Vascular access is the dialysis patient's lifeline. Lower extremity arteriovenous accesses are a potential vascular access option in hemodialysis patients who have exhausted all upper-limb sites.The lower extremity options are including autogenous and prosthetic arteriovenous accesses.Numerous challenges including patency rates and complications are encountered in the lower extremities that are not seen in the upper extremities.In this review,we focus on the advances in lower extremity accesses.

Objective To compare the results of three different registration methods in the kilovolt CBCT guided IMRT for nasopharyngeal cancer (NPC).Methods Total 560 CBCT images of 24 NPC patients who received kilovolt CBCT guided IMRT were analyzed off line.Three registration methods were used for alignment between CBCT and planning CT,including translational and rotational errors for bone and grey (BoneT + R,GreyT+ R),only translational errors for grey (GreyT).The registration results were analyzed by mean paired t-test respectively.Results With method BoneT+R,the translational errors on x,y and z axes were (-0.11 ± 1.35) mm,(0.40 ± 2.09) mm and (0.95 ± 1.56) mm and the rotational errors were 1.06° ±0.67°,0.01° ± 1.28° and 0.92° ± 1.00° respectively.With GreyT+R,the translational errors on x,y and z axes were (-0.02 ± 1.06) mm,(0.68 ± 1.92) mm and (0.81 ± 1.46) mm and the rotational errors were 0.85° ±0.61°,-0.05° ± 1.32° and 0.91° ±0.72° respectively.With GreyT,the translational errors on x,y and z axes were (0.58 ± 1.02),(0.52 ± 1.89) and (0.44 ± 1.43) mm.The results of compared mean t-test for different registration methods groups have significant difference (P =0.00-0.01) except for the rotational errors on y and z axes between BoneT+R and GreyT+R (P =0.05,0.62).Conclusions There have different alignment errors when different registration methods used for NPC kilovolt CBCT guided radiotherapy.If there have correct methods for rotation errors,GreyT+R registration method may be a better choice.In opposite,GreyT+R registration method would be used firstly to verify whether the rotational error ＞ 2°or 3°.If the rotational error ＞ 2°or 3°,the patient should be re-setup.If not,according to these alignment results,the GreyT method,manual method would be used to compensate the translational errors.

BACKGROUND:The materials for internal fixation of bone allografts have been used in the clinic.However,they are only used in the regions bearing little stress because of low strength.The focus of current studies is how to enhance the fixation strength of the materials to expand application range.OBJECTIVE:To compare the strength difference of cortical bone allografts among different fixation modes and to investigate the possible mechanisms of action.DESIGN,TIME AND SETTING:An in vitro biomechanical experiment was performed at the Laboratory of Biomechanics,Nanhua University between October 2005 and March 2006.MATERIALS:Twenty-seven pieces of cadaveric femurs were included in this study.A total of 45 cortical bone allografts with a size of 110 mm×10 mm×3 mm and 90 bone screws were also used.METHODS:Twenty-seven femurs were made into simulated fracture models and randomized to 3 groups,with 9 models per group:A,B,and C.In the group A,the models were fixed with two cortical bone all6grafts; the models from the groups B and C were fixed with two bone allografts plus 5 bone screws and one bone allograft plus 5 bone screws accordingly.MAIN OUTCOME MEASURES:Biomechanical tests were performed in the above-mentioned 3 groups to measure compressive,bending and torsional stiffness as well as the maximum loads.RESULTS:Different fixation models displayed different mechanical characteristics.The group A exhibited similar compressive stiffness compared to the group B,but the level was significantly higher compared to the group C (P ＜ 0.05).The other two stiffness parameters including bending and torsion were significantly greater in the group A than in the groups B and C (P ＜ 0.05).The maximum loads of compression,bending,and torsion were significantly greater in the group A compared to the group B (P ＜ 0.05) and group C (P ＜ 0.01).CONCLUSION:The strength of bone allograft is highly related to fixation mode. The two bone allografts showed greater strength and stiffness than struts fixed with bone screws,which meet the clinical requirements.

