1.Development of measurement methodology with reference air kerma of 192Ir source afterloding in bracytherapy
Suming LUO ; Zhijian HE ; Lei GAO
Chinese Journal of Radiological Medicine and Protection 2008;28(4):398-400
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.
2.Experience of management of 21 cases enteric fistula after surgery
Suming LUO ; Peng LI ; Qian ZHANG
International Journal of Surgery 2017;44(5):324-327
Objective To review the causes of 21 cases of exteric fistula after surgery,treatment and prognosis,and to explore the clinical treatment of exteric fistula after surgery.Methods To collection the Xinjiang Uygur Autonomous Region People's Hospital of Gastrointestinal Surgery from Aug 2013 to Aug.2016 admitted during the period of parenteral fistula patients after abdominal surgery,21 patients with intestinal fistula outside,12 cases were male,9 were female cases.According to the case records of descriptive statistics,the treatment methods was summarized and analyzed retrospectively.Results Au patients with intestinal fistula outside,12 cases were male,female 9 cases.Conservative treatment of 11 cases,healing in 2 cases,5 cases,4 cases died and the sigmoid colon perforation repair 1 case,postoperative ileus postoperative renal function failure in 1 case,gastric cancer by intraperitoneal hemorrhage after early postoperative restrictive ploration in 2 cases;Early surgical treatment of 10 cases,of which the deterministic operation in 1 case,late deterministic surgery in 9,were cured.Conclusions The early diagnosis of parenteral fistula and rapid processing,taken on the basis of the condition of the patients with timely complete drainage,infection control,reasonable nutrition support and correct homeostasis imbalance as the main content of a comprehensive individualized treatment,most patients can improve the self-healing,cannot heal patients to choose the appropriate surgical timing and proper operation method,can improve the cure rate and reduce the case fatality rate.
3.Development of measurement method using TLD for workers occupation personally exposed to 125Ⅰ seed source in the implant
Suming LUO ; Zhijian HE ; Jilong YUAN ; Baorong YUE ; Kedao WEI
Chinese Journal of Radiological Medicine and Protection 2011;31(4):398-403
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.
4.Development on Monte Carlo methodology with scatter correction factor of afterloading 192Ir source
Jilong YUAN ; Suming LUO ; Zhijian HE ; Lei GAO
Chinese Journal of Radiological Medicine and Protection 2011;31(1):79-82
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.
5.Evaluation and test of 192Ir air kerma strength for afterloading systems
Suming LUO ; Zhijian HE ; Lei GAO ; Baorong YUE
Chinese Journal of Radiological Medicine and Protection 2011;31(1):76-78
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.
6.Verification of dosimetric methodology for auditing radiotherapy quality under non-reference condition in Hubei province
Xinxing MA ; Suming LUO ; Zhijian HE ; Wenshan ZHOU
Chinese Journal of Radiological Medicine and Protection 2014;34(6):461-465
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.
7.Development of methodology for auditing dosimetric parameters for photon and electron beams under non-reference conditions
Suming LUO ; Zhijian HE ; Kaibao LI ; Xian XUE
Chinese Journal of Radiological Medicine and Protection 2014;34(6):441-445
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.
8.Progress of phage display technology in cancer
Junqian LUO ; Suming DONG ; Fan ZHANG ; Xiaofeng YANG
Journal of International Oncology 2015;(10):759-761
Phage display technology describes a genetic engineering technique in which a library of peptide or protein variants is expressed on the outside of a phage virion,while the genetic material encodes each variant resides on the inside and maintains the relatively independent spatial structure and biological activity. Studies have shown that the phage display technology can be used to screen tumor homing peptides,target trans-porting anti-substances,develop vaccines,research diagnostic regents and image in blood vessels.Thus phage display technology is a powerful method to overcome the challenge of tumor disease.
9.Development of the measurement method for MLC small field output factor in intensity modulated radiation therapy (IMRT)
Suming LUO ; Hao WU ; Zhijian HE ; Xian XUE ; Yanqiu DING
Chinese Journal of Radiological Medicine and Protection 2015;35(10):775-779
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.
10.Methods of verification and measurement of MLC-defined small field output factors for eight medical accelerators in Henan province
Xiaojun CHENG ; Chuanpeng HU ; Chenzhi JIA ; Suming LUO ; Hao WU
Chinese Journal of Radiological Medicine and Protection 2015;35(10):780-783
Objective To investigate muli-leaf collimator (MLC)-defined small field output factors calculated by the treatment planning system (TPS), and to study the measuring method of small field output factors verified by 0.015 cc PinPoint ionization chamber.Methods Eight medical accelerators for intensity-modulated radiation therapy (IMRT) were investigated in Henan province, and TPS-calculated output factors for various small fields (6 cm ×6 cm,4 cm ×4 cm,3 cm ×3 cm and 2 cm ×2 cm) were compared with published values recommended by IAEA.If the relative deviation was more than ± 3% for the 2 cm ×2 cm field size and ±2% for the fields of 6 cm ×6 cm, 4 cm ×4 cm and 3 cm ×3 cm, which was beyond the scope of IAEA allowed, the output factors will be measured and verified using 0.015 cc PinPoint ionization chamber and Unidos electrometer.Results TPS-calculated small field output factors for eight medical accelerators were compared with published values.The relative deviation of small field output factors for five pieces of equipment, which accounted for 62.5% of the total, met the IAEA's requirement, while the other three, which accounted for 37.5% of the total, did not.After measuring with PinPoint ionization chamber, the results from only three pieces of equipment met minimum IAEA's requirement.Conclusions MLC-defined small field output factors calculated by TPS for some medical accelerators in Henan need to be measured and corrected using micro-ionization chamber, and the measured values could be taken as the basis of radiation treatment planning.