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 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 evaluate the efficacy and adverse effects of the three dimensional conformal radia- tion therapy(3D-CRT) concurrently combined with chemotherapy for limited stage small cell lung cancer(LSCLC). Methods 33 patients with LSCLC received 6 cycles EP(cisplatin,etoposide) chemotherapy and 3 weeks was a cy- cle. The conventional radiotherapy was given after the first cycle chemotherapy or the third cycle chemotherapy, then the 3D-CRT and the total dose of the primary tumor was 45Gy per 3 weeks,1.5Gy for once,twice for a day. Results Toxicity was durable in 33 patients received 3D-CRT concurrently combined with chemotherapy. The total re- sponse was 97 %. Median time was 21.9 months, and the 1-,2-, 3-year survival rates was 69.7 % ,51.5 %, 30.3 %. The 1-,2-, 3-year local progress ion-freely survival rates were 66.7 %, 45.5 %, 30.3 %, respectively, with the median local progression-freely survival time of 18.5 months. Respectively during three year follow-up visit. Conclusion The 3D-CRT concurrently combined with chemotherapy for patients with limited stage small cell lung cancer could be more effectively, and the patients could tolerate the side effects, this therapy method was secure and received.

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.

BACKGROUND: Quite a number of in vitro experiments indicate that low dose He-Ne laser can stimulate the cell growth and blood vessel regeneration therefore to improve the damages caused by ischemia. However, it needs further study on the in vivo experiments.OBJECTIVE: To study the protective effects of intravascular low dose laser irradiation to ischemic reperfusion of rats and explore its mechanism.DESIGN: A randomised and controlled trial based on experinental animals.SETTING: Department of Neurology of a hospital of a university.MATERIALS: The experiment was completed in the Surgery Experimental Animal Center of West China Hospital of Sichuan University. Healthy male SD rats of class Ⅱ which aged between 5 to 6 months with weight of 372 to 418 grams[mean weight(388.48 ± 10. 57) g] were provided by Animal Research Center of Sichuan University.INTERVENTIONS: Middle cerebral artery ischemia model of rats was prepared. Forty SD rats were randomly divided into treatment group and control group with each of 20 rats. Intravascular low dose He-Ne laser irradiation was conducted to rats in treatment group one time every other day, 20 minutes per time and 3 times for a course. Vein puncture was conducted to rats in control group without laser input.MAIN OUTCOME MEASURES: Ratio of infarcted volume RESULTS: The ratio of the cerebral infarction volume in treatment group was (10.43 ± 1.04) and is much lower than that of control group(16.78 ± 1.12).There was statistical difference between two groups( t = 27.14, P ＜ 0.05).CONCLUSION: Intravascular low dose He-Ne laser irradiation has protective effects to cerebral ischemia of rats.

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.

The femora! arteries in 38 rabbits were transected and repaired with autogenous venous grafts with different diameters. The measurements of blood flow, patency rate and thrombosis rate, and scanning electron microscopic examination were made over a period of 14 days. The result showed that a venous graftl with a diameter 20 per cent less than that of the recipient artery was most satisfactory.

Objective To evaluate the curative effect and optimal indications of reformed percutaneous lumbar diskectomy (RPLD) for the treatment of lumbar disc herniation.Methods One handred and thirty-three patients with lumbar disc herniation were treated by RPLD, of them, 20 cases were lumbar disc extrusion and 113 cases were lumbar disc protrusion. After the procedure, 85 patients underwent flush of intervertebral space with antibiotic saline and 48 patients underwent 10 ml(40?g/ml) medical ozone-injection inside the disc to prevent infection. All patients were followed up over the course of 3 months. The therapeutic effect was evaluated according to the MacNab criteria. Results All 133 cases underwent RPLD were successful. The total efficacy was 81.9%, There were no serious complications after operations. Conclusion RPLD is an effective method in the treatment of lumbar disc herniation. Both intradiscal ozone-injection or intradiscal antibiotic saline flush after RPLD can reduce the opportunity of infection.

Purpose To observe the effect of Rongban Tongmai Granules on thrombosis and blood viscosity of in vitro rat model of blood stasis, and to study the activating blood circulation effect of the drug.Methods To observe the effect of the Rongban Tongmai Granules on thrombosis and blood viscosity of in vitro rat model of stasis, subcutaneous inject rat with epinephrine hydrochloride, and then copy "blood stasis" model by ice water stimulation in rats.Results According to a continuous 7 days′intragastric administration of Rongban Tongmai Granules, thrombus length of blood stasis model rats in vitro reduced significantly (P<0.05-0.01),wet and dry weight of thrombus reduced significantly (P<0.05), the shear rate of the whole blood viscosity under 100 S~(-1), 30 S~(-1), 5 S~(-1) decreased significantly as well (P<0.05-0.01), and the shear rate of whole blood viscosity had decreasing tendency under 200 S~(-1).Conclusion Rongban Tongmai Granules can inhibit thrombosis and lower blood viscosity.