Objective To compare and analyze the characteristics of intensity-modulated arc therapy (IMAT) versus fixed-gantry intensity-modulated radiotherapy (IMRT) in the treatment of cervical esophageal cancer.Methods Ten patients treated in our radiotherapy center were selected for this study.Based on the identical CT and planning target volume (PTV), two IMAT plans were generated with Eclipse ver8.6 planning system.IMAT1 consisting of a single 359.8° rotation, and IMAT2 consisting of two coplanar 359.8° rotations.PTV were prescribed to 60 Gy in 30 fractions.Planning objectives for PTV,corresponding with the IMRT plans, were V98 larger than 97% and V110 no more than 15%.The maximum dose of spinal-cord was constrained below 45 Gy.One-way ANOVA were applied to dose-volume values for PTV and OAR from DVH.Results There were no significant differences between IMRT and IMAT in PTV D98, V98, CI or total-lung V5, V10, V30, V40, V50 and mean lung dose (all P > 0.05).However, the differences were significant in terms of D2, V110 and HI of PTV, V20 of the total-lung (all P<0.05).On the MU,IMRT = 1174.8 MU,IMAT1 =709.7 MU,and IMAT2 =803.8 MU (F =39.25,P =0.000).On the treatment time,IMRT= 14.9 min,IMAT1 = 1.9 min, and IMAT2 =2.66 min (F=45.14,P=0.000).Conclusions IMAT is equal to IMRT in dosimetric evaluation.Due to much less MU and delivery time,IMAT is an ideal technique in treating patients by reducing the uncomfortable influences which could effect the treatment.However, IMAT1 is slightly inferior to IMAT2.

Objective To compare the dosimetric differences of target volume and organ at risk between intensity-modulated arc therapy (IMAT) and simultaneously integrated boost intensity-modulated radiotherapy (SIB-IMRT) in nasopharyngeal carcinoma. Methods IMAT and SIB-IMRT treatment plans of 10 nasopharyngeal carcinoma cases were generated by Varian Eclipse ver8. 6 treatment planning system. The dosimetric parameters of target volume and organ at risk (OAR), the monitor units (MU) and treatment time were compared between IMAT and SIB-IMRT treatment plan. Results The conformal index ( CI ) of PTV, PTV1, PTV2 of IMAT and SIB-IMRT were 0. 71 and 0. 75 ( Z = - 2. 32, P ＜ 0. 05 ), 0. 54 and 0. 59 (Z= -2.56,P＜0.05), 0.71 and 0.78(Z= -2.52,P＜0.05), respectively. the homogenous index (HI) of PTV, PTV1, PTV2 of IMAT and SIB-IMRT were 10.5 and 11.2(Z= -0. 84,P＞0.05),13. 1 and 17. 1(Z= -1.68,P＞0.05) and 14. 1 and 13.3(Z= -1. 01,P＞0.05) respectively;the brain-stem mean does were 3512. 8 cGy ± 406. 2 cGy and 3384. 3 cGy ± 361.3 cGy ( Z= - 1.82, P ＞ 0. 05 ); the brain-stem maximum dose were 5528. 1cGy ± 192. 9 cGy and 5727. 5 cGy ± 356. 3 cGy ( Z = - 1.12, P ＞ 0. 05 ); the maximum dose of spinal-cord were were 4186. 1cGy ± 88.7 cGy and 4390. 2 cGy ± 74. 9 cGy ( Z =-2. 38 ,P ＜ 0. 05 ). There were no significant differences between parotid dose and normal tissue ( P ＞0. 05. ) MU were 606 ± 96 and 1308 ± 213 for IMAT and SIB-IMRT ( Z= - 2. 52, P ＜ 0. 05 ). Conclusions The IMAT plan showed a better conformal index than SIB-IMRT plan, with the same dosimetric parameters of the target volume and OAR. The IMAT plan could reduce normal tissues dose, monitor units and treatment time in the treatment of nasopharyngeal carcinoma.

