<strong>Purpose:</strong> The purpose of this study is to provide technical information on commissioning the TrueBeam STx 6 MV flattening-filter free (FFF) beam in the RayStation treatment planning system ...<strong>Purpose:</strong> The purpose of this study is to provide technical information on commissioning the TrueBeam STx 6 MV flattening-filter free (FFF) beam in the RayStation treatment planning system (TPS) for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. <strong>Methods:</strong> For beam modeling, percent depth dose curves, profiles and output factors for jaw-collimated fields and stereotactic cones as well as X-jaws transmission were measured. For multi-leaf collimator (MLC) modeling, MLC model parameters such as offset, gain, curvature, leaf tip width, tongue and groove and transmission were determined and output factors for MLC-collimated fields were measured. Absolute dose calibration was also performed. For beam model and MLC model validation, the American Association of Physicists in Medicine Task Group-119 plans, clinical SRS and SBRT plans and end-to-end testing were performed. <strong>Results:</strong> Beam characteristics of the 6 MV FFF beam agreed well with those in the literature. Validation results showed that our beam model and MLC model were acceptable for SRS and SBRT treatments. <strong>Conclusions:</strong> The technical information and dosimetric data provided in this study will be a useful reference for other clinics/institutions which will commission the same machine energy in the RayStation TPS.展开更多
This study scrutinizes the thermomechanical dynamics of 3D-printed hydrofoil blades utilizing a carbon and glass bead-reinforced thermoplastic polymer.Comparative analyses underscore the pivotal role of polymer reinfo...This study scrutinizes the thermomechanical dynamics of 3D-printed hydrofoil blades utilizing a carbon and glass bead-reinforced thermoplastic polymer.Comparative analyses underscore the pivotal role of polymer reinforcement in augmenting mechanical strength and mitigating deformation and residual stress.The investigation elucidates the expeditious and cost-efficient manufacturing potential of low-cost Fused Filament Fabrication(FFF)printers for small-scale blades,revealing exemplary mechanical performance with nominal deflection and warping in the PA12-CB/GB printed blade.A comprehensive juxtaposition between Selective Laser Sintering(SLS)and FFF printing methods favors SLS due to its isotropic properties,notwithstanding remediable warping.Emphasizing the rigorous marine environment,the study cautions against the anisotropic properties of FFF-printed blades,despite their low mechanical warping.These discernments contribute to hydrofoil design optimization through numerical analysis,shedding light on additive manufacturing’s potential for small blades in renewable energy,while underscoring the imperative for further research to advance these techniques.展开更多
国际原子能机构(International Atomic Energy Agency,IAEA)与美国医学物理学家协会(American Association of Physicists in Medicine,AAPM)联合制定的外照射光子束小野静态射野剂量学操作规程(TRS-483)中提供的小野射野输出修正因子(k...国际原子能机构(International Atomic Energy Agency,IAEA)与美国医学物理学家协会(American Association of Physicists in Medicine,AAPM)联合制定的外照射光子束小野静态射野剂量学操作规程(TRS-483)中提供的小野射野输出修正因子(k_(Qclin,Qref)^(fclin,fref))未考虑均整模式(Flattening Filter,FF)、非均整模式(Flattening Filter Free,FFF)束流间差异,对于电离室在相同射野条件下测量的小野射野输出因子(Ω^(fclin,fref) _(Qclin,Qref))给出相同修正系数,可能引入超过1%的偏差。据此,提出利用蒙特卡罗模拟细化电离室k_(Qclin,Qref)^(fclin,fref)的方法,对FF、FFF束流下电离室小野测量数据进行分别修正,进一步提升临床小野剂量测量准确性。基于EGSnrc构建Elekta Synergy加速器机头模型,建立电离室k_(Qclin,Qref)^(fclin,fref)模拟方法。通过电离室在FF束流不同射野条件下Ω^(fclin,fref)_(Qclin,Qref)的测量及修正,验证蒙特卡罗计算模型,并分别计算了6款小灵敏体积电离室在FF、FFF束流不同射野范围(0.8 cm×0.8 cm~10 cm×10 cm)的k_(Qclin,Qref)^(fclin,fref)。研究发现,同一电离室在FF、FFF束流不同射野条件下计算的k_(Qclin,Qref)^(fclin,fref)存在明显差异,其中PTW 31015在FFF模式下计算的k_(Qclin,Qref)^(fclin,fref)与FF模式计算结果相比最大偏差超过1.02%。因此,通过细化电离室k_(Qclin,Qref)^(fclin,fref)的方法能够有效提升临床小野水吸收剂量测量准确性。展开更多
