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Objective To identify clinical and dosimetric parameters from dose-volume histogram(DVH) relating with incidence of severe acute radiation-induced esophagitis(RE)in patients with non-small cell lung can-cer(NSCLC)underwent tomotherapy with concurrent or sequential chemotherapy. Methods Records about clini-cal information and treatment plan parameters from DVH of 62 NSCLC patients treated with tomotherapy were pro-spectively collected to assess the correlation to severe acute RE from January 2012 to December 2016. Results There were 24.2％patients developed grade 3 RE,grade 4 or 5 in 0％patients. Multivariate analysis indicated that concurrent chemotherapy,esophagus median dose and esophagus V25 and V55 were the influencing factors of RE. The incidence of low frequencies RE was correlated with sequential chemotherapy ,esophagus median dose < 49 Gy,esophagus V25 < 64％ ,V55 < 33％ and V60 < 15％. Conclusions For NSCLC patients treated with tomo-therapy and chemotherapy,the occurrence of acute RE was similar to that of other techniques. It is recommended to balance such parameters for optimizing treatment planning.
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Objective To identify clinical and dosimetric parameters from dose-volume histogram(DVH) relating with incidence of severe acute radiation-induced esophagitis(RE)in patients with non-small cell lung can-cer(NSCLC)underwent tomotherapy with concurrent or sequential chemotherapy. Methods Records about clini-cal information and treatment plan parameters from DVH of 62 NSCLC patients treated with tomotherapy were pro-spectively collected to assess the correlation to severe acute RE from January 2012 to December 2016. Results There were 24.2％patients developed grade 3 RE,grade 4 or 5 in 0％patients. Multivariate analysis indicated that concurrent chemotherapy,esophagus median dose and esophagus V25 and V55 were the influencing factors of RE. The incidence of low frequencies RE was correlated with sequential chemotherapy ,esophagus median dose < 49 Gy,esophagus V25 < 64％ ,V55 < 33％ and V60 < 15％. Conclusions For NSCLC patients treated with tomo-therapy and chemotherapy,the occurrence of acute RE was similar to that of other techniques. It is recommended to balance such parameters for optimizing treatment planning.
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Objective To investigate the predictive value of dose?volume histograms ( DVHs ) of organs at risk ( OARs ) including the bladder, rectum, and small intestine in volumetric modulated arc therapy ( VMAT) plans for cervical cancer. Methods A total of 100 VMAT plans for cervical cancer were assigned into the learning group. The correlation of the anatomical information with the V30 , V40 , and V50 values of the bladder, rectum, and small intestine was evaluated in the group. The support vector regression ( SVR) algorithm was used to establish the correspondence between the anatomical information and the DVHs of OARs. The DVHs of OARs in the verification group containing 20 VMAT plans were predicted based on the anatomical information. Results The DVHs of the bladder, rectum, and small intestine were likely to be influenced mainly by the spatial relationship between these OARs and target volume. In the verification group, the prediction errors of V30,V40 and V50 by SVR algorithm were-2.4%±3. 5%,-2.5%±3. 8%, and-1.5%±4. 9% for the bladder, 0.5%±2. 6%,-1.5%±5. 1%, and-2.0%±7. 4% for the rectum, and-2.9%± 5. 3%, 2.7%±7. 7%, and 5.3%±11. 1% for the small intestine, respectively. Conclusions After learning the correlation between the anatomical information and the DVHs of OARs from prior VMAT plans for cervical cancer, SVR algorithm can precisely predict the DVHs of the bladder, rectum, and small intestine based on the anatomical information.
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Objective To compare the dosimetric difference in planning target volume(PTV)and organ at risk(OAR)with conventional and the three-dimensional treatment planning for limlted-stage small cell lung cancer.Methods Ten patients with limited-stage small cell lung cancer were chosen in the present study.Two treatment planning were designed twice respectively with the Cadplan R 3.1.2 treatment planning system for each patient in two-course.The total radiation dose was 50 Gy.The dosimetric parameters were assessed with dose volume histograms in PIT and OAR.Results For the first course,the dose homogeneity indices(HI)of PTV1,conformal indices(CI)of PTV2,contralateral lung V3o and eontralateral mean lung dose in the three-dimensional treatment planning were better than that in the conventional treatment planning.For the second course,the HI,CI and mean dose of PTV1,CI and mean dose of PTV2 in the three-dimensional treatment planning were better than that in the conventional treatment planning.Conclusions By comparison with conventional treatment planning,the three-dimensional conformal treatment planning could meet the demands of dosimetrie requirements well for limited-stage small cell lung cancer with three-dimensional conformal radiotherapy,but with no significant dnsimetric differences in the OAR.
