Induction d'aberrations chromosomiques de type stable par le technétium 99m. Études in vivo et in vitro chez des patients volontaires

Biological dosimetry, which determines the absorbed dose of radiation by measuring radiation-induced variation of various biological parameters, can help to assess radiation damage in a given patient and evaluate his or her sensitivity to radiation. The chromosomal aberration count in circulating lymphocytes is considered to be the most specific as well as the most sensitive method for measuring radiation exposure; as such, it is used in forensic medicine. Evaluation of radiation exposure requires setting up reference curves for each type of radiation. In nuclear medicine, exposure is currently calculated mathematically and not by considering its biological consequences. Biological dosimetry uses a more realistic approach towards the consequences of radiations received during an examination in nuclear medicine. The aim of the study was to evaluate the long-term consequences of the in vivo administration of 99mTc-sodium oxidronate (HDP), on the basis of the induction of stable chromosomal aberrations. Stable aberrations were scored before and after administration of the 99mTc-labelled radiopharmaceutical. First, a specific relationship between the dose of 99mTc and the frequency ofstable chromosomal aberrations was established in vitro to estimate whole-body dose. Six volunteer patients were included in the study. Blood samples were obtained before and 6 and/or 24 hours after 99mTc-HDP administration. Stable chromosomal aberrations in irradiated lymphocytes were scored using fluorescence in situ hybridization using human whole-chromosome-specific DNA probes for chromosomes 2, 4 and 12. Analysis of the in vitro data shows that the number of translocations has a quadratic linear relationship with the administered dose. Systemic administration of 99mTc-HDP at routine activity did not induce additional early translocations over the background level. Translocation scoring performed months or even years after the administration of 99mTc-HDP could be necessary to rule out side effects on bone marrow stem cells

Induction d'aberrations chromosomiques de type stable par le technétium 99m. Études in vivo et in vitro chez des patients volontaires

Biological dosimetry, which determines the absorbed dose of radiation by measuring radiation-induced variation of various biological parameters, can help to assess radiation damage in a given patient and evaluate his or her sensitivity to radiation. The chromosomal aberration count in circulating lymphocytes is considered to be the most specific as well as the most sensitive method for measuring radiation exposure; as such, it is used in forensic medicine. Evaluation of radiation exposure requires setting up reference curves for each type of radiation. In nuclear medicine, exposure is currently calculated mathematically and not by considering its biological consequences. Biological dosimetry uses a more realistic approach towards the consequences of radiations received during an examination in nuclear medicine. The aim of the study was to evaluate the long-term consequences of the in vivo administration of 99mTc-sodium oxidronate (HDP), on the basis of the induction of stable chromosomal aberrations. Stable aberrations were scored before and after administration of the 99mTc-labelled radiopharmaceutical. First, a specific relationship between the dose of 99mTc and the frequency ofstable chromosomal aberrations was established in vitro to estimate whole-body dose. Six volunteer patients were included in the study. Blood samples were obtained before and 6 and/or 24 hours after 99mTc-HDP administration. Stable chromosomal aberrations in irradiated lymphocytes were scored using fluorescence in situ hybridization using human whole-chromosome-specific DNA probes for chromosomes 2, 4 and 12. Analysis of the in vitro data shows that the number of translocations has a quadratic linear relationship with the administered dose. Systemic administration of 99mTc-HDP at routine activity did not induce additional early translocations over the background level. Translocation scoring performed months or even years after the administration of 99mTc-HDP could be necessary to rule out side effects on bone marrow stem cells