Objective To develop measurement of reference air kerma for192Ir sources with NE 2570 electrometer,2571 ion-chamber and machining measured holder.Methods The measuring holder was placed at the distance of 1 m from the walls,the floor and ceiling,the ion-chambet was insert into the oolymethyl methacrylate(PMMA)jig of the measuring holder,lhe optimum distance is 16 cm from the source centre to ionchamber centre.The source was transmitted by the afterloding system to the plastic pipe to measure reference air kerma of the source.According to calibration factors from60Coγrays and 250 kV X rays with air exposure to calculated the air kerma calibration factor,the air kerma calibration factor of 192Ir soHree was calculated bv60Co γ rays and the effective energy of the 250 kV X ray beam.The scatter correction factor was giverl by the shadow shield experiment for the wails,the floor,the air and the measuring holder,the correction factors were given for the attenuation of primary photons in air and the electrons entering the air cavity are mainly generated in the innerwall of the chamber by 1079 report in IAEA.Results Two measuring methods were used for192Ir source undersame environment condition,the ion-chatuber and well-type chamber values are 1.584×1011Bq and 1.561×1011Bq respectively,and the relative deviation from them is within 1.4%,Conclusions The air kerma measurement of 192Ir source the ion-chamber with is not depended on the source geometry(point seurce,line source etc),the size.and the material of shell,the shape,the quality of materials and the size of the chamber.The uncertainty error of the air kerma is lessin comparison to the air exposure.

Objective To develop the methods for using 0.015 cc pinpoint chambers, 0.007 cc miniature chambers and diode detector to measure Multi-leaf collimator (MLC) small field in IMRT.Methods MAX4000 and Unidos electrometers were connected with different types of small chambers and diode detectors.MLC shaped fields of10 cm×10 cm, 6 cm×6 cm, 4 cm×4 cm, 3 cm×3 cm, 2 cm× 2 cm were defined at 100 cm SSD.The field sizes for the Varian accelerator were defined by the tertiary MLC, while the secondary jaws were kept at 10 cm × 10 cm field, with the monitor units of 250 MU.Each field was measured three times to obtain the average value.The readings of all small fields were normalized to 10 cm × 10 cm field values for comparison of measured and published output factors.Results The relative deviations of the MLC small field output factors from the published outputs are 1.0％ , 1.7％ , 1.5％ and 2.4％, respectively, for Unidos electrometer connected with 0.015 cc pinpoint chamber;0.2％, 0.8％, 0.8％ and 1.4％, respectively, for Unidos electrometer connected with 0.007 cc miniature chamber;and 0.1％, 0.5％, 0.5％ and 0.9％, respectively, for MAX4000 electrometer connected with 0.007 cc miniature chamber.Conclusions The 0.015 cc chamber-measured MLC output factors for 3 cm × 3 cm and 2 cm × 2 cm fields are excellent.As required by IAEA, the relative deviations of the measured output factor from the published output factor are within ± 2％ for 2 cm × 2 cm fields and ± 3％ for larger fields.The results measured using 0.007 cc chamber are better than those measured using 0.015 cc chamber.The measured results using the diode detector, normalized to the 10 cm × 10 cm field, are consistent with the minimum requirements and excellent when being normalized to the 4 cm × 4 cm field.For dosimetric consideration, MLC small field output factor should be measured using small chamber and diode detector.The method is accurate and reliable, therefore, all measured output factors for MLC small fields should be input into radiation treatment plan system.