Objective To evaluate the performace of fixed field Intensity modulated radiation therapy (IMRT) and RapidArc in the radiotherapy for multiple intracranial metastases.Methods The clinical data of 10 patients with multiple intracranial metastases,8 male and 2 female,aged 65-73,were used to design 3 plans:fixed field IMRT,RapidArc with single Arc (RA1),and RapidArc with double Arc (Arc 2).Dose-volume-histogram analysis was used to compare dose results,monitor unit,and delivery time.Results All 3 plans met the clinical requirements.The best target conformity and homogeneity were observed in the RA2 plan (Z = -2.803,- 2.904,P ＜ 0.05) and there were no statistical differences between the IMRT plan and RA1 plan.The maximum doses to the lens,eyes,and brainstem of the two RapidArc plans were all significantly lower than those of the IMRT plan(Z = -2.803--2.191 ,P ＜0.05),and the maximum dose to the optic nerves of the RA2 plan was significantly lower than that of the IMRT plan (Z = -2.293,-2.701 ,P ＜0.05).Compared with the IMRT plan,the average monitor units of the RA1 and RA2 plans were reduced by 29% and 24%,respectively,and the delivery time of these plans were significantly shorter by 84% and 69%,respectively.Conclusions Compared to the IMRT plan,RapidArc plans with single or double Arcs show similar or better effects in the target dose distribution,reduction of irradiation doses on organs at risk and,moreover,significant decrease of the monitor units and delivery time.

Objective To study the dosimetric impact of different angle fields in intensitymodulated radiotherapy (IMRT) and the feasibility of beam angle optimization (BAO) for multiple intracranial metastases.Methods In total,11 patients with multiple intracranial metastases were included in these analyses.Two treatment techniques were designed for each patient:the 7 equal spaced fields (BAF group) IMRT,and 7 fields by beam angle optimization (BAO group) IMRT.The dose distribution in the target,the dose to the organs at risk and normal brain tissues,and total MU in two groups were compared to explore the dosimetric differences.Results In comparison to the BAF group,the BAO group reduced the maximum dose to left and right lenses by an average of 45％,37％ (t =-5.707,-4.438,P ＜ 0.05);the mean dose to the left and right eyes were reduced by an average of 42.6％,44.5％ (t =-4.380,-5.638,P ＜0.05);the maximum dose to the right eyes were reduced by an average of 32.5％ (t =-2.518,P ＜ 0.05).The maximum dose of the right optic nerve and the mean dose of normal brain tissue were reduced by an average of 23％ and 3％ (t =-3.105,-3.437,P ＜0.05),respectively.For the target dose,conformity and homogeneity in PTV,no statistical differences were observed between the two groups (P ＞ 0.05).The BAO group reduced the maximum dose of the brainstem and the optic chiasm,as well as the number of MU,however,the differences were not statistically significant (P ＞ 0.05).Conclusions In comparison to the BAF group,the BAO group shows a similar target dose and reduces the dose for the organs at risk.For multiple intracranial metastases,IMRT protocols with BAO are feasible and beneficial.

Objective To compare the dosimetric difference of RapidArc and fixed gantry IMRT for liver carcinoma.Methods The CT data of 10 liver cancer patients were used to design 3 groups of treatment plan:IMRT plan,single arc RapidArc plan(RA1) ,and dual arc RapidArc plan(RA2).The planning target volume (PTV) dosimetric distrubition,the organs at risk (OAR) dose,the normal tissue dose,mornitor units(MU) and treatment time were compared.Results The maximum dose of PTV in RA1 and RA2 plans were lower than that of IMRT(Z = -2.090,-2.666,P ＜ 0.05).RapidArc groups had an improved 90% prescription dose conformity index than IMRT(Z = -2.805,-2.809 ,P ＜ 0.05).For organs at risk,RapidArc group plan had a significantly lower dose in V40 of stomach and small bowel than I MRT plan,but higher in mean dose of left kidney (Z = -1.988,-2.191,P ＜ 0.05).The values of V5,V10 and V15 of healthy tissue in RapidArc plan groups were higher than those in IMRT plan,while the values of V20 ,V25 and V30 of healthy tissue in RapidArc plan groups were lower than those in IMRT plan.The number of computed MU/fraction of Rapid Arc plan was 40% or 46% of IMRT plan and the treatment time was 30% and 40% of IMRT.Conclusion RapidArc showed improvements in conformity index and healthy tissue sparing with uncompromised target coverage.RapidArc could lead to the less MU and shorter delivery time compared to IMRT.

