摘要 :
Purpose: We compare and investigate the dosimetric impacts on pencil beam scanning (PBS) proton treatment plans generated with CT calibration curves from four different CT scanners and one averaged ‘global’ CT calibration curve....
展开
Purpose: We compare and investigate the dosimetric impacts on pencil beam scanning (PBS) proton treatment plans generated with CT calibration curves from four different CT scanners and one averaged ‘global’ CT calibration curve. Methods: The four CT scanners are located at three different hospital locations within the same health system. CT density calibration curves were collected from these scanners using the same CT calibration phantom and acquisition parameters. Mass density to HU value tables were then commissioned in a commercial treatment planning system. Five disease sites were chosen for dosimetric comparisons at brain, lung, head and neck, adrenal, and prostate. Three types of PBS plans were generated at each treatment site using SFUD, IMPT, and robustness optimized IMPT techniques. 3D dose differences were investigated using 3D Gamma analysis. Results: The CT calibration curves for all four scanners display very similar shapes. Large HU differences were observed at both the high HU and low HU regions of the curves. Large dose differences were generally observed at the distal edges of the beams and they are beam angle dependent. Out of the five treatment sites, lung plans exhibits the most overall range uncertainties and prostate plans have the greatest dose discrepancy. There are no significant differences between the SFUD, IMPT, and the RO‐IMPT methods. 3D gamma analysis with 3%, 3 mm criteria showed all plans with greater than 95% passing rate. Two of the scanners with close HU values have negligible dose difference except for lung. Conclusion: Our study shows that there are more than 5% dosimetric differences between different CT calibration curves. PBS treatment plans generated with SFUD, IMPT, and the robustness optimized IMPT has similar sensitivity to the CT density uncertainty. More patient data and tighter gamma criteria based on structure location and size will be used for further investigation.
收起
摘要 :
Background Larger glenosphere diameters have been used recently to increase prosthesis stability and impingement-free range of motion in reverse total shoulder arthroplasty. The goal of this study was to evaluate the rate of polye...
展开
Background Larger glenosphere diameters have been used recently to increase prosthesis stability and impingement-free range of motion in reverse total shoulder arthroplasty. The goal of this study was to evaluate the rate of polyethylene wear for 32-mm and 40-mm glenospheres. Methods Glenospheres (32?mm and 40?mm, n?=?6/group) and conventional polyethylene humeral liners underwent a 5–million cycle (MC) wear simulation protocol. Abduction-adduction and flexion-extension motion profiles were alternated every 250,000 cycles. At each interval, mass loss was determined and converted to volume loss and wear rate. At 0, 2.5 MC, and 5 MC, liners were imaged using micro–computed tomography to determine surface deviation. White light interferometry was performed on liners and glenospheres at 0 and 5 MC to quantify surface roughness. Wear particle morphology was characterized by environmental scanning electron microscopy. Results Total volume loss was significantly higher in 40-mm liners from 1.5 MC onward ( P ? 3 /MC vs. 68.0?±?18.9?mm 3 /MC; P ? P ?=?.002). Surface roughness measurements showed no difference for liners; however, increased roughness was noted for 40-mm glenospheres at 5 MC compared with 32?mm ( P ? Conclusion Larger glenospheres underwent significantly greater polyethylene volume loss and volumetric wear rates, whereas smaller glenospheres underwent greater polyethylene surface deviations. The enhanced stability provided by larger glenospheres must be weighed against the potential for increased polyethylene wear. ]]>
收起
摘要 :
BackgroundFretting and corrosion at the modular femoral head-femoral neck (taper) interface have been reported in retrieved total hip arthroplasty (THA) prostheses. This study investigated associations among implant design, radiog...
展开
BackgroundFretting and corrosion at the modular femoral head-femoral neck (taper) interface have been reported in retrieved total hip arthroplasty (THA) prostheses. This study investigated associations among implant design, radiographic factors, and patient factors with corrosion and fretting at the taper interface in retrieved metal-on-polyethylene modular THA prostheses. MethodsNinety-two retrieved primary metal-on-polyethylene THA implants were evaluated and graded for fretting, corrosion, and damage at the taper interface, including the femoral stem trunnion and femoral head. Preoperative radiographs were assessed for osteolysis and femoral stem alignment; and medical records were reviewed for demographic data. ResultsMale patients had greater head corrosion (P?= .037), patient age at revision had a weak, negative correlation with trunnion corrosion (ρ?=??0.20,P?= .04), and both body mass index and duration of implantation had weak, positive correlations with head fretting (ρ?= 0.26,P?= .01 andρ?= 0.33,P?= .001, respectively). A weak, negative correlation was found between femoral head size and both head fretting and head corrosion (ρ?=??0.26,P?= .007 andρ?=??0.21,P?= .028, respectively), and a weak, positive correlation was found between head offset and trunnion fretting (ρ?= 0.23,P?= .030). Varus femoral stem alignment was associated with greater head fretting (P?= .038). ConclusionLarger femoral head sizes were correlated with less severe head corrosion and head fretting, with 28-mm heads exhibiting more moderate-to-severe damage. Other factors, such as head-taper engagement and geometry, rather than head size, may affect rates of corrosion and fretting damage at the taper interface.
