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Objective:To investigate the effects of different small monitor unit (MU) beam deletion optimization method in the CyberKnife treatment planning system on the calculated planned dose to brain tumors.Methods:A total of 17 patients with brain metastases treated in our hospital from June, 2021 to February, 2022 were selected for this study. A treatment plan was designed for each patient using the multiPlan system in the CyberKnife VSI system as the group without optimization. To improve the efficiency, the generated original plans should be optimized first by deleting some small MUs, forming an experience group and an optimization group for each patient. For the experience group, beams below 30 MU were deleted according to experience. For the optimization group, beams below the MU value calculated based on the second derivative method were deleted. Finally, the parameters of the two groups were statistically compared. The main evaluation parameters included the node number, the beam number, the total number of MUs, the estimated treatment duration, doses to 2% and 95% planning target volumes (PTV D2 and PTV D95), average dose to PTV ( Dmean), average dose to brain tissue ( Dmean-Brain), conformity index (CI), new conformity index (nCI), gradient index (GI), coverage, and the maximum doses to the brainstem and left and right lens ( Dmax-BS, Dmax-LL, and Dmax-RL), and the average doses to the dose shells 20 mm and 40 mm away from PTV (Shell20 and Shell40). Results:The two optimization method met the requirements for the prescription dose delivery to more than 98% PTV. There were statistical differences in the node number ( H = 7.97, P< 0.05) and estimated treatment duration ( H = 6.60, P < 0.05) among the group without MP optimization, the experience group, and the optimization group, with the estimated treatment duration and node number of the optimization group less than those of the group without MP optimization ( P < 0.05). There were no statistically significant differences in other parameters among the three groups ( P > 0.05). The PTV was moderately positively correlated with the treatment duration ( r=0.79, P < 0.01) and beam number ( r=0.78, P < 0.01) of the experience group, and was also moderately positively correlated with the treatment duration ( r=0.69, P < 0.01) and beam number ( r=0.71, P < 0.01) of the optimization group. Conclusions:For the CyberKnife planning of heads, the small MU beam deletion optimization method based on the second derivative can further shorten the treatment duration while ensuring no significant differences in the distribution of doses to organs at risk and targets. Moreover, this method is more effective in optimizing the plans for a large PTV volume.
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Objective:To investigate the consistency and correlation of the respiratory synchronization tracking and fiducial marker respiratory synchronization tracking in the Cyberknife stereotactic body radiotherapy (SBRT) with the diaphragm as the tracking target.Methods:A total of 11 patients hospitalized at Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology from April 2018 to November 2019 were enrolled, including 8 cases of lung cancer, 2 cases of liver cancer with lung metastasis and 1 case of colorectal cancer with lung metastasis. All enrolled cases used fiducial marker tracking plan (RT) and diaphragm contour tracking plan (DT), and then all received tumor visualization simulation tests. Bland-Altman method was used to make the consistency analysis of the offset in the visualization tests process of 2 tracking plans at each respiratory time point. The minimum tolerance distance, uncertainty and average standard deviation and maximum standard deviation in the optimal model state plans were compared between the both plans by using t test. Results:Compared with RT, the translational standard deviations of DT tracking were listed as follows: head-foot direction (0.4±2.9) mm, left-right direction (0.3±4.4) mm, anterior-posterior direction (-1.8±6.8) mm. The Bland-Altman method showed that the consistency between RT and DT was better in the head-foot and left-right directions, and worse in the anterior-posterior direction; the synchronization was only better in the head-foot direction, and worse in both the left-right and anterior-posterior directions. Results of the model quality comparison showed that the uncertainty of RT was higher than that of DT, and the difference was statistically significant [(23±6)% vs. (9±4)%, t=-5.24, P = 0.001], while the differences of the minimum tolerance distance, average standard deviation and maximum standard deviation were not statistically significant (all P>0.05). Conclusions:Patients who use respiratory synchronization Cyberknife SBRT with the diaphragm as the tracking target have better consistency and synchronization in the head-foot direction, but worse in the left-right and anterior-posterior directions. Under the corresponding marginal margin of the target area in the left-right direction, for tumors near the diaphragm that are not visible in the visual test, it is potentially feasible to use the diaphragm as a tracking target to implement respiratory synchronization SBRT. For larger motion amplitudes in the left-right and anterior-posterior directions, more caution is required.