Purpose To explore the clinical value of color Doppler ultrasound in monitoring hemodynamic changes in main renal artery of neonatal asphyxia. Materials and Methods A total of 60 cases of neonatal asphyxia were divided into mild asphyxia (38 cases) and severe asphyxia (22 cases) according to Apgar score 1 min after born. Then the peak systolic velocity (Vs), the end diastolic velocity (Vd) and the resistance index (RI) of the main renal artery were obtained by color Doppler ultrasound on day 1 and day 3;the level of endothelin-1 (ET-1) was also recorded accordingly. The above results were compared with those of 20 cases of healthy full-term new born infants. Results On day 1, Vs and Vd of the main renal artery in the groups with mild asphyxia and severe asphyxia were both lower than those in healthy group (P<0.05), but RI was higher (P<0.05), with more dramatic changes in the group with severe asphyxia (P<0.05). On day 3, Vs and Vd in the groups with mild asphyxia and severe asphyxia reduced compared with those on day 1, whilst RI was higher than that on day 1. Vd and RI in the group with severe asphyxia changed more significantly (P<0.01). As to the value of ET-1, both groups with mild asphyxia and severe asphyxia showed higher level than healthy group (P<0.01). More dramatic increase appeared in the group with severe asphyxia (P<0.05). In the groups with mild asphyxia and severe asphyxia, the Vs and Vd of the main renal artery were negatively correlated with ET-1 on day 1 and day 3 (r=-0.823,-0.845;P<0.01), while the RI was positively correlated with ET-1 (r=0.785, P<0.01). Conclusion Both color Doppler ultrasound imaging and neonatal urine ET-1 test can reflect degree of renal injury after neonatal asphyxia dynamically and noninvasively, which can be used to evaluate the injury severity.

Objective To verify the reliability of TLD-based quality audit for radiotherapy dosimetry of medical electron accelerator in non-reference condition by monitoring the dose variations from electron beams with different field sizes and 45° wedge and the dose variations from photon beams with different field sizes and source-skin distance.Methods Both TLDs and finger ionization chambers were placed at a depth of 10 cm in water to measure the absorbed dose from photon beams,and also placed at the depth of maximum dose from electron beams under non-reference condition.TLDs were then mailed to National Institute for Radiological Protection,China CDC for further measurement.Results Among the 70 measuring points for photon beams,58 points showed the results with a relative error less than ± 7.0％ (IAEA's acceptable deviation:± 7.0％) between TLDs and finger ionization chambers measurements,and the percentage of qualified point numbers was 82.8％.After corrected by P,value,62 points were qualified and the percentage was up to 88.6％.All of the measuring points for electron beams,with the total number of 24,presented a relative error within ± 5.0％ (IAEA's acceptable deviation:± 5.0％) between TLDs and finger ioization cylindrical chambers measurements.Conclusions TLD-based quality audit is convenient for determining radiotherapy dosimetric parameters of electron beams in non-reference condition and can improve the accuracy of the measuring parameters in connection with finger chambers.For electron beams of 5 MeV ＜ E0 ＜ 10 MeV,the absorbed dose parameters measured by finger ionization chambers,combined with TLD audit,can help obtain the precise and reliable results.

Objective To develop a methodology for auditing dosimetric parameters using TLD for photon and electron beams in non-reference conditions.Methods The correction experiments have been developed for non-linear dose response,PAAM holder,energy,fading and dispersion using TLD for 60Co γ-ray,high energy X-ray and electron beams.The measuring method was set up for absorbed dose estimation by TLDs in water.3 photon beams and 2 electron beams were selected for research purposes,and 5 photon beams and 4 electron beams for reliability research.Results The research results were evaluated for60Co source,6,10,15 and 18 MV photon beams in non-reference conditions at off-axis,with the relative deviation within-0.1％-7.2％ at-off axis (IAEA's acceptable deviation:± 7.0％).The verification results were evaluated for 5 photon beams in non-reference conditions at on-axis,with the relative deviation are within 0.1％-7.0％.The verification results were evaluated for 4 electron beams in non-reference conditions,with the relative deviation within 0-4.7％ (IAEA's acceptable deviation:±5.0％).Conclusions It is convenient and accurate to use TLD method for quality audits for clinic dosimetry parameters in radiotherapy.Two kinds of IAEA TLD holders are feasible for use in TLD audits.Absorbed doses for high energy electron beam were corrected using plane parallel chambers and verified using TLD,with good results obtained.

