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Objective:To explore a new technique for lung dose reduction in esophageal cancer radiotherapy based on the dose distribution characteristics of the half-field combined with intensity-modulated radiotherapy (IMRT) technique.Methods:A three-dimensional water tank was used to measure the dose distribution at the edge of the symmetrical field and half-field, which was then compared and analyzed. Twenty patients with the middle and lower thoracic esophageal cancer receiving radiotherapy with prescription doses of 50.4-60.0 Gy were selected. Based on the Varian Vital beam linear accelerator and Eclipse planning system, flattening filter (FF) technique symmetrical field and half-field beam design and the flattening filter-free (FFF) technique symmetrical field and half-field design were adopted to compare and analyze various dose data and treatment MU numbers for the target area and the endangered organs. The field settings were chosen in the front 1 and back 4 mode.Results:Compared with the symmetrical field plan, the half-field plan significantly improved the irradiated dose to the lung with a statistically significant difference ( P<0.05), and the half-field FFF was slightly better than the half-field FF mode. Compared with the total lung V 5Gy, V 20Gy, V 30Gy, and D mean dosimetric parameters (Gy), the FF symmetric field and FFF half-field were (49.64±5.39)% vs.(42.70±5.53)%, (15.99±3.93)% vs.(13.32±3.06)%, (9.24±2.77)% vs.(8.50±2.62)%, and (10.45±1.76)% vs.(9.50±1.53)%, respectively. There was a significant reduction in the volume dose values for all structures of the lung (all P<0.05). For other comparative data, the irradiated dose for the heart of the symmetrical field was better than that of the half-field mode ( P<0.05), and the differences in conformity index (CI) and homogeneity index (HI), number of treated MU, and spinal cord associated with the target area were not statistically significant (all P>0.05). Conclusions:During radiotherapy for esophageal cancer, target area coverage and dose volume data of the lung are the main parameters affecting the efficacy and side effects. IMRT treatment based on the half-field mode can give full play to the advantages of half-field and IMRT, and significantly improve the irradiated dose to the lung, which can offer an additional clinical option.
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Objective:To develop a verification platform based on Monte Carlo (MC) for independent dose verification of volumetric modulated arc therapy (VMAT) plans.Methods:The head model including collimator of Varian TrueBeam linear accelerator was constructed by using EGSnrc/BEAMnrc, and the independent dose verification platform for the patients’ VMAT plans was built based on the head model and an in-house code. The percent depth dose (PDD) curves and off-axis ratios for different field sizes, the dose distribution of two irregular fields and three VMAT plans of the head and neck, chest, and pelvis were simulated using the platform. The simulated results of the PDD curves and the off-axis ratios of different field sizes were compared with the blue water measurement results. The difference between the irregular fields and the actual ArcCHECK measurements was also investigated. Besides, the differences among the MC simulated dose, TPS calculated dose and the ArcCHECK measured dose were analyzed by several methods, such as γ analysis and dose-volume histogram to verify whether the platform could be independently employed for dose verification.Results:The MC simulated results of PDD curves and off-axis ratios from 4 cm×4 cm to 40 cm×40 cm were in good agreement with the measured results. And the γ passing rates between the MC simulation and the ArcCHECK measurement for the irregular fields were above 98.1% and 99.1% for 3%/2 mm and 3%/3 mm, respectively. For VMAT plans of three patients, the γ results between the MC simulated dose and ArcCHECK measured dose were better than 93.8% and 95.9% under the criteria of 3%/2 mm and 3%/3 mm respectively. At the same time, the γ passing rates of nasopharyngeal, lung, and rectal cancers were 95.2%, 98.6% and 98.9% based on 3D γ analysis using TPS calculated dose and MC simulated dose under the criteria of 3%/3 mm; the passing rates of these three were 90.3%, 95.1% and 96.7% for 3%/2 mm, respectively.Conclusions:The simulation results of the MC-based verification platform developed in this study show a good agreement with the actual measurement results, and the simulation results are closer to the real dose distribution using the patients’ data. The preliminary results demonstrate that the platform can be used for accurate independent dose verification of VMAT plans.
