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A set of new operational quantities for external radiation protection was proposed in ICRU Report 95. The new operational quantities were designed to overcome the conceptual and technical shortcomings of the existing operational quantities, and to achieve a better estimation of the protection quantities. This paper introduces the development of operational quantities, and the changes in their definitions, calculation phantoms and the application scopes, so as to fully understand the significance of the changes in the new operational quantities, which can be used as a reference for the relevant professionals.
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Objective:To calculate the conversion coefficient from dose area product (DAP) to organ absorbed dose by Monte Carlo method in order to conveniently estimate doses to patient organ during coronary intervention procedure.Methods:The Geant4 Monte Carlo simulation kit was used to calculate the organ absorbed dose conversion coefficients by simulating exposure scene.Results:The conversion coefficients used in coronary angiography (CAG) for lung, bone marrow, liver and heart were (0.283±0.068), (0.169±0.049), (0.110±0.077) and (0.080±0.032) mGy/(Gy·cm 2) for male, and (0.376±0.121), (0.192±0.056), (0.153±0.105), and (0.102±0.033) mGy/(Gy·cm 2) for female, respectively. These were similar to those in the case of percutaneous coronary intervention (PCI). The DAPs for different interventional procedures were statistically significant ( t=-6.012, P<0.05). The DAPs for difference gender groups had no statistically significant ( P>0.05). Conclusions:Conversion coefficient for organ absorbed dose has little correlation with CAG and PCI in the same sex group. Dose conversion coefficients for female group are greater than those for male group in the same procedure. Conversion coefficients from DAP to organ absorbed dose calculated with Monte Carlo method can provide convenience for rapidly estimating the organ absorbed dose to clinical patients.
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Objective To investigate effect of high dose irradiation on the performances of thermolumines-cence detectors (LiF:Mg, Cu, P). Methods The high-dose irradiated thermoluminescence detector was annealed by a thermoluminescence annealing furnace until the annealing was completed, and then the annealed thermoluminescent detector was irradiated 0.5Gy by 137Cs irradiator to verify the accuracy of the thermoluminescentdetector. Results The thermoluminescence detector after high-dose irradiation could not be completely annealed under the temperature condition of 240 ℃, and it could be completely annealed at a high temperature as 400℃. After 0.5 Gy irradiation by 137Cs irradiator, the measurement results of the annealed thermoluminescence detector were significantly smaller, and the dose response and dispersion of the detector were also changed significantly. Conclusions After a more than 5 Gy irradiation, the crystal structure of the thermoluminescence detector has changed, and a high temperature peak above 240 ℃ has appeared, which leads to the failure to completely anneal at normal temperature. Therefore, the thermoluminescence detector can no longer be used for dosimetry after high-dose irradiation.
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Objective To evaluate the radiation protection of occupational hazards in a hospital Clinac 23EX medical electronic accelerator construction project so as to ensure the health and safety of the relevant people involved.Methods According to the relevant laws,regulations and standards of China,combined with the relevant materials provided by the construction unit,the radiation protection tests and comprehensive assessment of this project were carried out.Results The performance test results of the medical electron accelerator met the requinements of GB/T 19046-2013 The ambient dose equivalent rate in the workplace was between the background dose rate (0.10 μ,Sv/h) and 11.5 μSv/h,which suggested the computer room shielding met the requirements of radiation protection.The total body effective dose,the for 7 radiation workers were 0.85,1.19,1.64 mSv,respectively,which were lower than the dose management control values of the construction unit and the national standards.Radiation protection supplies and the management system of the construction unit met the national requirements.Conclusions The construction project can effectively control the radioactive occupational hazard factors in normal operation,and the radiation protection facilities have reached the completion requirements.
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Objective To investigate the effect of SKP2 expression on radiation induced bystander effect (RIBE) of esophageal cancer cells.Methods The esophageal cancer cell lines with different SKP2 levels were applied for the study and the SKP2 expression was identified by Western blot.Micronuclei (MN) assay and DNA foci assay were used to evaluate the effect of SKP2 on RIBE.The cells were transfected with SKP2 gene or SKP2 siRNA to further verify the effect of SKP2 on RIBE.Results MN assay showed that the bystander effect induced by the cells with a high level of SKP2 was lower than that induced by the cells with a lower level of SKP2 (t =8.06,P ＜ 0.01).These results were further confirmed by the gene transfection experiments.When the expression of SKP2 was increased,RIBE was decreased (t=11.12,10.16,P ＜ 0.01).Contrarily,when the expression of SKP2 was reduced,RIBE was increased (t =8.39,8.83,P ＜ 0.01).γ-H2AX foci formation assay disclosed that when SKP2 expression in the irradiated cells increased,the repair ability of DNA damage in the bystander cells was higher than the control (t =6.85,7.10,P ＜ 0.01).With the expression of SKP2 decreased,the repair ability of DNA damage was lower than the control (t =7.66,8.47,P ＜ 0.01).Conclusions Over-expression of SKP2 inhibits RIBE of esophageal cancer cells,at least partly through regulating DNA damage repair ability.