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Tumor radiotherapy is established on the basis of clinical oncology, radio-physics and radiobiology, and has become one of the three major therapeutic methods for malignant tumors. With the pace of socialist construction in China, the subject of radiotherapy in Shanxi province has developed from scratch and from small to large for more than 60 years. Remarkable achievements have been made in the establishment of departments, the updating of technical equipment, the increase of employees and clinical scientific research. This article reviews and summarizes the development history of tumor radiotherapy in Shanxi province.
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Succinic acid is a high value-added organic acid widely used in food, chemical and pesticide industries. As a new robust non-conventional yeast, Yarrowia lipolytica attracts more and more attention due to its potential for industrial applications. Previously, we obtained a succinic acid-producing strain through gene deletion of succinic acid dehydrogenase subunit encoding gene Ylsdh5, resulting in the strain of PGC01003. However, the recombinant strain produced large amount of acetic acid due to imbalance between glycolysis and TCA cycle which hindered the efficient production of succinic acid. PDH bypass was interfered to decrease the overflow of acetic acid and produce succinic acid under natural pH. Acetic acid was reduced to 4.6 g/L through heterologous expression of acetyl coenzyme A synthase from Salmonella enteric, which was 75.4% of the control strain. Deletion of CoA-transferase gene Ylach1 eliminated acetate formation and improved succinic acid production, and the resulting strain produced as high as 7.0 g/L succinic acid. Our study provides foundation for further construction of efficient cell factory of succinic acid production.
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Objective To evaluate the influences of various field-defining method of Varian accelerator on radiation dosimetry parameters, and provide theoretical basis for the beam modeling of the treatment planning system ( TPS ) . Methods The percentage depth dose ( PDD ) , the off-axis ratio ( OAR ) and the total scattering factors ( Scp ) of radiation fields were measured in three different conditions, including collimators (JAW), multileaf collimator(MLC) and JAW +MLC. The measured data was analyzed and compared with each other. Results The PDD of central axis was marginally influenced by three field-defining method. In both directions, the MLC-defined field sizes were larger by a maximum of 2. 9 mm ( left-right) or 1. 7 mm ( gun-target) than the JAW-defined ones. In the left-right direction, the width of field penumbra shaped by MLC was larger than the field of the same size as defined by JAW. The result of gun-target direction was to the contrary. In both directions, the field penumbra and size displayed no significant differences as defined by JAW+MLC or JAW. Conclusions The field size, penumbra width, and the total scattering factors were influenced by field-defining method, which indicates that special attention should be paid to the dosimetric parameters of MLC during TPS beam modeling for IMRT planning.
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Objective To evaluate the influences of various field-defining method of Varian accelerator on radiation dosimetry parameters, and provide theoretical basis for the beam modeling of the treatment planning system ( TPS ) . Methods The percentage depth dose ( PDD ) , the off-axis ratio ( OAR ) and the total scattering factors ( Scp ) of radiation fields were measured in three different conditions, including collimators (JAW), multileaf collimator(MLC) and JAW +MLC. The measured data was analyzed and compared with each other. Results The PDD of central axis was marginally influenced by three field-defining method. In both directions, the MLC-defined field sizes were larger by a maximum of 2. 9 mm ( left-right) or 1. 7 mm ( gun-target) than the JAW-defined ones. In the left-right direction, the width of field penumbra shaped by MLC was larger than the field of the same size as defined by JAW. The result of gun-target direction was to the contrary. In both directions, the field penumbra and size displayed no significant differences as defined by JAW+MLC or JAW. Conclusions The field size, penumbra width, and the total scattering factors were influenced by field-defining method, which indicates that special attention should be paid to the dosimetric parameters of MLC during TPS beam modeling for IMRT planning.
