Objective： The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods： Three spheres with diameters of 2, 3 and 4 cm made of ti...Objective： The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods： Three spheres with diameters of 2, 3 and 4 cm made of tissue-equivalent materials used for simulating tumors were inserted into the upper lobe, middle lobe, lower lobe of the right lung, upper lobe, lower lobe of the left lung of the Rando phantom, respectively. Five-field simplified IMRT （slMRT） planning were designed. The prescribed dose was 60 Gy/2 Gy/30 f, 99% of the planning target volume received this dose. Dose-volume parameters of normal lung tissues including relative volume of lung receiving 〉 5, 10, 20, 30 and 50 Gy （V5, Vl0, V2o, V30, V50）, and mean lung dose （MLD） were analyzed and compared. Results： For the dose-volume parameters, the diameter and the position of the tumor had a significant effect （P 〈 0.05）. With the diameter expanding from 2 to 3 cm, the parameters associated with tumor lying in various lobes increased by a range between 3.83%-125.38%, while the parameters linked with tumors on different lobes increased by a range between 10.46%-51.46% with the diameter expanding from 3 to 4 cm. Conclusion： Location and size of sphere-like tumor have an obvious effect on dose-volume parameters. Knowing about the degree of influence will help oncologists and physicists better evaluate treatment planning, then the probability of radiation pneumonitis can be reduced.展开更多
BACKGROUND Radiation esophagitis(RE)is one of the most common clinical symptoms of regional lymph node radiotherapy for breast cancer.However,there are fewer studies focusing on RE caused by hypofractionated radiother...BACKGROUND Radiation esophagitis(RE)is one of the most common clinical symptoms of regional lymph node radiotherapy for breast cancer.However,there are fewer studies focusing on RE caused by hypofractionated radiotherapy(HFRT).AIM To analyze the clinical and dosimetric factors that contribute to the development of RE in patients with breast cancer treated with HFRT of regional lymph nodes.METHODS Between January and December 2022,we retrospectively analysed 64 patients with breast cancer who met our inclusion criteria underwent regional nodal intensity-modulated radiotherapy at a radiotherapy dose of 43.5 Gy/15F.RESULTS Of the 64 patients in this study,24(37.5%)did not develop RE,29(45.3%)developed grade 1 RE(G1RE),11(17.2%)developed grade 2 RE(G2RE),and none developed grade 3 RE or higher.Our univariable logistic regression analysis found G2RE to be significantly correlated with the maximum dose,mean dose,relative volume 20-40,and absolute volume(AV)20-40.Our stepwise linear regression analyses found AV30 and AV35 to be significantly associated with G2RE(P<0.001).The optimal threshold for AV30 was 2.39 mL[area under the curve(AUC):0.996;sensitivity:90.9%;specificity:91.1%].The optimal threshold for AV35 was 0.71 mL(AUC:0.932;sensitivity:90.9%;specificity:83.9%).CONCLUSION AV30 and AV35 were significantly associated with G2RE.The thresholds for AV30 and AV35 should be limited to 2.39 mL and 0.71 mL,respectively.展开更多
Objective To assess the dosimetric performance of HyperArc in comparison with coplanar volumetric modulated arc therapy(c-VMAT)and non-coplanar VMAT(nc-VMAT)in the radiotherapy of thyroid-associated ophthalmopathy(TAO...Objective To assess the dosimetric performance of HyperArc in comparison with coplanar volumetric modulated arc therapy(c-VMAT)and non-coplanar VMAT(nc-VMAT)in the radiotherapy of thyroid-associated ophthalmopathy(TAO).Methods This retrospective study involved 10 patients with TAO who received radiotherapy at our center from December 2021 to December 2023.A single qualified physicist generated treatment plans using c-VMAT,nc-VMAT,and HyperArc techniques on the TrueBeam machine with the Eclipse treatment planning system.We compared the dosimetric parameters for target volumes and organs at risk(OARs)among these planning approaches.Monitor units(MUs)were also evaluated to assess beam efficiency and delivery effectiveness for each plan type.Results Compared to c-VMAT and nc-VMAT plans,HyperArc plans achieved the highest conformity index(CI),with increases of 3.35%(t=3.84,P=0.004)and 4.05%(t=5.01,P=0.001),respectively.They also achieved the lowest gradient index(GI),with decreases of 29.41%(t=−10.41,P<0.001)and 25.11%(t=−5.55,P<0.001),respectively,and the lowest R_(50%),with decreases of 31.69%(t=−11.74,P<0.001)and 28.01%(t=−5.50,P<0.001),respectively.In terms of the dosimetric parameters of OARs,HyperArc plans produced the best results among the three types of plans.Furthermore,HyperArc plans reduced MUs by 31.39%(t=−8.59,P<0.001)and 20.60%(t=−2.70,P=0.024)compared to c-VMAT and nc-VMAT plans,respectively.Conclusions This study compared c-VMAT,nc-VMAT,and HyperArc for the radiotherapy of TAO and demonstrated the superior dosimetric performance of HyperArc.HyperArc provided better dose conformity for targets,sharper dose falloff outside targets,more effective sparing of OARs,and more efficient utilization and delivery of rays.展开更多
文摘Objective： The aim of the study was to study the effect of the size and location of tumors on the normal lung dose-volume parameters for lung cancer. Methods： Three spheres with diameters of 2, 3 and 4 cm made of tissue-equivalent materials used for simulating tumors were inserted into the upper lobe, middle lobe, lower lobe of the right lung, upper lobe, lower lobe of the left lung of the Rando phantom, respectively. Five-field simplified IMRT （slMRT） planning were designed. The prescribed dose was 60 Gy/2 Gy/30 f, 99% of the planning target volume received this dose. Dose-volume parameters of normal lung tissues including relative volume of lung receiving 〉 5, 10, 20, 30 and 50 Gy （V5, Vl0, V2o, V30, V50）, and mean lung dose （MLD） were analyzed and compared. Results： For the dose-volume parameters, the diameter and the position of the tumor had a significant effect （P 〈 0.05）. With the diameter expanding from 2 to 3 cm, the parameters associated with tumor lying in various lobes increased by a range between 3.83%-125.38%, while the parameters linked with tumors on different lobes increased by a range between 10.46%-51.46% with the diameter expanding from 3 to 4 cm. Conclusion： Location and size of sphere-like tumor have an obvious effect on dose-volume parameters. Knowing about the degree of influence will help oncologists and physicists better evaluate treatment planning, then the probability of radiation pneumonitis can be reduced.
