Daily quality control data analysis and process evaluation of linear accelerator / 中华放射肿瘤学杂志

Objective To analyze the quality control data of linear accelerator detected by Daily QA3 and to evaluate this quality control process using statistical process control.Methods After the calibrations of the accelerator and Daily QA3,Daily QA3 device was used to perform daily quality control by technicians and physicists and 100 groups and 30 groups of daily quality control data were collected.After the accelerator and Daily QA3 were re-calibrated,Daily QA3 device was utilized to perform daily quality control by technicians and 100 groups of the daily quality control data were repeatedly collected.The variations of normalized signal-to-noise ratio of quality control data collected after two calibrations were analyzed.The first 30 groups of daily quality control data measured by technicians and physicists were adopted to calculate the I-MR control chartsand compare the location of CL and the range of UCL and LCL.The process capability indices were calculated for three different quality control processes bytechnicians and physicists,respectively.Results For twice calibrations,normalized signal-to-noise ratio of quality control data significantly changed before 6 weeks,became stable between 6 and 8 weeks,and the changes became smaller after 8 weeks.For dose output measured by physicists,the rang of UCL and LCL was more narrow.In terms of flatness and symmetry,the location of CL was closer to zero.Regarding dose output and flatness,the process capability indices of three different quality control process were all satisfied ≥ 1,whereas unsatisfied for transverse symmetry.Conclusions The first 30-40 data points should be adopted to delineate I-MR control chart of the linear accelerator in daily quality control process.The quality control process should be completed by a fixed and small group of personnel and an optimal tolerance level should be customized.

Effect of CT artifact on calculation of radiotherapy dose / 中华放射医学与防护杂志

Objective@#To investigate the effect of simple artifacts on the calculation of radiation dose in actual clinical operations by the aid of artificially caused CT artifacts.@*Methods@#The phantom was scanned using CT before and after replacing the titanium alloy component. Then, the CT values were measured at different distances before and after replacement. After correcting the CT value of the titanium alloy region to the CT value of the water phantom, the doses to the phantom were calculated by using Varian′s AAA algorithm, AXB algorithm and Pinnacle system′s CCC algorithm. The absolute dose values at different distances were furtherly analyzed.@*Results@#Varian system was consistent with Pinnacle system in evaluating the CT values. When the CT value deviated by less than 30 HU for a uniform phantom, the dose deviations of the three different algorithms were within 6.0 %-12.0 % at a distance of 0.5 cm from the body surface, and less than 1.0% at a distance of more than 1.5 cm from the body surface. When the CT value deviated by 15 HU for the lung phantom, both Varian′s AAA algorithm and Varian′s AXB algorithm showed about 1.0% dose deviation. However, the CCC algorithm of the Pinnacle system had a significant difference (5.0%) in dose values under the same conditions.@*Conclusions@#CT artifacts have noticeable effects on the calculation of radiation dose and change tissue dose distribution which may result in insufficient or excessive exposure doses.

Influences of various field-defining methods of Varian accelerator on radiation dosimetry parameters / 中华放射医学与防护杂志

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.

Influences of various field-defining methods of Varian accelerator on radiation dosimetry parameters / 中华放射医学与防护杂志

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.

Application of a self-made positioning device in laryngeal CT-MRI image fusion / 中华放射肿瘤学杂志

Objective To investigate the application of a self-made positioning device in CT-MRI image fusion in patients with laryngeal tumor,as well as the precision of image fusion and the changes in target volume delineation after fusion.Methods A total of 10 patients with laryngeal cancer were enrolled,and a self-made positioning device was used to collect CT and MRI images in a fixed position.These images were fused by mutual information combined with manual fusion.The precision of image fusion was assessed by the positional deviation of internal and external markers and degree of gross tumor volume (GTV) overlap (PCT-MRI) between CT and MRI images.GTV was contoured based on CT images (VCr),MRI images (VMRI),and fused images (VCT+MRI).The overlapped volume of VCT and VMRI(VCT-MRI) Was calculated,and the target volume was analyzed and compared.Results The positional deviations of three external markers in the three directions were 0.996±0.222 mm,1.146±0.291 mm,and 1.368±0.298 mm (P=0.000),respectively,while those of the internal markers were 0.476±0.151 mm,0.561±0.083 mm,and 0.724± 0.125 mm (P=0.000),respectively.VCT,VMRI,VCT+MRI,and VCT-MRI were 26.355±7.876 cm3,33.556± 7.407 cm3,40.036±7.627 cm3,19.875±8.588 cm3(P=0.000),respectively.PCT-MRI was 73.7％±9.8％.Conclusions The self-made positioning device can improve the consistency of position during the collection of CT and MRI images,and fused CT-MRI images can provide more information and improve the precision of target volume delineation.

