Objective:To provide a new morning check method for the output dose stability of the multileaf collimator (MLC) of the CyberKnife M6 (CK-M6) system.Methods:The CT images of a verification phantom with a size of 20 cm × 20 cm × 10 cm were transmitted into the Precision Treatment Plan ning System (ver. 1.1.1.1). The high-precision alignment between the accelerator output front and the fixed position of the phantom surface was achieved using the fiducial tracking method. A 10 cm × 10 cm radiation field was formed by the MLC and a DailyCheck plan with an output of 200 MU was designed. The repeatability, sensitivity, and accuracy of the DailyCheck plan were measured, and the CK-M6 system was continuously tested for one month using the artificial fixed method and the DailyCheck plan designed in this study. Results:The average and the standard deviation of 10 repeated measurements by the DailyCheck plan were 492.28 pC and 0.09, respectively, indicating good stability. There was a linear correlation between the measured values and the output dose, with a correlation coefficient of R2 > 0.999. Moreover, there was a position deviation of 2 mm between the phantom and the accelerator output front, and the result ant effect on the measured values was equivalent to a dose deviation caused by an output of 1.24 MU. The result from the continuous measurement of both the artificial fixed method and the DailyCheck plan fell within permissible limits, showing high consistency. Conclusions:The DailyCheck plan established through the fiducial tracking of a verification phantom can achieve the convenient, quick, and accurate daily detection of the output dose stability of the MLC of CK-M6. Therefore, this method can be widely applied in the clinical quality control of the CK-M6 system.

Objective To evaluate the safety and effectiveness of ultra-hypofractionated stereotactic body radiotherapy in the treatment of prostate cancer.Methods A total of 26 patients with prostate cancer treated with Cyber-Knife from May 2010 to May 2018 were analyzed retrospectively.The median age of the patients was 69 years old (range,57 to 87).Ultra-hypofractionated radiotherapy was delivered in five fractions of 7.0-7.5 Gy for a total dose of 35.0-37.5 Gy.Androgen deprivation therapy (ADT) was administered in combination with the Cyber-Knife.The primary endpoints were radiation toxicity,PSA-response,local control and symptom alleviation,while the secondary endpoints were progression-free survival and overall survival.Results No graded ≥ 3 acute and late radiation toxicities occurred during follow-up.The acute toxicity of Grades 1 and 2 was 38.4％ and 19.2％,while the late toxicity of Grades 1 and 2 was 30.8％ and 3.8％,respectively.At a median follow-up of 22.44 months,for patients with localized stage,PSA level was decreased significantly after radiotherapy (Z =2.900,2.794,2.510,2.090,P＜0.05).However,there was no statistically significant difference for the metastatic group (P＞ 0.05).Conclusions Ultra-hypofractionated stereotactic body radiotherapy is a safe and effective treatment for patients with prostate cancer.

Objective To analyze the radiation dose to the normal lung tissue of patients with early stage of non-small cell lung cancer treated by Cyberknife. Methods A retrospective analysis was conducted by summarizing the treatment plans of 264 patients with early stage non-small cell lung cancer from January 2011 to December 2013 in Tianjin Medical University Cancer Institute and Hospital. Sorted by the tumor volumes and locations, the Cyberknife plans were evaluated by means of dose volume histograms ( DVH) , homogeneity indexes ( HI) , percentage volumes receiving at least x Gy ( Vx ) of dose, i. e. , V5 , V10 , V20 , and V30 of the ipsilateral and contralateral lungs. For the tumors approximate to the hilus, the contralateral lungs were included in the optimization process, and the dose-volume metrics were analyzed for the contralateral and bilateral lungs. Results For the tumors close to the chest wall, V5≥(15. 21 ± 3. 12)％ in ipsilateral lung tissue and V5≥(1. 34 ± 0. 67)％ in contralateral lung tissue were observed. For the tumors near the hilus, V5≥(39. 4 ± 11. 90) ％ in ipsilateral lung tissue and V5≥(1. 48 ± 0. 34) ％ in contralateral lung tissue were observed. The irradiated volume ratios of both ipsilateral and contralateral lung tissue increased with the enlargement of tumor sizes. After including the contralateral lung tissue into the optimization, the irradiated volume ratios of the contralateral and bilateral lung tissue (V5,V10) decreasedsignificantly(t=2.44,4.81,3.53,3.17,P<0.05). Conclusions Higherriskof radiation injury in both ipsilateral and contralateral lung tissue can be expected for tumors near the hilus than near the chest wall. After including contralateral lung tissue into the planning optimization, lower dose to the contralateral and whole lung tissue was achieved, indicating a better protection of normal lung tissue.

