Absorbed Dose to Water Rate in a Cyberknife VSI System Reference Field Using Ionization Chambers and Gafchromic Films

This work investigated the absorbed dose to water rate under reference conditions in a Cyberknife VSI system using radiochromic films EBT3 and MD-V3 and three ionization chambers: an Exradin A12 and two FC65P Welhöfer Scanditronix with different serial numbers. The correction factor,, was studied using a Varian iX linac and the Cyberknife system. The measurements in the Varian iX were performed in a 10 × 10 cm2 field, 10 cm depth in liquid water at 90 cm and 70 cm SSD and in a 5.4 × 5.4 cm2 field, 10 cm depth at 70 cm SSD to simulate the Cyberknife conditions. In the Cyberknife system, measurements were performed using ionization chambers and both film types at 70 cm SSD and 10 cm depth in its 6 cm diameter reference field. The results indicate that ?is independent of the dosimeters and the evaluation methods. Maximum differences of 0.22% - 0.55% (combined uncertainties of 1.22% - 1.98%, k = 1) are obtained on ?using Varian iX, whereas discrepancies of 2.08% - 2.09% (combined uncertainties of 1.87% - 2.13%, k = 1) are observed using the Cyberknife system. Given the agreement between detectors and the combined standard uncertainties, the data from Varian iX could be considered the most accurate and consequently a weighted average factor of 0.902 ± 0.006 could be used for the Cyberknife VSI system reference field. Within measurement uncertainties, the absorbed dose rate measured in the Cyberknife VSI system reference field was found to be independent of the dosimeters used. These results suggest that the absorbed dose measured at a point within a given field size should be the same, regardless the dosimeter used, if their dosimetric characteristics are well known. This highlighted the importance of performing dosimetry by controlling all parameters that could affect the dosimeter response. One can conclude that radiochromic film dosimetry can be considered as an appropriate alternative for measuring absorbed dose to water rate.

G4 CyberKnife——全新式立体定向放疗设备及其临床应用

目的:研究G4 CyberKnife系统的结构及工作原理,探讨该设备的临床应用情况。方法:对放疗科新引进的G4CyberKnife进行研究,初步探讨该立体定向放疗设备在临床应用上的技术特点。结果:与其他立体定向设备相比,G4CyberKnife在影像引导靶区定位精度及动态追踪病灶等方面具有明显的技术优势。结论:G4 CyberKnife是一种全新式全身肿瘤立体定向放射治疗设备,其临床数据有限,从临床相关性角度上仍需要对其物理学和放射生物学的技术差异进行更多的研究。

CyberKnife放射治疗肿瘤的临床研究

CyberKnife是一种影像引导下的无框架立体定向放射治疗肿瘤的国际前沿性新技术。它可使其放射线到达传统立体定向放射外科治疗技术无法接近的病变部位;在放射治疗前和放疗的过程中,其先进的影像导航系统可对病灶进行准确的实时监控和跟踪;目标如有移动,会补偿性的自动修正治疗床的位置或射束的方向;非等中心照射特征可使放射线的剂量分布在病变部位达到最大程度的均匀性和适形度,消除以往传统立体定向放射外科治疗技术在靶区剂量分布方面存在的冷点和热点问题;既可以实施单次治疗,也可以进行分次照射,是真正意义上的全新概念的肿瘤立体定向放射外科治疗系统。

