the radiolabelled macrophages was derived from enlarged autoradiographs. The data were supplied as input to a recently developed model of dosimetry for individual cells in a multicellular cluster (representing an 'organ') which was assumed to contain 99Tcm-labelled Microlite. The program accounts for differences in intracellular and extracellular concentration of radioactivity and for selective uptake of the radionuclide by specific cells in the cluster (in the present case, macrophages): finally it compares the dose estimates for the labelled cells to the ones predicted assuming a homogeneous deposition of 99Tcm-labelled Microlite over the whole cellular cluster volume (conventional approach). It is demonstrated that conventional dosimetry under-estimates the dose received by the 99Tcm-Microlite labelled cells by factors of 10 to 50 and 15 to 60 for human spleen and lung, respectively. The implications for both the diagnostic and the therapeutic use of radiopharmaceuticals is discussed. |
| Databáze: | OpenAIRE |
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