Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial measurement.We propose a geometric error identification method based on multi-station synchronization laser tracer...Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial measurement.We propose a geometric error identification method based on multi-station synchronization laser tracers to enable the rapid and high-precision measurement of geometric errors for gantry-type computer numerical control(CNC)machine tools.This method also improves on the existing measurement efficiency issues in the single-base station measurement method and multi-base station time-sharing measurement method.We consider a three-axis gantry-type CNC machine tool,and the geometric error mathematical model is derived and established based on the combination of screw theory and a topological analysis of the machine kinematic chain.The four-station laser tracers position and measurement points are realized based on the multi-point positioning principle.A self-calibration algorithm is proposed for the coordinate calibration process of a laser tracer using the Levenberg-Marquardt nonlinear least squares method,and the geometric error is solved using Taylor’s first-order linearization iteration.The experimental results show that the geometric error calculated based on this modeling method is comparable to the results from the Etalon laser tracer.For a volume of 800 mm×1000 mm×350 mm,the maximum differences of the linear,angular,and spatial position errors were 2.0μm,2.7μrad,and 12.0μm,respectively,which verifies the accuracy of the proposed algorithm.This research proposes a modeling method for the precise measurement of errors in machine tools,and the applied nature of this study also makes it relevant both to researchers and those in the industrial sector.展开更多
目的 探讨同步推量调强放疗技术在局部中晚期宫颈癌的应用价值。方法 回顾性选取2010年1月至2015年12月期间广西医科大学第四附属医院收治的局部晚期宫颈癌患者160例作为观察对象,按照住院尾号单双号情况将观察对象分为SMART组(n=87)和I...目的 探讨同步推量调强放疗技术在局部中晚期宫颈癌的应用价值。方法 回顾性选取2010年1月至2015年12月期间广西医科大学第四附属医院收治的局部晚期宫颈癌患者160例作为观察对象,按照住院尾号单双号情况将观察对象分为SMART组(n=87)和IMRT组(n=73),其中SMART组采用同步推量调强放疗技术治疗,IMRT组采用调强放疗技术治疗。对比分析两组治疗近期、远期疗效及放射性肠损伤及膀胱损伤情况。结果 SMART组治疗结束后3个月疗效评价的总有效率(91.95%)高于IMRT组(80.82%),差异具有统计学意义( P <0.05);SMART组急慢性放射性肠损伤及膀胱损伤的发生率均低于IMRT组,差异具有统计学意义( P <0.05);SMART组治疗后1年及2年生存率均高于IMRT组,但差异无统计学意义( P >0.05),SMART组治疗后1年及2年的疾病无进展生存率均高于IMRT组,差异有统计学意义( P <0.05)。结论 与调强放疗技术相比,同步推量调强放疗技术提高远期患者生存率方面优势不明显,但可提高局部中晚期宫颈癌治疗近期疗效,降低急慢性放射性肠损伤及膀胱损伤发生率,提高远期疾病无进展生存率,从而改善患者的生活质量,值得临床推广应用。展开更多
基金Supported by Natural Science Foundation of Shaanxi Province of China(Grant No.2021JM010)Suzhou Municipal Natural Science Foundation of China(Grant Nos.SYG202018,SYG202134).
文摘Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial measurement.We propose a geometric error identification method based on multi-station synchronization laser tracers to enable the rapid and high-precision measurement of geometric errors for gantry-type computer numerical control(CNC)machine tools.This method also improves on the existing measurement efficiency issues in the single-base station measurement method and multi-base station time-sharing measurement method.We consider a three-axis gantry-type CNC machine tool,and the geometric error mathematical model is derived and established based on the combination of screw theory and a topological analysis of the machine kinematic chain.The four-station laser tracers position and measurement points are realized based on the multi-point positioning principle.A self-calibration algorithm is proposed for the coordinate calibration process of a laser tracer using the Levenberg-Marquardt nonlinear least squares method,and the geometric error is solved using Taylor’s first-order linearization iteration.The experimental results show that the geometric error calculated based on this modeling method is comparable to the results from the Etalon laser tracer.For a volume of 800 mm×1000 mm×350 mm,the maximum differences of the linear,angular,and spatial position errors were 2.0μm,2.7μrad,and 12.0μm,respectively,which verifies the accuracy of the proposed algorithm.This research proposes a modeling method for the precise measurement of errors in machine tools,and the applied nature of this study also makes it relevant both to researchers and those in the industrial sector.
文摘目的 探讨同步推量调强放疗技术在局部中晚期宫颈癌的应用价值。方法 回顾性选取2010年1月至2015年12月期间广西医科大学第四附属医院收治的局部晚期宫颈癌患者160例作为观察对象,按照住院尾号单双号情况将观察对象分为SMART组(n=87)和IMRT组(n=73),其中SMART组采用同步推量调强放疗技术治疗,IMRT组采用调强放疗技术治疗。对比分析两组治疗近期、远期疗效及放射性肠损伤及膀胱损伤情况。结果 SMART组治疗结束后3个月疗效评价的总有效率(91.95%)高于IMRT组(80.82%),差异具有统计学意义( P <0.05);SMART组急慢性放射性肠损伤及膀胱损伤的发生率均低于IMRT组,差异具有统计学意义( P <0.05);SMART组治疗后1年及2年生存率均高于IMRT组,但差异无统计学意义( P >0.05),SMART组治疗后1年及2年的疾病无进展生存率均高于IMRT组,差异有统计学意义( P <0.05)。结论 与调强放疗技术相比,同步推量调强放疗技术提高远期患者生存率方面优势不明显,但可提高局部中晚期宫颈癌治疗近期疗效,降低急慢性放射性肠损伤及膀胱损伤发生率,提高远期疾病无进展生存率,从而改善患者的生活质量,值得临床推广应用。