Objective To evaluate the efficacy and safety of CyberKnife stereotactic body radiation therapy (SBRT) in the treatment of hepatic hilar cancer.Methods A retrospective study was performed on the clinical data of 36 patients with hepatic hilar cancer who were admitted to our hospital and treated with CyberKnife SBRT from 2009 to 2015.In the 36 patients,37 lesions were found with tumor diameters ranging from 1.5 to 5.5 mm (median diameter 3 cm).The Synchrony respiratory tracking system was used for 21 lesions in 20 patients,while the XSight spinal tracking system was used for 16 lesions in 16 patients.Local progression was evaluated based on contrast-enhanced computed tomography and/or magnetic resonance imaging.The Kaplan-Meier method was used to calculate local control (LC) and overall survival (OS) rates,and the log-rank test was used for survival comparison and univariate prognostic analysis.Results The median follow-up time was 12.7 months.The 1-and 2-year postoperative LC rates were 90％ and 76％,respectively.The 1-year OS and progression-free survival (PFS) rates were 63％ and 39％,respectively.The median OS and PFS times were 15.2 and 10 months,respectively.The incidence of grade 3 adverse reactions was 11％.Conclusions The CyberKnife SBRT is a safe and effective way to treat hepatic hilar cancer.

Objective To evaluate the response rate and efficacy of Cyberknife in the treatment of iliac lymph node metastases (ILNM).Methods Twenty-two patients with 27 ILNM were treated by Cyberknife from May 2010 to May 2016.Tumor volume range from 0.88 to 125.66 cm3 (median 18.87 cm3).The total doses ranged from 21 to 51 Gy (median 39 Gy) and biological effective doses from 35.7 to 100 Gy (median 72.6 Gy) in 3-8 fractions (median 5).Sixty-four percent to eighty-two percent (median 72％) isodose line covered planning target.The survival rates were calculated by Kaplan-Meier method and compared with Log-rank test.Results Follow-up time ranged from 8 to 97 months (median 33 months).The complete response,partial response,stable disease and progression disease rates were 37％,48％,7.5％,48％,respectively.In addition,effective rate was 92.5％.Overall survival range from 4 to 68 months (median 21 months).The 1-,2-,3-year local control rate was all 90.6％ and the survival rates were 78.8％,60.6％ and 43.3％,respectively.Adverse reactions after treatment were gastrointestinal reactions such as nausea,vomiting,fatigue.The chemotherapy before Cyberknife helped to improve overall survival.The patients with backache or edema of lower extremity got rapid relief after treatment.Conclusion The treatment of ILNM with Cyberknife has provided a high response rate with minimal side effects.Cyberknife is a safe and effective local treatment method for ILNM.

Objective Combination of nanoparticle with p53 and Rb gene therapy by gene targeting was applied to investigate its curative effect and safety evaluation on colorectal rabbit hepatic VX2 metastasis for tumor eradication and survival enhancement. Methods Recombinant expressing plasmids harboring wild type p53 and Rb were cotransferred or transferred separately to the rabbit hepatic VX2 metastasis by the emulsion of PLL-nHAP nanoplex and lipodiol through the hepatic artery in a tumor target manner. Subsequent co-expressions of p53 and Rb protein within the treated tumors were detected by Western blot and in situ analysis of confocal laser scanning microscope. The therapeutic effect was evaluated by the tumor growth velocity and the survival time of animals. Eventually, investigations of liver function were applied to evaluate the safety of the process. Results With safe procedure for the rabbits liver function, both p53 and Rb local nano-therapy showed favorable anti-tumor effects and increased animal survival time. p53+Rb local nano-therapy could significantly inhibit hepatic VX2 metastasis and enhance the animal survival time compared with p53 local nano-therapy or Rb local nano-therapy. Local nano-therapy showed no significant influence to animal liver function. Conclusions Rb can work synergistically with p53 in the combined therapy mediated by PLL-nHAP nanoplex to augment the anti-tumor effect. The local nano-therapy with p53 and Rb is likely to be an effective and safe anti-tumor therapy for hepatic colorectal metastasis.

Objective To assess the efficacy and safety of CyberKnife radiotherapy in the treatment of locally advanced pancreatic carcinoma. Methods The data of 59 patients with locally advanced pancreatic carcinoma who were treated with CyberKnife radiotherapy from 2006 to 2014 were retrospectively analyzed. The tumor volume ranged from 13?? 0 cm3 to 125?? 1 cm3 with a median value of 27?? 1 cm3 . A dose of 35?50 Gy (median value= 45 Gy) in 3?8 fractions (median value = 5 fractions) was prescribed. The tumor progression was evaluated based on computed tomography. The overall survival (OS) and local progression?free survival ( LPFS) rates were calculated using the Kaplan?Meier method. Results The 1?and 2?year sample sizes were 26 and 17, respectively. The 1?and 2?year OS rates were 54% and 35%, respectively, while the 1?and 2?year LPFS rates were 91% and 70%, respectively. The median OS and LPFS times were 12?? 5 and 10?? 9 months, respectively. The overall incidence of grade 1?2 acute and late gastrointestinal toxicity was 61%. One patient with grade 3 late gastrointestinal toxicity had incomplete intestinal obstruction. Conclusions CyberKnife radiotherapy can achieve excellent treatment outcomes and mild complications in the treatment of locally advanced pancreatic carcinoma.

BACKGROUNDSpine is the most common site of bone metastases in patients with cancer. Conventional external beam radiotherapy lacks precision to allow delivery of large fraction radiation but simultaneously limit the dose to spinal cord. The purpose of this study was to evaluate the safety and efficacy of CyberKnife(®) radiation therapy for spinal metastases.

