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Objective:To investigate the long-term prognosis and failure mode of patients with esophageal squamous cell carcinoma who achieved clinical complete remission (cCR) after receiving radical radio (chemo) therapy.Methods:Clinical data of 183 patients with esophageal squamous cell carcinoma eligible for inclusion criteria who received treatment in our hospital from January 2009 to December 2012 were retrospectively analyzed. The factors that affected the long-term prognosis of patients were identified, and the failure mode of cCR patients and the prognosis after failure were analyzed. SPSS 19.0 statistical software was used for data analysis.Results:As of the follow-up date, the 1-, 3-, 5-, and 10-year overall survival (OS) rates and disease-free survival (DFS) rates of the entire group were 83.1%, 53.4%, 36.2%, 12.8% and 68.9%, 45.9%, 30.5%, 12.0%, respectively. The median OS and DFS were 41.3 months and 33.4 months. The results of multivariate analysis showed that cT staging, cN staging and prescribed dose were the independent factors affecting the OS ( P=0.001, <0.001, 0.003); hoarseness, lesion length, cT staging, cN staging and prescribed dose were the independent factors that affected the DFS ( P=0.002, 0.033, 0.009, <0.001, 0.003). In the whole group, 72 cases (39.3%) had local regional recurrence, 58 cases (31.7%) had distant metastasis, and 26 cases (14.2%) had local regional recurrence with distant metastasis. Among 104 patients after treatment failure, the prognosis of patients receiving salvage treatment was significantly better than that of their counterparts receiving maintenance treatment ( χ2=39.153, P<0.001). Conclusions:The long-term prognosis of patients with esophageal squamous cell carcinoma who achieved cCR after receiving radical radio (chemo) therapy is still unsatisfactory. Clinically, it is necessary to strengthen the clinical observation and follow-up of these patients. The main treatment failure mode of cCR patients is local regional recurrence. Active salvage treatment can significantly improve clinical prognosis of these patients.
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Objective:To compare the influence of three-dimensional conformal radiotherapy and radiotherapy combined chemothera-py on the prognosis of patients with advanced esophageal cancer. Methods:A retrospective analysis from June 2007 to June 2010 in our hospital was conducted on 245 patients. Depending on the treatment, patients were classified into simple radiotherapy group and chemoradiothearapy group ,both of which received three-dimensional conformal radiotherapy. A total of 173 patients were in the radi-ation and chemotherapy combined treatment group, while 72 cases were in the simple radiothearapy group. One month after inter-vention, efficacy, adverse reactions, and survival rates of the two groups of patients were compared. Results:The proportion of wom-en in the combination therapy group, aged 0.05). The combined treatment group results were significantly higher than the efficiency of the radiotherapy group. The difference was statistically significant (P0.05). The five-year survival rate of combination group were significantly higher than that of the radiotherapy group, and the difference was statistically significant (P<0.05). Conclusion:For advanced esophageal car-cinoma patients, radiotherapy and chemotherapy combined with radiotherapy improved efficiency of treatment and effectively im-proved survival rate. Although the proposed treatment could lead to adverse reactions, these effects are within the range of tolerance, which makes the said treatment worthy of clinical promotion.
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Objective To investigate the optimization of therapeutic regimen through the adjustment of the minimum sub-field area in intensity-modulated radiotherapy (IMRT) for cervical cancer,under the premise of no influence on the dose to target volume or organs at risk.Methods A total of 12 patients with pathologically confirmed cervical cancer were enrolled,and the prescribed dose to the planning target volume (PTV) was 50 Gy in 25 fractions.The Pinnacle 8.0m treatment planning system was used for all patients,and 16 IMRT plans were developed for each patient,with the application of 9 evenly distributed fixed incidence directions (0°,40°,80°,120°,160°,200°,240°,280°,and 320°),a minimum sub-field number of 80,and a minimum sub-field hop count (MU) of 5 MU.The range of sub-field area was 2-81 cm2.Direct machine parameter optimization was used for inverse-planned optimization calculation,and all the plans met the requirements of the clinical prescribed dose.The dose-volume histogram was used to evaluate the dose distribution in target volume and organs at risk.Results With the sub-field area increasing from 2 cm2 to 81cm2,the total hop count of IMRT plan was reduced from (1405±170) MU to (490±47) MU (P=0.000),and when the sub-field area increased above 6 cm×6 cm,the total hop count was reduced significantly (P=0.000).In the IMRT plan with a minimum sub-field area of 2-49 cm2,there was no significant difference in dose between the target volume and the organs at risk (P＞0.05).The dose to the rectum,the bladder,and both femoral heads showed no significant differences across the IMRT plans with different minimum sub-field areas (P＞0.05).Conclusions When the Pinnacle 8.0m treatment planning system is used to develop IMRT plans for cervical cancer,the requirements for clinical dose can still be met with a minimum sub-field area reaching 7 cm×7 cm,and there are significant reductions in sub-field hop count and total hop count.
