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Objective @#To verify the feasibility of using a homemade lung phantom for quality control of Cyberknife by comparing the measurement results of the homemade lung phantom and CIRS dynamic phantom in E2E testing of Cyberknife lung tracking. @*Methods @#The patient treatment process was simulated, including CT positioning, plan design, irra- diation implementation, film scanning, and analysis using the homemade phantom and CIRS phantom. The two phantoms were measured five times using MLC under the S7 generation Cyberknife and five times using Iris under the M6 generation Cyberknife. The differences in measurement results between the two phantoms were analyzed using independent sample t-test.@*Results @#For the S7 generation Cyberknife, the statistical analysis of differences between the two phantoms in the detection values on the X-axis, Y-axis, Z-axis, and total deviation showed P values of 0.236, 0.175, 0.289, and 0.668, respect- ively. For the M6 generation Cyberknife, the statistical analysis showed P values of 0.880, 0.891, 0.573, and 0.433, respect- ively. The P values were all > 0.05. Therefore, there were no statistically significant differences in the detection results between the homemade lung phantom and the CIRS phantom under the S7 and M6 generation Cyberknife. The total deviation values were <1.5 mm.@*Conclusion @#The homemade lung phantom and CIRS phantom have consistent measurement results in the E2E testing of Cyberknife lung tracking and meet the requirements of Report of AAPM TG-135 and WS 667- 2019 standard. Therefore, the homemade lung phantom is feasible for clinical quality control of Cyberknife.
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Objective To explore the effects of different fractionation doses,fractionation methods,and other related parameters on the peripheral blood lymphocyte count of patients with liver cancer receiving CyberKnife radiotherapy.Methods The clinical data of 90 patients with liver cancer receiving CyberKnife radiotherapy in our hospital were retrospectively analyzed.The peripheral blood lymphocyte counts of patients 1 week before CyberKnife radiotherapy and 1 week,1 month and 3 months after treatment were determined.The effects of different prescribed doses,fractionation doses and numbers of fractionations on the peripheral blood lymphocyte count were analyzed.Results The peripheral blood lymphocyte counts of patients with different prescribed doses,fractionation doses and fractionation methods after CyberKnife treatment decreased to varying degrees compared with those 1 week before treatment(P<0.05).The peripheral blood lymphocyte counts of patients in the groups with≤5 fractionations and fractionation dose>7 Gy were significantly higher than those of patients in the groups with>5 fractionations and the fractionation dose≤7 Gy,respectively(P<0.05).There was no significant difference in peripheral blood lymphocyte counts between patients with different prescribed doses before and after CyberKnife treatment(P>0.05).Conclusion CyberKnife in the treatment of liver cancer with≤5 ractionations and a fractionation dose of>7 Gy is more beneficial to alleviate the decrease of lymphocyte count caused by Cyberknife treatment.
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@#Objective To investigate the efficacy and safety of Cyberknife in the treatment of elderly patients(aged≥75 years)with early stage non-small cell lung cancer(NSCLC),and to compare the results with those of patients aged<75 years.Methods We retrospectively analyzed 75 patients with early(T1-2N0M0)NSCLC admitted to the 960th Hospital of Jinan People's Liberation Army from January 2013 to October 2019.There were 32(42.7%)patients aged<75 years,and 43(57.3%)patients aged≥75 years.All patients were treated with 45-66Gy/3-8F,60%-85%isodose line as the prescription dose to cover planning target volume(PTV),and irradiation once a day and five times a week.The clinical efficacy,survival status and radiotherapy toxicity of the two groups were compared,and the factors affecting the efficacy of elderly patients were analyzed.Results The disease control rates of patients aged<75 and≥75 years were 96.9%and 93.0%,respectively(P>0.05).The 5-year local control rate(LC),progression-free survival(PFS)and cancer-specific survival(CSS)were 70.9%and 85.4%,58.5%and 54.4%,and 70.4%and 64.5%,respectively(P>0.05).However,the overall survival(OS)of patients aged≥75 years was significantly lower than that of patients aged<75 years,and the 5-year OS was 49.2%and 68.2%,respectively(P<0.05).There was no significant difference in the treatment complications between the two groups(P>0.05).Multivariate analysis showed that biologic effective dose(BED)was an independent factor affecting OS in patients aged≥75 years.Conclusion Stereotactic body radiotherapy with cyberknife is a safe and effective treatment for elderly patients with early stage NSCLC who are not suitable for surgery.