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Background and purpose:Intensity-modulated radiotherapy(IMRT) can significantly improve the dosimetric distribution of both the target and organs at risk compared to tangential irradiation for whole breast. However,its optimized methods remain different and conflicting for many radiotherapy institutions.In order to achieve the optimized planning of IMRT for the irradiation of intact breast,we investigated different optimizing methods in three dimensional radiotherapy planning system.Methods:Ten patients with early-stage breast cancer after breast conserving surgery were eligible for the study.Two kinds of plans were performed on each patient in three-dimensional treatment planning system,inverse planning IMRT and forward planning IMRT which included 3 different optimizing methods as manual optimizing(MO),multiple points optimizing(PO) and automated inverse optimizing(AO).Various parameters were used to evaluate the efficacy of different IMRT plans.All plans were compared using dose volume histograms(DVH) for the planning target volume(PTV) and organs at risk(OARs).Results:For MO,PO,AO forward plans and inverse plans,median number of segments were 5,5.5,5 and 20 respectively,and mean total MU were 225.8, 228.4,226.4 and 345.8 MU,respectively.Comparing the different forward planning optimizations,the best target coverage and dose homogeneity of PTV was observed in AO plans(P(?)0.01),and PO and AO plans showed a better reduction of OARs exposure compared with MO plans(P(?)0.05).A further improvement of dose homogeneity in the PTV and better sparing of OARs was achieved using inverse planning(P(?)0.05).Conclusion:Forward planning IMRT with AO optimization for intact breast irradiation could provide both efficacy and dosimetric advantages better than others.The inverse IMRT plan showed more potential in improving the dosimetric outcomes.However,further studies are required for inverse optimizing plans.
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Purpose:To evaluate the safety and efficacy of the box-shape field technique of radiotherapy for postoperative gastric carcinoma.Methods:Thirty-two patients of gastric carcinoma after subtotal or total gastrectomy with an extensive (D2) lymph-node dissection were irradiated with a total dose of 46～50Gy Gy of external box-shape field technical in 23-25 fractions by linac with 6-MV photons. All patients received concomitant chemotherapy which two cycles of paclitaxel (135mg/m~2 ) and cisplatin (70mg/m~2) in d1-3 and d29-31.Results:The overall survival,the relapse free survival of two years of all patients was 87.50% and 16.67%, respectively. 32 patients with treatment failure had recurrent disease, 4 (6.3%)in the liver,2(6.3%) in the peritoneum, 2(12.5%) in the anastomosis ,respectively. the plan of box-shape fields were evaluated with dose-volume histogram of three-dimensional therapy plan system, The 90% isodose line included the whole clinical target volume,and the dose of organat at rist was under the tolerance dose, except the dose of left kidney.Conclusions:The box-shape field technique of radiotherapy for postoperative gastric carcinoma were a technique which the dose distribution of clinical target volume was satisfaction ,and well tolerated with no severe side effects.[
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Objective To assess and delineate the dosimetric shortcomings of conventional radiotherapy planning,as compared with the three dimensional treatment planning system, and to obtain a better technique in the treatment of lung cancers.Methods Thirteen patients with stage ⅢA ⅢB non small cell lung cancer were chosen in the present study. Using the Cadplan 6.0.8 treatment planning system , three different methods of radiotherapy planning: conventional planning, conventional and conformal planning, and conformal planning were designed for each patient. The total radiation dose was 66 ?Gy and DVHs were used to assess the dosimetric distribution in the gross tumor volume and the surrounding organs at risk. Results No significant dosimetric disparity in the target volume was found among the three designs, according to anticipated therapeatic requirements. The conformity indices were 0.13,0.24 and 0.35 for these three radiotherapy designs. The mean lung volumes which received radiation dose of≥20?Gy were 32%,26% and 25%.The mean maximum dose at the spinal cord were 42?Gy,49?Gy and 33?Gy.The mean esophageal volume which received radiation of ≥50?Gy were 32%,34% and 22%, and the mean radiation dose to the heart were 18?Gy,15?Gy and 12?Gy,respectively. Conclusions Conventional radiotherapy planning is able to meet the demands of dosimetric requirements for radiation treatment of lung cancers. The three dimensional conformal radiation therapy planning system is able to provide superior delivery of high dose to the target volume without inflicting too high a risk to the surrounding normal tissues and organs.