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Objective To construct the uniform electron density couch model (model A ED =0.25) and two components non uniform electron density couch model (model B FD =0.5and foam core=0.1) in the Monaco treatment planning system for the iBEAM(R) evo Extension 415,and to compare which model can better quantify the treatment couch influence on radiation dose.Methods Phantom was positioned in the center of the couch,the attenuation of the couch was evaluated with 6 MV for a field size of 10 cm× 10 cm.Dose measurements of couch attenuation were performed at gantry angles from 180.0° to 122.8°,using a 0.125cc semiflex ionization chamber (PTW),isocentrically placed in the center of a homogeneous cylindrical phantom.Each experimental setup was first measured on the linear accelerator and then reproduced in the TPS.By adjusting the relative-to water electron density (ED) values of the couch,the measured attenuation was replicated.The model accuracies of the model A and model B were evaluated by comparing the measured and calculated results at the minimum computational grid (2 mm) and maximum computing grid (5 mm),respectively.Results The maximum measured and calculated percentage deviation for the central phantom position was 4.01％.The couch model was included in the TPS with a uniform ED of 0.25 or a 2 component model with a fiber ED=0.5 and foam core ED=0.1.For model A and B under 2 and 5 mm voxel grid size,the mean absorbed dose with couch was reduced to 0.61％,0.84％,0.71％ and 0.92％from 2.8％ without couch.Conclusions Model A has a good agreement between measured and calculated dose distributions for all different voxel grid sizes and gantry angles.It can accurately describes the dose perturbations due to the presence of the couch and should therefore be used during treatment planning.
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Objective To investigate the application of the Monte Carlo dose calculation of output factors for electron beams in radiotherapy.Methods The code EGS4/MCTP was used to simulate the head of a medical linear accelerator (Varian 23EX) to calculate the output factors for 6 MeV,9 MeV and 18 MeV electron beams.The source-to-surface distance used was 100 cm.The field sizes ranged from 2 cm × 2 cm to 25 cm × 25 cm.The calculated output factors agreed with the corresponding measured factors which were measured by the IBA Phantom system to within 2％.Then,the output factors of direct articles and indirect articles which were under different energy and various cone-insert combinations were calculated by the code EGS4/MCTP.Results The calculated output factors agreement with the measurements is found to be mostly under the 1％ level.The variation of output factors depends on the characteristics of the beams and the modifications that the various cone-insert combinations introduce to these characteristics.Conclusions Monte Carlo dose calculations for electron beams in homogeneous water phantoms have been demonstrated to be accurate under the 1％ level in comparison with measurements.The output factors were influenced by energy and cone-insert combinations in complex ways.
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Objective Comparing the dosimetric characteristics of volumetric modulated arc therapy (VMAT) and constant dose rate intensity modulated arc therapy (IMAT) in esophagus cancer to evaluate the performance of the two different arc therapy delivery techniques.Methods 22 cases of esophageal cancer patients were selected for the planning comparison study.All plans were done for IMAT and VMAT treatment plans on Oncentra 4.1 treatment planning system,prescription dose of 2 Gy in total 30 fractions.Planning objectives for PTV were at least 95％ reached the prescription dose and V110 no more than 10％.The maximum dose of spinalcord below 45 Gy and double lung dose V20 ≤ 28％,V30 ≤ 18％ were constrained.Plans were evaluated based on the ability to meet the dose volume histogram.The dose homogeneity index (HI),radiation conformity index (CI),radiation delivery time,monitor units and γ pass rate were also compared.SPSS 19.0 software paired ttest analysis was carried out on the two sets of data.Results The results showed that the IMAT plans in terms of the PTV's CI (t =3.35,P=0.003),D2(t =-2.27,P=0.034) lung's V30(t =-2.46,P=0.023) were better than that of VMAT group.But the VMAT plans spinal's V40 (t =2.37,P =0.027),lung's V5 (t =2.43,P =0.024) were superior to that of IMAT plans.There were no significant differences between IMAT and VMAT plans in the average dose of PTV,CTV,GTV,heart,spinal cord,double lung and the γpass rate.Conclusion IMAT presents a slight improvement in the OAR sparing in high dose with shorter treatment time when compared to VMAT.While in terms of delivered MU and tissue of low dose irradiated area is higher than that of in VMAT.These two treatment methods all can meet the clinical demand,which should be selected according to the actual situation of the patient.
