Objective To fulfill the requirements for uncertainty of the calibration apparatus for dosimeters used in X-ray mammography through setting standard radiation quality at the SSDL and developing calibration procedures.Methods According to IEC 61267-2005 and IAEA TRS No 457 to recommend RQR-M and RQA-M series standard radiation quality,the calibration apparatus was evaluated for long term stability of the radiation field over 8 years from 2006 to 2014,including 10 response quantities,such as field homogeneity,change rate of mean air kerma and scatter radiation contributions and so on.In addition,the reference dose instrument was traced back to the PSDL of PTB in Germany by post during 2008 and 2012.Results The field homogeneity (φ 40 mm) relative error was ± 1.4％.The long term stability of the calibration apparatus was less than ± 2％ (limits of variation).The scatter radiation contributions at their points of test were below 0.12％.The calibration factors traced to PTB were 0.999-1.000.As a result of the calibration apparatus,the expanded uncertainty was ± 3％ (k =2,95％ confidence interval).Conclusions The calibration apparatus may meet the requirements of IEC 61267-2005 and IAEA TRS No 457 and has obtained the license of metrology from national regulatory authority.The laboratory now performs very well to calibrate dosimeters used in X-ray mammography.

Objective To calculate effective dose based on the dose-area Product (DAP) measured in dental cone beam computed tomograhic (CBCT) scanning and using a conversion coefficient.Methods The method of the DAP was used to calculate the effective dose from KODAK 9500 dental CBCT scanner with fields of view (FOV) of 16 cm×15 cm and 12 cmu×8 cm.The DAP-values (mGy · cm2) were measured using a transmission ionization chamber connected to an electrometer (Doseguard 100,RTI Electronics AB,Sweden) and the chamber was placed directly on the exit of the X-ray tube.All measurements were repeated three times and averaged on each FOV data.The conversion coefficient of 0.080 μSv/mGy · cm2 was used to estimate the effective dose on the basis of DAP values,which was quoted from a literature.Results DAP values were found between the two FAOs to vary from 512 to 1 083 mGy · cm2,and the effective doses calculated with 0.080 μSv/mGy · cm2were 41 to 87 μSv.The effective doses given in this paper was lower than those reported in other literatures.Conclusions DAP measurement was found to be well defined and easy-to-use method of determining effective dose for some CBCT Units.However,determination of specific conversion coefficient in the CBCT must be further developed.

Objective To evaluate whether eight kinds of dosimeters satisfy the clinical mammography dose measurement through the comparison of energy response.Methods According to GB/T 19629-2005,the energy responses of eight available mammography dosimeters were determined for ten standard radiation qualities in the range 25-40 kVp at the SSDL using a refrence-class dosimeter.Results Except 2000S,the energy response factors of all the other dosimeters were consistent within ±5%.Conclusions The energy response of ionizing chamber type is better than other types of dosimeters.

Objective To assess the feasibility of ESD measurements in the mammography by the comparative study of energy dependence of the three passive solid detectors on low energy X-ray.Methods Two thermoluminescent TL) detectors ( LiF(Mg,Ti) and LiF( Mg,Cu, P) and one optically stimulated luminescence (OSL) detector( Al2O3: C ) were irradiated for the same air kerma by ten kinds of beam quality between 25-40 kV in a Mo/Mo low energy X-ray generator,respectively. Results The energy dependences of TL and OSL were 25% and 11% between 25-40 kV, respectively. Conclusions considerable potential for OSL detector can be used in routine quality control and ESD measurements in the mammography.