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Objective:To explore the clinical application value of personalized positioning using a cervical collar combined with a vacuum pad in the Cyberknife radiosurgery for cervical spine metastases.Methods:This study enrolled 68 patients with cervical spine metastases to be treated with Cyberknife stereotactic radiotherapy for cervical spines. These patients consisted of 41 males and 27 females, aged from 43 to 78 years (average: 51.5 years). They were divided into groups A, B, and C using the random number table method. The patient positioning in these groups was achieved using a cervical collar combined with a vacuum pad (personalized positioning), a vacuum pad, and a small head mold, respectively. After the first treatment, the comfort levels of the positioning molds during treatment were investigated. After radiotherapy, the average deviations in translational and rotational directions, the minimum tolerance distance (dxAB), the minimum rotational deviation angle (drAB), the proportion of false nodes, and the comfort level of the three positioning method were acquired for analysis.Results:The three groups showed statistically significant differences in the inf-sup, left-right, ant-post, pitch, roll, and yaw directions during the first treatment ( F = 7.13, 2.56, 3.41, 4.21, 2.71, 8.14, P < 0.05). Compared with groups B and C, Group A had significantly lower dxAB, drAB, and the proportion of false nodes, showing statistically significant differences ( F = 5.06, 4.31, 3.30, P < 0.05). Furthermore, patients in groups A and B felt more comfortable with the positioning molds than those in Group C ( χ2 = 12.46, P < 0.05), with no statistically significant differences between groups A and B ( P > 0.05). Conclusions:For patients with cervical spine metastases undergoing Cyberknife radiosurgery for cervical spines, the personalized positioning using a cervical collar combined with a vacuum pad can improve the accuracy and safety of Cyberknife spinal tracking while remaining the comfort level.
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Objective:To evaluate the dosimetric characteristics of Zap-X system and CyberKnife (CK) G4 system of stereotactic radiosurgery (SRS) for single brain metastasis.Methods:Twelve patients with single brain metastasis had been treated with CK were selected retrospectively. The prescribed dose of planning target volume (PTV) was 18-24 Gy for 1-3 fractions. The PTV was ranged from 0.44 to 11.52 cm 3. The 12 patients were re-planned in the Zap-X planning system using the same prescription dose and organs at risk constraints, and the prescription dose of PTV was normalized to 70% for both Zap-X and CK. The planning parameters and dosimetric parameters of PTV and organs at risk were compared and evaluated between two plans. All data were read at MIM Maestro. A paired Wilcoxon' signed-rank test was adopted for statistical analysis. A P value of less than 0.05 was considered as statistical significance. Results:For the target coverage, CK was significantly higher than Zap-X (99.14±0.57% vs. 97.55±1.34%, P<0.01), but Zap-X showed a higher conformity index (0.81±0.05 vs. 0.77±0.07, P<0.05), a lower Paddick gradient index (2.98±0.24 vs. 3.15±0.38), and a higher gradient score index (GSI) than CK. The total monitor unit (MU) of Zap-X was significantly lower than that of CK (11 627.63 ±5 039.53 vs. 23 522.16 ±4 542.12, P<0.01) and the treatment time was shorter than that of CK [(25.08 ±6.52) vs. (38.08 ±4.74) min, P<0.01]. Zap-X had lower dose volumes than CK for the dose of brain ( P<0.05). Zap-X had a lower D mean and D max of brainstem (both P<0.05), but a higher value of eyes and lens. For optic nerves and optic chiasm, there were no significant differences between two groups. In addition, for the protection of skin (V 22.5 Gy), Zap-X seemed better than CK [(4.15±4.48) vs. (4.37±4.50) cm 3, P<0.05]. Conclusions:For SRS treating single brain metastasis, Zap-X could provide a high quality plan equivalent to or even better than CK, especially reducing the treatment time. With continuous improvement and upgrading of Zap-X system, it may become a new SRS platform for the treatment of brain metastasis.