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Objective:To explore a new technology that can protect the lungs and heart better by utilizing the dose distribution attributes of the half-field and the characteristics of the VMAT (volumetric modulated arc therapy) technology.Methods:A three-dimensional water tank was used to measure the dose of symmetrical field and half field edge and analyze them comparatively. A total of 50 patients with left breast cancer receiving the postoperative radiotherapy were selected. Among them, 25 patients were performed conserving surgery and 25 patients were performed radical mastectomy. After the operation, all the patients received the prescription dose of 50 Gy in 25 fractions. Based on the Eclipse system, the symmetrical field continuous arc VMAT technology and the semi-field segmented arc VMAT technology were used to design the plan. Besides, the dose suitability data and the treatment efficiency of target areas and organs at risk were compared and analyzed.Results:The radiation size of half-field did not increase with the increased depth in the water mode. The symmetric field gradually enlarged due to the angle of tensor factor, increased to about 2 cm at the depth of 30 cm, and the delivery dose in the half-field was lower than that in the symmetric field. The closer the field edge is, the more obvious it is. Compared with the symmetric field continuous arc plan, the half-field segmental arc VMAT plan significantly improved the delivery dose of the lungs and heart ( t=-4.11, -4.42, P=0.00), in which the mean values of V5, V30, and Dmean for the whole structure of the heart were reduced by 52.5%, 65.5%, and 47%, respectively. The left anterior descending coronary artery, which was closely related to the target area, had a decrease of more than 20%. The mean values of V5, V10, V20, and Dmean of the affected lung were reduced by 21.6%, 24.8%, 25.0%, and 23.2%, respectively. The mean values of the doses of other endangered healthy organs, and the execution time of half-field segment arc plan were also better than the continuous arc plan. Conclusions:For breast cancer radiotherapy, the combination of half-field and VMAT can give full play to the advantages of half-field and VMAT, and significantly reduce the irradiated dose of the heart, affected lung, and healthy side of the breast.
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Objective:In this paper, based on the 4D dose distribution of the treatment plan, the effects of respiratory movement on the dose distribution of three-dimensional conformal radiation therapy (3DCRT) and sliding window intensity-modulated radiation therapy (SW-IMRT) techniques were analyzed, and the dose errors caused by respiratory movement based on the 4D dose distribution were evaluated.Methods:In this study, the dynamic thoracic phantom (CIRS-008A) was used to simulate the patient with a 3 cm spherical insert as the tumor. Four motion patterns were simulated with cos 4( x) and sin ( x) wave forms of 10 mm and 5 mm amplitudes. The 4DCT scans with the phantom were performed in different breathing modes, and the maximum intensity projection (MIP), average intensity projection (AIP) and 10 separate 4DCT phase images were transferred to the Eclipse treatment planning system. The targets were contoured on MIP, with corresponding 3DCRT and SW-IMRT plans designed and dose calculated on AIP. By copying the plan designed on the AIP to each phase image of the 4DCT set, the MATLAB software package was employed to register and superimpose all the phase-specific doses onto one of the reference phase to create a 4D-accumulated dose distribution. Both films (EBT2) and optically stimulated luminescence (OSLD) detectors were inserted in and around the target area of the phantom to measure the delivered doses. The calculated 4D-accumulated doses were compared to the measured doses and their differences were evaluated using Gamma analysis. Results:Under different respiration modes, the average Gamma index (3%/3 mm) passing rates between the 4D-accumulated doses and EBT2-measured doses for 3DCRT and SW-IMRT plans were (98.8±0.78)% and (96.4±1.89)%, respectively. The absolute measurements of OSLDs both inside and outside of the target area well matched the 4D-accumulated doses.Conclusions:4DCT can be effectively applied to evaluate the treatment plan dose distribution through 4D dose accumulation, which can potentially avoid cold spots and target under-coverage. Under different respiration modes, both 3DCRT and SW-IMRT plans provide dose measurements consistent with those predicted by the 4D-accumulated dose of treatment plan.
