Edge加速器Calypso 4D电磁定位系统精确性评估
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摘要
目的:研究Calypso 4D电磁定位系统的几何精度和电磁阵列对加速器射线的衰减。方法:分别把植入式转发器和表面转发器安装在体模上,对比Calypso测量的体模等中心位移和实际位移,分析系统的定位精度;使用指型电离室测量有和没有电磁阵列时固体水内剂量,验证电磁阵列对射线的衰减;重复测量相同位置的体模等中心,评估系统稳定性。结果:植入式转发器的定位精度是(0.02±0.01)cm,表面转发器的定位精度是(0.01±0.01)cm;在机架角325°到35°范围内,6和10 MV能量电磁阵列对加速器射束的衰减低于2%,在305°和55°衰减低于3.4%;重复测量时出现偏移的标准差在0.012 cm以内。结论:Calypso系统定位精度能够稳定在亚毫米级,电磁阵列对射线的衰减在临床接受范围内,Calypso 4D电磁定位系统是精确、可靠的,能够大大提高放疗精度。
Objective To evaluate the geometric accuracy of Calypso 4 D electromagnetic localization system and study the attenuation of ray caused by electromagnetic array. Methods Implantable transponders and superficial transponders were placed in the phantom, separately. The localization precision was analyzed by comparing the displacement of the phantom isocenter measured with Calypso and actual displacement, and the attenuation of ray caused by electromagnetic array was evaluated by measuring the dose of solid water with and without electromagnetic array. The phantom isocenter at the same position was measured repetitively for assessing the system stability. Results The accuracies of implantable and superficial transponders were(0.02 ±0.01) cm and(0.01 ±0.01) cm. The attenuation caused by electromagnetic array was below 2% for both 6 MV and 10 MV energies at gantry angles between 325° and 35°, and was lower than 3.4% at gantry angles of 305° and 55°. The standard deviation of displacement was within 0.012 cm in repeated measurements. Conclusion The accuracy of Calypso localization system is steadily at submillimeter level, meanwhile, the attenuation of ray caused by electromagnetic array is clinically insignificant.Calypso 4 D electromagnetic localization system which is accurate and reliable can greatly improve the accuracy of radiotherapy.
Objective To evaluate the geometric accuracy of Calypso 4 D electromagnetic localization system and study the attenuation of ray caused by electromagnetic array. Methods Implantable transponders and superficial transponders were placed in the phantom, separately. The localization precision was analyzed by comparing the displacement of the phantom isocenter measured with Calypso and actual displacement, and the attenuation of ray caused by electromagnetic array was evaluated by measuring the dose of solid water with and without electromagnetic array. The phantom isocenter at the same position was measured repetitively for assessing the system stability. Results The accuracies of implantable and superficial transponders were(0.02 ±0.01) cm and(0.01 ±0.01) cm. The attenuation caused by electromagnetic array was below 2% for both 6 MV and 10 MV energies at gantry angles between 325° and 35°, and was lower than 3.4% at gantry angles of 305° and 55°. The standard deviation of displacement was within 0.012 cm in repeated measurements. Conclusion The accuracy of Calypso localization system is steadily at submillimeter level, meanwhile, the attenuation of ray caused by electromagnetic array is clinically insignificant.Calypso 4 D electromagnetic localization system which is accurate and reliable can greatly improve the accuracy of radiotherapy.
引文
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[19]ZUCCA A,MANCOSU P,COMITO T,et al.On line tracking of abdominal compression efficacy for pancreas SBRT by Calypso surface transponders[J].Radiother Oncol,2015,115(1):S609-S610.
[20]SILVA C,MATEUS D,VIEIRA S,et al.Calypso's array attenuation[J].J Radiother Prac,2015,14(2):202-207.
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[3]WILLOUGHBY T R,KUPELIAN P A,POULIOT J,et al.Target localization and real-time tracking using the Calypso 4D localization system in patients with localized prostate cancer[J].Int J Radiat Oncol Biol Phys,2006,65(2):528-534.
[4]MURALIDHAR K R,KRISHNA K,ROUT B K,et al.Commissioning and quality assurance of Calypso four-dimensional target localization system in linear accelerator facility[J].Med Phys,2013,38(3):143-147.
[5]Varian Medical Systems.Calypso system operator's manual[R].Palo Alto:Varian Medical Systems,2013.
[6]BALTER J M,WRIGHT J N,NEWELL L J,et al.Accuracy of a wireless localization system for radiotherapy[J].Int J Radiat Oncol Biol Phys,2005,61(3):933-937.
[7]FRANZ A M,SCHMITT D,SEITEL A,et al.Standardized accuracy assessment of the Calypso wireless transponder tracking system[J].Phys Med Biol,2014,59(22):797-810.
[8]SHARP G C,JIANG S B,SHIMIZU S,et al.Tracking errors in a prototype real-time tumor tracking system[J].Phys Med Biol,2004,49(23):5347-5356.
[9]SCHMIDHALTER D,FIX M K,WYSS M,et al.Evaluation of a new six degrees of freedom couch for radiation therapy[J].Med Phys,2013,40(11):111710.
[10]OGUNLEYE T,ROSSI P J,JANI A B,et al.Performance evaluation of Calypso 4D localization and kilovoltage image guidance systems for interfraction motion management of prostate patients[J].J Sci World,2009,9:449-458.
[11]WEN N,SNYDER K C,SCHEIB S G,et al.Evaluation of the systematic accuracy of a frameless,multiple image modality guided,linear accelerator based stereotactic radiosurgery system[J].Med Phys,2016,43(5):2527-2537.
[12]MURPHY M J,EIDENS R,VERTATSCHITSCH E,et al.The effect of transponder motion on the accuracy of the Calypso electromagnetic localization system[J].Int J Radiat Oncol Biol Phys,2008,72(1):295-299.
[13]BELANGER M,SALEH Z,VOLPE T,et al.Validation of the Calypso surface beacon transponder[J].J Appl Clin Med Phys,2016,17(4):223-234.
[14]XU Q,LI J,SHAN G,et al.Comparison of prostate rotation and Calypso beam rotation for prostate margin evaluation[J].Med Phys,2009,36(6):2704-2707.
[15]ZOU W,BETANCOURT R,YIN L,et al.Effects on the photon beam from an electromagnetic array used for patient localization and tumor tracking[J].J Appl Clin Med Phys,2013,14(3):72-80.
[16]RAU A W,NILL S,EIDENS R S,et al.Synchronized tumor tracking with electromagnetic transponders and k V X-ray imaging:evaluation based on a thorax phantom[J].Phys Med Biol,2008,53(14):3789-3805.
[17]SILVA C,MATEUS D,EIRAS M,et al.Calypso 4D localization system:a review[J].J Radiother Prac,2014,13(4):473-483.
[18]SANTANAM L,MALINOWSKI K,HUBENSHMIDT J,et al.Fiducial-based translational location accuracy of electromagnetic tracking system and on-board kilovoltage imaging system[J].Int J Radiat Oncol Biol Phys,2008,70(3):898-899.
[19]ZUCCA A,MANCOSU P,COMITO T,et al.On line tracking of abdominal compression efficacy for pancreas SBRT by Calypso surface transponders[J].Radiother Oncol,2015,115(1):S609-S610.
[20]SILVA C,MATEUS D,VIEIRA S,et al.Calypso's array attenuation[J].J Radiother Prac,2015,14(2):202-207.