The bioinert nature of polyether ether ketone(PEEK)material limits the widespread clinical application of PEEK implants.Although the porous structure is considered to improve osseointegration of PEEK implants,it is ha...The bioinert nature of polyether ether ketone(PEEK)material limits the widespread clinical application of PEEK implants.Although the porous structure is considered to improve osseointegration of PEEK implants,it is hardly used due to its mechanical properties.This study investigated the combined influence of the porous structure and in vivo mechanical stimulation on implantation safety and bone growth based on finite element analysis of the biomechanical behavior of the implantation system.The combined control of pore size and screw preloads allows the porous PEEK implant to achieve good osseointegration while maintaining a relatively high safety level.A pore size of 600μm and a preload of 0.05 N·m are the optimal combination for the long-term stability of the implant,with which the safety factor of the implant is>2,and the predicted percentage of effective bone growth area of the bone-implant interface reaches 97%.For further clinical application,PEEK implants were fabricated with fused filament fabrication(FFF)three-dimensional(3D)printing,and clinical outcomes demonstrated better bone repair efficacy and long-term stability of porous PEEK implants compared to solid PEEK implants.Moreover,good osteointegration performance of 3D-printed porous PEEK implants was observed,with an average bone volume fraction>40%three months after implantation.In conclusion,3D-printed porous PEEK implants have great potential for clinical application,with validated implantation safety and good osseointegration.展开更多
文摘目的对比分析非均整(FFF)模式下Acuros XB(AXB)算法与各向异性解析算法(AAA)在宫颈癌容积旋转调强放射治疗(VMAT)中的剂量学差异,探讨其临床适用性。方法选取15例宫颈癌术后患者,年龄46~75岁,中位年龄62岁;病理类型为13例鳞状细胞癌,2例腺癌。在Eclipse16.1计划系统设计VMAT-FFF计划,分别应用AXB算法与AAA计算剂量,对比靶区剂量、适形度(CI)、均匀性(HI)、危及器官(OAR)受量及正常组织低剂量暴露(V_(1)~V_(40))。结果AXB算法与AAA的靶区D_(max)、D_(mean)、D_(2%)、D_(50%)差异有统计学意义[(5377.07±21.84)cGy vs(5322.22±23.91)cGy、(5086.07±5.22)cGy vs(5077.49±7.34)cGy、(5191.01±10.47)cGy vs(5169.13±14.30)cGy、(5087.33±5.62)cGy vs(5079.59±7.67)cGy。P<0.05],AXB算法所得CI(0.9200±0.0034 vs 0.9172±0.0022。P<0.05)及OAR的V_(50)预测值显著高于AAA[膀胱:(22.63±7.33)%vs(22.11±7.05)%;直肠:(24.33±5.55)%vs(23.24±5.39)%。P<0.05],但HI较差(0.0450±0.0029 vs 0.0409±0.0034。P<0.001)。AAA计算的正常组织V_(1)和V_(5)较AXB算法显著更高[(73.70±7.02)%vs(72.37±7.06)%、(53.47±6.68)%vs(53.27±6.71)%。P<0.05],其余V_(10)~V_(40)差异无统计学意义(P>0.05)。结论AXB算法更适用于需精准保护OAR的宫颈癌VMAT-FFF计划,而AAA在靶区HI上更具优势。临床应根据治疗需求优化算法选择。
文摘<strong>Purpose:</strong> The purpose of this study is to provide technical information on commissioning the TrueBeam STx 6 MV flattening-filter free (FFF) beam in the RayStation treatment planning system (TPS) for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. <strong>Methods:</strong> For beam modeling, percent depth dose curves, profiles and output factors for jaw-collimated fields and stereotactic cones as well as X-jaws transmission were measured. For multi-leaf collimator (MLC) modeling, MLC model parameters such as offset, gain, curvature, leaf tip width, tongue and groove and transmission were determined and output factors for MLC-collimated fields were measured. Absolute dose calibration was also performed. For beam model and MLC model validation, the American Association of Physicists in Medicine Task Group-119 plans, clinical SRS and SBRT plans and end-to-end testing were performed. <strong>Results:</strong> Beam characteristics of the 6 MV FFF beam agreed well with those in the literature. Validation results showed that our beam model and MLC model were acceptable for SRS and SBRT treatments. <strong>Conclusions:</strong> The technical information and dosimetric data provided in this study will be a useful reference for other clinics/institutions which will commission the same machine energy in the RayStation TPS.