收起
摘要 :
Abstract Background Simultaneous vs staged bilateral total knee arthroplasty (BTKA) has long been debated. The primary objective of this study was to compare actual hospital costs and complication rates in patients undergoing simu...
展开
Abstract Background Simultaneous vs staged bilateral total knee arthroplasty (BTKA) has long been debated. The primary objective of this study was to compare actual hospital costs and complication rates in patients undergoing simultaneous BTKA (simBTKA) and staged BTKA (staBTKA) at a single institution. Methods A total joint arthroplasty database from a single hospital was used to identify all patients who underwent primary BTKA from 2013 to 2016 and divided into simultaneous and staged groups. StaBTKA patients were included if both procedures were performed within 1 year by the same surgeon. The combined total hospital cost of both procedures was used, and inpatient rehabilitation (IPR) costs were added for all patients discharged to IPR. Results There were 225 simBTKA and 337 staBTKA patients. SimBTKA patients were younger (61 ± 8 vs 66 ± 8 years, P P P ?= .029), and more likely to require IPR as compared with staBTKA patients. There was no difference in total hospital cost for simBTKA as compared with staBTKA ($24,596 ± $5652 vs $24,915 ± $5756, P ?= .586). Complications were more prevalent in the simBTKA group, including venous thromboembolism (5.4% vs 1.4%, P ?= .006) and blood transfusions (15.8% vs 6.2%, P ? Conclusion There were higher complication rates with no significant cost savings in actual hospital costs associated with simBTKA, when accounting for the cost of IPR, as compared with staBTKA. The total cost analysis of simBTKA vs staBTKA, using actual cost data, merits further evaluation.
收起
摘要 :
Abstract Background Periprosthetic joint infection (PJI) is a rare yet challenging problem in total hip and knee arthroplasties. The management of PJI remains difficult primarily due to the evolution of resistance by the infecting...
展开
Abstract Background Periprosthetic joint infection (PJI) is a rare yet challenging problem in total hip and knee arthroplasties. The management of PJI remains difficult primarily due to the evolution of resistance by the infecting organisms. Methods This review profiles acquired mechanisms of bacterial resistance and summarizes established and emerging techniques in PJI diagnosis, prevention, and treatment. Results New techniques in PJI diagnosis and prevention continue to be explored. Antibiotics combined with 1 or 2-stage revision are associated with the higher success rates and remain the mainstay of treatment. Conclusion With higher prevalence of antibiotic-resistant organisms, novel antibiotic implant and wound care materials, improved methods for organism identification, and well-defined organism-specific treatment algorithms are needed to optimize outcomes of PJI.
收起
摘要 :
Purpose: To fulfill precision radiotherapy via adaptive dose painting by number, voxel‐by‐voxel dose response or radio‐sensitivity in individual human tumor needs to be determined in early treatment to guide treatment adaptatio...
展开
Purpose: To fulfill precision radiotherapy via adaptive dose painting by number, voxel‐by‐voxel dose response or radio‐sensitivity in individual human tumor needs to be determined in early treatment to guide treatment adaptation. In this study, multiple FDG PET images obtained pre‐ and weekly during the treatment course were utilized to determine the distribution/spectrum of dose response parameters in individual human tumors. Methods: FDG PET/CT images of 18 HN cancer patients were used in the study. Spatial parametric image of tumor metabolic ratio (dSUV) was created following voxel by voxel deformable image registration. Each voxel value in dSUV was a function of pre‐treatment baseline SUV and treatment delivered dose, and used as a surrogate of tumor survival fraction (SF). Regression fitting with break points was performed using the LQ‐model with tumor proliferation for the control and failure group of tumors separately. The distribution and spectrum of radiation sensitivity and growth in individual tumors were determined and evaluated. Results: Spectrum of tumor dose‐sensitivity and proliferation in the controlled group was broad with α in tumor survival LQ‐model from 0.17 to 0.8. It was proportional to the baseline SUV. Tlag was about 21～25 days, and Tpot about 0.56～1.67 days respectively. Commonly tumor voxels with high radio‐sensitivity or larger α had small Tlag and Tpot. For the failure group, the radio‐sensitivity α was low within 0.05 to 0.3, but did not show clear Tlag. In addition, tumor voxel radio‐sensitivity could be estimated during the early treatment weeks. Conclusion: Dose response distribution with respect to radio‐sensitivity and growth in individual human tumor can be determined using FDG PET imaging based tumor metabolic ratio measured in early treatment course. The discover is critical and provides a potential quantitative objective to implement tumor specific precision radiotherapy via adaptive dose painting by number.
