Objective To compute and compare the tumor control probability(TCP) of volumetric modulated arc therapy(VMAT) for breast cancer after conservative surgery based on two types of multileaf collimator(MLC) through a retr...Objective To compute and compare the tumor control probability(TCP) of volumetric modulated arc therapy(VMAT) for breast cancer after conservative surgery based on two types of multileaf collimator(MLC) through a retrospective planning study.Methods For a group of 9 patients diagnosed with left breast cancer,VMAT plan based on Agility MLC and beam modulator(BM) MLC were designed.The prescription dose was 50 Gy covering at least 95% of the planning target volume,2 Gy per fraction.TCPs were calculated according to dose-volume histogram(DVH) analysis.Results The TCP of the BM VMAT plan was slightly higher than that of the Agility VMAT plan(94.61% vs 94.23%) but was inferior with respect to delivery efficiency;the delivery time was reduced for Agility VMAT plan by 35% compared to BM VMAT plan.Conclusion For breast cancer radiation therapy after conservative surgery,BM VMAT plans provide slightly higher TCP while the delivery of Agility VMAT plans is significantly faster than the BM VMAT plans.展开更多
Inhibition effects, control probabilities and pathology tissue changes of mouse transplanted tumors S180 after irradiation with 50 MeVu 12C6+ ions are reported. Doses of single irradiation were 0.5, 1, 2, 5, 10, 20, 4...Inhibition effects, control probabilities and pathology tissue changes of mouse transplanted tumors S180 after irradiation with 50 MeVu 12C6+ ions are reported. Doses of single irradiation were 0.5, 1, 2, 5, 10, 20, 40 Gy, respectivelyl at a dose rate of 3 Gy/min. Observing time was 24 days. The results show that each group had significant inhibition action on S180 tumors and all inhibitory probabilities were more than 90%; the initial time of inducing tumor inhibition effects were within one week in high dose groups （20, 40 Gy）, and after two weeks in medium dose groups （5, 10 Gy） and low dose groups （0.5, 1, 2 Gy）; also, inhibitory effects in high dose groups were obviously greater than other groups （p <0.05）; tumor control probabilities were different in each group) those in high dose groups （20, 40 Gy） were higher and TCD50 （50% tumor control dose） was 20Gy; the results for curing tumors are different in different doses; pathology inspection presented here were tumor tissue necrosis and degeneration in each dose group and they depended on doses.展开更多
The quality of radiation therapy depends on the ability to maximize the tumor control probability while minimizing the normal tissue complication probability.Both of these two quantities are directly related to the ac...The quality of radiation therapy depends on the ability to maximize the tumor control probability while minimizing the normal tissue complication probability.Both of these two quantities are directly related to the accuracy of dose distributions calculated by treatment planning systems.The commonly used dose calculation algorithms in the treatment planning systems are reviewed in this work.The accuracy comparisons among these algorithms are illustrated by summarizing the highly cited research papers on this topic.Further,the correlation between the algorithms and tumor control probability/normal tissue complication probability values are manifested by several recent studies from different groups.All the cases demonstrate that dose calculation algorithms play a vital role in radiation therapy.展开更多
