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Objective:To evaluate the volumetric modulated arc therapy (VMAT) dose verification of cervical cancer based on γ rule and dose volume histogram (DVH) and to perform correlation analysis between the evaluation results and the dose differences.Methods:Twenty cervical cancer VMAT plans were selected and performed on TrueBeam Linac. The delivered point and surface dose was measured by FC-65 G and ArcCheck and the results were compared to those calculated by Eclipse. The dose of patients was reconstructed by 3DVH. Then, differences between the reconstructed and plan value of D mean, D 95%, D 98% and D 2% of PTV, V 20Gy of left and right femoral head, V 40Gy of rectum, D 1cm 3 of cord, D 98%, D 2% and D 50% of the 50% prescription iso-dose volume (IDV), were evaluated and 3-dimensional (3D) γ was assessed for each organ. Lastly, Pearson’s correlation coefficient was used to analyze the relationship between point dose difference, 2D γ pass-rate (γ%), γ mean and 3D γ% of each organ and the dose difference. Results:Small differences were found between the point dose measured, reconstructed and the plan value. Differences between D mean of PTV, all dose parameters of IDV and plan values were all within 3% and V 40Gy of rectum showed the largest difference. As for the 3D γ%, the maximum pass rate was found for the left and right femoral head and the maximum variance for cord D 1cm 3. There was a moderate correlation between measured and reconstructed point dose deviation and dose difference of each organ, while no significant correlation was found for 2D γ%. Strong correlation was found between 3D γ% of target and D 50% of PTV/IDV and no correlation was found for other organs. Conclusion:The performance of both γ-and DVH-based evaluation can reveal dose error for dose verification, but both of them have some limitations and should be combined in clinical practice.
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Objective:To study the changing characteristics and impact factors of helical tomotherapy (HT)for longitudinal dose fall-off outside the target, in order to guide the plan junction or pretreatment target and implementation efficiency in clinical.Methods:Eight patients with head and neck tumors admitted to the Department of Oncology Radiotherapy of the First Affiliated Hospital of Zhengzhou University in December 2019 were retrospectively selected as the research objects. The planning target area and dose drop structure were outlined in the head and neck images with a thickness of 1 mm obtained by Siemens SOMATOM Definition AS positioning computerized tomography (CT). Different field widths (FW, 5.0 cm/2.5 cm/1.0 cm) and pitches (0.430/0.287/0.215) were assembled for planning with the same modulation factor (1.8), finest does calculation grid (0.195 cm ×0.195 cm) and other planning parameters were consistent. The plans were designed by different parameters, and the result was analyzed by univariate analysis.Results:The that different pitch curves coincided under the same field width by comparative analyzing, so pitchs had no effect on dose drop. The different field width curves were independent of each other, indicating that the field width had an effect on dose drop in the head and foot direction. The relationship between the longitudinal dose drop speed outside the target and the change of the field width was inversely correlated: the larger field widths meant the slower dose fall-off and the larger penumbra, while the smaller field widths meant the faster fall-off and the smaller penumbra. When the dose fall-off to 50% of the prescribed dose, the distance from the target was approximately equal to half the field widths, and the pitchs had not affect the rate of dose-drop, while the dose at different distances from the target boundary could be calculated by the fitting formulas. The field widths and pitchs had little effect on the CI and HI index of the target, relatively, the target area was best when the field width was 2.5 cm. The total beam-on time gradually decreased with the increase of the field widths and pitches.Conclusions:When segment target therapy needs to consider planning junction, execution efficiency, and controlling longitudinal dose fall-off and considered the execution, the optimal planned parameters such as field widths and pitches could be selected or the target at the junction regions could be adducted according to the longitudinal dose drop formula, so as to achieve the ideal dose distribution.