CyberKnife中Fixed/Iris准直器对肝癌患者治疗计划的影响及评价

目的:探讨及评价不同准直器(Fixed/Iris)的选择对治疗计划剂量学特点的影响。方法:选取12例肝癌患者影像数据,统一给予靶区剂量50 Gy/5 F,在相同条件下分别对每例患者选择Fixed与Iris准直器进行治疗计划设计,通过靶区适形度指数(CI)、均匀性指数(HI)、梯度指数(GI)、正常肝脏平均受量以及治疗时间等参数,分析评估计划优化质量及实施效率。结果:Iris组计划执行的平均治疗时间明显优于Fix组[(48.33±1.92)min vs(51.50±1.88)min,t=4.23,P=0.001],而CI(0.79±0.07 vs 0.80±0.08,t=0.52,P=0.613)、HI(0.42±0.14 vs 0.41±0.14,t=0.35,P=0.733)、GI(3.66±0.61 vs 3.60±0.50,t=1.15,P=0.273)、处方剂量归一值[(76.92±6.55)%vs(77.00±6.34)%,t=0.18,P=0.857]以及正常肝脏平均受量[(5.15±1.25)Gy vs(5.16±1.27)Gy,t=0.63,P=0.542]则无统计学差异。结论:CyberKnife系统中使用Iris相对Fixed准直器而言,除治疗时间明显缩短外,没有显著的剂量学差异。而对于其他部位肿瘤患者的治疗计划有无差异,还需进一步探讨和研究。

CyberKnife系统日检结果稳定性分析

目的:对G4 CyberKnife系统日检剂量数据进行分析,研究其长期稳定性,寻求建立一套临床上针对CyberKnife系统更为有效的日检剂量学验证方法。方法:采用PTW公司的Quickcheck系统采集每日质控数据,评价其剂量输出稳定性、能量输出稳定性,并同时分析其对称性及平坦度的稳定性。结果:采集2个月的数据分析显示,其剂量输出稳定性在±2%之内;能量输出稳定性保持在±2%之内;射束平坦度稳定性≤±5%;对称性稳定性≤±2%。结论:G4 CyberKnife系统具有很好的长期稳定性;Quickcheck系统能够保障其安全和精确治疗。

CyberKnife在肿瘤立体定向放射治疗中的应用

CyberKnife是一种新型的立体定向放射治疗设备 ,在许多方面具有传统立体定向放射治疗设备无可比拟的优势 ,并已在临床应用中取得了较好的疗效。现主要介绍CyberKnife的临床特点及应用。

原发性肝癌射波刀(Cyberknife)治疗前后IGF-Ⅱ、CA199、AFP的变化

目的:探讨原发性肝癌患者射波刀(Cyberknife)治疗前后血清胰岛素样生长因子-II(IGF-Ⅱ)、CA199、AFP水平变化及临床意义。方法:对125例原发性肝癌患者Cyberknife治疗前后检测血清中IGF-Ⅱ、CA199、AFP的水平。结果:原发性肝癌患者Cyberknife治疗前血清中IGF-Ⅱ、CA199、AFP水平均显著高于对照组(P<0.01),Cyberknife治疗后患者血清IGF-Ⅱ、CA199、AFP的水平显著低于Cyberknife治疗前的水平,具有统计学意义(P<0.05)。125例肝癌患者CR23例,PR82例,NC14例,PD6例,近期有效率(CR+PR)为84.0%。结论:血清IGF-Ⅱ、CA199、AFP的水平的监测可以作为原发性肝癌的辅助诊断及放射治疗疗效的监测;Cyberknife是治疗不能手术的中晚期肝癌的有效手段,不良反应较轻,值得推广应用。

全身立体定向放射外科系统Cyberknife的临床应用

射波刀（CyberKnife）是一种图像引导的无头颅金属固定框架的新型立体定位放射外科治疗设备。它拥有高阶智能计算机化立体定位导向，自动跟踪靶区系统和精确的机械手臂系统和体部呼吸同步自动跟踪系统，1994年由美国Stanford大学的Dr．John Adler首先提出并研究成功。CyberKnife在许多方面优于传统的立体定向放射治疗设备，是目前一种新的肿瘤精确治疗手段，可用于全身肿瘤及一些良性疾病的治疗，并在国外临床应用中取得了肯定的疗效。

