Search PubMed⌕ Search

Biomedical subjects

E Righi

Publications and source records attributed to E Righi.

69 records · Page 4Linked to original sources
PubMedDate not supplied

Medical surveillance of workers exposed to ionizing radiations.

The principal directives on radiation protection (ICRP, EEC, national regulations) are the basis of a critical analysis of the concrete aspects, as typically found, of medical surveillance of exposed workers. It is shown how doctrinal, regulatory and legal hypertrophy produced by radiation protection often results in poor medical surveillance. This situation also arises by virtue of the rigid application of the ALARA principle (primary prevention) that considers workers in most cases as "virtually exposed". National regulations tend to privilege diagnostic exploration of deterministic damage, applying selective criteria to "slices" of the "state of health", whereas a global evaluation is required by the ICRP and by EEC regulations. In this context, there is a veiled intention, by now historically consolidated, to use such diagnostic tests as biodosimetric indicators. Another and persistent cause for concern is the practice of acquiring data on the radiosensitivity of some organs and systems for the (unlikely) occurrence of an accident. Instead, less consideration seems to be given to the early diagnosis of stochastic damage (leukemia and solid tumours). The physician has to confront not only the possible tumours due to occupational irradiation, but inevitably and prevalently (and often exclusively) the so-called "spontaneous" tumours that lead to an estimated mortality of 25% or more. Both radio-induced and spontaneous are in the end clinically observed in their globality, without distinction. In this context, medical surveillance undoubtedly acquires obligations with regard to tumour prevention (secondary prevention), considering also that sites with a high coefficient of risk of tumoral radio-induction basically coincide with the most frequently occurring cancers in the average population. Based on the above considerations, a diagnostic protocol is proposed that reconciles, with due economy but with the right balance, the real requirements of medical surveillance, reducing as far as possible undesirable effects such as "damage from excessive protection" (often of a formal character) and patient/physician delay, which is extremely dangerous for the early diagnosis of tumours.

Adolescent↗
PubMedDate not supplied

[Cytogenetic dosimetry: dose-effect curves and a methodological comparison].

When physical dosimetry is unavailable, the biological dosimetry of ionizing radiations is considered the best method for evaluating the individual absorbed dose. In order to apply this method, it is essential to know the dose-response relationship (calibration effect) regulating the phenomenon. The results obtained on human lymphocytes after in vitro X-ray treatment are presented. Two cytogenetic methods were used: the dicentric chromosomes assay in metaphase cells and the micronuclei assay in binucleated cells. The two were compared in order to verify the best utilization of each in the context of prevention and radioprotection. For the dicentric assay, 20 samples were treated with increasing doses of X-rays (from 0.5 to 2.0 Gy) and for the micronuclei assay, 25 samples were treated with doses from 0.1 to 4.0 Gy. The biological response was then evaluated. The data obtained were fitted by a second-grade polynomial regression. The dose-response relationship for the dicentric yield was F(dic) = 0.01-0.2D + 0.091D2 (regression coefficient better than 0.95); for the micronuclei yield, it was F(mn) = 0.015 + 0.043D + 0.083D2 (regression coefficient better than 0.97). The absorbed dose in exposed individuals was evaluated by the micronuclei frequency using a mathematical process (inverse prediction) that takes into account the measurement error and the 95% confidence intervals of the calibration curve. For this purpose a programme in Basic (DOSIME) was generated that was capable of estimating the dose and its variability. Since the micronuclei assay is simple and quick to carry out, it permits extensive screening and facilitates the identification of radiosensitive subjects. The estimated dose values of individuals submitted to radiotherapy are also given.

Adult↗