Temperature-controlled power modulation compensates for heterogeneous nanoparticle distributions: a computational optimization analysis for magnetic hyperthermia

Purpose: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia.

Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.

Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.

Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.     

User experiences with second-generation 32-gauge × 4 mm vs. thinner comparator pen needles: prospective randomized trial

Abstract

Objective

Two similarly designed studies compared user experiences with a second-generation extra-thin-wall, 5-bevel 32?G?×?4?mm pen needle (PN) with redesigned hub versus four thinner commercially available PNs.     

Demonstration of a modelling-based multi-criteria decision analysis procedure for prioritisation of occupational risks from manufactured nanomaterials

Several tools to facilitate the risk assessment and management of manufactured nanomaterials (MN) have been developed. Most of them require input data on physicochemical properties, toxicity and scenario-specific exposure information. However, such data are yet not readily available, and tools that can handle data gaps in a structured way to ensure transparent risk analysis for industrial and regulatory decision making are needed. This paper proposes such a quantitative risk prioritisation tool, based on a multi-criteria decision analysis algorithm, which combines advanced exposure and dose-response modelling to calculate margins of exposure (MoE) for a number of MN in order to rank their occupational risks. We demonstrated the tool in a number of workplace exposure scenarios (ES) involving the production and handling of nanoscale titanium dioxide, zinc oxide (ZnO), silver and multi-walled carbon nanotubes. The results of this application demonstrated that bag/bin filling, manual un/loading and dumping of large amounts of dry powders led to high emissions, which resulted in high risk associated with these ES. The ZnO MN revealed considerable hazard potential in vivo, which significantly influenced the risk prioritisation results. In order to study how variations in the input data affect our results, we performed probabilistic Monte Carlo sensitivity/uncertainty analysis, which demonstrated that the performance of the proposed model is stable against changes in the exposure and hazard input variables.     

食管癌根治性放疗剂量研究进展

同步放化疗是不可手术局部晚期食管癌的标准治疗模式,国际推荐根治性放疗剂量为50.0~50.4Gy,但中国食管癌与西方国家在病理类型、生物学行为等方面大有不同,行根治性放疗剂量仍倾向于60Gy。增加放疗剂量能否带来生存获益成为临床亟待解决的问题。有研究认为高剂量放疗可提高局控率、改善生存,但也有研究认为提高剂量未能带来生存获益,且可增加不良反应事件发生率。因此,本文就食管癌根治性放疗剂量对预后的影响进行探讨,并通过放化疗后疗效评估对放疗剂量做出适当调整,以期达个体化放疗。     

睾丸扭转和精索扭转的诊断与治疗(附68例报告)

目的:探讨睾丸和精索扭转的诊断与治疗方法,提高睾丸和精索扭转的治疗水平。方法:对68例睾丸和精索扭转的临床资料进行总结,68例平均年龄21岁,<20岁者占84%,左侧55例占80.8%.发病至确诊时间6h～30天,12h以上者占90.2%。结果:53例术前彩色多普勒血流动态显象(CDFI)应作为诊断疾病的常见与首选检查方法。诊断并经手术证实,符合率100%,经手术探查;41例行手术复位、固定,睾丸获救。27例行患侧睾丸切除术,所有病例均行对侧探察,固定。结论:阴囊X核素显象,B超对睾丸精索扭转早期诊断有帮助。早期诊断,及时治疗是提高疗效的关键。彩色多普勒血流动态显象应作为诊断该疾病的常见及首选检查方法,对睾丸精索一旦确诊或疑有精索扭转的患者应及早行紧急复位,以期挽救睾丸,同时行睾丸固定术也十分必要。对于确诊毫无保留价值的睾丸需行切除术。