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Objective:To compare the dosimetric characteristics of beams between Zap-X and G4 CyberKnife and provide reference for clinical application of Zap-X.Methods:PTW three-dimensional water tank and dosimetry diode ionization chamber were used to measure the two orthogonal off-axis ratio and field size at isocenter of 7 different collimators (5 mm, 7.5 mm, 10 mm, 12.5 mm, 15 mm, 20 mm and 25 mm) of Zap-X and CyberKnife at the water depth of maximum dose, 50 mm, 100 mm, and 200 mm. The penumbra, flatness, symmetry and field size under each parameter condition were analyzed by using PTW supporting software PTW MEPHYSTO (version 5.1). Data analysis and graph were performed using Origin 2021 software.Results:With the same collimator, the dose plateau area of Zap-X was wider than that of G4 CyberKnife, and the dose fall-off at the field edge of Zap-X system was faster. With the increase of the collimator, the penumbra of Zap-X and CyberKnife tended to become larger, and the flatness tended to become smaller, the penumbra and flatness of Zap-X were significantly smaller than those of CyberKnife. Both of them had excellent symmetry (<1%), and the symmetry results of CyberKnife (<0.39%) were better than that of Zap-X (0.99%). The accuracy of Zap-X collimator size at isocenter was better than that of CyberKnife.Conclusion:Compared with G4 CyberKnife, Zap-X system has smaller penumbra, better flatness and higher accuracy of collimator size, which is suitable for stereotactic radiosurgery.
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Objective:To evaluate the feasibility of a novel liver fiducial marker implantation method for internal fixation and removal of rabbit livers, in order to use in Cyberknife tracking therapy.Methods:Experiments were conducted in vivo and in vitro. In the in vivo experiment, three fiducial markers were implanted percutaneously in each liver of ten rabbits under anesthesia, and the fourth fiducial marker with an external catheter and fixed thin wire was implanted ten days later. After the reference group (the first and the second maker), and the casing group (the first and the fourth marker) were respectively registered and tracked with the Cyberknife, the implantation success rate, registration accuracy, and removal safety of fiducial markers were assessed. The tensile test was performed using liver in vitro by measuring the resistance required to dislodge the spring coil fiducial markers and the fiducial markers without spring coil from liver. Results:The intrahepatic catheter implantation and removal of fiducial marker in rabbit liver had a success rate of 100% and no distant migration. The operation-related and postoperative complications were not occurred. All fiducial markers were successfully traced. Compared to the reference group, the casing group had slightly higher translational errors in supero-inferior and antero-posterior directions ( Z=-11.77, -4.57, P<0.05), and lower translational errors in left-right direction ( Z=-2.52, P<0.05). The dislodgement forces for spring coil fiducial markers was (2.23±0.85) N, significantly different with (0.81±0.13) N for fiducial markers without spring coil ( Z=- 2.31, P < 0.05). Conclusions:The spiral coil structure provides superior fixation in the punctured needle channel, the thin line limits the distant displacement of the fiducial marker outside the liver, and the catheter establishes a channel for the removal. The general operation is simple and easy.
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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 necessity and feasibility of the virtual simulation teaching experiment software of the bronchoscopy intelligent navigation-based fiducial marker implantation technology in the clinical application of radiotherapy.Methods:This study developed a 3D virtual operation and interactive system using the Unity3D engine, tools including 3Dmax and Maya, and the SQL database. The scenes in the system were produced using the currently popular next-generation production process. Targeting the priorities and difficulties in the implantation of fiducial markers, the system developed in this study allowed for simulated demonstration and training based on 12 steps and 10 knowledge points. Internal tests and remote evaluation tests were adopted in this system to obtain the test result of each subject. Then, the application value of the system was analyzed based on the test result.Results:As of May 1, 2022, the system had received 2 409 views and 425 test participants, with an test completion rate of 100% and an experiment pass rate of 96.5%. Moreover, this system won unanimous praise from 167 users, primarily including the students majoring in multilevel medical imaging technology and medical imaging science from the Fujian Medical University, as well as the radiotherapy-related staff of this university.Conclusions:The virtual simulation teaching experiment software of the bronchoscopy intelligent navigation-based fiducial marker implantation technology can be applied to the teaching of students and the training of related professionals.