基于蒙特卡罗模拟的CyberKnife病人治疗计划剂量验证

目的:为保证CyberKnife的精确治疗,本研究利用蒙卡方法建立一套适用于CyberKnife的蒙卡剂量验证系统,并与实际计划的放射治疗计划系统(Treatment Planning System,TPS)优化结果相比较,验证TPS所得的优化剂量。方法:采用BEAMnrc和DOSXYZnrc模拟代码,模拟Accuray第4代CyberKnife治疗系统。研究中对直径分别为25 mm、30 mm、40 mm、50 mm、60 mm的5个准直器进行模拟得到组织体模比(Tissue Phantom Ratio,TPR)数据和剂量离轴比(Off Axis Ratio,OAR)数据,并与测量数据比较,以确保系统的精确性。结果:在TPR和OAR数据的比较中,模拟系统所得数据和实际测量所得数据吻合的很好。在深度为5 cm时,准直器视野范围内OAR数据的全局相对误差均小于1%;自动化质量验证模体40%等剂量线内伽玛因子通过率为99.88%(3 mm,3%),1例肝部病人计划模拟中,对应的伽玛因子通过率为88.56%(3 mm,3%)。结论:建立的蒙卡系统能够正确地模拟CyberKnife出束情况,实施治疗前病人计划的剂量验证工作,适用于作为基于蒙卡的第三方剂量检验软件。

Comparison of percutaneous radiofrequency ablation and CyberKnife®for initial solitary hepatocellular carcinoma:A pilot study

AIM To compare therapeutic outcomes and adverseevents in initial solitary hepatocellular carcinoma（HCC） treated with radiofrequency ablation （RFA） andCyberKnife？.METHODS： Seventy three consecutive patients withinitial solitary HCC treated with RFA （38 patients;RFA group） and CyberKnife （35 patients; CK group）were enrolled in this study. Background factorswere compared between the two groups. Local andintrahepatic distant recurrence control, and cumulativesurvival rates were compared between the two groups.These were determined using the Kaplan-Meier method,and the significance of differences was analyzed by log-rank test. The presence of more grade 3 on CTCAE ver.4.0 early and late adverse events was investigated.RESULTS： In background factors, age was significantlyhigher （P = 0.005） and the tumor diameter wassignificantly larger （P = 0.001） in the CK group. The1-year local recurrence control rates were 97.4%and 97.1% in the RFA and CK groups, respectively （P= 0.71）; the 1-year intrahepatic distant recurrencecontrol rates were 85.6% and 86.1%, respectively （P= 0.91）; and the 1-year cumulative survival rates were100% and 95.2%, respectively （P = 0.075）, showingno significant difference in any rate between the twogroups. There were no late adverse event in the RFAgroup, but 11.4% in the CK group had late adverseevents. In the CK group, the Child-Pugh score at 12 moafter treatment was significantly higher than that in theRFA group （P = 0.003） and significantly higher than thescore before treatment （P = 0.034）.CONCLUSION： The occurrence of adverse events is aconcern, but CyberKnife treatment is likely to becomean important option for local treatment of early HCC.

An Overview of CyberKnife Radiosurgery

Stereotactic radiosurgery is a non-invasive procedure that utilizes precisely targeted radiation as an ablative surgical tool. Conventional radiosurgery devices, such as the Gamma Knife, rely upon skeletally attached Stereotactic frames to immobilize the patient and precisely determine the 3D spatial position of a tumor. A relatively new instrument, the CyberKnife (Accuray, Inc., Sunnyvale, CA), makes it possible to administer radiosurgery without a frame. The CyberKnife localizes clinical targets using a very accurate image-to-image correlation algorithm, and precisely cross-fires high-energy radiation from a lightweight linear accelerator by means of a highly manipulable robotic arm. CyberKnife radiosurgery is an effective alternative to conventional surgery or radiation therapy for a range of tumors and some non-neoplastic disorders. This report will describe CyberKnife technology and oncologic applications in neurosurgery and throughout the body.

