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Objective:To introduce the stereotactic cardiac radioablation (SCRA) based on the stereotactic body radiotherapy (SBRT), and comprehensively evaluate the new approach by short-term effectiveness and safety.Methods:Patients with ventricular arrhythmia (VA) were evaluated and included in this clinical trial, who were immobilized by vacuum bag and performed simulation with 4-dimensional computed tomography (4DCT). In this study, the planning target volume (PTV) was set as the target to design a SBRT plan using volumetric modulated arc therapy (VMAT), which was evaluated by dose parameters such as R 50%, homogeneity index and conformity index, etc. The results of Holter and echocardiography were monitored during the follow-up and compared with the data before treatment. Results:Three subjects with ventricular tachycardia (VT) and one with premature ventricular contraction (PVC) received the same prescription of 25 Gy in a single fraction. The average volume of PTV was 71.4 cm 3(60.3-89.4 cm 3). The average time of beam delivery was 12.0 min (4.5-21.0 min). And the short-term follow-up lasted for an average of 18 weeks (14-25 weeks), which showed significant decrease in both VT and PVC load without complications. Conclusion:This study reports the implementation method of SCRA and proves its short-term effectiveness and safety, but the effects and standards of the key radiotherapy techniques still need to be explored.
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MRI simulation images quality of head and neck coil scanning is better than that of radiotherapy surface coil, but currently the head and neck coil is not compatible with radiotherapy positioning devices. In this paper, a new fixation device is developed based on computer reverse engineering technology, which can be used in combination with head and neck coil. This article focuses on discussing the feasibility of the new device in radiotherapy. The obtained ACR phantom and Cat phantom 504 images were used to analyze MR and CT images quality assurance indicators. The dose attenuation of 6 MV photons was measured using the ionization chamber. The results showed each index met the clinical application requirements of intracranial tumor radiotherapy, thereby it can be used in intracranial tumor radiotherapy.
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Humans , Feasibility Studies , Head and Neck Neoplasms , Diagnostic Imaging , Magnetic Resonance Imaging , Phantoms, Imaging , Radiotherapy Planning, Computer-AssistedABSTRACT
Objective To observe the MVD and integrin αvβ3 mRNA expression changes in tumor -bearing rats by using endostar combined with radiotherapy ,and to explore the potential synergy mechanism .Meth-ods We randomly divided the tumor -bearing rats into four groups:control group(NC),endostar group(ES), radiation treatment group ( RT) and endostar combined radiotherapy group ( ES +RT) .Tumor inhibition rate was calculated every other day .Microvessel density and αvβ3mRNA were texted by immunohistochemical or real time PCR in each group.Results (1)ES+RT group showed the most obvious inhibition rate;(2)Compared with NC group,microvessel density of RT was increased ,but decreased in ES group and ES +RT group significantly ( P<0.05);(3)Compared with NC group,αvβ3 mRNA expression of RT group was increased,while decreased in ES group and ES+RT group,and ES +RT group displayed a greater decrease when compared to ES group ( P<0.05).Conclusion Endostar combined radiotherapy can inhibit the growth of cancer and the expression ofαvβ3mRNA,improve the disorders of tumor vascular network .It may be one of the mechanisms of increasing radi-osensitization.
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Objective To investigate reasonable method of deciding internal target volume (ITV) by comparing physical phantom volumes (including moving volume) with reconstruction volumes of spiral CT scanning.Methods The various-volume wax blocks which were labeled No.1-9 were made and put on the respiratory motion simulator.The range of motion was set 2.5 cm and frequency 18 beats/min.All blocks were scanned 10 times continuously and imported into the Eclipse TPS.All blocks volumes were calculated and then compared with the true physical volumes and paired t-test.Results The reconstruction volumes of 1-9 blocks were bigger than their stationary volumes (121.77 cm3 vs.103.14 cm3,P =0.038),but significantly smaller than their moving volumes (121.77 cm3 vs.161.75 cm3,P =0.045).The results can be gotten in different volume block scanning.The relative deviation of reconstruction volumes and the moving volumes tends to increase as the stationary physical volume decreases.Conclusions As to moving targets,conventional spiral CT scanning speed is too fast to collect all volume information of targets.So the one-time-scanning volume does not represent the ITV.