Objective To reconstruct three-dimensional (3D) image of heart and coronary artery on internet and explore the reliability. Methods After the contrast medium was injected into coronary artery of 2 heart specimens, hearts were scanned by UFCT with enhancement volume. One patient's UFCT images of coronary artery angiography were also chosen.Then the primitive images were transposed format, removed noise, specified interesting areas. 3D software on server was applied to reconstruct heart and coronary artery. Results The reconstructed 3D images of the heart and coronary artery were realistically displayed, freely rotated and transected.Main parts and branches of coronary artery were similar to those in the images of the UFCT. Conclusion Heart and coronary artery can be reconstructed on internet,which offers a new approach for reconstructing organs and tissues of human being.;

Objective To facilitate activity measurement by using the thimble ionization chamber in hospitals,to obtain air kerma scatter correction factor of medical afterloading of 192Ir source by developing an available and convenient calculation method.Methods According to International Atomic Energy Agency (IAEA) 1079 Report to calculate the scatter correction factor of 192 Ir source,to measure air kenna of 192Ir source with and without lead shield using thimble ionization chamber.Simulation measurement conditions were used to calculate scatter correction factor of 192Ir source and comparison was made between experimental results and literature records.At the same time,the different ionization chamber models were simulated at different room sizes to obtain scattering correction factor of 192 Ir source.ResultsComparison was made between the simulation scatter correction factors of 192Ir source and experiment by the shadow shield,and the relative deviation was 0.8%.The deviation of the 192 Ir activity calculated according to the simulated scatter correction factor and measured by well type ionization chamber was 2.4%.By comparison between the calculated results by using two kinds of spherical ionization chamber and those ones deduced by IAEA 1079 Report,the relative deviations ranged within 0.3%-0.4%.Five different types of thimble ionization chamber and different room sizes were simulated and calculated by MC simulation,with the relative deviation within 3%.Conclusions Monte Carlo simulation method for calculating afterloading 192 Ir source's scatter correction factor is feasible,and this method is convenient for use in the thimble chamber for brachytherapy QA work in the hospital.

Objective To study the method of measuring air kerma strength of afterloading units with 192Ir source by using well type ionization chamber.MethodsThe air kerma strength of 30 afterloading units with 192Ir source was measured using 2000A electrometer and 1000 plus well type ionization chamber,and apparent activity of the source was calculated with the air kerma strength and apparent activity conversion factor.The measured activity of the source was compared with the original value of the source provided by the manufacturer,and the relevant deviation should be within ± 5%.Results Theair kerma strength of afterloding units with 192Ir sources was tested.The relevant deviation of the measured activity and the original value was within -0.1%-4.4%.Conclusions The measurement method with a well type ionization chamber is convenient and highly accurate which can be used for the test of quality control in hospitals.