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Objective To investigate the factors affecting the dose distribution to the tumor target volume(GTV)and normal tissues in cerebral arteriovenous malformation(AVM)treated with CyberKnife,and to analyze the effect of collimators of different diameters on the dose distribution of cerebral AVM,so as to provide references for cerebral AVM CyberKnife treatment plans.Methods Totally 12 cerebral AVM patients receiving CyberKnife treatment after embolization in some hospital between 2015 and 2020 were selected.Collimators were determined according to 30％,40％,50％,30％+40％+50％of the GTV cross-sectional long diameters,and four different treatment plans were developed for each patient and then enrolled into Group A,Group B,Group C,and Group D,respectively.The effects of the shape and volume of GTV and the size of collimator on the dose distribution in the target area were analyzed,and the dose fall-off outside the target area was investigated.SPSS 20.0 software was used for statistical analysis.Results The effects of width,height,volume and regularity of GTV on the conformity index(CI),new conformity index(nCI),geometric conformity index(gCI)and number of beams were statistically significant(P＜0.05).When compared with group A,B and D,group C had the minimum dose,median absorbed dose,target area coverage,target gradient index and prescription dose line of GTV increased while the CI,nCI,gCI of GTV and the number of monitor units,treatment nodes and beams decreased significantly(P＜0.05).In group C median absorbed dose of normal tissue more than 20 mm apart from the target area decreased,while median absorbed dose of normal tissue not longer than 15 mm apart from the target area increased.Conclusion During CyberKnife treatment of cerebral AVMs,collimator selection based on 50％of the GTV cross-sectional long diameter can achieve an optimal dose distribution while improving the efficiency of the execution of the CyberKnife treatment plan.[Chinese Medical Equipment Journal,2023,44(11):56-60]
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Objective To explore the dosimetric effects of a self-developed planning mode of boundary range scattering dose(BRSD)on Cyberknife treatment of lung cancer brain metastases.Methods The positioning images of 15 patients with lung cancer brain metastases treated in the radiotherapy department of some institution from January 1,2021 to December 31,2021 were selected and introduced into Cyberknife Multiplan 4.0.3 treatment planning system.A fractionated stereotactic radiotherapy(FSRT)plan(as the FSRT planning group)and a BRSD plan(as the BRSD planning group)were developed for each patient.The FSRT planning group developed a plan for the planning target volume(PTV)in the conventional way,so that V100 covered more than 95％of the PTV;the BRSD planning group prepared a plan for the gross tumor volume(GTV)with the same parameter conditions as the FSRT planning group and the prescription dose was normalized to the PTV so that V100 covered more than 95％of the PTV.The dosimetric parameters of the target area and normal tissue of the 2 groups were compared by dose-volume histograms and isodose curves.Statistical analysis was performed using SPSS 24.0 software.Results The D98,Dmax and Dmean in the target area of the BRSD planning group were significantly higher than those of the FSRT planning group,and the differences were statistically significant(P<0.05);the differences in the conformity index,dose gradient index,and Dmean,V30,V24 and D3cc in normal tissue of the 2 groups were not statistically significant(P>0.05);the BRSD planning group gained a denser dose distribution when compared with the FSRT planning group.Conclusion The BRSD planning mode gains significant dosimetric advantage by enhancing the absorbed dose to the target area without increasing or decreasing the dose to normal tissue.
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OBJECTIVE@#To assess the potential dosimetric effects of arms movement in patients with Cyberknife spine tumors.@*METHODS@#In the study, 12 patients with thoracic and lumbar tumors were retrospectively selected respectively. The contour of the patient's arms was sketched and the CT density was modified to be equivalent to air in order to simulate the extreme case when the arm was completely removed from the radiation fields. The dose of simulated plan was re-calculated with the original beam parameters and compared with the original plan. The changes of V100, D95, and D90, conformity index (CI) and heterogeneity index (HI) in planning target volume (PTV), as well as Dmax, D1cc and D2cc in the spinal cord, stomach, esophagus, and intestines were analyzed by comparing with the original plans.@*RESULTS@#Compared with the original treatment plan, V100, D95, D90 and CI of PTV for the simulated plan was increased by 0.86%, 2.02%, 1.97% and 0.80% respectively, the difference was statistically significant (P < 0.05). Dmax, D1cc and D2cc of spinal cord was increased by 2.35%, 0.59% and 1.49% on average, compared with the original plan, the difference was statistically significant (P < 0.05). The difference was statistically significant only in average D2cc of stomach, which was increased by 1.70%, compared with the original plan (P < 0.05). There was no significant difference in dose change of eso-phagus and intestine between the original and simulated plans.@*CONCLUSION@#This study analyzed the most extreme arm position in spinal tumor of radiation therapy based on Cyberknife. It was found that the change of arm position had little effect on dosimetry. In addition, with the change of arm position, the dose in PTV and organ at risk (OAR) increased, but the increase was relatively small. Therefore, in some special cases where the patient really can't keep the arm position consistent during treatment, reasonable adjustment can be accepted. However, in order to ensure accurate radiotherapy, patient position should be as stable and consistent as possible.