Objective To study the dosimetric characteristics of two different radiochromic films used to estimate peak skin dose(PSD) of patients.The characteristics of these two films were investigated and compared after exposure to ionizing radiation in the diagnostic energy range,including post-exposure gray growth,sensitivity,energy dependence and dose response.Methods GafChromic XR-RV3 film and KODAK EDR2 film were exposed to air kerma 800 mGy free-in-air using five X-ray beam qualities (60,80,100,120 and 140 kVp) in a SSDL.The measurement for each energy was normalized to 80 kV to analyze energy dependence of films.The films were calibrated to different dose level (0.025-10 Gy) onphantom by 80 kV X-rays.The response curve were plotted to analyze sensitivity and dose response.The films were scanned with Epson V750 commercial flatbed scanner.Color channel analysis was performed.Results The post-exposure gray growth of XR-RV3 film was found to be fairly stable.The change were 2％,4％,6％ at 24 h,72 h and 6 weeks after exposure respectively.EDR2 film was found to be more sensitivity than XR-RV3 film in low dose.The energy response of the XR-RV3 film and EDR2 film were within 9％ and 23％ over the clinical diagnostic x-ray energies,respectively.In the dose range of 0.025-10 Gy,for the XR-RV3 film,the red channel with the dose response curve was most obvious.For EDR2 film,the pixel value of three color channels was coincident.The EDR2 film appeared to be saturated when receiving doses greater than 500 mGy.Conclusions The XR-RV3 film is superior to EDR2 film in gray growth,energy dependence,dose-response and other aspects.This film is very suitable for measuring and analyzing PSD of patients in interventional radiology procedures.

Objective To study the angular dependence of four different mammographic dosimeters to monoenergetic X-ray beams and observe the variation tendency in angular dependence to different energy X-rays and to discuss the evaluation of average glandular dose(AGD)in digital breast tomosynthesis(DBT)system.Methods One ionization chamber and three semiconductor dosimeters were exposed by four kinds of beam quality.The signal of each dosimeter was tested over an angular range of 0° to 90°.The dosimeters were exposed for three times at each selected angular position.The measurement at each angle was normalized to the appropriate measurement at perpendicular incidence.Results The responses from all the dosimeters had a maximum at 0° and decreased with increasing angles.When the radiation incidence angle was 10°,the angular dependence were 0.99,0.99,0.96 and 0.96 for dosimeters A,B,C and D,respectively.And the angular dependence decreased to 0.96,1.00,0.78 and 0.52 when the incidence angle was up to 25°.For semiconductor dosimeters,no signal was recorded when incidence angle was beyond 45°.For ionization chamber,the magnitude of the angular dependence generally decreased with increasing energy.Conclusions All of the dosimeters will underestimate the dose if used in DBT.In order to minimize the error due to the rotation angle of X-ray tube,correction factor of mammography dosimeter should be used for the measurement of AGD in DBT systems.

Objective To investigate the expression of hypoxia-inducible factor-1 alpha (HIF-1 α),vascular endothelial growth factor-A (VEGF-A) and vascular endothelial growth factor-D (VEGF-D)in hypoxic environment as well as the relationship between HIF-lα and VEGF-D.Methods Human esophageal cancer cell line EC9706 was cultured under hypoxia environment for 6,12 and 24 h,the cell radiosensitivity was evaluated by survival curve.HIF-1 α siRNA was constructed and transfected into human EC9706 cells.Protein expressions of HIF-1 α,VEGF-A and VEGF-D were analyzed by Western blot before and after RNA interference.Results EC9706 cells under hypoxia showed radioresistance with a SF2 of 0.62 higher than that of normoxic cells of 0.43.Moreover,the protein expressions of HIF-1α,VEGF-A and VEGF-D were all increased (F =205.24,227.88,130.55,P ＜0.05) due to hypoxia treatment.On the contrary,after HIF-1α siRNA transfer,the protein expressions of HIF-1α,VEGF-A and VEGF-D in EC9706 cells were not influenced by hypoxia treatment.Conclusions EC9706 cells in hypoxic environment was radioresistance,and the upexpressions of HIF1α,VEGF-A and VEGF-D may be involved.

Objective To measure the peak skin dose (PSD) in two cardiovascular interventional procedures,including coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA) using radiochromic film.Methods Gafchromic XR-RV3 film was selected to measure PSD in two hospitals.The films were placed on the table underneath the patient during interventional surgery.The kV,mA,fluoroscopy time,dose-area product (DAP),and cumulative dose at reference point and other relevant information were recorded for all cases.Using the Epson V750 flatbed scanner for scanning and analyzing film,FilmQA software was chosen to analyze the pixel value of red,green and blue color channels.The PSD was determined using red channel data.The correlation and linear regression analysis between PSD and device-displayed parameters was carried out.Results PSD were measured using XR-RV3 film for 26 CA and 19 CA + PTCA procedures.For CA procedures,maximum fluoroscopy time,cumulative dose and DAP were 17.62 min,1 498.50 mGy and 109.68 Gy · cm2,respectively.The maximum PSD was 361.20 mGy.However,for CA + PTCA procedures,maximum fluoroscopy time,cumulative dose and DAP were 64.48 min,6 976.20 mGy and 5 336.00 Gy· cm2,respectively.One patient with CA + PTCA procedures was found to have received the PSD value more than 2 Gy,up to 2 195.70 mGy.DAP was found to be a good indicator (R2 =0.815,P ＜0.05) of PSD for CA procedure,and correlated with cumulative dose (R2 =0.916,P ＜ 0.05) for CA + PTCA procedures.Conclusions The PSD value of some patients in cardiac interventional procedures would exceed 2 Gy,the threshold of deterministic effects recommended by ICRP.The dose-related parameters value showed on DSA device can only used to estimate PSD roughly.Using XR-RV3 film accurate measurement of the PSD in interventional projects is a very fast and effective method.