CyberKnife机房改造辐射防护评价

目的:介绍某院的CyberKnife机房改造情况,对其防护水平进行评价,给出CyberKnife机房屏蔽设计的建议。方法:防护设计以Accuray公司生产的CyberKnife G3机型治疗时的最大散射条件(6 MV X线,SSD(源皮距)=800 mm、准60 mm准直器,输出剂量率为400 cGy/min),按照NCRP151报告屏蔽设计要求进行计算。结果:理论计算中工作人员所受外照射剂量值约为10μSv/a,公众约为27.5μSv/a;实测结果中工作人员所受外照射剂量约为19.5μSv/a,公众约为7.2μSv/a。结论:改造后的CyberKnife机房达到了防护设计的要求。

Evaluation of Magnetic Resonance Imaging Findings and Short-Term Outcome in Brain Metastatic Tumors after CyberKnife Treatment

Objective: To evaluate the treatments’ outcomes in brain metastatic tumors after CyberKnife treatment according to magnetic resonance imaging (MRI) findings and improvement of symptoms. Methods: A retrospective analysis of CyberKnife treatment;63 cases of patients with brain metastases;the use of CyberKnife treatment;short-term outcome evaluation after treatment and the MRI findings and measured before treatment and underwent diffusion-weighted imaging MRI scan of apparent diffusion coefficient (ADC) values. Results: 3 months after CyberKnife treatment and effectiveness were 82.5% and 96.8% respectively;6 months and one year survival rates were 82.5% and 55.6% respectively;the median survival time was 16 months. MRI of 52 patients (67 lesions) ADC values after treatment increased to some extent than before treatment. There are 38 lesions volume to shrink or disappear, no enhancement or slight enhancement in the lesion, no edema zone;27 lesions does not change in volume, no edema (18 lesions significantly weakened the degree of enhancement;6 lesions showed no obvious change enhancement;3 lesions showed ring enhancement, internal cystic);2 lesions volume were larger, heterogeneous enhancement, peripheral edema. Conclusion: CyberKnife is an effective method for treating brain metastatic tumor. MRI can accurately evaluate tumor lesions after treatment.

全身肿瘤治疗设备CyberKnife

在2007年12月10日南宁市举行的“肿瘤放疗新进展研讨会”上美国斯坦福大学医学院著名神经外科及放射肿瘤科教授John Adler对CyberKnife作了专门介绍。他说CyberKnife是目前世界上最先进的全身肿瘤治疗设备。与普通放疗相比其为更灵活、准确，总精准度达亚毫米级，能应用于全身大部分器官组织的肿瘤进行治疗。

Treatment for paraganglioma with stereotactic radiotherapy

BACKGROUND Paragangliomas(PG)are rare neoplasms of neuroendocrine origin that tend to be highly vascularized,slow-growing,and usually sporadic.To date,common treatment options are surgical resection(SR),with or without radiation therapy(RT),and a watch-and-wait approach.AIM To evaluate the local control and effectiveness of exclusive fractionated stereotactic RT(FSRT)treatment in unresectable PG(uPG).METHODS We retrospectively evaluated patients with uPG(medically inoperable or refused SR)treated with FSRT with a Cyberknife System(Accuray Incorporated,Sunnyvale,California).Toxicity and initial efficacy were evaluated.RESULTS From May 2009 to January 2023,6 patients with a median age of 68(range 20-84)were treated with FSRT.The median delivered dose was 21 Gy(range 20-30 Gy)at a median isodose line of 75.5%(range 70%-76%)in 4 fractions(range 3-5 fractions).The median volume was 13.6 mL(range 12.4-65.24 mL).The median cumulative biological effective dose and equivalent dose in 2-Gy fractions were 70 Gy and 37.10 Gy respectively.Site of origin involved were the timpa-nojugular glomus(4/6),temporal bone,and cervical spine.In 1 of the 6 patients,the follow-up was insufficient;5 of 6 patients showed a 5-year overall survival and 5-year progression-free survival of 100%.We observed negligible toxicities during and after RT.The majority of patients showed stable symptoms during follow-up.Only 1 patient developed spine metastases.CONCLUSION Our preliminary results on this small cohort of patients suggest that FSRT could be an effective and safe alternative to SR.