A clinical application research of 3D dose verification for esophageal carcinoma intensity-modulated radiation therapy with Compass (R) / 中华放射肿瘤学杂志

Objective To study the clinical application of Compass (R) system,a novel 3D quality assurance system for the verification of esophageal carcinoma intensity-modulated radiotherapy (IMRT) plan.Methods 12 esophageal carcinoma IMRT plans were optimized with Eclipse 8.6 treatment planning system (TPS),and then Compass (R) reconstructed 3D dose distributions with the patient anatomy.Comparison was performed among the reconstructed and calculated with TPS,Dose-volume parameters (γ pass rate、average dose deviation) to the planning target volume (PTV) and critical structures were quantitative valuated.Furthermore two-dimensional dose verification were performed use MatriXX,γ pass rate were evaluated with 3％/3 mm criteria.Results The γ pass rate of actual gantry angle was found generally declined seemingly compared with 0 degree gantry angle in two dimensional verification,difference was statistically significant (P =0.018-0.001).In 3D dose verification,the γvolume of PTV were exceed 93％,the deviation of D95,D50,D2 were less than 3％;The γvolume of lungs and heart were exceed 95％,the average dose deviation were less than 3％;The γ pass rate of spinal cord and trachea were exceed 98％.The independent check verified more conformed with the TPS calculated.Dose deviations appeared in the radiation field edge area.Conclusions 3D dose verification can provide more information to comprehensively evaluate the plan which is benefit for evaluating the clinical value of verification.

Design of intensity modulated radiotherapy plan in chest wall and supraclavicular region for patients with breast cancer after radical mastectomy / 肿瘤研究与临床

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.

A clinical test and application research of IMRT 3D dose verification system / 中华放射医学与防护杂志

Objective To test the accuracy of a three-dimensional dose verification system CompassR,which reconstructing dose distribution based on measurements and independent dose calculation,and to evaluate the feasibility of its application in clinical intensity-modulated radiotherapy (IMRT) quality assure.Methods A set of square-wave chart patterns of 2 cm,1 cm and 0.5 cm gaps was designed and 11 completed IMRT lung plans were selected for the test.EDR2 film and the ionization chamber were used for test and verifying of plane dose distribution and some special points dose of CompassR.The IMRT phantom plans were verified by CompassR with three-dimension based on anatomical information.Parameters including the volume γ pass rate and the average dose deviation were tested using dose volume histograms.Results In square-wave chart patterns test,the dose distribution reconstructed and calculated by CompassR coincided with the measurement using film.The γ pass rates (3％/3 mm,2％/2 mm) exceeded 90％.When the width of field is 0.5 cm,the γ pass rate was a little lower on account of the penumbra zone.Compared to the dose distribution profile which was measured by film,the maximum deviations of the dose distribution profile which was reconstructed and calculated by CompassR were 3.21％ and 2.70％.The absolute dose deviation of specific point in the IMRT plans was less than 3％,the maximum deviation occurred in the lung.Compared to film,the averageγpass rates on the isocenter plain in IMRT plan were (94.65 + 1.93)％ (3％/3 mm) which was reconstructed by CompassR.In three-dimensional dose verification,the volume γ pass rates of targets and risk organs were not less than 90％,and the deviation of average dose was less than 1％.Conclusions Accuracy of the tested system satisfies the demand of IMRT dose verification.CompassR could provide information of volumetric dosimetry and anatomical location of dose error,which is benefit for evaluating the clinical value of verification result.

Dosimetric comparison between RapidArc and fixed gantry dynamic IMRT for postoperative rectal cancer radiotherapy / 肿瘤研究与临床

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.

A dosimetric comparison of volumetric modulated Arc therapy with conventional intensity-modulated radiotherapy for breast cancer radiotherapy after breast-conserving surgery / 中华放射医学与防护杂志

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.

Accuracy comparison of enhanced dynamic wedge modles among Pinnacle3 9.0 ACA and Eclipse7.3 AAA, PBC algorithm / 中华放射肿瘤学杂志

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.

The clinical effect of low molecular heparin calcium on early onset severe pre-eclampsia / 中国综合临床

Objective To analyze the clinical effects of low molecular heparin calcium on early onset severe pre-eclampsia.Methods Sixty patients with early onset severe pre-eclampsia at 26-34 weeks of gestational age were divided into treatment group(28 cases)and control group(32 cases).The conventional treatment was delivered in control group and low molecalar heparin calcium(LMWHC)was used in treatment group additionally.The time of prolonged gestational age,umbilical arterial S/D ratio,amniotic fluid index,placenta weight,neonatal weight and Apgar score were measured in two groups.Results The time of prolonged gestational age was 10.19 ±4.57days in treatment group and 6.14 ±3.56 days in control group,which were significantly different(P ＜ 0.01).Umbilical arterial S/D ratio,amniotic fluid index,placenta weight and neonatal weight were all significantly different between the two groups(P ＜ 0.05).Neonatal Apgar score in treatment group was remarkably improved(P ＜ 0.01).Conclusion LMWHC treatment in the patients with early onset severe pre-eclampsia could extend gestational age,increase neonatal weight and improve perinatal outcomes.