METHODSSeventy-three lesions in 62 patients treated with CyberKnife radiotherapy from September 2006 to June 2010 for spinal metastases were retrospectively reviewed. Thirteen tumors in 12 patients had received prior radiation. Patients were followed clinically and radiographically for at least 12 months or until death. In all patients, the spinal cord and thecal sac were contoured for dose-volume constraints, and maximum doses to 0.1, 0.5, 1, 2, and 5-ml volumes were analyzed.

RESULTSUsing the CyberKnife System, 20-48 Gy in one to five fractions for unirradiated patients, and 21-38 Gy in one to five fractions for the previously irradiatied patients, were delivered. Median 2-Gy normalized Biological Equvalent Dose (nBED) of unirradiated targets and irradiated targets were 49.6 Gy10/2 (range, 31.25-74.8 Gy10/2) and 46.9 Gy10/2 (range, 29.8-66 Gy10/2), respectively. With a median follow-up of 9.4 months (range, 2.5-45 months), twenty-nine patients (46.7%) were alive, whereas the others died of progressive disease. Fifty-six patients (93.3%) reported complete or partial reduction of pain after CyberKnife radiotherapy at one-month follow-up, 17 patients (28.3%) reported some degree of pain relief after first fraction of the treatment course. Two patients experienced local recurrence at fifth and ninth months post-radiotherapy. Median maximum nBED for spinal cord and thecal sac of naive targets were 68.6 Gy2/2 (range, 8.3-154.5 Gy2/2) and 83.5 Gy2/2 (range, 10.5-180.5 Gy2/2), respectively. Median maximum nBED for spinal cord and thecal sac for the re-irradiated targets were 58.6 Gy2/2 (range, 17.7-140 Gy2/2) and 70.5 Gy2/2 (range, 21.7-141.3 Gy2/2), respectively. No patient developed radiation related myelopathy during the follow-up period.

CONCLUSIONCyberknife radiotherapy is clinically effective and safe for spinal metastases, even in previously irradiated patients.

Adult ; Aged ; Aged, 80 and over ; Female ; Humans ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; radiotherapy ; Prospective Studies ; Robotics ; methods ; Spinal Neoplasms ; radiotherapy ; secondary ; Young Adult

Objective To investigate the value of local progression-free survival (LPFS) for evaluating the local long-term outcome of peripheral lung cancer treated by cyberknife.Methods Retrospective analysis was performed on the clinical records of 81 cyberknife-treated lung cancer patients (90 foci),including 43 primary lung cancer patients (43 foci) and 38 metastatic lung cancer patients (47 foci).Of all the patients,58(63 foci) were treated at a dose of 60 Gy/3 fractions (20 Gy/fraction),and 23 (27 foci) at a dose of 54 Gy/3 fractions (18 Gy/fraction).The short-term treatment outcome and LPFS were used as the indices for observation;a logistic regression was used for analyzing the predictive value of LPFS for local long-term treatment outcome.Results After the evaluation of short-term treatment outcome,63％ of all the foci needed further evaluation.As the follow-up lasted,the number of foci which needed further evaluation decreased,most rapidly during 0.5-2 years after treatment.Re-evaluation results had predictive value for the treatment outcome in the subsequent follow-up,but the predictive value declined as the follow-up lasted.Conclusions LPFS is a recommendable index for evaluating the local outcome of primary or metastatic lung cancer treated by cyberknife,and it also has predicative value for local long-term treatment outcome.

Objective To investigate the impacts of fiducial tracking and X-sight tracking on the short-term therapeutic effect of cybernikife in the treatment of lung cancer.Methods Retrospective analysis was performed on 64 lung cancer patients (72 lesions),including 40 primary tumor patients (41 lesions) and 24 metastatic tumor patients (31 lesions),who were treated with cyberknife.Fiducial tracking was used for 45 lesions,while X-sight tracking was used for 27 lesions.The planning target volume was covered by 70％-94％ (median 80％) isodose contour.The irradiation dose was 60 Gy/3 fractions.The relationship between short-term therapeutic effect and tracking method was determined.Results Overall,the lesions undergoing fiducial tracking showed significantly higher response rate than those undergoing X-sight tracking (93％ vs.74％,x2 =6.84,P=0.033),and so was in lower lung lesions (15％ vs.7％,x2 ＝7.18,P=0.028).But the two tracking methods achieved similar effects in upper lung lesions (28％ vs.12％,x2 =2.36,P =0.310).In the lesions with treatment volumes smaller than 15 cm3,the fiducial tracking achieved significantly higher response rate than the X-sight tracking (25 ％ vs.12％,x2 =6.53,P =0.038),but the two tracking methods achieved similar effects in the lesions with treatment volumes not smaller than 15 cm3 (17％ vs 8％,x2 =1.57,P =0.460).Overall,the lesions undergoing X-sight tracking had significantly highertreatment failure rate than fiducial tracking (1 9 ％ vs.2 ％,x2 =6.33,P =0.021).Conclusions Different tracking methods may lead to different therapeutic effects of cyberknife in the treatment of lung cancer,which are related to lesion location and treatment volume.