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Objective:To analyze the setup and residual errors of spinal cord during online CT-guided radiotherapy for patients with esophageal cancer, and to discuss the necessity of segmental extension of spinal cord.Methods:According to the radiotherapy site, 60 cases of esophageal cancer were divided into the neck, chest and abdomen groups, 20 cases in each group. Cervical pleura or vacuum bag was fixed, IMRT technology was adopted, and pre-treatment CT images were obtained by CT Vision, and 20 consecutive CT scans were collected for each case. CT images were imported into MIM software. The parameters of the setup errors were processed and extracted. The CT spinal cord was delineated for verification and planning, and the Dice coefficient, Hausdorff maximum distance and centroid coordinate of the delineated spinal cord were processed and extracted. Compatibility anova data were adopted. The calculation formula of the extension margin is M PRV= 1.3 ∑ total+ 0.5 σ total. Results:Residual centroid method was employed. Non-on-line and on-line CT-guided radiotherapy, the extension margins of neck, chest, abdominal spinal cord in the x-, y-and z-axis were 3.86, 5.37, 6.36 mm; 3.45, 3.83, 4.51 mm; 4.05, 4.83, 7.06 mm, vs, 2.85, 2.19, 2.83 mm; 2.32, 2.20, 2.16 mm; 2.86, 2.21, 2.83 mm, respectively. During residual Hausdorff distance method, non-on-line and on-line CT guided radiotherapy, the extension margins of neck, chest, abdominal spinal cord in the x-, y-and z-axis were 3.10, 5.33, 6.15 mm; 3.30, 3.77, 4.61 mm; 3.35, 4.76, 6.87 mm, vs, 2.12, 2.06, 2.32 mm; 2.12, 2.06, 2.32 mm; 2.12, 2.06, 2.32 mm, respectively.Conclusion:The setup errors and residual errors are different in each segment of spinal cord. Henc, different extension margins should be given.
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Objective:To propose an automatic planning platform of the Raystation planning system suitable for multi-disease and multi-plan technique by using the Raystation built-in script function.Methods:IronPython and WPF user interface framework were utilized for programming and resolving the differences in the design of different types of plans for different diseases. The program was designed from prescription identification, visual plan parameter input and cost-function setting. The efficiency of automatic planning and manual planning was compared when applied in whole brain irradiation, nasopharyngeal carcinoma, cervical cancer, esophageal cancer and breast cancer, including IMRT and VMAT. The dosimetric parameters of the whole brain irradiation were chosen.Results:Physicists were only required to enter and select the necessary parameters to achieve the plan design by using the program. Compared with the five types of diseases, the maximum efficiency of automatic planning was 1.4 times higher than that of manual planning. In the dosimetric evaluation of the whole brain irradiation plan, both manual and automatic planning could meet the clinical needs, and the D 2%, CI and HI of the target area did not significantly differ (all P>0.05). The mean D 98% of the target area and the D max of lens in the manual plan were significantly higher than those in the automatic plan by 0.4% and 7.1%(both P<0.05). Conclusion:The developed program has the function of automatic planning system, which can realize the automatic planning of multi-disease and multi-type radiotherapy, significantly improve the efficiency of plan design and has important clinical application value.
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Objective To compare relevant dosimetric parameters of non-coplanar volumetric modulated arc therapy (VMAT) in treating brain tumors in conventional flattening filter (FF) or flattening filter-free (FFF) delivery mode,aiming to explore the appropriate evaluation method of accelerator for stereotactic radiosurgery (SRS).Methods Clinical data of 10 patients with single cranial tumor were retrospectively analyzed.All patients received non-coplanar VMAT at a prescription dose of 25 Gy in 1 fraction.Dosimetric parameters including conformity index (CI),heterogeneity index (HI),gradient index (GI50,GI25),gradient,volume of the brain tissue receiving larger than 10 Gy and 12 Gy (V10 and V12) and beam-on time were statistically compared between two treatment plans by paired sample t-test.Results When FFF-VMAT was compared with FF-VMAT in SRS for intracranial tumors,Paddick gradient index GI50 was 2.91±0.34 vs.3.07±0.35,6.91±0.28 vs.7.35±0.27 for GI25,(0.57±0.07) cm vs.(0.61±0.08) cm for gradient,respectively (all P＜0.05),whereas CI did not significantly differ (P＞0.05).For the normal brain tissues,the average dose was (160.64±43.64) cGy vs.(174.27± 53.98) cGy,(45.35± 30.32) ％ vs.(48.37± 30.88) ％ for V10 and (36.69±25.15) ％ vs.(39.48±25.37) ％ for V12,respectively (all P＜0.05).Conclusions Non-coplanar VMAT in FFF delivery mode can improve dose distribution and normal brain tissue sparing in the treatment of intracranial single tumors.Meanwhile,supplement of GI index and gradient index can implement comprehensive evaluation of the SRS planning.