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Objective:By comparing the comprehensive differences between volume-modulated arc therapy (VMAT)-and CyberKnife-6D Skull (CK-6D Skull) tracking technology-based stereotactic radiotherapy (SRT) plans in the treatment of multiple brain metastatic tumors, and explore the advantages of multi-target intracranial technology.Methods:Clinical data of 42 patients with more than 2 brain metastases who received STR between January 2017 and August 2018 were retrospectively analyzed. For each patient, two radiotherapy plans were designed by selecting CK-6D Skull and VMAT technologies. The quality of VMAT and CK-6D Skull was compared by calculating the gradient index (GI), dose sag volume and organ at risk (OAR) of target area. The total number of monitor unit and single treatment time were recorded to compare the execution efficiency of these two technologies.Results:The GI of intracranial 2-target and 3-target plans of CK-6D Skull technology was significantly superior to that of VMAT technology ( P<0.05). The GI did not significantly differ between the 4-target and the 5-target groups ( P>0.05). The contribution of these two technologies to the maximum dose of OAR was not significantly different ( P>0.05), whereas the treatment time of VMAT technology was shorter ( P<0.05). Conclusions:Both technologies can meet the requirements of clinical SRT for multiple brain metastatic tumors. From the perspective of treatment plan and implementation, SRT based on CK-6D skull technology is recommended for patients with less than 4 intracranial metastatic tumors, and VMAT-based SRT is considered for those with > 4 metastatic tumors. Patients with poor physical condition and difficulty in maintaining a fixed position for a long time shall give priority to VMAT technology. More differences between these two technologies in the implementation of SRT for intracranial multiple brain metastases remain to be elucidated by more case data for statistical analysis.
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Objective To explore the clinical value of an auxiliary set-up method with fiducial markers and Synchrony tracking implanted in spine during Cyber-knife stereotactic radiotherapy by comparing the rotational setup errors between auxiliary setup with less than and more than three fiducial markers.Methods A total of 145 cases of tumor patients with fiducial tracking and Synchrony tracking were selected for radiotherapy,including 94 cases in the observation group (＜3 fiducial markers) and 51 cases in the control group (≥ 3 fiducial markers).Before treatment,one spinal alignment plan was added to all the cases in the observation group,and the rotation deviation of the selected spinal distance and the assisted spinal alignment correction of the fiducial marker tracking and the fiducial marker respiratory tracking were counted respectively,and the result of the rotation deviation calculated in the observation group and the control group were analyzed.Results Fiducial tracking spine auxiliary setup result:fiducial marks and selected the spine center distance ＜ 20,20-40,40-60,60-80 and ＞ 80 mm rotating statistical average deviation (0.494±0.350) °,(1.291±0.590) °,(1.705±0.739) °,(2.512±0.761) ° and (2.796± 1.081) °,respectively,rotate observation group and control group total deviation (1.742±0.784) °,(1.805±0.562) °,respectively.Synchrony tracking result in the above case rotation statistical average deviation was (1.190± 0.547) °,(1.956± 0.735) °,(2.141 ± 0.670) °,(2.957±0.648) ° and (4.027±0.695) °,respectively,while rotation total deviation in observation group and control group (2.619±0.906) °,(2.233 ±0.763) °,respectively.There was no significant difference in the rotation deviation between the assisted spinal set-fup and the calculation of rotation deviation between the fiducial tracking and the synchrony tracking (P ＞ 0.05).Conclusions In the fiducial tracking treatment,the range of rotation deviation for the spinal auxiliary set-up correction increases with the increase of the distance between the fiducial markers and the selected spinal center.When the distance between the fiducial marker and the selected spinal is less than 60 mm,the rotation deviation calculated by the spinal auxiliary setup has the same tumor rotation correction effect as that calculated by the fiducial markers.When less than 3 fiducial markers are available and the minimum distance between the fiducial marks and the center of the adjacent spine is relatively close (＜ 60 mm),the deviation of the rotation direction of the tumor can be calculated by adding the spinal auxiliary setup plan.
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Objective@#To improve synchrony tracking components of CyberKnife (tracking vest and tracking markers) and to analyze the clinical application value of the improved tracking components in CyberKnife treatment of thoracic and abdominal tumors.@*Methods@#The tracking apron was made of knitted four-side elastic spandex cloth and suture design of Velcro, which was used to stick the tracking markers on the chest and abdomen of patients. The tracking markers added a 2 cm thick light foam block to the bottom of the original markers, and then the hook face of the Velcro was fixed to the bottom of the light foam. The improved trace component (the improved component) and the original component (the vendor component) were applied to the lung tracking treatment model, and the manufacturer components were included in the reference group. Adoption of improved components into the observation group; 20 different types of respiratory waveforms were simulated and applied to the same mold plan. After treatment, the coverage rate, mean standard deviation, maximum standard deviation and the slope of XYZ-axis vs. R correlation graph were recorded. The relevant parameters of Synchrony model and wearable time of two components were compared, and the application significances of the improved tracking component in the breathing tracking process of the CyberKnife were evaluated.@*Results@#The maximum slope [median(interquartile range)] of XYZ-axis vs. R related graph in the reference group was 0.73 (3.89), 0.27 (0.49) and 0.34 (1.02), respectively. The maximum slope of XYZ-axis vs. R related graph in the observation group was 0.70 (2.78), 0.31 (0.30) and 0.36 (0.75), respectively. There was no statistically significant difference in the slope of XYZ-axis vs. R between the reference group and the observation group (all P > 0.05). There was no significant difference in the average standard error and maximum standard error between the reference group and the observation group [(1.7±0.4) mm vs. (1.7±0.5) mm, t=-0.382, P= 0.710; (2.0±0.6) mm vs. (1.7±0.5) mm, t=-0.877, P= 0.401], and the difference of the model coverage rate between the two groups was statistically significant [(48±18)% vs. (60±22)%, t= 2.762, P= 0.042]. The setup time of tracking components in the observation group was less than that in the reference group, and the difference was statistically significant [(44±24) s vs. (81±15) s, t=-4.310, P= 0.001].@*Conclusions@#The improved tracking components are comparable to the manufacturer tracking components in the standard error of the Synchrony model. The improved components shorten the wear time and appropriately improve the coverage of the Synchrony model.
