Balter, Henia; Savio, Eduardo; Souto, Beatriz
A review of current methods of contamination control for radioisotopes 131I, 125I and 99mTc, periodic control of personnel exposed to radiation.Maximum permissible body burden (Mpbb) for each radionuclide,radiotoxicity as danger of internal contamination directly related with Let, type of radiation,Ali values for various radionuclides and external irradiation as an opposed factor.Effective half life,examples, 99mTc in urine,iodine in thyroid caption, 99m Tc absorption by skin and mouth. Procedure of control and calculation by measurement of urine samples in a gamma spectrometer. Iodine thyroid caption by monitoring of thyroid with a solid NaI(TI)scintillator taking as background radiation the activity of upper leg muscle. Standard solutions are prepared to fill a thyroid phantoms.Results must not be higher than Mpbb of corresponding radionuclide.Bibliography
Jee, W.S.S.; Kimmel, D.B.
No human toxicity data exist from which to evaluate the current MPBB for 239 Pu of 0.04 μCi. The current method of estimating MPBB for 239 Pu in humans uses 239 Pu: 226 Ra ratios in terms of an average skeletal dose in dogs, then compares them to the experience with 226 Ra and 228 Ra in humans. In this paper, a new approach is used that is based on data about 239 Pu toxicity in dogs and on the cellular distribution of the dose. This information has been assimilated in a computerized model of the skeleton which stimulates 239 Pu location as a function of the bone turnover rate; the model then calculates the total number of bone cell- 239 Pu disintegration interactions occurring after one intravenous injection. The number obtained is compared for beagles with a 12.5-year life span and humans with a 50-year life span. We conclude that the current human MPBB for 239 Pu from a single intravenous exposure is adequate for skeletal protection
The present study is mainly concerned with an internal individual monitoring program for workers dealing with 239 Pu, by measuring the 239 Pu content in their urine. General aspects related with the plutonium radiotoxicity and its chemical, physical and metabolic properties are discussed. The methodology chosen for the 239 Pu analyses in urine is based on the wet ashing of the urine sample, followed by the plutonium separation by precipitation with lanthanium nitrate and extraction with thenoyltrifluoroacetone. After the separation, the samples is electrodeposited and the activity measured by alpha spectrometry. The results were then analyzed by taking into account the couting efficiency obtained of 23.72%, the chemical recovery of 85.3% and the lower limit of detection of 1.1 x 10 -3 Bq. Finally, the bases for the establishment of reference levels for urinary excretion are discussed by considering the maximum permissible body burden (MPBB) and the annual limit of intake (ALI). (author) [pt
José Maria Filardo Bassalo
Full Text Available In this article we will try to give a pale idea to the reader of what could be the Cosmic Microwave Background (RCFM that, according to the traditional Big Bang model, was generated by a primordial explosion. With this purpose we find it very important to present a brief historical summary of how the Microcosm, based on the Standard Model of Elementary Particle Physics (MPPE, and the Macrocosm, based on the Standard Big Bang Model (MPBB, have evolved over time. In addition, in the final part of the article we will analyze the two physical processes presented in the literature that seek to explain the RCFM: Bariogenesis and Plasma Quark-Gluon.
Nino, Nelcy Yasmin; Lagares, Luis Carlos; Veloza, Luz Stella; Martinez, Maria Cristina; Reyes, Amelia de los
Full text: In nuclear medicine, unsealed radioactive substances are administered to patients for diagnosis, treatment or research. The manipulation of these radionuclides, particularly those volatile, like iodine 131 (I-131), generates a risk of internal contamination by ingestion and inhalation. The inhaled radioactive particles are retained in the lungs or uptake by the thyroid tissue and could produce health effects. The IAEA provides regulatory practices in handling radioactive material to reduce internal contamination in the staff, based on the radiation protection principle to achieve occupational doses as low as reasonably achievable (ALARA). A quality assurance program in radioprotection should include the monitoring of occupational intakes. This paper describes a pilot study which determined quantitative methods to monitoring the nuclear medicine staff. The estimates of intakes and doses of I-131 were derived from the review and interpretation of urine monitoring data, using a Ludlum model 203 Shielded Well Scintillator (2 inches diameter x 1.8 inches thick), with a ratemeter model 2200. This study included workers occupationally exposed to I-131: physicians, technicians, radio pharmacists and physicists. The initial tests of the activity levels of I-131 in urine showed an average MPBB (Maximum Permissible Body Burden) of 0.035%, i.e. 0.025 μCi. Comparing with the maximum value of whole body 0.7μCi, the percentages of I-131 MPBB indicate the presence of small activities of I-131 in the urine, suggesting low-level chronic exposures from occupational workers in Nuclear Medicine. The higher values are the medical personnel who perform treatments for thyroid disorders. Conclusion: To do statistically significant the sampling and to protect individuals in each area it should be considered the daily urinary excretion, which is due to implement a protocol for regular assessment of the levels of incorporation of iodine 131 for jobs and activities, personnel in