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Objective To study how to design the treatment plan to reduce the influence of respiratory movement and the dose of heart and lung as few as possible,to improve the dosage distribution in the target area after radical mastectomy of breast cancer.Methods Twelve patients with breast cancer after radical mastectomy were selected.A dose of 50 Gy with 2 Gy every day and 5 times per week was prescribed.Based on the treatment planning system (TPS),4-field intensity modulated radiotherapy (4FIMRT) and hybrid intensity modulated treatment planning 2-field conformal radiotherapy (2FCRT) + 4FIMRT were designed respectively.The two plans were compared from the aspects of target conformity index (CI),the homogeneity index (HI) and exposure dose volume delivered to organ at risk.Results According to the hybrid plan of 2FCRT + 4FIMRT,HI was 1.08±0.01,which was superior to that from 4FIMRT (1.11±0.01,t =9.587,P ＜ 0.05).While CI was 0.74±0.08,based on the plan of 2FCRT+4FIMRT,which was slightly lower than that from 4FIMRT (0.80±0.03,t =2.497,P ＜ 0.05).Considering the dose volumes on ipsilateral lung in two plans,the values of V5,V10,Dmean of 2FCRT+4FIMRT plan were significantly less than those of 4FIMRT plan.V5,V10,Dmean from the former plan were 13 ％,23 ％,7 ％ less than those from the latter plan (t =6.002,P ＜ 0.05;t =6.826,P ＜ 0.05;t =3.645,P ＜ 0.05).Meanwhile,Dmean of contralateral lung,Dmean of heart,Dmean and V5 of contralateral breast from the 2FCRT +4FIMRT plan were all lower than those of 4FIMRT plan.Those differences between two plans were statistically significant (P ＜ 0.05).Differences of V20 and V30 of ipsilateral lung,and V30 of heart between two plans did not make sense by the statistics analysis (P ＞ 0.05).Conclusion Hybrid radiotherapy theoretically reduces the influence of respiratory movement,improves the uniformity of target dose and lowers the risk of complications of radiation therapy on breast cancer.
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Objective To explore the influence of dose rate reference control level on the design of accelerator shielding.Methods According to the standards of GBZ 126-2011,GBZ/T 201.1-2007 and GBZ/T 201.2-2011,two different shielding calculation methods,based on the dose rate reference control level and week dose control level,were used to calculate and compare the thickness of accelerator room shielding.Results Under the same condition of maximum weekly workload,the obtained results were different when the calculated dose rate reference control value was larger than dose rate reference control level (2.5 μSv/h).The maximum difference of shielding thickness reached 64 cm.Meanwhile,considering dose rate reference control level,the different accelerator rates could lead to different radiation shielding thickness.Conclusions The dose rate at reference point must be first calculated before calculating shielding thickness.The calculation should be made on the premise that dose rate reference control level is met.
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Objective To investigate the feasibility and potential advantages of RapidArc applied to the radiotherapy of the postoperative rectal cancer.Methods 8 postoperative patients with rectal cancer were selected to be treated with a dose of 50Gy in fraction of 2Gy every time and 5 times a week.IMRT and RapidArc were used respectively to compare different target conformities,homogeneity index,dose-volume histogram data,treatment times and monitor units.Results The conformal index by RapidArc was 0.89±0.02 which was better than those by 5F-IMRT,0.87±0.02 (t =3.286,P ＜ 0.05),while the homogeneity index of target volume (1.060±0.005) and average dose [(52.55±0.76) Gy] by RapidArc were a little less than the homogeneity index of target volume (1.064±0.007) and average dose [(52.90±0.82) Gy] by 5F-IMRT (t =-1.459,-1.000,P ＞ 0.05).The exposure dose and mean dose of bladder and small bowel in high dose region by RapidArc were lower than those by 5F-IMRT,as well as bone marrow.The differences were statistical significant (P ＜ 0.05).The monitor units by RapidArc and by 5F-IMRT were (631±68) MU and (1046±146) MU,respectively (t =-5.830,P ＜ 0.05),while the mean treatment times were (78±5) s and (348±29) s,respectively (t =-26.358,P ＜ 0.05).Conclusion Compared with 5F-IMRT,RapidArc improves the target conformities and lowers the exposure dose for the organs at risk in high dose region while using fewer monitor units and less treatment time,which helps comforting patients and improving the efficiency.