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OBJECTIVE：To improve the quality standard of M ongolian med icine Artemisia sacrorum ，and to provide scientific basis for comprehensive quality evaluation. METHODS ：The appearance and microscopic characteristics of A. sacrorum were identified；scopoletin，chlorogenic acid ，caffeic acid ，scopoletin and 3，5-dicaffeoylquinic acid were identified quantitatively by TLC；the contents of above 5 components were determined by HPLC. The water content ，total ash and extract were examined. RESULTS：The stem of A. sacrorum was cylindrical ，and its surface was purple or purple-brown or cyan-brown ；the leaves were ovate or oblong-ovate ，fragrant；the flowers were yellow ，head-shaped，subglobose or hemispherical. The powder was green or yellow-green，its pollen grain had three germination ；the parenchymal cell clusters with sharp edges and numerous threaded ducts ， occasionally having marginal pitted ducts ；its wood fibers were in bundles mostly. Results of TLC showed that the spots of the same color were found in the corresponding positions of chromatogram for 5 substance control and samples. The linear range of scopoletin， chlorogenic acid ， caffeic acid ， scopolactone and 3，5-dicaffeoylquinic acid were 85.60-428.00， 10.16-101.60， 10.20-102.00，40.84-408.40 and 40.80-408.00 μg/mL（all r＞0.999 0）. RSDs of precision ，stability，repeatability tests were all less than 3.00％（n＝6）. The average recoveries were 103.07％，99.66％，98.37％，97.78％，98.40％（all RSDs ＜3.00％，n＝6）. The contents of the above-mentioned 5 compounds in 10 batches of samples were 0.36％-1.23％，0.09％-0.51％，0.04％-0.13％， 0.61％ -1.13％ ，0.12％ -1.11％ ，respectively；the average com contents of water ，total ash and water soluble extract were 6.25％，5.86％，26.50％，respectively. CONCLU SIONS：O the basis of the original quality standard of A. sacrorum ， microscopic identification，TLC identification ，content determination and examination items of water ，total ash and extract are added. The method shows good precision ，accuracy and stability ，which can provide reference for more scientific and standardized evaluation of the quality of this medicinal material.
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Objective:To summarize the relationship between the clinicopathological features and prognosis of immunoglobulin A nephropathy (IgAN) after renal transplantation.Methods:A total of 34 patients with IgAN after renal transplantation confirmed by renal biopsy were enrolled. And another 34 patients with primary IgAN confirmed by initial renal biopsy were adopted as controls. Clinical and pathological features of two groups were compared to explore the relationship between clinicopathological features and prognosis of allograft IgAN.Results:As compared with primary IgAN group, renal function in allograft IgAN group included serum creatinine [(158.5±75.9) vs (84.8±26.8) umol/L], urea nitrogen [(9.7±6.1) vs (5.2±1.4) mmol/L], uric acid [(406.7±87.8) vs (359.0±92.6) umol/L], estimated glomerular filtration rate {(57.4±25.4) vs (91.2±28.6) [ml/(min·1.73m 2)]}. All were statistically significantly higher ( P<0.05) while other parameters showed no differences. Pathologically, the proportion of T1 type (50.0% vs 17.6%) of renal tubular atrophy/interstitial fibrosis was significantly higher in allograft IgAN group than control group ( P<0.05). Furthermore, univariate and multivariate Logistic regression analyses were performed between various pathological parameters and prognosis in allograft IgAN patients. It indicated that the degree of mesangial hyperplasia of patients with transplanted IgAN had a significantly negative impact on the prognosis. Conclusions:The clinicopathological features of patients with allograft IgAN show no difference from those of patients with primary IgAN. And among patients with allograft IgAN, those with severe mesangial hyperplasia often have a worse prognosis.
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Objective@#To achieve quantitative analysis of image quality parameters and establish warning and action thresholds for the on-board imaging (OBI) system of linear accelerator.@*Methods@#The Catphan604 phantom was repeatedly scanned in the Full-Fan and Half-Fan CBCT scanning modes on a Varian EDGE linear accelerator, and the software based on Python language development in-house was utilized to analyze image quality parameters, such as CT number linearity, geometric consistency, slice thickness, spatial resolution, uniformity and low-contrast resolution. The quantitative analysis results of each image quality parameter obtained from 16 times of scanning within 16 months were normalized to the mean and the standard deviations were recorded. A run chart analysis was created to determine the warnings and action thresholds.@*Results@#The software built in-house can quantitatively analyze the image parameters of the two scanning modes of OBI system. The low-contrast resolution of Half-Fan was better than that of Full-Fan, whereas the spatial resolution of Full-Fan was superior to that of Half-Fan. One standard deviation (1σ) was set as the warning threshold and 2 standard deviations (2σ) as the action threshold, respectively. The tolerance level of Half-Fan was smaller than that of Full-Fan.@*Conclusion@#Self-developed software enables quantitative analysis of accelerator image quality parameters, establishes warning and action tolerance of quality assurance and provides guidance for image quality assurance under image-guided radiotherapy specification.
