Evaluation of internal exposure of nuclear medicine staff working with radioiodine in Poland.

The iodine-131 (I-131) content in the thyroid of staff members working with this radionuclides has been measured with about 500 employees in about 25 hospital's departments of nuclear medicine performing therapy and diagnosis of thyroid disease in Poland. The measurements were performed with portable detection unit for in situ measurements of radioiodine. This is consist with scintillation detector sodium iodine activated by thallium (NaI(Tl)) - battery-powered and portable tube base Multichannel Analyzer Canberra UniSPEC. Based on direct measurements of the iodine content, the effective dose equivalent for workers due to inhalation of I-131 was estimated. All individuals actively working with iodine show measurable amounts of this isotopes in their thyroids. The average measured activity in the thyroid of the nuclear medicine staff was found to be equal at average 550 Bq within the range 70 Bq-2.5 kBq. There is no apparent correlation between the measured I-131 levels and risk categories. Nevertheless the technical and nuclear medicine staff show higher I-131 thyroid level comparing to hospital services staff. Calculated maximum committed effective dose for particular exposed person is <10% of 20 mSv/year. Int J Occup Med Environ Health. 2023;36(5):587-95.

Retrospective Biological Dosimetry at Low and High Doses of Radiation and Radioiodine Impact on Individual Susceptibility to Ionizing Radiation.

Iodine-131 (I-131) is often used in thyroid diagnostics and therapy. External and internal exposure to radioiodine can lead to molecular and cellular damage in peripheral blood lymphocytes. The aim of this study was to explore the influence of low and high doses of I-131 on susceptibility to ionizing radiation. Study groups consisted of 30 individuals free of thyroid diseases, 41 patients exposed diagnostically to low doses of I-131, and 37 hyperthyroidism patients exposed therapeutically to high doses. The standardized DNA repair competence assay was used to test the efficacy of the fast DNA repair process in G0 cells. Cytogenetic preparations were made in fresh blood samples before and after challenging cells in vitro with X-ray dose. The frequency of sister chromatid exchanges (SCE) and percentage of cells with significantly elevated numbers of SCE were used as cytogenetic biomarkers associated to homologous recombination and compared to reported earlier cytogenetic biomarkers of cancer risk. Strong individual variation in the biomarkers is observed in all investigated groups before and after challenging. Nevertheless, the efficiency of post challenging fast repair is significantly high in the patients exposed to diagnostic I-131 doses than in unexposed control group and linked to decreased cytogenetic damage. However, 5 weeks after administration of therapeutic doses, significant increases of unrepaired post challenging DNA and cytogenetic damages were observed indicating a health risk. Results also suggest that the appearance of cancers in immediate families might influence DNA repair differently in patients exposed to low than to high doses.

Assessment of exposure of workers to ionizing radiation from radioiodine and technetium in nuclear medicine departmental facilities.

BACKGROUND: Due to its use of ionising radiation, the field of nuclear medicine is a unique and significant part of medical diagnostics and patient treatment. The aim of this study was to assess the internal exposure of nuclear medicine employees to radioiodine 131I and technetium 99mTc as well as to assess the external exposure doses. MATERIAL AND METHODS: The radioiodine 131I and technetium 99mTc contents in the thyroid of staff members (about 100 persons) dealing with these radionuclides have been measured in four departments of nuclear medicine. The measurements were conducted with a portable detection unit for in situ measurements of radioiodine and technetium. High sensitivity environmental thermoluminescent dosimeters (TLD) were used to measure the external exposure dose. RESULTS: The average values and ranges of radioiodine 131I activity measured in the thyroids of all of the medical units' employees were: 83 Bq (range: 70-250 Bq), 280 Bq (range: 70-4000 Bq), 275 Bq (range: 70-1000 Bq) for technical staff, nuclear medicine staff and hospital services staff, respectively. The mean value of technetium 99mTc content in the thyroids of nuclear medicine staff was approximately 1500 Bq (range: 50--1800 Bq). External exposure dose rates were in the range of 0.5-10 microGy/h. CONCLUSIONS: The calculated average effective dose for particular person caused by the inhalation of radioiodine 131I is below 5% of 20 mSv/year (occupational exposure limit).

Abnormal nerve conduction velocity as a marker of immaturity in childhood muscle spinal atrophy.

Motor conduction velocity (CV) was tested in 117 infants and children with proximal spinal muscular atrophy (SMA), aged 1-53 months, and in 99 age-adjusted healthy controls. The children were classified into SMA forms 1 and 2 according to SMA International Consortium Criteria. In all children CV was tested in four nerves and the following parameters were taken into account: distal latency, conduction velocity, amplitude of muscle response. The electromyography of muscles revealed neurogenic changes. In all cases of severe form 1 motor CV was markedly slowed, with significantly prolonged distal latency and reduced amplitude of M response. In surviving children CV, although increasing with age, was always below the values of normal age-adjusted children. The slowing was particularly pronounced in the femoral nerve. In SMA2 children the values of all tested parameters were closer to the values of age-adjusted healthy children, nevertheless they were always below the edge of normal values, also the rate of maturation was much slower than in normal children. Sensory CV was normal in all tested groups. The findings are suggestive of delayed nerve maturation in childhood SMA.