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Objective@#To compare relevant dosimetric parameters of non-coplanar volumetric modulated arc therapy (VMAT) in treating brain tumors in conventional flattening filter (FF) or flattening filter-free (FFF) delivery mode, aiming to explore the appropriate evaluation method of accelerator for stereotactic radiosurgery (SRS).@*Methods@#Clinical data of 10 patients with single cranial tumor were retrospectively analyzed. All patients received non-coplanar VMAT at a prescription dose of 25 Gy in 1 fraction. Dosimetric parameters including conformity index (CI), heterogeneity index (HI), gradient index (GI50, GI25), gradient, volume of the brain tissue receiving larger than 10 Gy and 12 Gy(V10 and V12) and beam-on time were statistically compared between two treatment plans by paired sample t-test.@*Results@#When FFF-VMAT was compared with FF-VMAT in SRS for intracranial tumors, Paddick gradient index GI50 was 2.91±0.34 vs.3.07±0.35, 6.91±0.28 vs.7.35±0.27 for GI25, (0.57±0.07) cm vs.(0.61±0.08) cm for gradient, respectively (all P<0.05), whereas CI did not significantly differ (P>0.05). For the normal brain tissues, the average dose was (160.64±43.64) cGy vs.(174.27±53.98) cGy, (45.35±30.32)% vs.(48.37±30.88)% for V10 and (36.69±25.15)% vs.(39.48±25.37)% for V12, respectively (all P<0.05).@*Conclusions@#Non-coplanar VMAT in FFF delivery mode can improve dose distribution and normal brain tissue sparing in the treatment of intracranial single tumors. Meanwhile, supplement of GI index and gradient index can implement comprehensive evaluation of the SRS planning.
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Objective@#To investigate the feasibility of assessing the treatment response using diagnostic-quality CT imaging features during radiotherapy for esophageal cancer.@*Methods@#Thirty-three patients with stage Ⅰ to IV esophageal cancer undergoing intensity-modulated radiotherapy were recruited in this study. CT images were acquired using a CT-on-rail imaging system. Imaging data of CT images including gross tumor volume (GTV), the volume of spinal cord and non-irradiated tissue (NIT), CT mean (MCTN), standard deviation , and skewness were collected and analyzed by using MIM image processing system. Patients were divided into the effective group (complete remission and partial remission, n=24) and ineffective group (no change and progression, n=9) based on the outcomes of 3-month follow-up. The imaging data were statistically compared between two groups using the self-designed Matlab software.@*Results@#The tumor volume and MCTN of 33 patients were gradually decreased with the increase of radiotherapy dose. The tumor volume and MCTN were decreased by 42.46% and 5.76 HU in the effective group, more significant compared with 21.76% and 3.66 HU in the ineffective group (both P<0.005). The skewness in the ineffective group was decreased by 0.503 with the increasing radiation dose, whereas that in the effective group was increased by -0.450(P=0.034). Spinal cord and NIT did not significantly change with the increasing radiation dose.@*Conclusion@#Analysis of the characteristic data of CT images of patients with esophageal cancer during radiotherapy may early predict the clinical efficacy of radiotherapy.
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Objective To investigate the feasibility of assessing the treatment response using diagnostic-quality CT imaging features during radiotherapy for esophageal cancer.Methods Thirty-three patients with stage Ⅰ to Ⅳ esophageal cancer undergoing intensity-modulated radiotherapy were recruited in this study.CT images were acquired using a CT-on-rail imaging system.Imaging data of CT images including gross tumor volume (GTV),the volume of spinal cord and non-irradiated tissue (NIT),CT mean (MCTN),standard deviation,and skewness were collected and analyzed by using MIM image processing system.Patients were divided into the effective group (complete remission and partial remission,n=24) and ineffective group (no change and progression,n=9) based on the outcomes of 3-month follow-up.The imaging data were statistically compared between two groups using the self-designed Matlab software.Results The tumor volume and MCTN of 33 patients were gradually decreased with the increase of radiotherapy dose.The tumor volume and MCTN were decreased by 42.46％ and 5.76 HU in the effective group,more significant compared with 21.76％ and 3.66 HU in the ineffective group (both P＜0.005).The skewness in the ineffective group was decreased by 0.503 with the increasing radiation dose,whereas that in the effective group was increased by-0.450(P=0.034).Spinal cord and NIT did not significantly change with the increasing radiation dose.Conclusion Analysis of the characteristic data of CT images of patients with esophageal cancer during radiotherapy may early predict the clinical efficacy of radiotherapy.