基金Supported by Handan City Science and Technology Research and Development Program,No.21422083353The Guangdong Medical Science and Technology Research Fund,No.20221115181236662.
文摘BACKGROUND Radiation esophagitis(RE)is one of the most common clinical symptoms of regional lymph node radiotherapy for breast cancer.However,there are fewer studies focusing on RE caused by hypofractionated radiotherapy(HFRT).AIM To analyze the clinical and dosimetric factors that contribute to the development of RE in patients with breast cancer treated with HFRT of regional lymph nodes.METHODS Between January and December 2022,we retrospectively analysed 64 patients with breast cancer who met our inclusion criteria underwent regional nodal intensity-modulated radiotherapy at a radiotherapy dose of 43.5 Gy/15F.RESULTS Of the 64 patients in this study,24(37.5%)did not develop RE,29(45.3%)developed grade 1 RE(G1RE),11(17.2%)developed grade 2 RE(G2RE),and none developed grade 3 RE or higher.Our univariable logistic regression analysis found G2RE to be significantly correlated with the maximum dose,mean dose,relative volume 20-40,and absolute volume(AV)20-40.Our stepwise linear regression analyses found AV30 and AV35 to be significantly associated with G2RE(P<0.001).The optimal threshold for AV30 was 2.39 mL[area under the curve(AUC):0.996;sensitivity:90.9%;specificity:91.1%].The optimal threshold for AV35 was 0.71 mL(AUC:0.932;sensitivity:90.9%;specificity:83.9%).CONCLUSION AV30 and AV35 were significantly associated with G2RE.The thresholds for AV30 and AV35 should be limited to 2.39 mL and 0.71 mL,respectively.
文摘Objective To assess the dosimetric performance of HyperArc in comparison with coplanar volumetric modulated arc therapy(c-VMAT)and non-coplanar VMAT(nc-VMAT)in the radiotherapy of thyroid-associated ophthalmopathy(TAO).Methods This retrospective study involved 10 patients with TAO who received radiotherapy at our center from December 2021 to December 2023.A single qualified physicist generated treatment plans using c-VMAT,nc-VMAT,and HyperArc techniques on the TrueBeam machine with the Eclipse treatment planning system.We compared the dosimetric parameters for target volumes and organs at risk(OARs)among these planning approaches.Monitor units(MUs)were also evaluated to assess beam efficiency and delivery effectiveness for each plan type.Results Compared to c-VMAT and nc-VMAT plans,HyperArc plans achieved the highest conformity index(CI),with increases of 3.35%(t=3.84,P=0.004)and 4.05%(t=5.01,P=0.001),respectively.They also achieved the lowest gradient index(GI),with decreases of 29.41%(t=−10.41,P<0.001)and 25.11%(t=−5.55,P<0.001),respectively,and the lowest R_(50%),with decreases of 31.69%(t=−11.74,P<0.001)and 28.01%(t=−5.50,P<0.001),respectively.In terms of the dosimetric parameters of OARs,HyperArc plans produced the best results among the three types of plans.Furthermore,HyperArc plans reduced MUs by 31.39%(t=−8.59,P<0.001)and 20.60%(t=−2.70,P=0.024)compared to c-VMAT and nc-VMAT plans,respectively.Conclusions This study compared c-VMAT,nc-VMAT,and HyperArc for the radiotherapy of TAO and demonstrated the superior dosimetric performance of HyperArc.HyperArc provided better dose conformity for targets,sharper dose falloff outside targets,more effective sparing of OARs,and more efficient utilization and delivery of rays.