收起
摘要 :
Purpose: We investigate the spot characteristic and dose profiles properties from a compact gantry proton therapy system. This compact design features a dedicated pencil beam scanning nozzle with the scanning magnet located upstre...
展开
Purpose: We investigate the spot characteristic and dose profiles properties from a compact gantry proton therapy system. This compact design features a dedicated pencil beam scanning nozzle with the scanning magnet located upstream of the final 60 degree bending magnet. Due to the unique beam line design, uncertainty has been raised in the virtual source‐to‐axis distance (SAD). We investigate its potential clinical impact through measurements and simulation. Methods: A scintillator camera based detector was used to measure spot characteristics and position accuracy. An ion chamber array device was used to measure planar dose profile. Dose profile in‐air simulation was performed using in‐house built MATLAB program based on additional spot parameters directly from measurements. Spot characteristics such as position and in‐air sigma values were used to general simulated 2D elliptical Gaussian spots. The virtual SAD distance changes in the longitudinal direction were also simulated. Planar dose profiles were generated by summation of simulated spots at the isocenter, 15 cm above the isocenter, and 15 cm below the isocenter for evaluation of potential clinical dosimetric impact. Results: We found that the virtual SAD varies depending on the spot location on the longitudinal axis. Measurements have shown that the variable SAD changes from 7 to 12 meters from one end to the other end of the treatment field in the longitudinal direction. The simulation shows that the planer dose profiles differences between the fixed SAD and variable SAD are within 3% from the isocenter profile and the lateral penumbras are within 1 mm difference. Conclusion: Our measurements and simulations show that there are minimum effects on the spot characteristics and dose profiles for this up‐stream scanning compact system proton system. Further treatment planning study is needed with the variable virtual SAD accounted for in the planning system to show minimum dosimetric impact.
收起
摘要 :
Intravenous immunoglobulin (IVIG) products are prepared from plasma immunoglobulins from healthy donors. Pilot studies suggest that IVIG may stabilize cognitive functioning in patients with mild-to-moderate Alzheimer's disease. Th...
展开
Intravenous immunoglobulin (IVIG) products are prepared from plasma immunoglobulins from healthy donors. Pilot studies suggest that IVIG may stabilize cognitive functioning in patients with mild-to-moderate Alzheimer's disease. This study measured antibodies to recombinant human tau protein in the IVIG products Gammagard (Baxter), Gamunex (Talecris), and Flebogamma (Grifols). Anti-tau antibodies were measured by ELISA, subtracting IVIG's polyvalent binding from its binding to tau-coated wells to calculate specific anti-tau antibody levels. Because polyvalent binding of IVIG products may interfere with ELISA measurement of their specific antibody levels, the percentage of binding of each IVIG product to tau-coated wells that was specific for tau was also determined. Specific anti-tau antibodies were detected in all three IVIG products, with significant differences between these products (p < 0.001) even when Flebogamma's anti-tau antibodies were doubled to account for its preparation as a 5% solution vs. 10% solutions for Gammagard and Gamunex (means: Gammagard, 3.1 μg/ml; Gamunex, 2.5 μg/ml; Flebogamma, 1.2 μg/ml). The percentages of each IVIG product's specific binding to tau-coated wells also varied between the various products (p < 0.001) and between all pairs of IVIG products (means: Gammagard, 73.1%; Flebogamma, 54.5%; Gamunex, 37.4%; p < 0.01 for all pairwise comparisons). These findings indicate that IVIG products contain specific anti-tau antibodies. The concentrations of these antibodies and the percentages of specific binding of IVIG to tau-coated wells vary between IVIG products. Further studies are indicated to determine if IVIG also contains antibodies to pathologic forms of tau.
收起
摘要 :
Jacobsen syndrome is an uncommon but well-known contiguous gene syndrome caused by partial deletion involving the long arm of chromosome 11. Most common features include: psychomotor impairment, facial dysmorphism, and thrombocyto...
展开
Jacobsen syndrome is an uncommon but well-known contiguous gene syndrome caused by partial deletion involving the long arm of chromosome 11. Most common features include: psychomotor impairment, facial dysmorphism, and thrombocytopenia. Cleft palate has been rarely reported.A case of Jacobsen syndrome confirmed by cytogenomic analysis is presented with review of the literature. Main clinical features were phonological disorder, submucous cleft palate (SMCP) and velopharyngeal insufficiency (VPI). VPI was corrected surgically according to findings of videonasopharyngoscopy and videofluoroscopy.It is concluded that clinicians should consider that VPI associated with SMCP may be the main manifestations of a chromosomal syndrome.
收起
原文获取