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Objective To analyze the high risk factors of obstetric brachial plexus palsy(OBPP),and to explore how to evaluate the relationship between fault medical behavior and OBPP in the process of medical damage forensic identification.Methods A retrospective analysis was carried out on 25 cases of medical damage liability disputes related to OBPP from 2017 to 2021 in Beijing Fayuan Judicial Science Evidence Appraisal Center.The shortcomings of hospitals in birth weight assessment,delivery mode selection,labor process observation and shoulder dystocia management,and the causal relation-ship between them and the damage consequences of the children were summarized.Results Fault medi-cal behavior was assessed as the primary cause in 2 cases,equal cause in 10 cases,secondary cause in 8 cases,minor cause in 1 case,no causal relationship in 1 case,and unclear causal force in 3 cases.Conclusion In the process of forensic identification of OBPP,whether medical behaviors fulfill diagno-sis and treatment obligations should be objectively analyzed from the aspects of prenatal evaluation,de-livery mode notification,standardized use of oxytocin,standard operation of shoulder dystocia,etc.Meanwhile,it is necessary to fully consider the objective risk of different risk factors and the diffi-culty of injury prevention,and comprehensively evaluate the causal force of fault medical behavior in the damage consequences.
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Objective Cervical disc herniation(CDH)is one of the common orthopaedic diseases.With the in-depth study of it and the development of cervical implants,the establishment of cervical fusion animal models has become an indispensable part.Notably however,studies of the establishment and evaluation of cervical fusion animal models in China are currently lacking.This study aimed to provide a suitable animal model and evaluation scheme for implants for cervical spine-related research.Methods Small-tailed Han sheep were chosen for anterior cervical discectomy fusion(ACDF)after modified surgery,and a polyetheretherketone(PEEK)interbody fusion cage(Cage)(control group),3D-printed Ti6Al4V Cage(group 1),and new method Ti6Al4V Cage(group 2)were implanted in different cervical segments(C2/3～C4/5)in each sheep,respectively.Hematology and histopathological analyses were carried out after surgery to evaluate recovery of sheep and the biosafety of the materials.Bone in-growth and bone fusion were assessed by X-ray,computed tomography(CT),Micro-CT and quantitative analysis,hard tissue section staining,and biomechanical tests.Results The modified ACDF ovine model was established successfully.There were no significant differences in important hematology indexes(P＞0.05)and histopathological analysis showed no pathological changes,such as inflammatory cell infiltration.The implants had good biosafety.Furthermore,X-ray and CT examinations showed that the position of internal fixation and the interbody fusion were good.Micro-CT and quantitative analysis at 3 and 6 months after operation showed that compared with PEEK Cage group,the bone volume/total volume and trabecular number were significantly increased(P＜0.01)while the trabecular spacing was significantly decreased in the new method Ti6Al4V and 3D-printed Ti6Al4V groups compared with the PEEK Cage group(P＜0.01).Moreover,the new method new method Ti6Al4V Cage group had more bone growth(P＜0.01).Hard tissue section staining demonstrated that the pores of the new method Ti6Al4V Cage and 3D-printed Ti6Al4V Cage had obvious bone growth and relatively dense pores in the new method Ti6Al4V and 3D-printed Ti6Al4V groups,and the combination was slightly better than that of PEEK Cage.Biomechanical evaluation indicated that the new method Ti6Al4V Cage and 3D-printed Ti6Al4V Cage reduced the range of cervical flexion-extension,lateral bending,and axial rotation(P＜0.05)compared with the PEEK cage,as well as enhancing the stability of the cervical vertebra,and the new method Ti6Al4 V Cage was more advantageous(P＜0.05).Conclusions After the establishment of the modified ACDF ovine model,reasonable and effective assessment method were used to demonstrate the suitability and effectiveness of the model and the good biosecurity of all three Cage materials.Compared with the PEEK Cage,the new method Ti6Al4V Cage and 3D-printed Ti6Al4V Cages showed better performances in terms of bone growth and bone fusion,which could enhance the stability of the cervical vertebrae.The new method Ti6Al4V Cage was particularly advantageous.