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Objective To study the influence of the angle of multileaf collimator leaves on segments (control point for sliding windows) number and monitor units in intensity-modulated radiotherapy (IMRT) plan optimization.Methods 10 cases undergone IMRT with rectangle target volume were choosed,2 plan were designed with step and shot technique and sliding windows technique for running direction of collimator with target long axis vertical and parallel respectively,compared the plans with similar optimization parameters for different angle of the collimator.Results The number of segments and monitor units increased by 52.8％ and 49.6％ more than longitudinal direction of leaf collimator with static IMRT respectively,there appeared significant difference (P =0.000) ; and the number of segments and monitor units increased by 58.2％ and 61.9％ more than longitudinal direction of leaf collimator with dynamic IMRT respectively,there appeared significant difference (P =0.000).Conclusions For the optimization of IMRT based on multileaf collimator,the direction of collimator perpendicular to the target long axis,there could be obviously decrease the number of monitor units,shorten the treatment time,improve the treatment efficiency with similar dose distribution.
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Objective To investigate the impact of accelerator′s multi-leaf collimator (MLC) on the radiotherapy dose with different gantry angles.Methods Measured with Mapcheck 2D diode array and 30 cm×30 cm×3 cm solid water, Pre-selecting the 30 appropriate single fields and 0°,45°,90°,270°,315° gantry angles of static and dynamic intensity modulated radiation therapy (IMRT), quantification analysis of the passing rate with MapCheck γ(3%/3 mm) and (5%/3 mm) analysis methods, and the same method to 30 examples static and dynamic IMRT plans.Results When the accelerator collimator angle is 0°,the 30 appropriate single fields′ passing rate of between 0°gantry angle and 45°,90°,270°,315°gantry angles of static and dynamic IMRT accordingly is 97.71% and 96.25%(t=1.70, P=0.389), 96.34% and 93.72%(t=2.95, P=0.002), 96.65% and 92.98%(t=2.87, P=0.005), 95.87% and 93.15%(t=2.71, P=0.006), 96.09% and 93.51%(t=2.89, P=0.004) with MapCheck γ(3%/3 mm) analysis methods, however, the passing rate also does not have the difference, respectively is 99.31%-99.73% and 98.89-99.68%(t=0.57-1.90, P=0.913-0.725) with MapCheck γ(5%/3 mm) analysis methods;the passing rate of 30 examples static and dynamic IMRT plans accordingly is 96.11%-96.76% and 94.88%-95.78%(t=1.02-1.61, P=0.317-0.235).Conclusions When the accelerator collimator angle is 0°, at different gantry angles, MLC leaves due to gravity, friction, inertia, etc caused by errors in place, the physical penumbra and leakage radiation will indeed affect the IMRT dose, however, the deviation of dose distribution is within acceptable 5%.
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Objective:To compare the dosimetric parameters between three-dimensional conformal and intensity-modulated radiotherapy for cervicothoracic spine metastases.Methods:Totally 10 cases of patients with cervicothoracic spine metastases were devided into 2 groups:3 patients with vertebral metastases;the other 7 patients with vertebral+annex metastases.The prescription dose for gross target was 60 Gy,D_(max) of spinal cord≤50 Gy,D_1≤45 Gy.Each patient was designed.One set of 3DCRT plan and three sets of IMRT plan were designed for each patient.We used 6 beams for 3DCRT plan,including 2 beams for the upper neck.3 sets of Step and shoot IMRT plans were consisted of 5-fields,7-fields and 9-fields,respectively,with equal angle and coplanar.DVH.CI and HI dose distributions of PTV and OARs were compared between 3DCRT and different set of IMRT plans.Results:(1)When the gross target included only vertebral,the CI of 3DCRT plan was lower than that of IMRT plan,but the HI of3DCRT plan was higher than that of IMRT plan.Moreover,5-fields IMRT plan was better than other plans.(2)When the gross target included vertebral and annex,the D_(80)、D_(mean) of IMRT PTV were higher than that of 3DCRT.As for spinal cord,5-fields D_(max)＜50Gy,7-fields D_(max)=49 Gy-51 Gy,9-fields D_(max)＞50 Cry.The CI of 3 sets of IMRT plans were 0.69,0.66,0.69,respectively.The CI of 3DCRT PTV was 0.53,worse than that of IMRT(P＜0.05).The average segments of 3 sets of IMRT plans were 83,104,160,and the average Mu of IMRT plans were 727,755,953,respectively.Conclusion:Compared with 3DCRT plan,the dose distribution,OAR and CI Of MRT plans were better.5-fields IMRT plan is recommended strongly.