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Objective To compare the MdaccAutoPlan (MDAP)software with Manual planning in intensity modulated radiotherapy (IMRT) planning for nasopharyngeal carcinoma (NPC) patients.Methods A total of 20 newly diagnosed NPC patients were enrolled and their IMRT plans were designed with MDAP software and manually,respectively with identical field angle,optimization parameters and other planning requirements.Dosimetric differences and planning efficiency were compared for these two planning method.Results The PGTV Dgs％,PGTV D PTV1 Dgs％,PTV1 D PTV2 D98％,PTV2 D of plans generated from MDAP were reduced by 2.5％,0.3％,0.1％,0.5％,0.6％,1.0％,respectively,compared with those in plans generated manually.The D2％ of the PGTV,PTV1,PTV2 in MDAP plans were increased by 1.7％,1.5％,0.6％ compared with those in manual plans,respectively.There were significant differences observed in the PGTV D9s％,PGTV D2％ and PTV2 Dg8％ between these two planning method (t =5.519,6.701,0.937,P ＜ 0.05).The D50％ of right parotidand left parotid,the D and D of the spinal cord in MDAP plans were reduced significantly by 24.8％,27.7％,11.4％,14.0％,respectively,compared with those in manual plans (t =5.447,5.375,6.786,3.810,P ＜ 0.05).The dose of both lens increased significantly by 65.0％ and 19.3％,respectively,in MDAP plans compared with Manual plans (t =9.863,3.440,P ＜ 0.05).There was no significant dosimetric difference observed in opticnerve,opticchiasm and brainstem between these two planning method.The dose distribution of post neck in MDAP plans were better than those in manual plans.The dose-volume histogram curves of planning target volume,brainstem and spial cord in the manul plans were higher than those in the MDAP plans.The labor time of MDAP planning was reduced by 54.4％ compared with Manual planning,while computer working time was increased by 34.4％ with MDAP planning compared with Manual planning.Conclusions MDAP planning is clinically valualbe in its applicaion for a NPC IMRT planning with a better sparing for OARs,a decreased planning time and improvement on planning efficiency compared with manual planning.
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Objective To investigate the effect of respiratory motion on inadvertent irradiation dose (ⅡD)to the microscopic disease(MD)and expanding margin of target volume in stereotactic body radiotherapy for lung cancer. Methods Based on the pattern of respiration-induced tumor motion during lung radiotherapy, a probability model of MD entry into or exit from internal target volume(ITV)was established and the theoretical dose to MD was calculated according to the static dose distribution by four-dimensional computed tomography. The experimental dose to MD during respiratory motion was measured using a respiration simulation phantom and optically stimulated luminescence(OSL)and then compared with the theoretical value for model validation.Results For the target volume in periodic motion,the deviation of the theoretical dose to MD from the experimental value measured by OSL was less than 5%. A 10-mm margin around ITV received a biological dose higher than 80 Gy. Conclusions The dose model established in this study can accurately predict the irradiation dose to MD in the target volume in periodic motion. Respiratory motion increases ⅡD to MD and there is no need to expand clinical target volume.
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Objective To investigate the value of computed tomography (CT)-magnetic resonance imaging (MRI) image fusion in target volume delineation of postoperative precise radiotherapy for gliomas.Methods Thirty-six patients newly diagnosed with gliomas were enrolled and received postoperative intensity-modulated radiotherapy.Landmark (L) combined with manual fusion (M) and maximization of mutual information (MI) was used for image fusion.Target volume and organs at risk were delineated based on CT images and fused images,respectively.Comparison of the volume was made by pairwise t test.The distance from a landmark on CT image to the corresponding one on MRI image was calculated.The volume method and geometric center method were used to calculate the degree of volume overlap and changes in central positions after image fusion.Results The L+M+MI method achieved a high registration accuracy in image fusion,with a registration error less than 2 mm.In patients with grade Ⅲ-V gliomas,the CT images yielded significantly smaller gross tumor volume (GTV) and clinical target volume (CTV) than the MRI images (74.62±46.91 vs.105.99±58.86 cm3,P=O.042;304.03± 130.05 vs.387.94± 150.12 cm3,P=0.040).After image fusion,the smallest change in central position occurred in the chiasma (1.32± 1.42 mm),and the largest change occurred in CTV (7.99± 11.06 mm),followed by GTV and the brain stem.Conclusions CT-MRI image fusion helps to reduce the uncertainty of target volume delineation in patients with gliomas,especially in those with edema and residual tumor after surgery.
