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  • 28 September 1999 Volume 8 Issue 3
      
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  • Experimental study on the conversion factor between ambient dose equivalent and air kerma for external photon radiations
    Xie Xiangdong, et al
    1999, 8(3): 129-133.
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    In accordance with the recommendations of the International Commission on Radiation Units and Measurements, operational quantities should be used in environmental or individual monitoring for external photon radiations.Therefore, the conversion factor between ambient dose equivalent, H*(10), and air kerma, Ka, was studied.A sphere made of polyethylene with 30cm diameter was chosen as a substitute of ICRU sphere.The absorbed doses on the surface and at a depth 10mm of the sphere measured by thermoluminescence dosemeters were converted to the dose value in ICRU sphere with necessary corrections.The measurement of H*(10), Ka was performed for ISO-4037 narrow X rays and for gamma ray s from 137Cs and 60Co.The source and value of uncertainty were analyzed and the total uncertainty was 3.2%.Comparisons were made between our results and other published values.The results obtained are in agreement with the theoretical studies within uncertainties, and they can be used for the calibration of environmental monitors or individual dosemeters.
  • The adaptive response of the micronucleated normochromatic erythrocytes from bone marrow and peripheral blood formed by 147Pm irradiation of mice
    Yang Zhanshan, et al
    1999, 8(3): 134-136.
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    The effects of low doses of internally deposited 147Pm on the erythrocytes mutation from the peripheral blood and the bone marrow of mice induced by subsequent high dose of internally deposited 147Pm were studied.Kunming male mice were injected through tail vein with low doses of 147Pm (NO3)3 of 0.37, 3.7 and 37 Bq/g body weight.Three days later the mice were injected with a high dose of 147Pm (NO3)3 of 18.5 kBq/g body weight.The animals were sacrificed at 24 h after the injection of the high dose of 147Pm.The experimental results show that the frequency of micronucleated normochromatic erythrocytes (mn-NCE) from the peripheral blood and the bone marrow of the mice exposed to the pure high dose of 147Pm increased significantly over the controls at 24h after irradiation (P <0.01).However, the frequency of the mn-NCE from the peripheral blood and the bone marrow of the mice pre-exposed to 0.37~37 Bq/g of in vivo 147Pm decreased significantly (P <0.01), as compared with that of the pure high dose of the 147Pm injection group, and it doesn't have statistical difference than that of the controls (P > 0.05).The results suggest that low doses of in vivo 147Pm β irradiation can induce a adaptive response of the erythrosblasts in longer times, the radioadaptive erythrocytes have a obvious resistance to the radiogenetic damages induced by sebsequent high dose of internally deposited 147Pm.Incorporating our previous studies, this may be due to the increase of DNA repair fuction in the radioadaptive cells.The induction of the adaptive response has a dose ranges.In the dose ranges lower dose of in vivo 147Pm irradiation can produce higher level of the adaptive response.The frequency of the mn-NCE from the peripheral blood and the bone marrow of the mice is a more sensitive radiobiological parameter.