Objective： The aim of this work was to quantify the extent of set-up errors to conduct a quality assurance （QA） aspect of treatment delivery, verification of the treatment field＇s position on different days using ...Objective： The aim of this work was to quantify the extent of set-up errors to conduct a quality assurance （QA） aspect of treatment delivery, verification of the treatment field＇s position on different days using electronic portal. Methods： This study was carried out on 12 patients, treated for pelvis tumor; and total of 240 images obtained by electronic portal image device （EPID） were analyzed. The EPIs acquire using EPID attached to the Siemens linear accelerator. The anatomy match- ing software （Theraview） was used and displacement in two dimensions were noted for each treatment field to study patient setup errors. Results： The percentages of mean deviations less than 5 mm in X direction were 65% ＆ 92%, from 5-10 mm were 31% ＆ 19% and more than 10 mm were 11% ＆ 9% forNP and lateral direction respectively. The percentages of mean deviations less than 5 mm in Y direction were 65% ＆ 63%, from 5-10 mm were 33% ＆ 28% and more than 10 mm were 22% ＆ 29%. The mean deviations in 2D-vector errors were 〈 5 mm in 47% and 46%, 5-10 mm in 36% and 37% and 〉 10 mm in 37% and 37% of images in the NP and lateral direction respectively. Conclusion： The results revealed that the ranges of set up errors are immobilization method to improve reproducibility. The observed variations were not within the limits..展开更多
目的:分析断层径照(TOMODirect,TD)治疗局部中晚期下咽癌的剂量学特性及其肿瘤控制概率(tumor control probability,TCP),评估TD治疗局部中晚期下咽癌的临床可行性。方法:随机选取26例局部中晚期下咽癌患者,分别采用螺旋断层(TOMOHelica...目的:分析断层径照(TOMODirect,TD)治疗局部中晚期下咽癌的剂量学特性及其肿瘤控制概率(tumor control probability,TCP),评估TD治疗局部中晚期下咽癌的临床可行性。方法:随机选取26例局部中晚期下咽癌患者,分别采用螺旋断层(TOMOHelical,TH)和TD设计放疗计划。采用配对t检验对比分析2组计划的靶区包络质量、危及器官(organs at risk,OAR)保护、计划执行效率及TCP。结果:TD和TH治疗计划的各项指标均满足临床要求。与TH相比,TD计划中PTV1的靶区适形指数略差(P=0.009),平均剂量增大0.48%(P=0.010)。TH和TD计划中SIB和PTV2的各参数剂量差异不大,且均无统计学差异(P>0.05)。TD中除脊髓的最大剂量较TH计划增加3.64%(P=0.044),以及身体的V5 Gy和V10 Gy分别降低3.98%(P=0.002)和3.46%(P=0.002)之外,2种计划中其他危及器官的剂量均差异不大,且无统计学差异(P>0.05)。TD比TH的机器跳数减少8.04%(P=0.000),但治疗时间却增加54.08 s(P=0.000)。TD和TH的TCP均值分别为94.74%和94.71%,两者无统计学差异(P>0.05)。结论:TD可以取得与TH相接近的靶区包络质量和危及器官受量,降低了低剂量区的范围,虽治疗时间有所延长,但降低了机器跳数,且平均肿瘤控制概率接近。TD可能是治疗局部中晚期下咽癌的一种优选放疗方式,在临床中值得推广应用。展开更多
基金Supported by a grant from the Innovation Project of the PLA Army General Hospital of China(No.2015-LC-18)
文摘Objective To compute and compare the tumor control probability(TCP) of volumetric modulated arc therapy(VMAT) for breast cancer after conservative surgery based on two types of multileaf collimator(MLC) through a retrospective planning study.Methods For a group of 9 patients diagnosed with left breast cancer,VMAT plan based on Agility MLC and beam modulator(BM) MLC were designed.The prescription dose was 50 Gy covering at least 95% of the planning target volume,2 Gy per fraction.TCPs were calculated according to dose-volume histogram(DVH) analysis.Results The TCP of the BM VMAT plan was slightly higher than that of the Agility VMAT plan(94.61% vs 94.23%) but was inferior with respect to delivery efficiency;the delivery time was reduced for Agility VMAT plan by 35% compared to BM VMAT plan.Conclusion For breast cancer radiation therapy after conservative surgery,BM VMAT plans provide slightly higher TCP while the delivery of Agility VMAT plans is significantly faster than the BM VMAT plans.
基金President Special Foundation of the Chinese Academy of Sciences
文摘Inhibition effects, control probabilities and pathology tissue changes of mouse transplanted tumors S180 after irradiation with 50 MeVu 12C6+ ions are reported. Doses of single irradiation were 0.5, 1, 2, 5, 10, 20, 40 Gy, respectivelyl at a dose rate of 3 Gy/min. Observing time was 24 days. The results show that each group had significant inhibition action on S180 tumors and all inhibitory probabilities were more than 90%; the initial time of inducing tumor inhibition effects were within one week in high dose groups （20, 40 Gy）, and after two weeks in medium dose groups （5, 10 Gy） and low dose groups （0.5, 1, 2 Gy）; also, inhibitory effects in high dose groups were obviously greater than other groups （p <0.05）; tumor control probabilities were different in each group) those in high dose groups （20, 40 Gy） were higher and TCD50 （50% tumor control dose） was 20Gy; the results for curing tumors are different in different doses; pathology inspection presented here were tumor tissue necrosis and degeneration in each dose group and they depended on doses.