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Humanos , Braço , Radiocirurgia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada , Estudos Retrospectivos , Neoplasias da Coluna Vertebral/cirurgiaRESUMO
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 explore the feasibility of recoverable fiducial marker implantation guided using the intelligent navigation bronchoscopy technology in the Cyberknife Synchrony-based respiratory tracking.Methods:CT scans of an inflatable pig lung after anti-rot processing were obtained. Then, eight simulated tumor lesion sites were designed in the left and right lung lobes using intelligent navigation software, with four classified as the sputum bronchial environment group and four classified as the wet bronchial environment group. Based on the implantation principle of Cyberknife fiducial markers, 32 recoverable fiducial markers were implanted around various simulated tumor lesions via bronchus under intelligent guidance. Then, the end-expiratory state of the pig lung was simulated, the pig lung was scanned again to obtain CT images of the implanted recoverable fiducial markers, and the number of successfully implanted fiducial markers was recorded. Eight deliverable Synchrony treatment protocols were designed using the Cyberknife planning system (Multiplan v4.6), and then the pig lung with simulated respiratory movements was exposed to radiation. After radiation, the implanted recoverable fiducial markers were retrieved using the bronchoscopy technique, and the number of successfully retrieved fiducial markers was recorded. Moreover, the translational errors, rotational errors, and rigid body errors were extracted from the Cyberknife log file and analyzed.Results:No recoverable fiducial markers slipped or fell during the experiment. Thirty-two recoverable fiducial markers were successfully implanted and recovered under the guidance of intelligent navigation bronchoscopy, with implantation and recovery success rates of both 100%. Moreover, the tracking rate and rigid body errors of the fiducial markers were 100% and less than 5 mm, respectively. The data from the Cyberknife log file indicated that there was no significant difference between the sputum bronchial environment group and the wet bronchial environment group in the translational errors in the left-right direction, the rotational errors in the roll direction, and the rotational errors in the pitch direction ( P>0.05). Compared to the wet bronchial environment group, the sputum bronchial environment group had slightly higher translational errors in front-back ( Z=-3.57, P<0.01) and cranio-caudal ( Z=-2.53, P<0.05) directions, lower rotational errors along the yaw axis ( Z = -3.88, P < 0.01), and lower rigid body error ( Z=-3.32, P<0.01), and the differences were all statistically significant. Conclusions:The recoverable fiducial marker implantation guided using the intelligent navigation bronchoscopy technology is feasible. Recoverable fiducial markers are stable in the bronchus of the phantom, and the Cyberknife tracking precision can meet clinical requirements. Therefore, the recoverable fiducial marker implantation guided using the intelligent navigation bronchoscopy technology has promising prospects in clinical and teaching applications.
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Objective:To verify radiation shielding effect of the maze of the CyberKnife room, so as to identify and correct the deficiencies in the shielding designs in certain circumstances.Methods:In line with the radiation protection shielding design scheme of the CyberKnife room provided by the producer, the consideradtions are focused on the useful beam that could mainly pass through the image center, but not the outer wall of the maze. However, during the inspection and acceptance of radiological protection in the built room, it was found that in a certain situations useful wire did not pass through the imaging center. Therefore, the additional shielding and protection facilities were built and verified.Results:After verification and acceptance on the scene, in the case where the useful beam was passing through the image center, the highest ambient dose equivalent rate at the concerned points 30 cm away from the outer wall of the maze was 0.31 μSv/h, less than the control level 10 μSv/h. In the opposite case, the highest ambient dose equivalent rate at the same points as above was 301.67 μSv/h, ablut 30 times as much as the control level. After the thickness in maze outer wall was enhanced, the highest ambient dose equivalent rate at the same as above was 2.14 μSv/h. This testing result met the concerned national standard.Conclusions:It is desirable that in designing the outer wall shielding in the maze in a CyberKnife room, attention should be paid to whether or not the useful beam could pass through the image center, or otherwise directly irradiate on the maze on the basis of the movement range of the accelerator. Shielding wall thickness should be calculated on the basis of the irradiation ragne and the distance between source location and the concerned points to ensure being in compliance with the requirements of the concerned national standard. Meanwhile, it should protect the workers occupying at the concerned locations from receiving higher radiation doses.