Errors analysis of prone position in intensity modulated radiation therapy of cervical cancer / 肿瘤研究与临床

Objective To study the spatial distribution of set-up errors for cervical cancer with intensity modulated radiation therapy (IMRT) and to provide referential safety margin out of clinical tumor volume (CTV) during treatment plan design. Methods Six patients with cervical cancer were treated with IMRT in prone position, belly board and thermoplastic cast was used for immobilization. Measurement were made on a daily basis setup under five consecutive treatments with electron portal images device (EPID).Portal films from two projection (one anter-posterior and one opposite lateral)were taken. Sixty portal films were analyzed. The translational and rotational deviations were analyzed by registering and comparing the bony structures of EPID and digitally reconstructed radiographs (DRR). Results The translational deviations were (3.1 ±1.8) mm, (3.9 ±3.3) mm, (4.2 ±2.6) mm in medi-lateral, cranio-caudal and anterior-posterior directions, the rotational deviations were in coronal plane (0.8±0.9)° and sagittal plane (1.2±1)°. Conclusion For the patients with cervical cancer undergoing IMRT, the margins between the CTV and PTV should be 7.1 mm in lateral direction, 10.4 mm in cranio-caudal and 10.8 mm in anterior-posterior directions. The sign on patients body can help to reduce the setup errors.

Application of E-flow in ultrasound examination of fetal pulmonary vein / 中华超声影像学杂志

Objective To explore the value of E-flow technique in ultrasound examination of fetal pulmonary vein.Methods The pulmonary veins of 332 fetus were examined using lungs as acoustic window by two-dimensional echocardiography(2DE), color Doppler flow imaging (CDFI) and E-flow.Visualization ratios of the three methods were compared.Results The fetal pulmonary veins were displayed as following:7 cases were showed by 2DE,49 cases by CDFI and 73 cases by E-flow among 118 cases during 12 - 22 gestational weeks.The visualization ratio of E-flow was higher than that of the other two methods (P ＜0.001).Fourty-one cases were showed by 2DE, 171 cases by CDFI and 177 cases by E-flow among 214 cases during 23 - 40 gestational weeks.The visualization ratios of E-flow and CDFI were higher than that of 2DE (P ＜ 0.001).The visualization ratio of E-flow and CDFI has no distinct differrence (P ＞ 0.0167).Conclusions E-flow was sensitive to pulmonary vein blood flow and better than 2DE and CDFI in early stage of the second trimester.

Dosimetric study in intensity-modulated radiotherapy with dissimilar position for cervical cancer / 肿瘤研究与临床

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.

Evaluation CT with MRI image fusion technique on delineation GTV for glioma / 肿瘤研究与临床

Objective To investigate the way to accurately delineate gross tumor volume (GTV) of high grade gliomas(HGG) for intensity modulated radiation therapy (IMRT) by using computed tomography (CT) and magnetic resonance imaging (MRI) image fusion technique. Methods CT and MRI images were fused from 19 patients. The GTV of each patient were independently delineated by one chief doctor and one resident doctor on CT and MRI image. The GTV contoured on CT (GTVCT), MRI (GTVMRI) were measured, and composite volumes (GTVCT+MRI) were the sum of CT-defined GTV and MRI-defined GTV. The differences of these volumes were compared. Results Whether chief or resident doctors delineated, all were GTVMRI ＞GTVCT(P ＜0.050). The percentages of GTVMRI on GTVCT+MRI were (98.57±7.00)% by chief doctors, and (97.84±10.00)% by resident doctors. Compared the difference between GTVCT and GTVMRI in postoperative patients and preoperative patients, P =0.046, and the difference between chief doctors and resident doctors was statistically significant for GTV defined by CT (P =0.020), but not by MRI and composite image (P ＞0.050).Conclusion The GTV of HGG patients must be delineated on both CT image and MRI image, including using CT and MRI image fusion. But the composite volumes(GTVCT+MRI) should be the sum of CT-defined GTV and MRI-defined GTV. Especially for the postoperative patients,delineating GTV should be taken more attention. And the GTV should be delineated by doctors with full experiences.