椎体转移瘤立体定向放射治疗剂量跌落梯度分析

目的:分析评价利用Cyberknife系统实施立体定向放射治疗(SBRT)技术治疗椎体转移瘤时,脊髓方向的剂量跌落趋势。方法:利用Cyberknife治疗8例胸椎转移瘤患者,根据放射治疗剂量的不同将其分为两组,其中4例患者给予靶区剂量40 Gy/5次(40 Gy组);4例患者给予靶区剂量33 Gy/3次(33 Gy组)。采用Cyberknife系统自带的Multi Plan4.0.2治疗计划系统设计优化治疗计划,针对靶区处方剂量跌落梯度、相对剂量跌落梯度以及单位距离剂量跌落梯度3方面。统计分析Cyberknife系统治疗计划中在脊髓方向的剂量跌落趋势。结果:40 Gy组单位绝对剂量跌落速度为(0.208±0.085)mm/100 c Gy,相对剂量跌落为(0.87±0.60)mm/5%Dmax,单位距离跌落速度为(353.63±160.48)c Gy/mm。33 Gy组单位绝对剂量跌落速度为(0.311±0.089)mm/100 c Gy,相对剂量跌落为(0.69±0.16)mm/5%Dmax,单位距离跌落速度为(266.27±94.41)c Gy/mm。40 Gy组优于33 Gy组。结论:Cyberknife系统治疗椎体转移瘤时脊髓方向剂量跌落极快,对脊髓保护好;将Cyberknife精确的追踪系统应用于椎体转移瘤的立体定向放疗,对脊髓的保护安全有效。

Stereotactic body radiotherapy using Cyber Knife for locally advanced unresectable and metastatic pancreatic cancer

AIM: To evaluate the efficacy and toxicity of stereotactic body radiotherapy using Cyber Knife for locally advanced unresectable and metastatic pancreatic cancer.METHODS: From June 2010 to May 2014,25 patients with locally advanced unresectable and metastatic pancreatic cancer underwent stereotactic body radiotherapy.Nine patients presented with unresectable locally advanced disease and 16 had metastatic disease.Primary end-points of this study were overall survival,relief of abdominal pain,and toxicity.RESULTS: Fourteen patients were treated with a total dose of 30-36 Gy in three fractions and the remainder with 40-48 Gy in four fractions.Median follow-up was 11 mo(range: 2-25 mo).The median survival duration calculated from the time of stereotactic body radiotherapy for the entire group,the locally advanced group,and the metastatic group was 9.0 mo,13.5 mo,and 8.5 mo,respectively.Overall survival was 37% and 18% at one and two years,respectively.Abdominal pain relief was achieved within 2 wk of completing radiotherapy in the patients who received successful palliation(13 of 20 patients had significant pain).Five patients(20%) had grade 1 nausea,and one(4%) had grade 2 nausea.No acute grade 3+ toxicity was seen.CONCLUSION: Stereotactic body radiotherapy using the Cyber Knife system is a promising,noninvasive,palliative treatment with acceptable toxicity for locally advanced unresectable and metastatic pancreatic cancer.

射波刀治疗晚期胰腺癌回顾性分析

目的 :回顾性分析射波刀对于晚期胰腺癌的治疗作用。方法 :收集2012年11月至2017年6月经射波刀治疗的晚期胰腺癌患者96例。采用PET/CT或增强CT定位,X-sight脊柱追踪照射,有梗阻性黄疸患者先行胆汁引流,缓解胆道梗阻有效后再行射波刀治疗。利用统计软件SPSS 13.0采用Cox Regression分析性别、年龄、KPS评分、肿瘤分期、CA19-9、放疗剂量、是否化疗、合并其他治疗等因素对生存期的影响,采用Kaplan-Meier法进行生存率分析,并对远期并发症情况进行分析。结果:87.5%的患者症状改善,平均生存时间为10.5个月、中位生存时间为8个月;肿瘤分期、CA19-9阳性是影响患者生存的主要因素(P<0.05),性别、年龄、KPS评分、放疗剂量、是否化疗、合并其他治疗等因素没有显著差异,对生存率影响不大(P>0.05);胰头癌远期的肠道、胆道并发症须引起注意。结论:射波刀是晚期胰腺癌有效的姑息治疗手段,可缓解局部症状,但对患者的生存期延长有限,远期并发症可危及生命。