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Objective:To investigate the correlation between the expression of GLI1 and im-mune invasion and clinical prognosis in gastric cancer.To study the effect of GLI1 expression on drug resistance in gastric cancer.Methods:The expression difference of GLI1 in gastric cancer and normal tissues was analyzed by using TCGA database,and the effect of clinical features and GLI1 gene ex-pression level on prognosis of patients with gastric cancer was analyzed.The correlation between GLI1 gene expression and tumor immune cell infiltration in gastric cancer tissues was analyzed to explore its influence on drug resistance of chemotherapy drugs and targeted drugs.Clinical samples were collect-ed to analyze the difference of GLI1 expression in gastric cancer and paracancer tissues.Results:The expression of GLI1 in gastric cancer tissues was 1.7 times that in normal tissues,and the overall sur-vival and disease-free survival of patients with high expression are shorter than those with low ex-pression(P＜0.05).The interstitial score,immune score and abundance of immunoinfiltrating cells were higher in the high expression of GLI1 in gastric cancer tissues.High expression of GLI1 reduces drug sensitivity and is positively correlated with the expression of immune checkpoint markers PDCD1(P＜0.05).GLI1 expression was significantly increased in patients with subdifferentiated gastric cancer.Conclusions:GLI1 expression is associated with the prognosis and immune infiltration of patients with gastric cancer,and it may lead to poor prognosis of patients by regulating chemotherapy resis-tance,which may be a potential therapeutic target and molecular marker for gastric cancer.
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OBJECTIVE：To investigate the clini cal features of thrombocytopenia induced by antidepressants ，and to provide reference for the rational use of clinical drugs. METHODS ：Retrieved from CNKI ，Wanfang database ，VIP，PubMed and Web of Science，during Jan. 1st in 1985 to Aug. 31st in 2020，case reports about antidepressants-induced thrombocytopenia was collected and analyzed descriptively in terms of demographic characteristics ，medication，clinical manifestations ，treatment and outcome. RESULTS：A total of 17 literatures were retrieved ，and 19 patients were included ，involving 10 male and 9 female，aged from 5 to 95 years old ，with an average of （48±24）years old. Nine kinds of drugs were involved ，including 4 cases of escitalopram ，3 cases of citalopram ，3 cases of fluoxetine ，3 cases of mirtazapine ，2 cases of amitriptyline ，1 case of sertraline ，1 case of paroxetine，1 case of mianserin and 1 case of imipramine. There were 9 cases of single drug and 10 cases of drug combination. All 19 patients suffered from thrombocytopenia at 3 d-10 years after medication ，14 of them had hemorrhage tendency. Main clinical manifestations included mucocutaneous hemorrhage ，gingival bleeding ，black stool ，hematochezia，vaginal bleeding ，ocular hemorrhage，alveolar hemorrhage. No bleeding was found in 5 cases. After drug withdrawal/changing drugs and other symptomatic treatment， platelet count of 19 patients recovered to normal ， and bleeding symptoms disappeared. CONCLUSIONS ： Thrombocytopenia caused by antidepressants has no obvious clinical features and is not easy to be found ，but it may lead to severe； bleeding symptoms if it is not found in time. The changes of platelet count should be closely monitored in clinical application of such drugs to ensure the safety of drug use.
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The surgical treatment of recurrent anterior shoulder dislocation is a difficult problem in the field of sports injury medicine. The main reason focus on dynamic and osseous constraints of shoulder joint could not recover well. At present, arthroscopic surgery is used at home and abroad, and could receive statisfied postoperative effect, but the choice of specific surgical methods is still controversial. According to presence and size of glenoid and humeral skull defects, different treatments should be selected in clinic. The author recommends that no articular glenoid defect or glenoid defect 40% or Bristow-Latarjet if the surgical repair fails, bone grafting is used. In addition, if (humeral avulsion of glenohumeral ligaments, HAGL) injury existed, HAGL injury repair should be used. In addition to considering the important factor of bone defects, it is necessary to combine patient's age, exercise level and surgeon's technique to comprehensively select the bestsurgical method.