基金Supported by In part,under a grant with the Pennsylvania Department of Health
文摘The quality of radiation therapy depends on the ability to maximize the tumor control probability while minimizing the normal tissue complication probability.Both of these two quantities are directly related to the accuracy of dose distributions calculated by treatment planning systems.The commonly used dose calculation algorithms in the treatment planning systems are reviewed in this work.The accuracy comparisons among these algorithms are illustrated by summarizing the highly cited research papers on this topic.Further,the correlation between the algorithms and tumor control probability/normal tissue complication probability values are manifested by several recent studies from different groups.All the cases demonstrate that dose calculation algorithms play a vital role in radiation therapy.
文摘Objective： The aim of this work was to quantify the extent of set-up errors to conduct a quality assurance （QA） aspect of treatment delivery, verification of the treatment field＇s position on different days using electronic portal. Methods： This study was carried out on 12 patients, treated for pelvis tumor; and total of 240 images obtained by electronic portal image device （EPID） were analyzed. The EPIs acquire using EPID attached to the Siemens linear accelerator. The anatomy match- ing software （Theraview） was used and displacement in two dimensions were noted for each treatment field to study patient setup errors. Results： The percentages of mean deviations less than 5 mm in X direction were 65% ＆ 92%, from 5-10 mm were 31% ＆ 19% and more than 10 mm were 11% ＆ 9% forNP and lateral direction respectively. The percentages of mean deviations less than 5 mm in Y direction were 65% ＆ 63%, from 5-10 mm were 33% ＆ 28% and more than 10 mm were 22% ＆ 29%. The mean deviations in 2D-vector errors were 〈 5 mm in 47% and 46%, 5-10 mm in 36% and 37% and 〉 10 mm in 37% and 37% of images in the NP and lateral direction respectively. Conclusion： The results revealed that the ranges of set up errors are immobilization method to improve reproducibility. The observed variations were not within the limits..
文摘目的:分析断层径照(TOMODirect,TD)治疗局部中晚期下咽癌的剂量学特性及其肿瘤控制概率(tumor control probability,TCP),评估TD治疗局部中晚期下咽癌的临床可行性。方法:随机选取26例局部中晚期下咽癌患者,分别采用螺旋断层(TOMOHelical,TH)和TD设计放疗计划。采用配对t检验对比分析2组计划的靶区包络质量、危及器官(organs at risk,OAR)保护、计划执行效率及TCP。结果:TD和TH治疗计划的各项指标均满足临床要求。与TH相比,TD计划中PTV1的靶区适形指数略差(P=0.009),平均剂量增大0.48%(P=0.010)。TH和TD计划中SIB和PTV2的各参数剂量差异不大,且均无统计学差异(P>0.05)。TD中除脊髓的最大剂量较TH计划增加3.64%(P=0.044),以及身体的V5 Gy和V10 Gy分别降低3.98%(P=0.002)和3.46%(P=0.002)之外,2种计划中其他危及器官的剂量均差异不大,且无统计学差异(P>0.05)。TD比TH的机器跳数减少8.04%(P=0.000),但治疗时间却增加54.08 s(P=0.000)。TD和TH的TCP均值分别为94.74%和94.71%,两者无统计学差异(P>0.05)。结论:TD可以取得与TH相接近的靶区包络质量和危及器官受量,降低了低剂量区的范围,虽治疗时间有所延长,但降低了机器跳数,且平均肿瘤控制概率接近。TD可能是治疗局部中晚期下咽癌的一种优选放疗方式,在临床中值得推广应用。
