[Absence of chromosomic and genotoxic damage from the radiation dose administered in scintigraphic examinations].

INTRODUCTION

The cytokinesis-blocked (CB) micronucleus test (MN) on irradiated human lymphocytes is normally used to evaluate chromosomal and genotoxic damage produced by various physical and chemical agents.

OBJECTIVE

Determine any possible genotoxic effect induced by the different types of ionizing radiation employed in medical diagnostic radiology and nuclear medicine.

MATERIAL AND

METHODS

The frequency of the MN appearance was determined in CB lymphocyte cultures of a total of 4 different groups of patients: (1) in 35 supposedly healthy volunteers to establish the MN spontaneous frequency in the medium; (2) in 9 volunteers to measure the in vitro dose-response curves in order to calculate the MN frequency following X-ray irradiation and gamma radiation; (3) in 25 patients in whom a specific diagnostic and/or therapeutic procedure employing diagnostic radiology techniques involving X-ray exposure was applied, and (4) in 26 patients in whom the diagnostic procedure in question involved nuclear medicine techniques (scintiscan).

RESULTS

A lineal relationship was observed between the MN frequency and the dose of ionizing radiation administered in vitro, both in X-rays and gamma radiation. A significant increase in the MN is observed after radiation is given to patients during medical diagnostic radiology examinations when compared with the control values obtained from the same patients prior to being subjected to the radiological procedure (p < 0.01). No significant MN increase is observed following exposure to radiation involved in diagnostic examinations in patients studied in Nuclear Medicine.

CONCLUSION

Ionizing radiation employed in complex medical diagnostic radiology examinations produces a significant increase in the MN appearance frequency and as such indicates both radiation induced chromosomal and genotoxic damage. However, the ionizing radiation used in diagnostic nuclear medicine examinations does not induce any significant increase in MN appearance frequency.