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Humans , Arthroscopy , Joint Instability , Recurrence , Scapula , Shoulder Dislocation/surgery , Shoulder JointABSTRACT
Recurrent anterior dislocation of shoulder with bone defect is one of the common diseases of shoulder joint. How to effectively repair glenoid bone defect and reduce recurrence rate of shoulder dislocation is a problem that clinicians focus on. Bone grafting could stimulate bone, promote bone regeneration and bone remodeling, and restore the normal anatomical structure of glenoid. Among them, Bristow-Latarjet procedure is a classic operation for recurrent shoulder dislocation. Latarjet procedure could repair larger glenoid bone defects, but with higher surgical skills for surgeons;autogenous iliac grafting is the first choice for revision once Latarjet procedure failed;osteochondral grafting (autogenous and allogenous) has certain advantages in reconstructing original articular surface and preventing joint degeneration, but autologous osteochondral grafting may cause secondary injury, while immune rejection is difficult to avoid for allogenous osteochondral grafting. With the improvement of composite materials, and the mechanism of bone regeneration and remodeling, as well as the advantages and disadvantages of bone grafting, tissue engineering technology may become an effective method for the treatment of glenoid bone defect in the future.
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Humans , Bone Transplantation , Joint Instability , Recurrence , Shoulder , Shoulder Dislocation/surgery , Shoulder JointABSTRACT
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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Rotator cuff repair is a common treatment for rotator cuff tear, which could effectively relieve shoulder pain and improve shoulder movement, and the incidence of rotator cuff retear after rotator cuff repair is still high. The main reason is poor tendon-bone healing in rotator cuff enthesis after rotator cuff repair and could not recover the original histological structure and biomechanical properties. Therefore, the key to solve the problem is how to effectively improve the healing of tendon bone at the end of rotator cuff. With the in-depth study of rotator cuff enthesis, various treatments have made great progress on improving tendon to bone healing of rotator cuff. Our study will discuss the researchprogress on tendon to bone healing of rotator cuff in recent years from three following aspects to provide some guidance for the clinical treatment of rotator cuff tear:the factors affecting the tendon to bone healing of rotator cuff, the recovery of tendon to bone interface promoting the tendon to bone healing of rotator cuff and the application of tissue engineering in tendon to bone healing.
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Humans , Arthroplasty , Rotator Cuff , General Surgery , Rotator Cuff Injuries , General Surgery , Tendons , General Surgery , Wound HealingABSTRACT
Objective:To evaluate the multi-leaf collimator (MLC) performance of TrueBeam accelerator using trajectory log files.Methods:All tests were performed 5 times under different gantry-collimator angle combination. The 1 mm picket fences were constructed by static or dynamic MLC. The control ability for small-field accuracy of accelerator was evaluated. Repeatability was assessed by MLC repeat motion. The movement performance of difference velocities along one direction and the opposite direction were evaluated via a 1 cm picket fences which slipped from -7 cm to 7 cm with a uniform velocity and stopped or immediately back at 7 cm. The MLC performance in a complex program was evaluated by a cross movement test.Results:Both the static and the dynamic picket fences yielded high accuracy. The deviation spectrums of MLC in different gantry angle were consistent, however, an absolute difference of 0.001 1 mm was found. For uniform velocity movement tests with 0°gantry, the RMSE of MLC was increased from 0.015 0 mm to 0.059 8 mm when the speed was accelerated from 5 mm/s to 25 mm/s. Similar results were obtained in non-zero gantry angle. The "overspeed" effect caused by the direction change movement of MLC was less obvious than that caused by speed changed from zero to a uniform velocity movement state. There was no significant change in speed before and after the MLC crossing. The MLC speed fluctuated around the set value, which was independent of the gantry angle.Conclusion:A method for evaluating the performance of MLC using trajectory log files is established, which can evaluate the MLC performance of TrueBeam accelerator and be used for MLC rapid quality control in clinical practice.
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Titanium alloy has good biological properties and is commonly used in orthopedics, but its bone integrity and antibacterial properties are poor, so surface modification is needed to make up for its shortcomings. Chitosan has good biocompatibility and film forming ability, and can be used as a carrier to introduce the target drug to the surface of titanium alloy, which can effectively improve the biological properties of titanium alloy materials and increase its application range. In this paper, the related research of chitosan surface modified titanium alloy materials in recent years is summarized. The modification methods of chitosan coating, the improvement of osteogenesisand antibacterial properties of titanium alloy materials are discussed in order to provide guidance for the clinical application of coating modification of titanium alloy materials.