Objective To analyze the displacement of titanium clips for tumor bed localization after breast-conserving surgery for breast cancer and its influential factors.Methods A retrospective analysis was performed on the cone-beam computed tomography (CT) images of 14 patients with breast cancer who received radiotherapy after breast-conserving surgery from April to October,2016.The relative position of the chest wall and the errors of the titanium clips in radiotherapy were measured.A Pearson correlation analysis was used to analyze the correlation of the displacement of titanium clips with the relative position of titanium clips,the breast volume,the vertical distance between the titanium clips and the tangential line of the chest wall,and the maximum thickness of the breast.Results The system errors of the chest wall in left-right,superior-inferior,and anterior-posterior directions were 4.42,3.44,and 5.13 mm,respectively,and the random errors were 3.55,3.07,and 4.54 mm,respectively.The titanium clips had a large displacement relative to the chest wall,mainly in the left-right direction.The maximum system error was 4.39 mm and the random error was 2.42 mm.The displacement of titanium clips was not significantly correlated with the breast volume and the maximum thickness of the breast (P>0.05).However,the relative position of titanium clips in superior-inferior direction was significantly correlated with the displacement of the lowest,the most lateral,the most anterior,and the most posterior titanium clips (P<0.05).As to the uppermost clips,there was a significant difference in displacement between the clips close to the chest wall and the clips far from the chest wall (P=0.02).Conclusions Due to large setup error and displacement of titanium clips during radiotherapy,simultaneous integrated boost is not suitable for patients with breast cancer who are immobilized by vacuum cushion and received radiotherapy.The unstable immobilization may be the major influential factor for the displacement of titanium clips.

To investigate the impact of respiratory movement to determine the target volume on cone beam CT (CBCT) for lung tumor, we used CIRS dynamic thorax phantom (Model-CIRS008) to simulate the sinusoidal motion of lung tumor. With a constant amplitude, the ratio of the time of near-end-expiratory and near-end-inspiratory (E/I) changed when it was scanned with CBCT. We analyzed the contrast changes of target by extracting the CT value of each pixel on the center line of the target movement direction. The targets were contoured with region growing method and compared with the motion volume generated by the tumor trajectory method. The result showed that the contrast of near-end-expiratory increased and the contrast of near-end-inspiratory decreased with increasing E/I. The contoured volume generated by region growing method decreased with increasing E/I. When E/I = 4, the amplitude A = 1 cm, diameter of 1 cm and 3 cm target volumes were reduced by 48.2% and 22.7%. The study showed that CBCT was not suitable to be used to accurately determine the range of lung tumor movement. The internal target volume (ITV) may be underestimated in CBCT images.
Cone-Beam Computed Tomography ; Humans ; Lung Neoplasms ; diagnostic imaging ; Movement ; Phantoms, Imaging ; Respiration

Objective To evaluate the image quality and registration accuracy of a three?dimensional ( 3D ) dynamic phantom in four?dimensional computed tomography ( 4DCT ) and four?dimensional cone?beam computed tomography ( 4DCBCT) . Methods The Computerized Imaging Reference Systems Dynamic Thorax Phantom Model 008A was scanned to get 4DCT and 4DCBCT images. Two balls with different diameters ( ?= 1 cm and ?= 2 cm) were used to simulate tumors with different sizes. The motion mode of the balls was 3D sinusoidal motion at 0?25 Hz ( the amplitudes along the x, y, and z axes were ±1?0 cm, ±0?4 cm, and ±0?2 cm, respectively). Gross target volumes (GTVs) from 10?phase bins, internal gross target volumes (IGTV), and target volumes on maximum intensity projection (MIP) and mean intensity projection (MeanIP) images were contoured and calculated. Target volumes on 4DCT or 4DCBCT images were compared with the static and dynamic volumes of the balls ( VS and VD ) . The matching index ( MI) of target volumes between the 4DCT and 4DCBCT images was analyzed after rigid image registration. Results The GTV in each phase of the image was larger than VS . The difference between the average GTV derived from 10 phases of 4DCT or 4DCBCT images and Vs of the small ball was larger than that of the large ball ( 35?03% vs. 22?66%;32?62% vs. 17?00%) . All the IGTVs and target volumes on MIP images were slightly larger than VD , but target volumes on MeanIP images were smaller than VD . The average MI of 10?phase bins of the small ball was smaller than that of the large ball ( 66?76% vs. 82?21%) . Moreover, MIs of IGTV,MIP, and MeanIP of the small ball were also smaller than those of the large ball ( 77?39% vs. 90?29%;75?90% vs. 89?28%;74?47% vs. 82?74%) . Conclusions In the case of a relatively small tumor volume and a relatively large motion amplitude, 4DCT and 4DCBCT should be used with caution for comparison of image registration.