Objective To explore the method for measuring and calculating both absorbed dose and effective dose received in organ and tissues of occupational workers by using TLDs for the implantation of 125Ⅰ seed sources.Methods The experiments with 60Co γ-rays were carried out for the stability.A group of TLD chips was exposed to 125Ⅰ seed sources to establish standard dose curve for air kerma.During the 125Ⅰ seed implantation, the TLD chips were pasted to 13 locations like thyroid inside and outside the lead aprons worn by occupational workers to measure average absorbed dose and calculate the absorbed doses and effectives to organs and tissues.Results For 3 cases of prostate cancers with implantation of 125Ⅰ seeds, the worker's organs and tissues received the absorbed dose 0.02 -3.80 μ Gy and effective dose 0.06- 1.81 μSv outside lead aprons and the highest absorbed dose 2.35 μ Gy and effective 0.02 μSv inside lead aprons, respectively, with more than 65.9% of rays shielded.For 3 cases of brain cancers with implantation of 125Ⅰ seeds, the workers received the absorbed dose 0.23 - 11.31 μGy and effective dose 0.88 - 4.07 μSv outside lead aprons and the highest absorbed dose 2.22 μ Gy and effective dose 0.09 μSv inside lead aprons, respectively, with more than 54.5% of rays shielded.For 3 cases of lung cancers with implantation of 125Ⅰ seeds, the workers received the absorbed dose 0.03 - 14.78 μGy and effective dose 0.35 -7.59 μSv outside lead aprons and the highest absorbed dose 4.09 μGy and effective 0.22 μSv inside lead aprons, respectively, with more than 58.4% of rays shielded.For 2 cases of mediastinum cancers with implantation of 125Ⅰseeds, the workers received the absorbed dose 0.06 - 74.91 μGy and effective dose 0.83 - 17.96 μSv outside lead aprons and the highest absorbed dose 10.29 μGy and effective 0.5 μSv inside lead aprons, respectively, with more than 85% of rays shielded.For one case of ovary cancer with implantation of 125Ⅰ seeds, the worker received the absorbed dose 0.09 - 14.29 μGy and effective dose 2.40 - 4.50 μSv outside lead aprons and the highest absorbed dose 7.77 μGy and effective 0.12 μSv inside lead aprons, respectively, with more than 34% of rays shielded.For one case of eye cancer with implantation of 125Ⅰ seeds, the workers received the absorbed dose 2.2 -39.84 μGy and effective dose 4.48 - 10.06 μSv outside aprons and the highest absorbed dose 5.19 μGy and effective 0.16 μSv inside aprons, respectively, with more than 54.6 % of rays shielded.Conclusions The method of using TLDs to measure the doses to the occupational workers in the course of the implantation of 125Ⅰ seed sources is simple and easy to operate.It would be an effective approach to protecting medical workers in the case of brachytherapy.

Objective To observe the levels of Livin and Caspase-3 in renal tissue of rats following acute paraquat (PQ) poisoning and the intervention effects of ulinastatin (UTI) . Methods Fifty-four Sprague-Dawley (SD) rats were randomly divided into three experimental groups: control group (group A),PQ poisoning group (group B) and UTI group (group C) (n = 18 in each group) . Rats in group B and group C were administered intragastrically with 80 mg/kg PQ, and rats in group C were treated with 100,000U/kg ulinastatin injected intra-psritoneally once a day; and rats in group A were administered intragastrically with the same volume of saline instead of PQ. At 24, 48, 72 hours after poisoning, the levels of Livin in renal tissue were detected by Westen blotting and the levels of Caspase-3 were detected by immunohistochemistry 24, 48, and 72 hours after poisoning, and the histopathological changes of renal tissue were observed at the same time. Results In the group A, the structure of renal tissue was distinct. In the group B, the distinctness of the structure of renal tissue declined significantly, and swelling, edema and vacuolar degeneration were observed 24 h after poisoning, and pathological changes became more and more obvious keeping pace with time elapsing, and sometimes karyopyknosis appeared and celluar structures disappeared with involvement of renal glomerulus and medulla. These pathological changes were significantly lessened in rats of group C. In the group A, there was little Caspase-3 in renal tissue of rats. Twenty-four hours after poisoning, the caspase-3 in renal tissue of rats of group B was found on the membrane and in the kytoplasm of renal tubular epithelial cells of cortical part. Compared with group B, the level of Caspase-3 in renal tissue of rats of group C decreased significantly to lower level (P ＜0. 01 ) . Compared with group A,the levels of Livin in renal tissue in rats of group B and group C increased significantly at all different intervals (P ＜0. 01 ), and as group B was compared with group C, the difference was statistically significant (P ＜0. 01 ) . Conclusions The main pathologyical changes of renal injury induced by PQ are epithelial swelling, vacuole degenerateion and necrosis. Caspase-3 is involved in the process of renal injury. UTI has a protective effect on the renal tissue of rats following paraquat poisoning through up-regulating the level of Livin and down-regulating the level of Caspase-3, however, the regulation mechanism as well as the pathway is still needed to further study.