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Alloys , Anti-Bacterial Agents/pharmacology , Chitosan , Orthopedics , Surface Properties , TitaniumABSTRACT
Objective To investigate the inter-hemispheric resting-state functional connectivity and its relation with cognitive function in patients with end-stage renal disease (ESRD) by using resting-state functional magnetic resonance imaging (rs-fMRI) based on voxel-mirrored homotopic connectivity (VMHC). Methods A total of 52 patients with ESRD (ESRD group), admitted to our hospital from July 2018 to January 2019, were enrolled; 36 age-, gender-, and education level-matched healthy controls (HCs group) were collected at the same time period. The cognitive function of all subjects was assessed by Mini Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Trail Making Test (TMT)-A, TMT-B and Symbol Digit Modalities Test (SDMT). The rs-fMRI and 3D-T1WI data were acquired from all subjects; after image preprocessing, VMHC values between brain hemispheres were calculated and the regions with significantly different VMHC values were obtained. The correlations between VMHC values in significant regions and cognitive scale scores were analyzed. Results MMSE, MoCA and SDMT scores of ESRD patients were significantly lower than those of the HCs group (P<0.05), and ESRD patients took longer time to complete TMT-A and TMT-B tests than the HCs group (P<0.05). As compared with that of the HCs group, significant decrease of VMHC values of ESRD patients was found in the hippocampus, lingual gyrus, superior temporal gyrus, caudate nucleus and anterior cingulate gyrus (P<0.01, AlphaSim correction); the VMHC values of the anterior cingulate gyrus and hippocampus were positively correlated with MMSE and MoCA scores (P<0. 05). Conclusion Significant abnormal inter-hemisphere functional connectivity is found in patients with ESRD, which is associated with cognitive function.
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Objective To discover antitumor drugs showing a synergistic effect with the cannabinoid receptor agonist sildenafil mesylate (WIN55212-2), so as to provide a new strategy for potential drug combinations for improving the life quality of cancer patients. Methods Firstly, the antitumor activity was tested for the combination of cannabinoid receptor 1 (CB1R) receptor agonist WIN55212-2 with each of 25 antitumor drugs using three tumor cell lines with high CB1R, HepG2, DU145 and HCT-8, by highthroughput assay. Then, the in vitro tumor colony-forming assay and 3D tumor spheroid assay were conducted to confirm the synergistic effect for the effective drug combination. Flow cytometry was used to investigate the effect of the synergistic drug combination on the apoptosis and cell cycle progression. Results Three drugs showed a synergistic inhibitory effect on the proliferation of tested tumor cells by combining with WIN55212-2, and among them, the combination of exemestane with WIN55212-2 displayed best effect, which showed a dose-dependent synergistic antitumor effect in the in vitro tumor colony-forming test and 3D tumor spheroid assay (CI＜1).Compared with the single-exemestane treatment, the combination of exemestane with WIN55212-2 significantly increased the apoptosis of HepG2 cells (P＜0.01) and caused G2/M phase arrest of the HepG2 cells. Conclusion The study is the first to report that the combination of exemestane with WIN55212-2 showed a synergistic anti-tumor activity on HepG2 cells, which was likely related to the promotion of apoptosis and induction of cell cycle arrest.