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Objective To compare the dosimetric differences between two plans of RapidArc and 5F-IMRT for breast cancer radiotherapy after breast-conserving surgery.Methods Eight female patients with left-sided breast cancer after breast-conserving surgery were selected.A dose of 50 Gy in 25 fractions was prescribed for plans of RapidArc and 5F-IMRT.Target conformity index (CI),homogeneity index (HI),target coverage,exposure dose volume delivered to organ at risk were compared between two plans.At the same time,treatment delivery time and monitor units (MU) were also compared.Results The target conformity index (CI) in RapidArc plan (·0.88 ±0.03) was higher than that in 5F-IMRT plan (0.79 ±0.02,t =8.28,P ＜ 0.05).The homogeneity index (HI) in RapidArc plan 9.01 ± 0.73 was significantly lower than that in 5F-IMRT plan10.44 ± 1.08 (t =-2.73,P ＜0.05).For the dose volume delivered to the ipsilateral lung in two plans,the values of V10,V20,V30,and Dmean in RapidArc plan were lower than those in 5F-IMRT plan(t =-7.53,-7.20,-8.39,-7.80,P ＜ 0.05).However,the value of V5 in RapidArc plan was higher than that in 5F-IMRT plan (t =5.67,P ＜0.05).For the heart,the values of V5,V10 and Dmean in RapidArc plan were higher than those in IMRT plan(t =10.46,28.76,5.40,P ＜ 0.05),while the value of V30 in RapidArc plan was lower than that in 5F-IMRT plan(t =-6.12,P ＜0.05).The values of V5 in contralateral lung and breast were higher in RapidArc plan than those in 5F-IMRT plan(lung:t =21.50,P ＜0.05;breast:t =5.44,P ＜0.05).The MU in RapidArc plan was decreased by 25％,and the average treatment delivery time was saved by 60％,compared with that of 5F-IMRT plan.Conclusions During breast cancer radiotherapy after breast-conserving surgery,compared with 5F-IMRT plan,the RapidArc plan could improve the target HI,and reduce both the irradiated dose in high-dose volume and MU,and shorten the treatment time,but increased the exposed volume in low-dose volume of normal tissues.
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ObjectiveTo compare the accuracy of enhanced dynamic wedge (EDW) models of adaptive convolution algorithm (ACA) in Pinnacle3 9.0 and anisotropic analytical algorithm (AAA),and pencil beam convolution (PBC) algorithms in Eclipse7.3 treatment planning systems (TPS).MethodsTo evaluate the accuracy of the three algorithm models,we compared actual measurement values with TPS calculation values of EDW wedge factors under for different fields in which Varian-21EX 6 MV X-ray was applied,and also compared the actual dose distribution profile with that of TPS.ResultsThe deviations of EDW wedge factors of symmetry fields and asymmetric fields are within 2.8％ and 19.4％ for ACA in Pinnacle3 9.0.Meanwhile,the deviations are 1.0％ and 2.0％ for AAA,1.2％ and 3.0％ for PBC in Eclipse7.3.The deviations between measurement and calculation of all fields profile for ACA is within 3％ and within 2.7％ for AAA within 4.0％ for PBC in wedge direction.For the dose distributions,we evaluated the pass rates of three algorithms using gamma analysis.The gamma pass rates among all the three algorithms in symmetry and asymmetric fields are above 87％ and 85％ respectively.After the removal of the penumbra zone,the pass rates among all the three algorithms are above 96％ in symmetry fields,and above 95％ in asymmetric fields,respectively.Conclusions AAA and PBC algorithms in symmetric and asymmetric fields can meet the need of clinical applications.While,wedge factor of ACA should not be used in clinical due to its greater error in asymmetric fields.
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Objective To analyze the difference of irradiation dose and volume of organs at risk (OAR) particularly in small intestine between supine position and prone position on intensity-roodulated radiotherapy(IMRT) for cervical cancer. Methods 11 patients with Ⅱ_B-Ⅲ_B cervical cancer were scanned with supine position and prone position by CT.The CT images were transported to TPS,then target volumes were delineated and the IMRT plans were designed respectively.The prescribed dose was 95%PTV receiving 45 Gy in 23 fractions of 2 Gy.The exposure volumes of the OAR at different position and different dose levels in the dose volume histograms (DVH) were compared and analyzed.Results When tlle dose di8tributions met to the clinic request,the exposure volumes of small intestine at prone position were redueed than that at supine position in dose range 46-30 Gy(P<0.05),but this phenomenon Was not distinct in low dose range(< 20 Gy)(P>0.05).The exposure volumes of bladder, rectum, femur head and spine cord were no obviously differences at dissimilar position. Conclusion IMRT of cervical cancer should adopt prone position.because their small intestine will be protected better.