Comparison of the clinical effects of three artificial abortion methods in mid-term pregnancy / 中国综合临床

Objective To compare the effects of three artificial abortion methods, Mifepriston with Misopro-fil,Rivanol with Mifepristone and Rivanol,in mid-term pregnancy. Methods 235 women who were pregnant for 12 to 28 weeks and volunteered to abort with drugs were selected and observed. The total subjects were randomly divided into three groups,study group Ⅰ (n=80),study group Ⅱ (n=78),and control group (n=77). In study group Ⅰ, each was given Mifepristone 50 mg, po, bid, for 3 days. On the fourth day, Misoprofil 200-1000 μg was administered though vagina. In study group Ⅱ, Rivanol(70-100 mg) was injected into amniotic cavity and at the same tame, Mife-pfistone,75 mg was given bid,po,for each case for 1 day. In study group Ⅲ,each case was injected with Rivanol (70-100 nag) only into amniotic cavity. Results The complete abortion rate in study group Ⅰ, Ⅱ and Ⅲ was 88.75% (71/80), 65.38% (51/78), 38.96% (30/77) respectively. The success rate was 98.75% (79/80), 71.79% (56/78),76.62% (59/77) respectively. The mean time from the initial uterine contraction to the expulsion of the fetus and placenta was (6.85±3.68) h, (8.87±3.58) h, (14.67±3.50) h respectively. The volume of in-trapartum and postpartum vaginal hemorrhage within 2 hours was (80.86±40.28) ml, (94.70±42.35) ml, (120. 68±43.30)ml respectively. The complete abortion rate and success rate in study group Ⅰ was significantly greater than that in study group Ⅱ and study group Ⅲ. In addition, the birth process was shorter and the vaginal hemorrhage was less significantly in study group Ⅰ than those in the other two groups (P<0.01). The complete abortion rate in study group Ⅱ was significantly greater than that in study group Ⅲ (P<0.01). Conclusions Mffepristone admin-istered with Misoprpfil has many advantages usages, such as high complete abortion rate and success rate, short birth process, and less volume of vaginal hemorrhage, when used for artificial abortion in mid-term pregnancy. They are es-pecially suitable for the mid-term artificial abortion under 20-week pregnancy. Rivanol administered with Mifepristone can raise complete abortion rate,shorten labor process and decrease vaginal hemorrhage when they are used in artifi-cial abortion. They are suitable for the mid-term artificial abortion above 16-week pregnancy. The stage of labor lasts long when using only Rivanol for artificial abortion. The pain is relatively heavier and the rate of incomplete abortion is higher.

Posology study on 3DCRT and IMRT for lung cancer with mediastinum lymphonode metastasis / 肿瘤研究与临床

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.

Dosimetry study of three-dimension conformal radiation therapy(3DCRT) in treating cervical cancer recurred in pelvis / 肿瘤研究与临床

Objective To eompare the dose distribution of three-dimension conformal radiation therapy(3DCRT) and common radiation therapy (CRT) of the planning target volume(PTV) and organ at risk (OAR) in recurred cervical cancer treatment planning. Methods Thirteen patients,who had cervical cancer recurred in pelvis treated with 3DCRT in Shanxi Cancer Hospital from May to August 2007, were selected. After CT simulation, the CT images were transferred into Topslane treatment system. The same physicist designed 3DCRT plan and common radiation therapy plan for every patient,total dose 50 Gy, 90 % is dose covered PTV, then compared the dose distribution of PTV and OAR.Results At the same prescribed dose of 50Gy,there were no significant differences on OAR maximum dose between 3DCRT plans and common radiation therapy plans(P >0.05), however, there was significant differences on PTV maximum dose(P <0.01). The difference of PTV uniformity were significant between 3DCRT plans and common radiation therapy plans (P <0.001). Compared the high dose region of OAR(V40), the difference was significant (P <0.001). Between 3DCRT plans and common radiation therapy plans, they showed 53.31 ml (90.69 %), 124.00 ml (79.47 %), 655.16 m1(92.22 %) median reduction in the V40 of rectum, bladder, intestine, respectively. Conclusion At the same PTV coverage of the prescribed dose, 3DCRT plans showed worse dose uniformity, however, the radiation volume to organs at risk in 3DCRT plans were smaller than common radiation therapy plans. So patients with cervical cancer recurred in pelvis received 3DCRT may be potentially diminish the Normal Tissue Complications Probability(NTCP).

The study of 3DCRT plan for hepatic tumors / 肿瘤研究与临床

Objective To study the 3D CRT plan for hepatic tumors. Methods The 3DCRT plan of 50 cases of primary or metastasis hepatic cancer were designed according to the request of the doctors for CTV and the restricted receiving dose of the peripheral normal sensitive organs. The best plan was chosen referring the dose-volume histogram. Results By using ICRU dose reference point (the central point of tumor) as the dose 100 % and 80 % ~ 90 % dose line can be surrounded above 90 % of the PTV(planning tumor volume). The degree of 90 % dose line surrounding PTV was related to the scope of target area and its location. Conclusion The focus in different localization can be treated with different design when devise the treatment plan of the hepatic tumors. The reaction to radiotherapy was directly influenced by the volume of dosage of radiation to the normal hepatic tissues, and it also had great influence to the choice of prescription dose and the dose division style.