ABSTRACT
The neutron dose resulting from external irradiation can be evaluated by measuring the counts of characteristicγrays produced by24Na in the human body. The detection geometry with the highest detection efficiency for measuring the whole-body24Na activity has not been studied. In this work, the MCNP code is used to calculate the spatial distribution of24Na in the human body irradiated by neutrons with different energies in different irradiation geometries. The fluence distribution of24Na characteristicγrays on the body surface is calculated. The counts of24Na characteristicγrays induced by monochromatic neutron irradiation are simulated to fit the scenarios of neutron irradiation by a continuous energy spectrum neutron. When the spontaneous neutrons from252Cf with 1Gy dose irradiate the human body, (3.63-4.35) × 1010 24Na atoms are produced. The lower detection limit for the neutron absorption dose is reduced from â¼100 to less than 1 mGy when the radiation detector is placed over the back of the human body close to the liver. The relative error between the measured counts of24Na characteristic γ rays caused by252Cf neutron irradiation and the counts fitted by monochromatic neutron irradiation data is less than 5.7%. The neutron dose received from a continuous energy spectrum neutron can be acquired quickly and accurately by weighted summing of the data for monochromatic neutron irradiations calculated in this paper, which is more convenient and practical than the previous method.
Subject(s)
Human Body , Neutrons , Humans , Radiation DosageABSTRACT
There are differences and inconsistencies to some degree in the radioactive contamination control level of personnel′s body surface availiable in many national standards, thus puzzling the users. Therefore, it is proposed to compare the applicable scope, conditions and differences between relevant national standards, and combine with similar clinical nuclear medicine standards of radiological protection content to presevent recommendations on the contamination control level that should be correctly applied in an event of nuclear and radiological emergency. Based on the discussion of similar standards, the contaminated personnel with α of 0.04-10 Bq/cm 2 and β of 0.4-100 Bq/cm 2 are advised to be treated in the institutions with higher than secondary medical insititution. Both α econtamination control levels less than 0.04 Bq/cm 2 and β levels less than 0.4 Bq/cm 2 could be achivable, if fully decontaminated.
ABSTRACT
21 patients with obstructive sleep apnea-hypopnea syndrome(OSAHS)and hypertension were treated by orthodontic applince for 3 months.All complains of snore were alleviated or disappeared during sleep,the short of breath and drowsy in the daytime were disap-peared,AHI decreased(P<0.01)and the lowest SaO2 increased(P<0.01).The blood pressure tend to normal.The orthodontic appliance can effectively control OSAHS and hypertension.
ABSTRACT
Objective To calculate the electric field intensity and transmembrane voltage of spherical cells and ellipsoi -dal red blood cells ( RBC) in an extremely low frequency electromagnetic field .Through this calculation , we can provide reference to the search for interaction targets and mechanics between the extremely low frequency electromagnetic field and organisms.Methods The Finite Element Method was used in the numerical computation for the spherical cell model and the ellipsoidal RBC model .Results The electric field intensity of the two types of cells on the cellular membrane was both significantly higher than the applied electric field strength , and the values of the induced field strength and transmembrane voltage varied with the direction of the electric field periodically .Conclusion The cell shape and direction of the applied electric field are not the main determinants of the cellular membrane electric field intensity and the transmembrane voltage compared with electromagnetic parameters .The distribution of the electric field intensity and transmembrane voltage are re-lated to the direction of the applied electric field.