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Objective To study the relationship between parameter settings in the intensity-modulated radiation therapy (IMRT) planning in order to explore the effect of parameters on absolute dose verification.Methods Forty-three esophageal carcinoma cases were optimized with Pinnacle 7.6c by experienced physicist using appropriate optimization parameters and dose constraints with a number of iterations to meet the clinical acceptance criteria.The plans were copied to water-phantem,0.13 cc ion Farmer chamber and DOSE1 dosimeter was used to measure the absolute dose.The statistical data of the parameters of beams for the 43 cases were collected,and the relationships among them were analyzed.The statistical data of the dosimetry error were collected,and comparative analysis was made for the relation between the parameters of beams and ion chamber absolute dose verification results.Results The parameters of beams were correlated among each other.Obvious affiliation existed between the dose accuracy and parameter settings.When the beam segment number of IMRT plan was more than 80,the dose deviation would be greater than 3％ ; however,if the beam segment number was less than 80,the dose deviation was smaller than 3％.When the beam segment number was more than 100,part of the dose deviation of this plan was greater than 4％.On the contrary,if the beam segment number was less than 100,the dose deviation was smaller than 4％ definitely.Conclusions In order to decrease the absolute dose verification error,less beam angles and less beam segments are needed and the beam segment number should be controlled within the range of 80.
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Objective With the Monte Carlo method to recaleulate the IMRT dose distributions from four TPS to provide a platform for independent comparison and evaluation of the plan quality.These results wiU help make a clinical decision as which TPS will be used for prostate IMRT planning.Methods Eleven prostate cancer cases were planned with the Corvus,Xio,Pinnacle and Eclipse TPS.The plans were recalculated bv Monte Cado using leaf sequences and MUs for individual plans.Dose-volume-histograms and isodose distributions were compared.Other quantities such as Dmin(the minimum dose received by 99% of CTV/PTV),Dmax(the maximum dose received by 1%of CTV/PTV),V110%,V105%,V95%(the volume of CTV/PTV receiving 110%,105%.95% of the prescription dose),the volume of rectum and bladder receiving>65 Gy and>40 Gy,and the volume of femur receiving>50 Gy were evaluated.Total segments and MUs were also compared.Results The Monte Carlo results agreed with the dose distributions from the TPS to within 3%/3 mm.The Xio,Pinnacle and Eclipse plans show less target dose heterogeneity and lower V65 and V40 for the rectum and bladder compared to the Corvus plans.The PTV Dmin is about 2 Gy lower for Xio plans than others while the Corvus plans have slightly lower female head V50(0.03%and 0.58%)than others.The Corvus plans require significantly most segments(187.8)and MUs(1264.7)to deliver and the Pinnacle plans require fewest segments(82.4)and MUs(703.6).Conclusions We have tested an independent Monte Carlo dose catculation system for dose reconstruction and plan evaluation.This system provides a platform for the fair comparison and evaluation of treatment plans to facilitate clinical decision making in selecting a TPS and beam delivery system for particular treatment sites.
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Objective To evaluate the optimized conformal and IMRT plans for the upper esophageal carcinoma. Methods Eight patients with upper esophageal carcinoma underwent CT simulation.GTV was contoured on the CT image,referring the esophagogram and endoscopy simuhaneously,then CTV and PTV were also defined using the same criteria.Different conformal radiotherapy plans consisting of 3 fields(F),4F or 6F,IMRT plans consisting of 3F,4F,5F,7F,9F or 11F,and a simplified IMRT(s-IMRT)plan were designed for these patients.The minimum prescription dose that 95%of PTV volume received was 6000 cGy.Dose distributions of the PTV and OARs in different 3 DCRT and IMRT plans were compared and the optimized plans for the upper esophageal carcinoma were then recommended. Resuits Dose and volume parameters of PTV were similar among the 3DCRT plans(P＞0.05).4F 3DCRT plan reduced lung V20 as compared to 6F plan(P＜0.05),and mean lung dose(MLD)of 3F and 6F 3DCRT plans were higher than that of4F plan(P＜0.05).PTV D100 of 3F IMRT plan was lower than that of 9F and 11F plans(P＜0.05).IV of 4F IMRT plan was larger than that of 9F and 11F IMRT plans(P＜0.05).PTV dose and volume parameters of the 9F IMRT and 1 1 F IMRT were similar comparing with 5F.7F and s-IMRT plans,and OARs dose was also similar among IMRT plans(P＞0.05).PTV CI,D100,D95,V100 and V95 of the 4F 3DCRT plan were all lower than those of 5F,7F and s-IMRT plans(P＜0.05).5F,7F and s-IMRT plans reduced lung V20 as compared to 4F 3DCRT plan(P＜0.05).Conclusions For the upper esophageal carcinoma.4F 3DCRT plan is recommended among the 3DCRT plans.5F.7F and s-IMRT plans are recommended among the IMRT plans,which are superior than 4F 3 DCRT plan.