Objective To compare the dosimetric differences of three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy(V-MAT) for external beam partial breast irradiation.Methods Twelve patients with breast cancer receiving breast-conserving surgery and external beam partial breast irradiation were enrolled.Three different techniques including 3D-CRT,IMRT and V-MAT were designed for each patient.The dosimetry in the target,the dose to the organs at risk(OAR),the MU and delivery time were compared.Results All three plans met the clinical requirement. 3D-CRT showed the worst conformity in target. V-MAT provided the lowest target coverage and homogeneity in target.3D-CRT plans showed the lowest values for the V5,V10,mean dose and the highest values for V30 in the ipsilateral lung.No statistically significant differences were observed in V20 of the ipsilateral lung among three plans.V-MAT showed the lowest values in ipsilateral normal breast volume 15,20 and 25 Gy post-irradiation.For V5,the mean and max dose in heart,the mean dose in contralateral lung and the mean,max dose in thyroid,IMRT and 3D-CRT showed the highest and lowest value respectively(z =-2.94 - -2.09,P ＜ 0.05 ).The MUs in 3D-CRT,IMRT and V-MAT were 417.6 ± 34.4,772.8 ± 54.4 and 631.0 ± 109.0,respectively (z =- 2.93, - 2.76,-2.93,P ＜ 0.05 ). V-MAT significantly reduced the delivery time. Conclusions V-MAT shows significant advantages in reducing the dose in the ipsilateral normal breast and the delivery time compared with 3D-CRT and IMRT.

Objective To compare the dosimetric difference in forward intensity modulation radiotherapy (fIMRT)and inverse IMRT(iIMRT)planning for breast cancer.Methods Six patients received radiotherapy alone after left breast-conserving surgery were selected.For each patient,two treatment phns(flMRT and iIMRT)were designed with Pinnacle3 7.4f.In each plan,the volume of PIT received prescription dose was not less than 95 %.The dosimetrie parameters were assessed with dose volume histograms in planning target volume (PIT)and organ of around risk(OAR).Results Of flMRT and ilMRT plans,the PTV average canformal indexwere(0.67±0.06)and(0.66±0.06)(t = 2.423,P ＞ 0.05),average homogeneity index were (28.2±6.0)% and(26.1±6.8)%(t = 2.164,P ＞ 0.05);the volume of left lung received 20 Gy(V20)were(18.7±3.3)% and(17.0±2.8)%(t =5.087,P<0.05),and V30 of left lung were(15.5±3.0)%and(14.0±2.6)%(t =7.272,P<0.05);V30 of heart were(4.1±3.1)% and(3.5±2.5)%(t=1.916,P ＞ 0.05);the total monitor units were(262±5)MU and(308±14)MU(t = 7.515,P < 0.05).Conclusions There were no significant differences of CI,HI,and V30 of heart between flMRT and iIMRT.Because of fewer MUs,fIMRT plan could reduce the machine abrasion and treatment time,but V30 and V30 of left lung are higher significantly than iIMRT plan.