Influence of Cy berKnife Prescription Isodose Line on the Discrepancy of Dose Results Calculated by the Ray Tracing and Monte Carlo Algorithms for Head and Lung Plans: A Phantom Study

Incorporation of the Monte Carlo(MC)algorithm in optimizing CyberKnife(CK)plans is cumbersome,and early models unconfigured MC calculations,therefore,this study investigated algorithm-based dose calculation discrepancies by selecting different prescription isodose lines(PIDLs)in head and lung CK plans.CK plans were based on anthropomorphic phantoms.Four shells were set at 2-60 mm from the target,and the constraint doses were adjusted according to the design stratcgy.After optimization,30%-90%PIDL plans were generated by ray tracing(RT).In the evaluation module,CK plans were recalculated using the MC algorithm.Therefore,the dosimetric parameters of different PIDL plans based on the RT and MC algorithms were obtained and analyzed.The discrepancies(mean+SD)were 3.72%+0.31%,3.40%+0.11%,3.47%+0.32%,0.17%+0.11%,0.64%+3.60%,7.73%+1.60%,14.62%+3.21%and 10.10%+1.57%for Djs,Dmeam),Dys,and coverage of the PTV,DGI,V,,V;and V,in the head plans and-6.32%+1.15%,-13.46%+0.98%,-20.63%+2.25%,-34.78%+25.03%,12248%+175.60%,-12.92%+5.41%,3.19%+4.67%and 7.13%+1.56%in the lung plans,respectively.The following parameters were significantly correlated with PIDL:dp98%at the 0.05 level and dpal,dys and dv3 at the 0.01 level for the head plans;dp98e%at the 0.05 level and do1e%,dpmeam,Ccoweange,dool,dvs and dv;at the 0.01 level for the lung plans.RT may be used to calculate the dose in CK head plans,but when the dose of organs at risk is close to the limit,it is necessary to refer to the MC results or to further optimize the CK plan to reduce the dose.For lung plans,the MC algorithm is recommended.For early models without the MC algorithm,a lower PIDL plan is recommended;otherwise,a large PIDL plan risks serious underdosage in the target area.

Comprehensive Treatment Uncertainty Analysis and PTV Margin Estimation for Fiducial Tracking in Robotic Liver Stereotactic Body Radiation Therapy

Objective This study aims to quantify the uncertainties of CyberKnife Synchrony fiducial tracking for liver stereotactic body radiation therapy(SBRT)cases,and evaluate the required planning target volume(PTV)margins.Methods A total of 11 liver tumor patients with a total of 57 fractions,who underwent SBRT with synchronous fiducial tracking,were enrolled for the present study.The correlation/prediction model error,geometric error,and beam targeting error were quantified to determine the patient-level and fraction-level individual composite treatment uncertainties.The composite uncertainties and multiple margin recipes were compared for scenarios with and without rotation correction during treatment.Results The correlation model error-related uncertainty was 4.3±1.8,1.4±0.5 and 1.8±0.7 mm in the superior-inferior(SI),left-right,and anterior-posterior directions,respectively.These were the primary contributors among all uncertainty sources.The geometric error significantly increased for treatments without rotation correction.The fraction-level composite uncertainties had a long tail distribution.Furthermore,the generally used 5-mm isotropic margin covered all uncertainties in the left-right and anterior-posterior directions,and only 75%of uncertainties in the SI direction.In order to cover 90%of uncertainties in the SI direction,an 8-mm margin would be needed.For scenarios without rotation correction,additional safety margins should be added,especially in the superior-inferior and anterior-posterior directions.Conclusion The present study revealed that the correlation model error contributes to most of the uncertainties in the results.Most patients/fractions can be covered by a 5-mm margin.Patients with large treatment uncertainties might need a patient-specific margin.