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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.
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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.
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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.
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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.
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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.
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Objective To analyze the curative effects in hyperthyroidism radioiodine treatment which using different methods to measure thyroid weight in order to calculate therapeutic dose.Methods 265 hyperthyroidism underwent radioiodine treatment,then they were divided into 4 groups.Calculating therapeutic dose was done according to SPECT tomography,nuclear plane imaging,ultrasonography and palpation to measure thyroid weight.We Compared and analyzed the curative effects after 6 months.Results The curative effects of 4 groups had obviously difference(P