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Objective To compare the dose distributions of the volumetric modulated arc therapy ( VMAT) for early stage non?small cell lung cancer ( NSCLC) using conventional flattening filter ( FF) and the flattening filter free ( FFF) beams and to verify the dose calculation accuracy of the FFF beam through a three?dimensional verification system. Methods The treatment plans of 20 patients ( 2015 years hospitalized) treated with SBRT for early stage NSCLC using a TrueBeam accelerator were retrospectively analyzed. The patients were scanned with 4DCT and the average density projection images were used for organ segmentation and treatment planning using an Eclipse plan system. Two volumetric modulated arc therapy ( VMAT) plans with FF and FFF were designed with the same planning parameters for each patient. The dose distributions between the two plans were compared and their dose verifications were assessed with the ArcCheck device. Results With the same dose coverage for the target, there was no significant difference in the dose compatibility index 100%(CI100%) between FF and FFF beams (P=0. 82).CI80% and CI50% of FFF plan were lower than that of FF plan (P=0. 02,0. 01).The dose significantly decreased in the FFF plan comparing with the FF plan for the ipsilateral lung and the total lung (P<0. 01 for both).There was no significant difference between monitor units of the FF and FFF plans ( P=0. 34) ,while the delivery time of FFF was significant shorter than that of FF (P<0. 01).The DVH passing,γ pass rates and the absolute dose deviations of the FF and FFF plans at the central point were not significantly different ( P=0. 05,0. 16, 0. 26) . Conclusions FFF beams for NSCLC patients with VMAT planning can significantly improve the dose distribution compatibility and reduce radiation doses to lung. The beam delivery with FFF beams was also faster. Furthermore,the three?dimensional dose verification confirmed that the dose calculation in Eclipse plan system using FFF beams for VMAT plans were accurate and met the clinical need.
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Objective To compare the clinical target volume (CTV) expanding margins in the mid-and upper-thoracic esophageal carcinoma during radiotherapy measured with and without online image guidance technique by CT on rail.Methods 100 patients with mid-and upper-thoracic esophageal carcinoma undergoing intensity modulated radiotherapy received CT scanning.Image registration was conducted between the scanning results and the planned CT images,thus set-up error data were acquired and got on-line correction.Fifty patients were randomly selected to undergo additional post-treatment CT scanningso as to analyze the revised residuals,displacement during treatment,and infra-fraction GTV shifts.Results Compared to the radiotherapy without CT-based image guidance,the CTV expanding margins obtained with CT-based image guidance was reduced significantly from 9.1,8.8 and 6.1 mm to 4.1,4.5 and 4.3 mm in the left-right,head-feet,and belly-back directions respectively.Conclusions The on-line image-guided technology significantly improves the accuracy of target and reduces the CTV expanding margins.
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ObjectiveTo quantitatively characterize the inter-fractional anatomy variations and advantages of dosimetry for the adaptive radiotherapy in pancreatic cancer.MethodsA total of 226 daily CT images acquired from 10 patients with pancreatic cancer treated with image-guided radiotherapy were analyzed retrospectively.Targets and organs at risk (OARs) were delineated by the atlas-based automatic segmentation and modified by the skilled physician.Various parameters,including the center of mass (COM) distance,the maximal overlap ratio (MOR) and the Dice coefficient (DC),were used to quantify the inter-fractional organ displacement and deformation.The adaptive radiation therapy (ART) was applied to handle the daily GT images.The dose distributions parameters from the ART plan were compared with those from the repositioning plan.ResultsThe inter-fractional anatomy variations of pancreas head were obvious in the pancreatic cancer irradiation.The mean COM distance,MOR and DC of pancreas head after the bony or soft tissue alignment and registration was ( 7.8 ± 1.3 ) mm,( 87.2 ± 8.4 )％ and ( 77.2 ±7.9)％ respectively.Compared with the repositioning plan,the ART plan had better target coverage and OARs sparing.For example,the mean V100 of PTV was improved from (93.32 ± 2.89) ％ for repositioning plan to ( 96.03 ± 1.42) ％ for ART plan with t =2.79,P =0.008 and the mean V50.4 for duodenum was reduced from (43.4 ± 12.71 )％ for the repositioning plan to (15.6 ± 6.25)％ for the ART plan with t =3.52,P=0.000.ConclusionsThe ART can effectively account for the obvious inter-fractional anatomy variations in pancreatic cancer irradiation and be used to escalate the radiotherapy dose for the pancreatic cancer,which will lead to a promising higher local control rate.