The impact of canister geometry on chemical biological radiological and nuclear filter performance: A computational fluid dynamics analysis

Steady-state axisymmetric simulations using the Reynolds-Averaged Navier-Stokes equations have been carried out in order to optimize the performance of a Chemical, Biological, Radiological, and Nuclear (CBRN) canister filter for its use in a powered air-purifying respirator (PAPR). Alterations have been made to the shape of the canister, the spacing of the rear wall of the canister with regard to the carbon filter, and the bracketing between (i) the particulate filter and the carbon bed and (ii) the carbon bed and the canister wall. The pressure drops across the canister and the residence time distribution at the rear of the carbon bed have been analyzed in detail based on an extensive parametric analysis involving the aforementioned variations. It has been demonstrated that the non-uniform porosity profile of the carbon bed resulted in alternating regions of high and low velocity close to the canister wall, providing a possible route for breakthrough. Designs, which included a bracket at the rear of the carbon bed, blocked this route and consequently had a longer minimum mean residence time than those, which did not. It has also been shown that the spacing between the carbon bed and the canister rear wall had a large impact on both residence time and pressure drop. In cases where the carbon backed directly onto the canister rear wall flow in the axial direction from the outside wall toward the canister axis resulted in far greater pressure drop and a reduction in minimum mean residence time within the carbon bed.     

Interventional Radiological Treatment of Hepatocellular Carcinoma: An Update

Hepatocellular carcinoma is the commonest primary liver tumor and its incidence is on an increase.Transplantation and surgical resection are the gold standard curative treatment options but less than 20%patients are surgical candidates because of advanced liver disease and/or co-morbidities.Various interventional radiological procedures have been developed and intensively investigated for treatment of inoperable HCC.This review summarizes the various interventional radiological treatments in HCC including patient selection, procedural considerations and response evaluation. Transarterial chemoembolization, radioembolization and radiofrequency ablation are mainly discussed.     

CBRN considerations in a major incident

Chemical, biological, radiological and nuclear (CBRN) hazards may be encountered during any major incident. General considerations include modifications to triage, managing contaminated or contagious casualties, and the identification and appropriate management of intoxicated/infected/irradiated/injured casualties. In dealing with chemical incidents, characteristics such as toxicity, latency and persistency need to be understood in order to manage casualties appropriately in terms of triage category, life-saving interventions and assessment of contamination risk to responders. Biological agents can be differentiated into live agents (bacteria, viruses and fungi) and toxins. Live agent characteristics and management depend on pathogenicity, virulence, lethality, infectivity and transmissibility, whereas toxins are treated similarly to chemical agents. Radiological and nuclear hazards are managed similarly and may cause irradiation, contamination (external and internal) or a combination with or without trauma. A generic and structured approach is advised to deal with all major incidents including those with a suspected of confirmed CBRN hazard. All healthcare professionals that may be involved in the response to such an incident need to be familiar with the principles of CBRN incident management and of CBRN casualty management as described in this article.     

Efficacy of antibiotic‐impregnated cement in total hip replacement

Background and purpose?Antibiotic‐impregnated cement is used as a spacer or during re‐implantation surgery for the treatment of infected total hip arthroplasties. The routine use of antibiotic‐impregnated cement during primary or uninfected revision total hip arthroplasty remains controversial. With this meta‐analysis of the published literature, we intended to assess efficacy and safety in the use of antibiotic‐impregnated cement for uninfected arthroplasty.

Methods?Following a detailed literature search, only studies reporting on the outcome of total hip replacement performed with antibiotic cement were included. Strict inclusion criteria were used and studies lacking sufficient sample size or critical data were excluded. 19 studies reporting on 36,033 hip replacements in 35,659 patients met the initial inclusion criteria. The main aim of the meta‐analysis was to determine the rate of deep infection with and without the use of antibiotic cement, and to assess the revision rate and the ultimate survivorship of arthroplasty using antibiotic cement.

Results?The rate of deep infection following primary total hip arthroplasty, at 1.2%, was significantly lower when antibiotic cement was used than when cement without antibiotics was used (2.3%). Similarly, the rate of deep infection following revision total hip arthroplasty when a standard combination of cement and antibiotic—or a custom‐made combination of cement and antibiotic, depending on the results of culture—was used, was almost half of the rate of deep infection when no antibiotics were present in the cement. Overall, the survivorship was 98% (101 failures in 5,178 hips) for primary arthroplasty and 88% (100 failures in 855 hips) for revision arthroplasty. There were no reported adverse events or complications associated with the use of antibiotic‐impregnated cement.

Interpretation?The use of antibiotic‐impregnated cement lowered the infection rate by approximately 50% in primary hip arthroplasty. For revisions of previously infected hips, combinations or culture‐dependent antibiotics lowered infection rates by approximately 40%.     

Radiological impact assessment to the environment due to waste from disposal of porcelain

The present study aimed to assess the radiological parameters from gamma rays due to the uncontrolled disposal of porcelain waste to the environment. Qualitative and quantitative identification of radionuclides in the investigated samples was carried out by means of a high-purity germanium (HPGe) detector. The average activity concentrations of the local porcelain samples were measured as 208.28?Bq/kg for ²²⁶Ra, 125.73?Bq/kg for ²³⁸U, 84.94?Bq/kg for ²³²Th and 1033.61?Bq/kg for ⁴⁰K, respectively. The imported samples had an average activity of 240.57?Bq/kg for ²²⁶Ra, 135.56?Bq/kg for ²³⁸U, 115.74?Bq/kg for ²³²Th and 1312.49?Bq/kg for ⁴⁰K, respectively. Radiological parameters and the radium equivalent Ra_eq for the investigated samples were calculated. The external and internal hazard indices, representative level index (I_γ), alpha index (I_α), and the exemption level (I_x), were estimated to be higher than the recommended value (unity), while the average activity concentrations for the studied samples were higher than recommended levels. In conclusion, we are concerned that disposal of porcelain in the environment might be a significant hazard.     

可逆性后部白质脑病综合征临床特点及影像学改变--附12例临床分析

目的：探讨可逆性后部白质脑病综合征（PRES ）的临床特点和影像学改变。方法回顾性分析12例PRES患者的临床和影像学资料。结果原发病为慢性酒精中毒1例，系统性红斑狼疮伴特发性血小板减少性紫癜1例，余10例均与妊娠相关，其中7例原发病为妊娠高血压综合征（妊高征）。临床主要表现为癫痫发作（9例）、视力障碍（5例）、意识障碍（9例）、头痛（7例）、恶心呕吐（3例）；10例患者存在肾功能损害。颅脑C T 及M R检查示病灶累及顶枕叶（10例）、额叶（3例）、基底节（3例）、小脑（2例）和脑干（2例），M RI均呈长T1长T2信号，T2 flair高信号，DWI等信号（7例）或略高信号（1例）；颅脑CT 呈低密度（8例）或等密度（2例）；边界欠清。经积极对因对症治疗，本组患者症状在中位数4d（QL3.25d，QU5d）后几乎完全缓解，影像学表现在中位数9 d（QL 7.25 d ，QU 10.75 d）后得到完全或大部分恢复。结论 PRES以癫痫发作、视力障碍、意识障碍、头痛、恶心呕吐为主要临床表现，影像学改变以可逆的、多分布于后循环供血区的皮层下脑白质血管源性水肿为特点， MRI呈T1低信号、T2及T2 flair高信号，DWI等/略高信号，CT呈低/等密度。积极治疗后多数患者症状可完全缓解，影像学表现可完全或大部分恢复。