Dosimetry in radionuclide therapies with 90Y-conjugates: The IEO experience

M. Cremonesi, M. Ferrari, M. Chinol, M. Bartolomei, M. G. Stabin, E. Sacco, M. Fiorenza, G. Tosi, G. Paganelli

Research output: Contribution to journalArticlepeer-review

Abstract

The basis for a successful radionuclide therapy is a high and stable uptake of the radiopharmaceutical in the target tissue along with low activity concentration in other normal organs. The contribution of dosimetry in radionuclide therapy is to predict before the treatment the absorbed doses in tumor and normal organs, to identify the critical organs, to minimize any possible toxicity and to evaluate the maximum tolerated dose. We report our experience concerning pharmacokinetics and dosimetry of two 90Y-therapeutic protocols: 3-step pretargeting radioimmunotherapy (RIT) according to the biotin-avidin system and receptor mediated radio-nuclide therapy with the somatostatin analogue [DOTA-D-Phe1-Tyr3] octreotide named DOTATOC. For the dosimetric analysis, analogous approaches for the two radiolabeled compounds due to the similar pharmacokinetic characteristics were adopted; the MIRD formalism was applied, taking into account both the physical and the biological characteristics of the radioconjugate and patients' metabolism. In order to determine biological clearance, serial blood samples and complete urine collection were obtained up to 48 hours after injection; to evaluate biodistribution, several whole body scans were acquired. Both therapies showed the advantageous characteristics of a fast blood clearance and a predominantly renal excretion of the radiopharmaceuticals thus lowering the irradiation of the total body. Although pharmacokinetic characteristics were similar, different critical organs were found for the two therapies; in particular, some considerations regarding red marrow, spleen and kidneys were required. The results of our studies indicate that high activities of 90Y-biotin (3-step RIT) and 90Y-DOTATOC can be administered with acceptable radiation doses to normal organs.

Original languageEnglish
Pages (from-to)325-332
Number of pages8
JournalQuarterly Journal of Nuclear Medicine
Volume44
Issue number4
Publication statusPublished - 2000

Keywords

  • Y-[DOTA-D-Phe -Tyr]octreotide
  • Ittrium radioisotopes
  • Peptides
  • Radiation dosage
  • Radioimmunotherapy
  • Radiopharmaceuticals

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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