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OBJECTIVE@#Providing a risk assessment method for the implementation of radiotherapy to identify possible risks in the implementation of the treatment process, and proposing measures to reduce or prevent these risks.@*METHODS@#A multidisciplinary expert evaluation team was developed and the radiotherapy treatment process flow was drawn. Through the expert team, the failure mode analysis is carried out in each step of the flow chart. The results were summarized and the (risk priority ordinal) score was obtained, and the quantitative evaluation results of the whole process risk were obtained.@*RESULTS@#One hundred and six failure modes were obtained, risk assessment of (20%) high risk failure model are 22 and severity (≥ 8) high risk failure model are 27. The reasons for the failures were man-made errors or hardware and software failures.@*CONCLUSIONS@#Failure mode and effect analysis can be used to evaluate the risk assessment of radiotherapy, and it provides a new solution for risk control in radiotherapy field.
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Healthcare Failure Mode and Effect Analysis , Risk AssessmentABSTRACT
Objective To evaluate the radioprotective effects of metformin on radiation-induced pulmonary injury in rats. Method A total of 30 Sprague-Dawley ( SD) rats were randomly divided into three groups:control, radiation (20 Gy) and radiation (20 Gy) with metformin, with 10 rats in each group. The right lungs of rats were irradiated to 20 Gy with 6 MV X-rays. Computed tomography (CT) was performed and Hounsfield Units ( HU) were determined during the observation period. The tissue samples of lung were extracted to perform the histological analysis, measurement of hydroxyproline content, fibrosis score and evaluation of fibrosis/inflammatory markers by Western blot at 12 weeks post-irradiation. CCK-8 method was used to explore the effects of metformin on non-small cell lung cancer( NSCLC) cells A549 and H460. Results Metformin reduced radiologic and histologic signs of fibrosis, lung density(6. 52 ± 0. 43 vs. 3. 31 ± 0. 57, t=6. 37, P<0. 01) and hydroxyproline content(32. 58 ± 1. 59 vs. 23. 47 ± 2. 46,t=12. 72, P<0. 01) which had been increased due to irradiation. Meanwhile, it significantly decreased the expressions of Col1, p-AMPKα and TGF-β, while inhibited the expressions of p-Smad2 and p-Smad3 compared to the irradiation alone group. Moreover, metformin reduced A549 and H460 cells growth. Conclusions Metformin exerted a protective effect on normal tissues in radiation-induced pulmonary fibrosis. Thus, it might act as a promising radioprotective agent in the treatment of lung cancer.
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Objective To evaluate the radioprotective effects of metformin on radiation-induced pulmonary injury in rats. Method A total of 30 Sprague-Dawley ( SD) rats were randomly divided into three groups:control, radiation (20 Gy) and radiation (20 Gy) with metformin, with 10 rats in each group. The right lungs of rats were irradiated to 20 Gy with 6 MV X-rays. Computed tomography (CT) was performed and Hounsfield Units ( HU) were determined during the observation period. The tissue samples of lung were extracted to perform the histological analysis, measurement of hydroxyproline content, fibrosis score and evaluation of fibrosis/inflammatory markers by Western blot at 12 weeks post-irradiation. CCK-8 method was used to explore the effects of metformin on non-small cell lung cancer( NSCLC) cells A549 and H460. Results Metformin reduced radiologic and histologic signs of fibrosis, lung density(6. 52 ± 0. 43 vs. 3. 31 ± 0. 57, t=6. 37, P<0. 01) and hydroxyproline content(32. 58 ± 1. 59 vs. 23. 47 ± 2. 46,t=12. 72, P<0. 01) which had been increased due to irradiation. Meanwhile, it significantly decreased the expressions of Col1, p-AMPKα and TGF-β, while inhibited the expressions of p-Smad2 and p-Smad3 compared to the irradiation alone group. Moreover, metformin reduced A549 and H460 cells growth. Conclusions Metformin exerted a protective effect on normal tissues in radiation-induced pulmonary fibrosis. Thus, it might act as a promising radioprotective agent in the treatment of lung cancer.
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This paper discusses the brachytherapy with tumour interventional radiology technology.The structure and security of the intravascular iridium-192 sources afterloader are reviewed in comparison with general afterloader.