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Objective Based on lung cancer center database,we analyzed the clinical characteristics of lung patients with bone metastases.The relationship between bone metastases,skeletal-related events,survival time and different pathological subtypes of lung cancer were also evaluated in this study.Methods A total of 861 patients with lung cancer were studied from May 2010 to April 2012 at Tianjin Medical University Cancer Institute and Hospital.As to follow-up situation,patients' survival status and treatment information were collected by telephone follow-up and (or) examinationsin outpatient.The clinical characteristics,skeletal-related events and survival of bone metastaticpatients with different pathological types of lung cancer were analyzed.Logistic regression analysis was used to identify risk factors for bone metastases.The relationship between histological subtypes and the incidence of bone metastases was evaluated using Odds Ratios (ORs).The chi-square test was used to compare the proportion of bone metastases,synchronous bone metastases and SREs among different histological subtypes patients.The overall survivals was evaluated using the Kaplan Meier.Results A total of 861 patients with lung cancerwere enrolled in this study,including 293 cases with bone metastases.The average follow-up of our population was 14.2 months and the last follow-up time was September 2017.Among different pathological types of lung cancer,adenocarcinoma (39.14％,173/442) has the highest incidence of bone metastases,followed by other types (29.91％,35/117),squamous cell carcinoma (29.47％,56/190) and SCLC (25.89％,29/112).Spine (59.73％,175/293) was the most common location site of the bone metastases,followed by the ribs (49.15％,144/293),pelvis (20.48％,60/293),femur (16.38％,48/293) and sternal (16.38％,48/293).Lung adenocarcinoma was a risk factor for bonemetastases (P=0.002).In ORs analyze,adenocarcinoma patients were more likely to develop bone metastases [OR=1.60,95％CI (1.21～2.13)].In our cohort,58.36％of patients with lung cancer had skeletal related events.Among various types of skeletal related events of patients with bone metastases,the most common one was radiotherapy for bone metastases (51.88％,152/293),followed by pathological fractures (15.02％,44/293),spinal cord compression (6.48％,19/293),bone instability requiring surgery (4.78％,14/293) and hypercalcemia (1.71％,5/293).There was no significant difference between different types of skeletal related events.The median survival time of the patients with bone metastases was 11.5 months.There was no significant difference in survival between adenocarcinoma patients and non-adenocarcinoma patients (P=0.111).Conclusion This study suggested that the incidence of bone metastasis in lung adenocarcinoma was 39.14％ and lung adenocarcinoma was a risk factor for bone metastases,which supported early screening and monitoring of bone metastasis in the patients.
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Objective To evaluate the feasibility of total marrow and lymphatic irradiation (TMLI)with helical tomotherapy as a conditioning regimen before hematopoietic stem cell transplantation (HSCT).Methods Seven children with acute lymphoblastic leukemia and aplastic anemia were recruited as study subjects.The median age was 7 years old.The prescribed dose was 12 Gy/6 fractions twice daily.The exposure dose of the target and the organs at risk between helical helical tomotherapy-based TMLI regimen and total body irradiation (TBI) regimen were statistically compared,and acute toxicity grading was performed for all patients.Results Compared with the TBI regimen,the average exposure dose reduction for organs at risk after the TMLI regimen was ranged from 4.2％ to 40.6％.The average exposure dose reduction for the kidney was the largest among all organs.The acute toxicities experienced by all patients were graded and recorded including 2 cases of nausea,5 cases of vomiting,1 case of anorexia,1 case of eryhema,3 cases of diarrhea,and 1 case of oral mucositis.Only grade 1-2 toxicities were observed,and no grade 3-4 toxicities occurred.Conclusions The findings in this study confirm the feasibility of helical helical tomotherapy-based TMLI regimen.Compared with the TBI regimen,the mean duration of treatment for the TMLI regimen with an equivalent dose is not increased.The exposure dose experienced by organs at risk is reduced and the predicted incidence rate is decreased when the TMLI regimen is employed,which provides a myeloablative pretreatment strategy.However,the long-term toxicity of TMLI regime remains to be evaluated by clinical trials.