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Objective To explorer the application in detection the position accuracy of the multileaf collimator of Varian accelerator with dynamic therapy log files. Methods A pre-designed MLC format files named PMLC for two Varian accelerators, the dynamic treatment log files were recorded 10 times on a different date, and be converted into the MLC format files named DMLC, compared with the original plan PMLC, so we can analysis two files for each leaf position deviation. In addition, we analysis the repeatability of MLC leaves position accuracy between 10 dynalog files of two accelerators. Results No statistically significant difference between the average position of the 10 times leaf position of the two accelerators,their were 0. 29 -0. 29 and 0. 29 -0. 30(z = -0. 77, P=0. 442). About 40% ,30% ,20% and 10% of the leaf position deviation was at ≤0. 2 mm, 0. 3 mm,0. 5 mm and 0. 4 mm,respectively. the maximum value was 0. 5 mm. More than 86% of the leaf position are completely coincident between 10 dynamic treatment files of two accelerators,The rate of position deviation no more 0. 05 mm was 96. 6% and 97.3%, respectively.And the maximum value was 0. 09 mm. Conclusions Dynamic treatment log file is a splendid tool in testing the actual position of multi-leaf collimator. The multi-leaf collimator of two accelerators be detected are precise and stabilized.
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<p><b>BACKGROUND AND OBJECTIVE</b>Radiation sensitivity is closely related to tissue oxygen, and rh-endostatin can induce the high level of oxygen content in tumor by "normalizing" tumor angiogenesis which is associated with radiotherapy sensitivity. The aim of this study is to observe the effect of combination of radiotherapy with rh-endostatin in the rats with lung cancer.</p><p><b>METHODS</b>Immediate lewis cancerous ascetic injection method was used to make rats tumors bearing model, then the rats was divided into four groups randomly: group A was treated with saline; group B was treated with rh-endostatin; group C was treated with irradiation and group D was treated with rh-endostatin and irradiation. After all rats were treated, inhibition rates and the tumor growth curve were calculated. Immunohistochemisty was adopted to check the expressions of vascular endothelial growth factor (VEGF) and microvessel density (MVD).</p><p><b>RESULTS</b>Compared with group A, the growth rates of the tumors in the other group were obviously slower, and the tumor weights were significantly different form group A (P < 0.05). Compared with the other groups, the tumor weights of group D were obviously reduced (P < 0.05). Compared with group A, VEGF and MVD of other three groups were reduced (P < 0.05), and group D were significantly cut down.</p><p><b>CONCLUSION</b>Combination with radiotherapy and rh-endostatin could inhibit the lung cancer significantly in rats. The possible mechanisms are to decrease the expression ofVEGF and inhibit the production of angiogenesis.</p>
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Animals , Female , Mice , Carcinoma, Lewis Lung , Drug Therapy , Metabolism , Pathology , Radiotherapy , Endostatins , Therapeutic Uses , Immunohistochemistry , Lung Neoplasms , Drug Therapy , Metabolism , Radiotherapy , Mice, Inbred C57BL , Microvessels , Pathology , Random Allocation , Vascular Endothelial Growth Factor A , MetabolismABSTRACT
Objective To investigate antiproliferative activity of endostatin(ES), the combining effect of Endostar and radiation on VEGF and apoptosis of the A549 human lung adenoearcinoma cell line.Methods The cell of exponential phase of growth were divided into the control, radiation alone, ES alone,radiation after ES(ES→RT), ES after radiation(RT→ES), radiation and ES at equal paee (RT+ES), γ-ray radiation at a dose of 2 Gy, single fracination irradiation, YH-16 10 μg/ml in the cell culture bottle. The combining effect was quantified by the survival curve. ELISA was used to observe the VEGF of radiation with ES on A549 cell lines. Apoptosis was observed by Hoeehst staining. Results There showed that both of ES and combining treatment had the function of antiproliferative. But the union treatment's function was more obvious (P＜0.05). The expression of VEGF in ES and the combining treatment group was more lower than others (P＜0.05). On apoptosis, the rate of apoptosis in ES, RT, combining treatment group was higher than others (P＜0.05). Conclusion On antiproliferative activity and rate of apoptosis, the combining of ES and radiation is better than to use them alone. To reduce VEGF of the A549 human lung adenocareinoraa cell line by ES could enhance radioresponse. There is no evidences to show that the expression of VEGF is concerned with the different choronological order of radiation and ES.