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Objective@#To discuss the feasibility of applying home-made auto quality assurance (AQA) phantom in Cyberknife AQA test.@*Methods@#The same treatment plan for AQA test was designed in the Cyberknife treatment planning system. The AQA tests were performed under the same conditions using the home-made AQA phantom and the AQA phantom in the fourth-generation (G4) Cyberknife mode and the fifth-generation (VSI) Cyberknife mode, respectively, and each measurement was repeated five times to analyze and compare the differences in test results between the two phantoms.@*Results@#The total deviations of the home-made AQA phantom and the AQA phantom in the AQA test under the G4 Cy- berknife mode were (0.28 ± 0.12) mm and (0.28 ± 0.15) mm, respectively (P > 0.05); the test results under the VSI Cy- berknife mode were (0.46 ± 0.19) mm and (0.50 ± 0.07) mm, respectively (P > 0.05); the total deviations of all test results were smaller than 1.0 mm, which met the requirements of WS 667—2019 Specification for Testing of Quality Control in Ro- botic Arm Radiotherapy Device.@*Conclusion@#The test results of the home-made AQA phantom and the AQA phantom are consistent in the AQA test, and the home-made AQA phantom can be used for Cyberknife quality control.
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Objective:To analyze the influence of tracking error of Xsight lung tracking system caused by cardiac beating.Methods:48 patients with lung tumors adjacent to the heart were enrolled into this study. The tumor movement curves were collected by the Xsight lung tracking system and recorded in the treatment log files during the Cyberknife treatment process. The curves were subject to filtering analysis and the respiratory motion of < 1 Hz and the cardiac beating motion of > 1 Hz were separated. According to the filtering results, the patient treatment tracking data were divided into two groups based on whether the cardiac beating wave of >1 Hz existed. The tracking errors were statistically compared between two groups based on the X-ray imaging data collected by Xsight lung tracking system during treatment.Results:For the fractionation with cardiac beat information, the tracking errors of the patient′s related models were (1.45 ± 0.99), (0.46 ± 0.21) and (0.70 ± 0.54) mm in the left-right, superior-inferior and anterior-posterior direction, respectively. For the fractionation without cardiac beat information, the tracking errors of the patient′s related models were (1.52 ± 1.17), (0.63 ± 0.37) and (1.07 ± 0.62) mm in the left-right, superior-inferior and anterior-posterior direction, respectively. The tracking errors in the superior-inferior and anterior-posterior direction of patients with accurate cardiac beat models were 28.34% and 34.86% less than those of their counterparts without accurate cardiac beat models and there was significant difference (both P<0.05). Conclusion:The tracking accuracy of Xsight lung tracking system will be significantly improved if the cardiac beat model is accurately established.
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Introducción: La dupla Cyberknife y bisturí de rayos gamma (Infini) que se describe es la primera en Latinoamérica. Ambas máquinas han mostrado ser los mejores equipos para radiocirugía intracraneal. Se describe la experiencia inicial de Cyberknife en Centroamérica y su incorporación a un programa existente de bisturí de rayos gamma por vía de análisis comparativos dosimétricos. Material y método: En el año 2019 se realizaron planes comparativos y se trataron 180 pacientes con radiocirugía intracraneal con ambos sistemas tanto en patología tumoral, como vascular y funcional. Resultados: En el análisis dosimétrico comparativo en el gradiente de dosis de Infini mostró ser superior a Cyberknife en todos los casos. Para una esfera utilizando el colimador de 4 mm en Infini y de 5 mm en Cyberknife utilizando un plan isocéntrico con el -Trigeminal Path- el gradiente de dosis para Infini fue de 1.5 y para Cyberknife de 1.66. Para los casos de patología el gradiente de dosis media para Infini fue de 3 mm y para Cyberknife de 3.8 mm. Dando un puntaje de gradiente de dosis (Gradient Score Index) si Infini fuese de 100, Cyberknife obtuvo 87.3. Cyberknife mostró mejor conformalidad y cobertura (97% versus 96%) para todos los targets. Entre enero 2019 y enero 2020 se realizaron 180 radiocirugías, 60 con Cyberknife y 120 con Infini, 60 pacientes recibieron 146 sesiones con Cyberknife, radiocirugía fraccionada 39 (65%) y 21 (35%) en sesión única. Las dosis medias en tumores en dosis única fue 15 Gy (12.5 a 25 Gy) y en radiocirugía fraccionada 21 Gy (18 y 35). Ningún paciente ha experimentado toxicidad mayor a grado dos. Conclusiones: El bisturí de rayos gamma rotatorio reveló superioridad en gradiente de dosis con relación al Cyberknife. En su primer año Cyberknife ha mostrado ser una herramienta segura en el tratamiento de patología intracraneal. Más seguimiento clínico y radiológico es necesario para verificar su efectividad comparativa