ObjectiveTo observe the lung injury of rats caused by PM2.5 induced imbalance of TH17/Treg immune system and the intervention effect of two different TCM treatments.Methods Wistar male rats were randomly divided into normal group, model group, TCM-treated group1 and TCM-treated group 2. PM2.5-induced lung injury model was established by airway instillation. Model group was given normal saline for gavage. TCM- treated group 1 and 2 were given Yupingfeng Powder and Guomin Decoction combined with Zhisou Powder for gavage. The pathological changes of bronchial and lung tissues, the contents of IL-8, IL-10, IL-17, NE, and MUC5AC in serum and BALF were compared, and the expressions of Foxp3 and IL-17 in lung tissue of each group were analyzed.Results Compared with normal group, the contents of IL-8, IL-17, NE and MUC5AC in serum and BALF of model group increased significantly, while IL-10 decreased significantly (P<0.05,P<0.01); the expression of IL-17 increased significantly and the expression of Foxp3 decreased significantly in lung tissue (P<0.01). Compared with model group, the contents of IL-8, IL-17, and NE decreased in TCM-treated group 1 and 2, while the content of BALF IL-10 increased significantly (P<0.05). The content of IL-10 in serum increased significantly in TCM-treated group 2 (P<0.05); the protein expression of IL-17 of lung issue decreased significantly, and the protein expression of Foxp3 increased significantly (P<0.01). The pathological changes were improved significantly.Conclusion PM2.5 can induce lung injury caused by the imbalance of TH17/Treg. Both two treatments can significantly improve the lung injury induced by PM2.5 and the imbalance of TH17/Tregs immune system.

Objective To evaluate the radiation dose from a dual energy X-ray absorptiometry (DXA) study. Methods A Radcal multifunctional dosimeter (1800 cc ionization chamber, USA) was used, for purpose of comparison, to measure the entrance surface doses (ESD) from Norland XR-800 DXA ( pencil beam scan, 100/46. 8 kVp, 1. 3 mA) and from Hologic Discovery A DXA ( fan beam scan, 140/100 kVp, 5. 0 mA) . Ambient dose equivalent rate at 1 m away from studied phantom center and at 1 m above floor was measured using the US 451P ionizaion chamber survey meter ( Fluke, USA). Results The ESD measured using a Radcal dosimeter for Norland XR-800 DXA was 0. 43 μGy in high speed mode and 0. 73 μGy in standard mode ( AP spine ) , 1. 93 μGy ( hip ) , 0. 40 μGy ( wrist ) and 1. 06 μGy ( mandible) . The ESD measured for Hologic Discovery A DXA was 65. 6 μGy ( AP spine) and 63. 9 μGy ( hip) . The ESD measured for Norland XR-800 at different scan types and scan speeds was <2 μGy while Hologic Discovery A DXA showed a result of <66 μGy ( AP spine and hip scan ) , which were both consistent with the data given in their own respective operational manual. A comparison of DXA scanners with fan beam and pencil beam indicated that ambient equivalent dose rate, measured with 451P survey meter, from fan beam scan was 65 times that from pencil beam scan. Conclusions Compared with other medical X-ray studies, the ESD to the phantom undergoing a DXA study is relatively low. DXA pencil beam scan doses to lumbar spine and hip were about 1/153-1/33 of those from DXA fan beam scan. Pencil beam scan dose to DXA staff was negligible and fan beam scan dose to DXA staff was lower than the personal dose limits of 20 mSv per year.