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Objective To compare the differences of target-volume(PTV) coverage and organ at risk (OAR) protection between three dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy(IMRT) for patients with pelvis metastasis of cervical cancer underwent radical hysterectomy and pelvic lymphadenectomy. To explore the optimal treatment methods for pelvis metastasis of cervical cancer.Methods 10 patients with pelvis metastasis of cervical cancer underwent radical hysterectomy and pelvic lymphadenectomy were selected for this study. The images scanned by CT were transferred to treatment planning system to generate 3DCRT and IMRT plans. The impacts of 3DCRT on PTV were compared with those of IMRT. Isodose line and dose volume histograms(DVH) were used to evaluate to the dose-distribution in PTV and OAR. Results For 95 % confidence interval, the margin from CTV to PTV was 1 cm. Conformal indexs (CIs) of PTV for 3, 4, 5 and 6 fields 3DCRT were 0.46, 0.67, 0.68 and 0.68, respectively. When beyond 4 fields, the advantage of adding fields was not significant. CIs of PTV for 5, 7, 9, 11 and 13 fields IMRT were 0.75, 0.83 0.84, 0.85 and 0.85, respectively. When beyond 9 fields, the advantage of adding fields was not significant. The maximum dose of the bowl and spine cord in IMRT plans were lower than that in the 3DCRT plans (P <0.05). Maximum dose of OAR had no significant differences (includingt the bone, recttum and bladder) between IMRT and 3DCRT plans. Conclusion For patients with pelvis metastasis of cervical cancer after radical surgery, 4 fields planning in 3DCRT and 9 fields planning in IMRT are feasible. At high dose levels, the IMRT plans can more significantly protect the bowl and spine cord and decrease the radiation volume of colorectal and urinary bladder at risk than 3DCRT, so IMRT may potentially diminish probability of the normal tissue complications.
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Objective To provide a reference to the clinical application by comparing the posology difference of 3DCRT(three-dimensional conformal radiation therapy) and IMRT(intensity modulated radiation therapy) for lung cancer with mediastinum lymphonode metastasis. Methods From Aug.2007 to Feb.2008,11 patients of lung cancer with mediastinum lymphonode metastasis were treated by IMRT. IMRT plan and 3DCRT plan were designed by CT-simulator image. The conformity index, PTV uniformity and the organs at risk were compared by the target isodose curve and dose volume histogram(DVH) in two plans. The prescribe dose was 66 Gy/33 fracinations in 6 weeks, and 95 % dose curve covered 95 % target volume. The data were analyzed by t-test in SPSS 14.0. Results The conformity index in IMRT was superior than 3DCRT (P＜0.05).PTV above 110 % volume in IMRT was reduced than 3DCRT. On the protection of lung tissue,the volumes of V20,V30,V40 in IMRT were obviously less than 3DCRT (P＜0.05). Conclusion IMRT is a better selection to larger volume and irregular shape of CTV for lung cancer with mediastinum lymphonode metastasis.
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Objective: To correct the set-up error of patients during radiotherapy is very important for increasing treatment effective. Methods: This paper proposes a registration method based on portal images and reference images. Canny Operator was used to extract edge features. The extracted edge features were set as datum mark to calculate the maximal mutual information between the portal images and reference images. Parameters were optimized with simplex-simulated annealing optimization strategy. Results: The portal images and reference images of 29 patients with the cervix cancer and prostatic carcinoma were registrated in this paper. The results showed that the registration was precise, and the registration speed was increased remarkably. Conclusion: So this registration method can be applied for online estimation for set-up errors in clinical radiation.
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0.05).Conclusions Special protein gold measuring instrument had high sensitivity,good accuration and speediness,which was suitable for clinical LAB to test CRP.
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Medical image registration plays an important role in the research of medical image processing field. It is widely used in the areas of clinical diagnoses, treatment, quality assurance and evaluation of curative effect. This paper gives an overview on three medical image registration methods Correlation method, mutual information method, and wavelet transform method. Features of these method and their applications are reviewed.
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Objective To evaluate the feasibility of increasing the perfraction dose in treatment of neoplasms by 3DCRT (three- dimention confornial radiation therapy). Methods From May 1998 to June 2002, the radiation therapy plans of 300 out- cranial neoplasms patients were analysed retrospectively, including 143 patients with chest neoplasms and 157 patients with abdomen neoplasms. The PTV was 7.0 ~ 1 478 cm3, major PTV was encircled by 90 % isodose curve, minor 95 % PTV were encircled by 80 % isodose curve. Prescription dose was 90 % reference point dose, perfraction dose was 5 ~ 10 Gy, a majority of dose was 6 ~ 8 Gy, period of treatment was 5 ~ 15 days with an interval of 0 ~ 1 day. The general dose was given to radical cure dose or appeasement dose. The biological effect increased 10 % ~ 30 %. Results All treatment plans were accomplished and there were not complication which reduced patients' QOL. Conclusions 1.Owing to the f factor, increasing dose of perfraction, shortening general period of treatment and improving radiative biological effect were possible during the 3DCRT. 2. It was suggested that the larger out- cranial neoplasms should be treated by 3DCRT firstly, but precise plan, precise design and precise treatment can not intensely be pursued because of the limit of knowledge. 3. During the 3DCRT for out- cranial neoplasms, 2 ~ 3 times routine radiation therapy dose was secure, credible and effective according to different purpose.