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Objective To understand the influence of different conditions to the potential phenotypes of cells, through the transcriptome sequencing and analysis for two cancer cell lines with identical genetic background from different sources, so as to provide an experimental basis for rigorous cell model-based drug screening. Methods Human cervical cancer (HeLa) cell and human liver cancer (HepG2) cell lines, newly introduced from ATCC (HeLa-ATCC and HepG2-ATCC) and a previously laboratory-stored (HeLa-PLS and HepG2-PLS) cell lines were used in the present study. The second generation high-throughput sequencing platform Illumina Novoseq was used for transcriptome sequencing, and the Gene Ontology (GO) function and pathway enrichment analysis based on the GO data base and the Kyoto Encyclopedia of Genes and Genomes (KEGG) data base, fusion gene analysis and analysis of mutation sites were performed for the differentially expressed genes (DEG). Meanwhile, the sequencing and analytical work was also performed for evaluating the effect of different culture times on the transcriptome of the ATCC-sourced HeLa cells. Results Total 7366 and 8786 DEGs in the HeLa and HepG2 cell lines were found between the HeLa-ATCC and HeLa-PLS cells and between the HepG2-ATCC and HepG2-PLS cells, respectively, HeLa and HepG2 cells, which were classified into 519 and 778 metabolic pathways by the GO function and pathway enrichment analysis, respectively. The DEGs in the HeLa cells were mainly enriched in the extracellular matrix tissues, metabolic pathways, cancer signaling pathways, cytokines and their interaction systems with receptors. The DEGs in the HepG2 cells were mainly enriched in the extracellular matrix tissues, neural active ligands and their interaction systems with receptors, cancer signaling pathways and mitogen-activated protein kinase (MAPK) signaling pathways. The cancer signaling pathway was attenuated in the HeLa-PLS cell line, while the cancer signaling pathway was enhanced in the HepG2-PLS cell line, accompanied with changes in the neuroactive factor-receptor binding activity and cytokine-receptor binding activity. On the other hand, significant changes on the genes related to the ion channels, the cell membrane receptors, such as G protein-coupled receptors, and the intracellular calcium signaling pathways found in the HeLa-ATCC cells within 6-24 hours after the cells were fully adhered. Conclusion Compared with the HeLa-ATCC and HepG2-ATCC cells, the transcriptome of the HeLa-PLS and HepG2-PLS cells showed significant changes, involving a wide range of cellular functions. Cell transcriptome sequencing might likely provide useful informations for understanding cell identity and controlling experimental conditions for drug screening and evaluation.
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<p><b>OBJECTIVE</b>To investigate the effects of minimally invasive esophagectomy (MIE) and open esophagectomy (OE) on the level of circulating tumor cells (CTCs) in patients with esophageal cancer (EC).</p><p><b>METHODS</b>A total of 73 patients with EC undergoing MIE (n=38) or OE (n=35) in our department between October, 2015 and October, 2017 were enrolled, with 10 patients with benign esophagus disease and 10 healthy volunteers as controls. The levels of CTCs in the peripheral blood of the participants were detected using CanPatrol technique and analyzed for their association with the operation methods and perioperative complications.</p><p><b>RESULTS</b>CTCs were detected in 60.3% (44/73) of the EC patients but in none of the control subjects. CTC level after the surgery was significantly higher than that during the surgery, and CTC level during the surgery was significantly higher than that before surgery (P<0.001). The preoperative and intra-operative CTC levels were not significantly different between MIE and OE groups (P>0.05), but the postoperative CTC level was significantly lower in MIE group than in OE group, and postoperative increment of CTC level (from the preoperative level) was significantly lower in MIE group than in OE group (P<0.001). The total incidence of postoperative complications was significantly lower in MIE group than in OE group (28.9% vs 54.3%, P=0.023), and in both groups, CTC levels in patients with complications were significantly higher than those in patients without complications (P=0.001 and P=0.005 in MIE and OE groups, respectively).</p><p><b>CONCLUSION</b>MIE may help to reduce the number of peripheral blood CTCs early after the operation, and dynamic monitoring CTCs level assists in evaluation of the prognosis of EC patients. CTC level may serve as an indicator for monitoring the prognosis of EC.</p>
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Secondary ion mass spectrometry ( SIMS) as a powerful surface analysis technique has been widely applied in semiconductor industry and geology research. Recently, with the development of instrumental technology, SIMS is attracting more and more attention in life sciences. SIMS can provide surface MS spectra, 2D/3D chemical images and depth profiling of substances simultaneously. The minimal lateral resolution of 2D SIMS imaging is 80 to 100 nm, and the longitudinal resolution of 3D SIMS imaging is about 1-5 nm. However, due to lack of specific ions to render the structures of organelles, SIMS imaging for single cells still has great challenges. Optical microscopy, in particular laser scanning confocal microscopy ( LSCM) , has been emerged to be an indispensable technique for single cell imaging and can obtain high spatial 2D/3D imaging to visualize the structures of organelles. Thus, the combinational use of SIMS and LSCM, which takes advantages of SIMS for molecular imaging and LSCM for morphological imaging, has greatly extended the application of SIMS imaging and ensured its accuracy at single cells level, providing novel insights into better understanding of the biological events inside cells. In this review, we focus on the development and application of SIMS imaging and the correlated SIMS and LSCM imaging in the research of cell biology and drug discovery. We anticipate that the combinational use of SIMS and LSCM imaging has promising future in biomedicine and life sciences.