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Objective To investigate the optimal distance between upper and lower target volumes and their correlated planning parameters by analyzing the dose distribution in the abutment regions during total body irradiation ( TBI) using helical tomotherapy. Methods A total of 10 patients with acute leukemia and with a height around 120 cm were enrolled. All patients were scanned by a Siemens simulation computerized tomography (CT) at a slice thickness of 5 mm. A lead wire was placed 10. 0 cm above the patella as a marker of the separation boundary for the upper and lower target volumes. The delineations of target volumes and organs at risk ( OARs ) were performed in the Varian Eclipse 13. 5 workstation with targets shrunk beyond the separation boundary at different distances. After contours and CT images were transferred to HT workstation, treatment plans were designed with different field width (FW, 5. 0 cm/2. 5 cm/1. 0 cm) and pitch values (0. 430/0. 287) at a modulation factor of 1. 8. All the plans were optimized with a dose calculation grid of 0. 195 cm × 0. 195 cm and identical planning parameters. The correlation between treatment planning parameters and targets shrunk distances were investigated by analyzing the dose distributions in the abutment area. Results The study demonstrated that the dose distributions in the abutment area were influenced only by the field width parameters: when the gap distance between the upper and lower targets was 5. 0 cm, the optimal FW is 5. 0 cm;Similarly when the gap distances were 2. 0 cm and 1. 0 cm, and the optimal FW 2. 5 cm and 1. 0 cm, respectively. In another words, the dose distribution of the abutment region was optimal when the target gap distance was equal to FW. Pitch values did not affect the quality of dose distribution in the abutment region and the overall treatment time ratio. Overall treatment time was inversely related to the FW. Conclusions Consistent target distance and FW is helpful to improve the dose homogeneity in the abutment area during TBI with HT. Appropriate planning parameters is critical to balance the treatment efficacy and efficiency.
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Objective To investigate the optimal distance between the upper and lower targets in the subsection total body irradiation(TBI)using helical tomotherapy,and to analyze the dose distribution of abutment regions. Methods A total of 8 patients with acute leukemia with a height of about 120 cm were involved in the study. All patients were scanned from the calvarium to the toe by computerized tomography (CT,Siemens)with a thickness of 5 mm,and a lead wire was placed at a point 10 cm above the patella as a marker of the boundary between the upper and lower targets. The delineation of target volumes and organs at risk(OAR)was performed in the Varian Eclipse 10.0 doctor workstation. The different distances between the lead wires and the boundary of the two targets were delineated, and images were transferred to the HT workstation to design the radiotherapy planning,including Jaw width(5 cm),modulation factor(1.8),and pitch(0.43). The plans were superimposed together, and then the dose distribution in abutment regions with different target gaps was analyzed to find the optimal distance. Results When the target gap was 5 cm, the dose distribution in abutment regions was satisfactory. However,the dose was obviously insufficient when the gap was more than 5 cm;the doses in abutment regions significantly exceeded the prescribed doses when the gap was less than 5 cm. Conclusions In the subsection TBI using HT, different parameters were designed,including Jaw width(5 cm), modulation factor(1.8), pitch(0.43), and slice thickness(5 mm). The upper and lower borders of the targets should be 2.5 cm away from the lead wire,that is,a gap of 5 cm,thus avoiding the dose-related hot or cold spots in the target convergence and ensuring a safer and more accurate radiotherapy.
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Objective To explore the dosimetric difference between different radiotherapy technologies in the treatment of early peripheral stage non?small ?cell lung cancer ( NSCLC ) . Methods Four?dimensional computed tomography scans and delineation of target volumes and organs at risk ( OARs) were performed in 5 patients pathologically diagnosed with stage T1/T2 peripheral NSCLC who were admitted from 2014 to 2015. Target volumes contained gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV). ITV was contoured on the maximum intensity projection images. PTV was defined as ITV plus a 5 mm margin. OARs contained the heart, lung, esophagus, and spinal cord. The Monaco 5. 0 treatment planning system was used to design three plans. The three?dimensional conformal radiotherapy (3DCRT) plan had 11 fields in the diseased lung covering the PTV plus a 0. 2 cm margin. The sliding window intensity?modulated radiotherapy ( SW?IMRT ) plan had 9 fields in the same areas as the 3DCRT plan. The volumetric modulated arc therapy ( VMAT) plan had the gantry rotating 180° around the diseased lung. The evaluation criteria referred to the RTOG 0618 trial. Comparison was made by paired t test. Results The SW?IMRT plan had a significantly better homogeneity index than the 3DCRT plan ( 1. 03 vs. 1. 24,P= 0. 017 ) . Compared with the VMAT plan, the mean monitor units in the 3DCRT plan was significantly reduced by 24. 5%( P=0. 022) . The V30 and V40 of the 3DCRT plan were significantly reduced by 29. 4% and 28. 4%, respectively, compared with the SW?IMRT plan ( P=0. 003,0. 006) and 56. 7%and 59. 7%, respectively, compared with the VMAT plan ( P=0. 041,0. 019) . Conclusions 3DCRT may be an appropriate radiotherapy method for early stage NSCLC.