OBJECTIVETo assess the therapeutic strategies and risk factors of malignant fibrous histiocytoma of soft tissue.

METHODSThe 78 cases with malignant fibrous histiocytoma of soft tissue treated at Muscular Skeletal Tumor Center of People's Hospital, Peking University from December 1999 and October 2010 were retrospected. Univariate and multivariate analyses were performed to determine the probable risk factors including sex, age, tumor location, tumor size and so on.

RESULTSAll 60 cases were followed up ranged from 6 to 131 months (medium 35.5 months). The 1-, 3-, 5-year overall survival rate was 84.9%, 72.9% and 56.9% respectively. Local recurrence rate is 33.3% (20 cases) with a median time of 11.5 months (1 to 72 months) and metastatic rate is 15.0% (9 cases) with a median time of 7 months (1 to 26 months). Univariate analysis indicated that condition of presentation (primary case or recurrence case), tumor size and surgical margin were significantly related to survival rate (all P < 0.05, Kaplan-Meier Log-rank test), surgical margin and radiotherapy related to local recurrence rate (P value were 0.000 and 0.039 respectively), and surgical margin related to metastatic rate. Multivariate analysis showed that surgical margin was independent risk factors for survival rate (P = 0.002, OR = 5.753, 95%CI 1.904 - 17.386) and local recurrence rate (P = 0.000, RR = 0.044, 95%CI 0.010 - 0.188).

CONCLUSIONSSurgical margin was independent risk factors for survival rate and local recurrence rate. Comprehensive therapy of surgery followed by radiotherapy can improve survival rate, reduce local recurrence rate.

Adult ; Aged ; Aged, 80 and over ; Female ; Follow-Up Studies ; Histiocytoma, Malignant Fibrous ; diagnosis ; therapy ; Humans ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; Prognosis ; Retrospective Studies ; Soft Tissue Neoplasms ; diagnosis ; therapy ; Survival Rate

Objective To explore surgical experience of stenoses or occlusion of the vertebral artery .Methods In this group, there were 28 patients including 21 men and 7 females with average of 52 ~73 (68.3 ±0.03) y, duration 3 months to 4 years , and 15 lesions in the left and 13 lesions in the right .All patients were performed operation under general anesthesia .There were 16 vertebral artery endarterectomy , 10 subclavian-vertebral bypass and 2 end-side anastomosis between vertebral artery and common ca-rotid artery.Results One patient had to be performed second operation at the 7th day after endarterectomy because of anastomotic bleeding.All patients were cured.The patency rate of 6 months was 89.28%(25/28) in all patients.Conclusions Surgical man-agement of stenoses or occlusion of the vertebral artery has excellent curative effect with simply operation .However , the technique must be selected according to anatomic circumstances of vertebral artery and subclavian artery .

Objective To introduce the experience of prophylaxis and management of the complications of carotid endarterectomy (CEA) during perioperative period because those complications can not be avoided yet.Methods During Oct 2000 to Jan 2013,318 patients were performed CEA.There were 213 men and 105 women with an average age of 74.8 years ranged from 48 to 85y.There were 186 patients in the left,120 patients in the right,and 12 patients in two sides.Simply,CEA are performed in 166 patients,CEA and patch in 140,and 12 patients were performed bypass with the autogenously great saphenous vein after the lesions removal.Results The perioperative complications were preoperative stroke in 3 cases,hypotension during operation in 16,after-operation deaths in 3,hyperperfusion syndrome in 18,postoperative severe cerebral infarction in 1,hoarseness in 14,and hematoma in 28.Conclusions Perioperative complications of CEA can be decreased by cautious surgical procedure and postoperative observation.

AIM: To measure microcirculation function in type 2 diabetic patients and non-diabetic subjects with a new measurement method called capillary recruitment. METHODS: 276 type 2 diabetic patients in Shanghai downtown were enrolled and categorized into several groups, those with diabetes duration