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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 influence to dosimetry of the patient with rectum cancer by setup errors.Methods First an intensity modulated radiation treatment planning for a rectum cancer patient was designed,then the isocenter was moved 5 mm respectively to the left side,right side,abdomen side,back side,head side and foot side;and the isocenter was moved 5 mm to head side,back side and left side at the same time;and the isocenter was moved 5 mm to foot side,abdomen side and right side at the same time;and the isocenter was moved according to the largest set-up error for the first five Cone Beam CT scanning,thus nine new plans and a confirmed plan were got,the influence to dosimetry for targets and fermur head,bladder and intestine for these ten plans was analyzed.Results The influence to the dosimetry gained the maximum value in the planning target volume (PTV) with the isocenter moving 5 mm to three directions and normal organs.All the plans had little influence on clinical target volume (CTV),which posed few effects on small intestine and bladder while big influence to femoral head incase of high dose D2 to 2％ target volume and mean dose.Conclusion The set-up error may influence dosimetry of PTV,and the reduction of low dose D98 to 98％ target volume may affect treatment effect.For patients whose set-up errors are large,times of cone beam CT scanning have to be increased in order to ensure the precise implementation of the treatment plans.
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Objective To compare the dosimetric verification results of Varian Portal Dosimetry and Matrixx,and to assess the reliability of the clinical application of electronic portal imaging device (EPID) verification.Methods Varian TrueBeam linear accelerator,which was equipped with a 120-leaf multileaf collimator and an amorphous silicon EPID,as well as portal dose prediction software.IBA I′mRT Matrixx ion chamber array was used.EPID algorithm configuration,dose calibration,and testing before use were performed.The sliding-window protocol was used.There were 77 patients with tumors involving the head and neck (mainly nasopharyngeal carcinoma),mediastinum,abdomen,and pelvic cavity were selected.The verification plan of the portal dose was created with a source-detector distance of 100 cm,and the gantry angle was kept the same as the treatment plan.The verification plan was carried out in the TrueBeam machine,and the data were collected at the same time by EPID.Comparison between the measured and calculated dose images was performed,and the evaluation standard was gamma index (3%/3 mm).The paired t-test was used for difference analysis.Results For the 77 patients,the Gamma passing rates of both methods were above 97%.Except for head and neck carcinoma were a significant difference between the results of dosimetric results using EPID and Matrixx in intensity-modulated radiotherapy (P=0.018) other remaining all P> 0.05.Conclusions The dosimetric verification results of EPID are consistent with those of Matrixx.EPID can be used for dosimetric verification,and Matrixx ion chamber array can be used only in case of a low Gamma passing rate.
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Objective To investigate the influence to dosimetry of the patient with rectum cancer by setup errors.Methods First an intensity modulated radiation treatment planning for a rectum cancer patient was designed,then the isocenter was moved 5 mm respectively to the left side,right side,abdomen side,back side,head side and foot side;and the isocenter was moved 5 mm to head side,back side and left side at the same time;and the isocenter was moved 5 mm to foot side,abdomen side and right side at the same time;and the isocenter was moved according to the largest set-up error for the first five Cone Beam CT scanning,thus nine new plans and a confirmed plan were got,the influence to dosimetry for targets and fermur head,bladder and intestine for these ten plans was analyzed.Results The influence to the dosimetry gained the maximum value in the planning target volume (PTV) with the isocenter moving 5 mm to three directions and normal organs.All the plans had little influence on clinical target volume (CTV),which posed few effects on small intestine and bladder while big influence to femoral head incase of high dose D2 to 2％ target volume and mean dose.Conclusion The set-up error may influence dosimetry of PTV,and the reduction of low dose D98 to 98％ target volume may affect treatment effect.For patients whose set-up errors are large,times of cone beam CT scanning have to be increased in order to ensure the precise implementation of the treatment plans.