Introduction: The match between Cyberknife and Infini here described in this article is the first in Latinamerica. Both machines have proven to be the best for intracranial radiosurgery, we describe our initial experience with Cyberknife in Central America and how it was incorporated in an existing gamma ray program by ways of dosimetry comparisons. Methods: During 2019 comparative plans were made and a total of 180 patients received intracranial radiosurgery with both technologies, patients were treated for tumors, vascular anomalies, and functional pathology. Results: Basic dosimetry analysis regarding dose gradient the Infini proved superior to Cyberknife in all plans. For a sphere using the 4 mm collimator in Infini and the 5 mm in Cyberknife along with an isocentric plan using the -Trigeminal Path- dose gradient was 1.5 for Infini and 1.66 for Cyberknife. For the pathology cases Infini was 3 mm and for Cyberknife 3.8 mm on mean. Giving a Gradient Score Index (GSI) if Infini would be 100, Cyberknife would be 87.3. Cyberknife showed better conformality and coverage for all pathology targets (97% versus 96%). From January 2019 to January 2020, 180 intracranial radiosurgeries were done, 60 with Cyberknife and 120 with Infini, 60 patients received 146 sessions with Cyberknife, fractionated scheme 39 (65%) and 21 (35%) single dose. The median dose for tumors was 15 Gy (12.5 a 25 Gy) for single session and 21 Gy (18 y 35) for fractionated scheme. No patient experienced a higher toxicity tan grade two. Conclusions: In its first year Cyberknife has shown to be safe in treating intracranial pathology. Infini had a better dose gradient than Cyberknife. Longer clinical and radiological follow-up is needed to verify its comparative effectiveness.
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Humanos , Radiocirurgia , Cérebro , Metástase Neoplásica , Neoplasias , NeurocirurgiaRESUMO
Circumscribed choroidal hemangioma is a benign vascular hamartoma without systemic associations. For symptomatic cases, treatment options are photodynamic therapy (PDT), transpupillary thermotherapy (TTT), intravitreal injection of anti-vascular endothelial growth factor (VEGF), or radiation therapy. CyberKnife radiosurgery is an image-guided radiation therapy that delivers radiation to lesions anywhere in the body with an accuracy of 0.5 mm without damage to surrounding structures. We report a case of circumscribed choroidal hemangioma which was successfully treated with CyberKnife therapy. The literature search reveals cases of uveal melanoma, intraocular, and periocular lymphoma successfully treated with CyberKnife therapy. To the best of our knowledge, this is the first report on such treatment for choroidal hemangioma.
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Objective@#To compare the dosimetrics of the plan target volume (PTV) and organs at risk (OARs) between two treatment planning approaches for patients with multiple brain metastases from non-small cell lung cancer on CyberKnife.@*Methods@#20 patients with multiple metastases from lung carcinoma were reviewed and analyzed, who had been treated by CyberKnife from December 2017 to December 2018. The CyberKnife stereotactic radiotherapy plans of the 20 cases were re-planed with single plan for multiple lesions and multiple plans per lesion. The dosimetry differences of PTV and OARs isodose disribution, conformity index (CI), total beam counts and total monitor units (MUs) were compared in the two types of plans.@*Results@#The two types of plans could satisfy over 95% PTV coverage of the prescription dose. The maximum and mean dose of normal brain adjacent to the PTV were reduced in multiple plan approach effectively. Moreover, the maximum and mean dose of OARs (brainstem) dropped by 1.62% and 5.57% (t=1.09, P<0.01) respectively. The number of treatment nodes and total MU declined by 4.63% (t=1.87, P<0.01)and 1.06% in multiple plan approach, which could significantly shorten the clinical treatment time. The differences in CI index between these two types of plans was of no statistical significance.@*Conclusions@#For patients with multiple brain metastases of similar diameter and volume from non-small cell lung cancer to be treated on CyberKnife, multiple plans per lesion could not only reduce dose to normal brain tissue and OARs, but also improve the treatment efficiency.