Objective
Techniques have been studied for monitoring radiation effects in cutaneous and mucous tissues, in acute and chronic exposure. Cutaneous blood flow alterations, particularly in chronically radiation exposed skin, can also be studied by means of telethermography associated with a standardized thermal stimulation technique. This method gives thermal recovery times (TRT) which are more meaningful than the traditional baseline thermal gradients.
Using a binocular stereomicroscope, Nikon SMZ-X, with a fibre optic illuminator and a microcamera permits a 3-dimensional visualization of the microvessels. The chosen sites were the nail fold and the bulbar conjunctiva. The clinical investigation, still in course, involves a group of 350 radiation workers, chronically exposed for many years, with scarce or lacking dosimetric data.
In about 6% of the examined workers middle alterations of the capillary loops were found and in about 5% major alterations were identified.
In traditional thermography, the various energetic quanta are visualized in thermal points, with a minimal difference of only 0.1 C.
To improve the sensitivity of the thermographic method a thermal stimulus was utilized and applied to the skin and the subsequent TRT was recorded.
A computerized AGEMA 870 thermograph and a surgicon thermostimulator were employed and the temperature selected was 5 C for an application time of 20 s. This technique does not require climatization of the ambient or the patient.
The clinical investigation, still in course, concerns a group of radiation workers chronically exposed for many years, with or without clinical signs of skin (aspecific) damage.
45 radiation workers have been examined and in 19 subjects a slight onicopathy a complete hypothermia was observed immediately after the thermostimulation and TRT of 15 min +/- 2 min.
In 12 subjects with cutaneous atrophy and onicodistrophy complete hypothermia occurred after the thermal stimulation and a prolonged ther mal recovery time (8 min +/- 1 min).
In 4 subjects incomplete hypothermia after thermostimulation was observed, followed by a very precocious thermal recovery (30 s +/- 5 s). Thus the degree of the microvessels damage can be distinguished as severe (no response to thermal stimulation), moderate (with protracted hypothermia after thermostimulation), and mild (with very protracted hypothermia).
Local exposure of the skin and underlying tissue resulting in radiological burns is the most frequent type of accident of irradiation. The burns have specific clinical characteristics because of their particular physiopathological mechanisms. The gravity of a radiological burn depends mainly on the energy deposited in the tissue. The dose and its spread have to be determined as accurately as possible in order to evaluate the prognosis and to manage the treatment. Three teams [Institut Curie (F), ENEA (I) and General Hospital of Madrid (S)] are collaborating on a European Level to set up practical protocols for physical dosimetry assessment, diagnosis and treatment of radiological burns.
Physical dosimetry.
The elaboration of personalized phantoms taking into account individual anatomical variations and the development of computer programs to simulate reconstitution of accidents and to analyze dosimetric data will be carried out by all participants.
Diagnosis.
Available paraclinical methods using the modifications of the microcirculation, such as infrared thermography, capillaroscopy and isotopic investigations will be improved. For instance, dynamic thermographic studies following cryostimulation and computer image analysis will be performed and the knowledge of the normal pattern of the hand and its physiological variations will be improved (F, I).
The development of an image processing system for capillaroscopy will allow dynamic studies and quantification of images (F, I).
Isotopic investigations focus on vascular modifications and the reaction of bone. Early hyperfixation of bone-seeking tracers can be observed after irradiation with moderate doses. But after high doses fixation in bone because of metabolic functions sideration can be observed. A systematic study of these parameters will be carried out (F, S).
New methodologies (microwave thermography) will improve our understanding of the underlying physiological mechanisms (F, S, I). Biological dosimetry will be performed on fibroblast cultures to evaluate the dose-effect relationship (F) and to quantify chromosomal abnormality in skin and annex tissues (S).
Treatment.
Protocols for treatment will be developed by a joint effort of participants with emphasis on :
optimization of treatment with superoxide dismutase alone or combined with other enzymes during the acute and late phase as a way to reduce free radical production;
optimization of pain treatment and study of ultrastructural modification of irradiated nerves (F,I);
effect of aloa vera extracts on cicatrization (S).
indications and optimal time of surgical interventions, improvement of different methods to cover the defect such as graft, skin scrape and artificial skin.
Fields of science
Topic(s)
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Data not availableFunding Scheme
CSC - Cost-sharing contractsCoordinator
France