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Objective To compare the dosimetric effects of systematic MLC leaf position errors on flattening filter (FF) and flattening filter-free (FFF) IMRT for nasopharyngeal carcinoma (NPC).Methods In totaly of ten patients with NPC were enrolled in the current study.FF IMRT and FFF IMRT plans were designed for each patient, and in-house software was developed to modify the corresponding MLC files.Briefly, three kinds of systematic MLC error presented with 0.5 and 1 mm magnitudes error were simulated.The modified MLC files were re-imported into IMRT plans for dose recalculation, and differences in the dosimetry trends between FF-IMRT and FFF-IMRT plans were analyzed using a dosevolume histogram.Results Upon closed MLC, the average changes in D95％ of PTV and D of parotid glands in FFF-IMRT plans were more sensitive than in FF-IMRT plans (t =3.298-4.793, P ＜ 0.05).Otherwise, when MLC are shifted in the same direction, changes in D95％of PTV, D of PGTV, PTV as well as D of left parotid gland in FFF-IMRT plans were also more sensitive (t =2.372-6.844, P ＜ 0.05), whereas average changes in D of right parotid gland presented with less sensitivity (t =-4.049,-3.378, P ＜ 0.05).Conclusions For out-of-field or large organs, FFF-IMRT plans are more sensitive to leaf position error than FF-IMRT plans.
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The hybrid pencil beam model (HPBM) is an effective algorithm for calculating electron dose distribution in radiotherapy. The mean energy distribution of incident electron beam in phantom is one of the factors that affect the calculation accuracy of HPBM, especially in field edge areas near the end of the electron range. A new fitted formula based on Monte Carlo (MC) simulation data for electron beams with energy range of 6-20 MeV in the homogeneous water phantom is proposed in this paper. The precision of the fitted formula within the scope of the energy was evaluated by comparing the electron dose distribution of ECWG measured data with that obtained from HPBM which took the mean electron energy that calculated by the fitted formula and the existed empirical formula, respectively. The results showed that the accuracy of dose distribution that obtained by the mean electron energy calculated with the fitted formula increased about 1%.
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Humanos , Algoritmos , Electrones , Método de Montecarlo , Fantasmas de Imagen , Planificación de la Radioterapia Asistida por Computador , AguaRESUMEN
Sixty-six volunteers,including 24 subjects with normal glucose tolerance(NGT),18 patients with impaired glucose regulation (IGR),and 24 patients with type 2 diabetes mellitus ( T2DM ),underwent a test of continuous glucose monitoring.The data of continuous glucose monitoring were embedded into two-dimension Euclid space by Takens' embedding theory.Glycemic phase diagram was drawn by MATLAB.The area and center distance of glycemic phase diagram were calculated by computer.The distinction of glycemic variability and average glycemic level among different glucose regulation populations were analyzed.The results showed that there existed significant differences in body mass index,systolic blood pressure,diastolic blood pressure,low density lipoprotein-cholesterol,high density lipoprotein-cholesterol,triglyceride,total cholesterol,creatinine,and alanine aminotransferase among three groups( all P＜0.05 ).The levels of HbAIC,fasting plasma glucose( FPG ),postprandial 2 h plasma glucse (2hPG),area and center distance of glycemic phase diagram in T2DM group were higher than those in NGT and IGR groups( P＜0.01 ),and the levels of FPG,2hPG,area and center distance of glycemic phase diagram in IGR group were higher than those in NGT group( P＜0.01 ).The levels of FPG and 2hPG were correlated with area and center distance of glycemic phase diagram ( all P＜0.01 ).These results suggest that measuring the area and center distance of glycemic phase diagram is a good method to assess glycemic variability and average glycemic level during continuous glucose monitoring.
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A century ago the Flexner Report facilitated the process of modern medical education reform.Half a century ago,Problem-based learning initiated the student-centered medical education model.At present training medical students' competency will usher in the third reform in medical education.Over 100 years' development and in the global context of current medical education reform,China's medical education has become an important part of the world medical education.Harbin Medical University conducted an all-around reform through international cooperation and received the accreditation referenced according to global standards in medical education,which is an epitome of the medical education reform in China.
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As a method of dosimetric verification in radiotherapy, gamma index has been widely used for evaluating dose distribution in research and clinical cases. However, for three-dimensional dose distributions, gamma index calculation is very time consuming for the computers. In this paper, based on a pre-sorting technique, we implement a parallel computing algorithm of gamma index on graphic processing unit (GPU). Dose comparisons are performed for seven cases to test our new implementation. It was shown that the GPU-based gamma index calculations achieved a speedup of ten-folds in comparison with corresponding CPU implementation without losing accuracy. The result showed that utilizing GPU parallel computing to speed up gamma index calculations could be reliable and efficient in the implementation.