文摘This study scrutinizes the thermomechanical dynamics of 3D-printed hydrofoil blades utilizing a carbon and glass bead-reinforced thermoplastic polymer.Comparative analyses underscore the pivotal role of polymer reinforcement in augmenting mechanical strength and mitigating deformation and residual stress.The investigation elucidates the expeditious and cost-efficient manufacturing potential of low-cost Fused Filament Fabrication(FFF)printers for small-scale blades,revealing exemplary mechanical performance with nominal deflection and warping in the PA12-CB/GB printed blade.A comprehensive juxtaposition between Selective Laser Sintering(SLS)and FFF printing methods favors SLS due to its isotropic properties,notwithstanding remediable warping.Emphasizing the rigorous marine environment,the study cautions against the anisotropic properties of FFF-printed blades,despite their low mechanical warping.These discernments contribute to hydrofoil design optimization through numerical analysis,shedding light on additive manufacturing’s potential for small blades in renewable energy,while underscoring the imperative for further research to advance these techniques.
文摘国际原子能机构(International Atomic Energy Agency,IAEA)与美国医学物理学家协会(American Association of Physicists in Medicine,AAPM)联合制定的外照射光子束小野静态射野剂量学操作规程(TRS-483)中提供的小野射野输出修正因子(k_(Qclin,Qref)^(fclin,fref))未考虑均整模式(Flattening Filter,FF)、非均整模式(Flattening Filter Free,FFF)束流间差异,对于电离室在相同射野条件下测量的小野射野输出因子(Ω^(fclin,fref) _(Qclin,Qref))给出相同修正系数,可能引入超过1%的偏差。据此,提出利用蒙特卡罗模拟细化电离室k_(Qclin,Qref)^(fclin,fref)的方法,对FF、FFF束流下电离室小野测量数据进行分别修正,进一步提升临床小野剂量测量准确性。基于EGSnrc构建Elekta Synergy加速器机头模型,建立电离室k_(Qclin,Qref)^(fclin,fref)模拟方法。通过电离室在FF束流不同射野条件下Ω^(fclin,fref)_(Qclin,Qref)的测量及修正,验证蒙特卡罗计算模型,并分别计算了6款小灵敏体积电离室在FF、FFF束流不同射野范围(0.8 cm×0.8 cm~10 cm×10 cm)的k_(Qclin,Qref)^(fclin,fref)。研究发现,同一电离室在FF、FFF束流不同射野条件下计算的k_(Qclin,Qref)^(fclin,fref)存在明显差异,其中PTW 31015在FFF模式下计算的k_(Qclin,Qref)^(fclin,fref)与FF模式计算结果相比最大偏差超过1.02%。因此,通过细化电离室k_(Qclin,Qref)^(fclin,fref)的方法能够有效提升临床小野水吸收剂量测量准确性。
基金supported by the National Key R&D Program of China(No.2023YFB4603500)the Program for Innovation Team of Shaanxi Province(No.2023-CX-TD-17)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Shaanxi Province Qinchuangyuan“Scientist+Engineer”Team Construction Project(No.2022KXJ-106).
文摘The bioinert nature of polyether ether ketone(PEEK)material limits the widespread clinical application of PEEK implants.Although the porous structure is considered to improve osseointegration of PEEK implants,it is hardly used due to its mechanical properties.This study investigated the combined influence of the porous structure and in vivo mechanical stimulation on implantation safety and bone growth based on finite element analysis of the biomechanical behavior of the implantation system.The combined control of pore size and screw preloads allows the porous PEEK implant to achieve good osseointegration while maintaining a relatively high safety level.A pore size of 600μm and a preload of 0.05 N·m are the optimal combination for the long-term stability of the implant,with which the safety factor of the implant is>2,and the predicted percentage of effective bone growth area of the bone-implant interface reaches 97%.For further clinical application,PEEK implants were fabricated with fused filament fabrication(FFF)three-dimensional(3D)printing,and clinical outcomes demonstrated better bone repair efficacy and long-term stability of porous PEEK implants compared to solid PEEK implants.Moreover,good osteointegration performance of 3D-printed porous PEEK implants was observed,with an average bone volume fraction>40%three months after implantation.In conclusion,3D-printed porous PEEK implants have great potential for clinical application,with validated implantation safety and good osseointegration.