Objective To evaluate the impact of simultaneous integrated boost ( SIB) with different radiotherapy plans on the dosimetry of the target volume and organs at risk ( OAR) in patients with multiple brain metastases ( MBM ) , and to provide a basis for the selection of an optimal clinical radiotherapy. Methods Ten patients with MBM who were treated with whole-brain SIB radiotherapy were randomly selected in this analysis. The local imaging data from the enrolled patients were re-planned with dynamic intensity-modulated radiotherapy ( dynamic IMRT ) , dual-arc volumetric modulated arc therapy ( dual-arc VMAT) , and hybrid-IMRT ( h-IMRT) . h-IMRT plan was created by inversely optimizing 3 and 4 fixed fields of IMRT based on conformal radiotherapy. Two-tailed Wilcoxon matched pairs signed rank sum test was performed to analyze the differences between the three radiotherapy plans in the conformity index ( CI) and homogeneity index (HI) of the planning target volumes (PTV), Dmean and Dmax of OAR, monitor units ( MU) , and delivery time. Results CI of PTVs with VMAT plan was better than that with IMRT and h-IMRT plans (P=004,000), and no significant difference in HI was observed between the three plans( P>005) . There were no significant differences in CI and HI between 3 and 4 fields in dynamic IMRT ( P>005 ) . h-IMRT 3-and 4-field plans had significantly reduced doses to the eye lens and eyeballs than dynamic IMRT and VMAT plans (all P=000), and the three plans had similar doses to the brainstem and optic nerve ( P>005) . As for the MHs and delivery time, dynamic IMRT and VMAT plans showed the highest and lowest value, respectively ( all P= 000 ) . Conclusions All the three plans meet the clinical requirements. VMAT shows the highest treatment efficiency. H-IMRT protects the eye lens and eyeballs more effectively while maintaining the doses to the PTV, with reduced MU compared with IMRT. These offer a reference for designing the radiotherapy plan in MBM patients.

Objective The accelerometer log files generated when the simulation plans were executed on the chest phantom,the modified log files including multi-leaf collimator (MLC) and Gap motion error were imported into the treatment planning system and then the dose was reconstructed by Analytical Anisotropic Algorithm (AAA) and Acuros XB (AXB) algorithms.The calculation accuracy of these two algorithms was analyzed according to the measured value of film.Methods The targets and organs at risk (OARs) of the mediastinum and peripheral lung cancer were contoured on the chest phantom,intensity-modulated radiation therapy (IMRT) plans were designed and then the dose was calculated with the AAA and AXB algorithms.The films were placed in the phantom to measure the dose when the simulation plans were executed through the accelerator.The log files were extracted by Varian Argus software and the MLC,Gap motion deviation information was imported into the treatment planning system.The dose was reconstructed by two algorithms.The differences of target dose (D2,D98,Dmax,Vprescrited) and OAR dose (lung:V5,V10,V20,Dmean;Heart:V30,Dmean;Spinal cord:Dmax) were statistically compared between two algorithms.The measured dose of film was compared with the isocenter doses of the two algorithms.3mm/3％ standard was adopted to analyze the gamma-pass rates.Pass rates of high-dose region (target region) and low-dose region (upper,lower,left and right directions outside the target region) were analyzed with different size matrices.Results The dose differences were detected in the simulation plans of mediastinum and peripheral lung cancer by using the AAA and AXB algorithms.The maximum dose differences of the two targets were D98(2.47％) and Vprescribed (4.21％) using the AAA and AXB algorithms.The maximum differences of the OARs were the left lung (D =3.58％、V10 =-2.76％),the right lung (V5=-1.96％,D mean =0.18％),the heart (D =1.15％,D =0.18％) and the spinal cord (Dmax =-3.34％,1.79％),respectively.Compared with the measured dose of filn,the average gammapass rate in the mediastinum and peripheral lung cancer by using two algorithms of different sizes of matrix were 94.07％± 1.32％ (AAA),93.81％± 1.43％ (AXB) and 93.73％± 1.31％ (AAA),94.39％± 1.32％ (AXB).In the low dose region of the two targets,the average gamma-pass rate by the AXB algorithm was higher than that by the AAA algorithm.Conclusions The AAA and AXB algorithms differ in the calculation of target areas for the mediastinum and peripheral lung cancer simulated on the chest phantom.The average gamma-pass rate of the AXB algorithm is better compared with that of the AAA algorithm referring to the measured dose of the film,which is closer to the measured value of the film in the cavity.