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 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 investigate the safety,efficacy of CO2 insufflations during ERCP.Methods One hundred and forty eligible patients who underwent ERCP in Fuzhou General Hospital of Nanjing Military Command from January to December 2012 were randomized according to random digits in a double blind manner to receive either CO2 insufflations or air insufflations (65 vs 75).The patient's experience of abdominal pain and distension at 1 h,2 h,6 h and 24 h post-ERCP were evaluated by visual analogue scale (VAS).The heart rates,blood pressure,SpO2,PaCO2 were recorded before,during,after ERCP,and 24 h after the examination.Plain abdominal radiographic images were collected to show abdominal distention before and after ERCP,waist circumference,operative time,recovery time,intraoperative and post-ERCP complications were also determined.Results Post-ERCP the VAS of abdominal pain at 3 h was (4.08 ± 1.36) in CO2 group,which was significantly lower than that in air group [(4.59 ± 1.66),P ＜ 0.01].The VAS of abdominal distension at 1 h,3 h,6 h after ERCP were(1.78 ± 1.90),(0.72 ± 1.15),(0.12 ±0.45),which were significantly lower than those in air group [(3.53 ± 2.71),(2.51 ± 2.04),(0.84 ± 1.24),P ＜ 0.05] ; the intraoperative SpO2 was (93.29 ± 1.40)％,which was significantly lower than that in air group [(93.52 ± 1.06) ％,P ＜ 0.01].The waist circumference at 1 h after ERCP increased by (2.48 ± 1.33)cm,which was significantly lower than that in air group [(3.56 ± 2.13) cm,P =0.00).Recovery time was (11.2 ± 2.5) rain in CO2 group,which was significantly longer than that in air group [(9.7 ± 1.7) min,P =0.00].And the difference between the two groups was statistically significant.The plain abdominal radiographic images showed the degree of bowel distension was severer in air group than that in CO2 group (P =0.04).Conclusions CO2 insufflations are safe and efficacy during ERCP.CO2 can better alleviate abdominal pain and distension than air.

Objective To investigate the preventive effect of somatostatin and nitroglycerin on post-ERCP pancreatitis (PEP) and hyperamylasemia.Methods A total of 184 patients who underwent endoscopic retrograde cholangiopancreatograph (ERCP) were enrolled,and randomly divided into three groups to receive somatostatin or nitroglycerin or normal saline according to random number table.Incidence of PEP and hyperamylasemia were observed and compared among the three groups.Results Nine patients stopped the medication and dropped out of the study after occurence of adverse reactions from receiving nitroglycerin injections.The incidence rates of hyperamylasemia were 38.7％ (24/62),51.8％ (28/54) and 37.3％ (22/59) in somatostatin,nitroglycerin and control group respectively,with no significant differences among the three groups (P ＞ 0.05).The incidence rates of PEP were 6.4％ (4/62),9.3 ％ (5/54) and 23.7％ (14/59) in somatostatin,nitroglycerin and control group,respectively.The incidence rates of PEP in somatostatin and nitroglycerin group were both significantly lower than that in control group (somatostatin group vs control group:x2 =7.13,P =0.01 ; nitroglycerin group vs control group:x2 =4.22,P =0.03).There was no significant difference between somatostatin group and nitroglycerin group (x2 =0.32,P =0.41).Conclusion Somatostatin and nitroglycerin injections after ERCP show similar efficacy on preventing PEP,but the former is safer.Both have little effects on the prophylaxis of hyperamylaemia.

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.

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.

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 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.