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Abstract: 134-1

134-1

An overview of the workers' dose assessment service provided by Biodosimetry Laboratory of IRD

Authors:
Gabriela Loureiro de Bonis Almeida Simões (IRD - Instituto de Radioproteção e Dosimetria) ; Sueli de Mesquita (IRD - Instituto de Radioproteção e Dosimetria) ; Samara Carvalho Rodrigues (IRD - Instituto de Radioproteção e Dosimetria) ; Marcia Pereira da Silva (IRD - Instituto de Radioproteção e Dosimetria)

Abstract:

The cytogenetic dosimetry service at the Biodosimetry Laboratory of the Radioprotection and Dosimetry Institute (IRD) treats workers with suspected doses above 100mSv, recorded on a physical dosimeter over a one-month period. The chromosomal aberrations technique, specifically dicentric chromosomes, was used to calculate the dose. Peripheral blood samples are collected, stored, and sent to the IRD laboratory within 24 hours. The blood is processed, slides are prepared and evaluated under an optical microscope after staining. At least 500 metaphase cells are evaluated for each case. The aberration findings are entered into the CABAS statistical program (available at http://www.pu.kielce.pl/ibiol/cabas), which provides not only the dose but also information on how the dose was received, whether whole-body or partial. In the latter case, it is even possible to determine the percentage of the body that was exposed. Between 2012 and 2024, the IRD's biodosimetry laboratory evaluated peripheral blood samples from 34 individuals: 21 men and 13 women, with an average age of 37 ± 11 years, from seven Brazilian states: SP, RJ, ES, MG, PA, RO, SC. Most of the requests (65%) came from hospitals and clinics. As for the type of radiation, 55% of the individuals worked with X-rays, 24% with gamma radiation, 9% with both, and 12% of the cases did not provide any information. The state with the highest number of sample submissions was SP (38%), followed by RJ (29%), MG (15%), ES (6%). The states of RO, PA and SC each accounted for 3% of submissions. One case did not provide any information. Two (6%) of the 34 cases analyzed had doses above the radioprotection standards. For the others, there was no dose above the technique's detection limit (100mSv), thus discarding the dose recorded on the physical dosimeter. Both cases of overexposure were smokers. In this case, the analysis of dicentric chromosomes is the most suitable cytogenetic technique because it is not affected by lifestyle habits, age or exposure to toxic substances and, as previously mentioned, is very specific for radiation damage. The IRD's biodosimetry laboratory is historically important in helping people with radio accidents, since it was actively involved in helping the population exposed to cesium in the Goiania accident in 1987. The laboratory currently has four members, aiming to provide services to workers and individuals in the public who are under suspicion of overexposure to ionizing radiation, implementing new cytogenetic methodologies and supporting postgraduate work.

Keywords:
 Dosimetry, cytogenetics, high dose, workers