NURBS Parameterization for Medical Surface Reconstruction

InVesalius is an open-source software for reconstruction of computed tomography and magnetic resonance images, which allows the user to make analysis and segmentation of virtual anatomical models. Physical models can be printed with the aid of rapid prototyping, giving the medical community a reliable instrument to help planning surgeries. To offer the user more control over the model, this work describes a methodology and tool developed for NURBS parameterization that provides mechanisms for adjusting the shape or even selecting a particular region of interest of the surface. Furthermore, the tool gives the option to export the final results of the process to a STEP file, which allows further edition in any well-known CAD software.

Criticality Search of an Accelerator Driven System Using the ANET Code

One of the most important safety parameters taken into consideration during the design and actual operation of a nuclear reactor is its control rods adjustment to reach criticality. Concerning the conventional nuclear systems, the specification of their rods’ position through the utilization of neutronics codes, deterministic or stochastic, is considered nowadays trivial. However, innovative nuclear reactor concepts such as the Accelerator Driven Systems require sophisticated simulation capabilities of the stochastic neutronics codes since they combine high energy physics, for the spallation-produced neutrons, with classical nuclear technology. ANET (Advanced Neutronics with Evolution and Thermal hydraulic feedback) is an under development stochastic neutronics code, able to cover the broad neutron energy spectrum involved in ADS systems and therefore capable of simulating conventional and hybrid nuclear reactors and calculating important reactor parameters. In this work, ANETS’s reliability to calculate the effective multiplication factor for three core configurations containing control rods of the Kyoto University Critical Assembly, an operating ADS, is examined. The ANET results successfully compare with results produced by well-established stochastic codes such as MCNP6.1.

Fatty liver disease,an emerging etiology of hepatocellular carcinoma in Argentina

AIM To investigate any changing trends in the etiologies of hepatocellular carcinoma(HCC) in Argentina during the last years. METHODS A longitudinal cohort study was conducted by 14 regional hospitals starting in 2009 through 2016. All adult patients with newly diagnosed HCC either with pathology or imaging criteria were included. Patients were classified as presenting non-alcoholic fatty liver disease(NAFLD) either by histology or clinically, provided that all other etiologies of liver disease were ruled out, fatty liver was present on abdominal ultrasound and alcohol consumption was excluded. Complete follow-up was assessed in all included subjects since the date of HCC diagnosis until death or last medical visit.RESULTS A total of 708 consecutive adults with HCC were included. Six out of 14 hospitals were liver transplant centers(n = 484). The prevalence of diabetes mellitus was 27.7%. Overall, HCV was the main cause of liver disease related with HCC(37%) including cirrhotic and non-cirrhotic patients, followed by alcoholic liver disease 20.8%, NAFLD 11.4%, cryptogenic 9.6%, HBV 5.4% infection, cholestatic disease and autoimmune hepatitis 2.2%, and other causes 9.9%. A 6-fold increase in the percentage corresponding to NAFLDHCC was detected when the starting year, i.e., 2009 was compared to the last one, i.e., 2015(4.3% vs 25.6%; P < 0.0001). Accordingly, a higher prevalence of diabetes mellitus was present in NAFLD-HCC group 61.7% when compared to other than NAFLD-HCC 23.3%(P < 0.0001). Lower median AFP values at HCC diagnosis were observed between NAFLD-HCC and non-NAFLD groups(6.6 ng/m L vs 26 ng/m L; P = 0.02). Neither NAFLD nor other HCC etiologies were associated with higher mortality.CONCLUSION The growing incidence of NAFLD-HCC documented in the United States and Europe is also observed in Argentina, a confirmation with important Public Health implications.

Intermediate-advanced hepatocellular carcinoma in Argentina:Treatment and survival analysis

BACKGROUND Hepatocellular carcinoma(HCC) represents the sixteenth most frequent cancer in Argentina. The rise of new therapeutic modalities in intermediate-advanced HCC opens up a new paradigm for the treatment of HCC.AIM To describe real-life treatments performed in patients with intermediateadvanced HCC before the approval of new systemic options.METHODS This longitudinal observational cohort study was conducted between 2009 and2016 in 14 different regional hospitals from Argentina. Included subjects had intermediate-advanced Barcelona Clinic Liver Cancer(BCLC) HCC stages(BCLC B to D). Primary end point analyzed was survival, which was assessed for each BCLC stage from the date of treatment until last patient follow-up or death.Kaplan Meier survival curves and Cox regression analysis were performed, with hazard ratios(HR) calculations and 95% confidence intervals(95%CI).RESULTS From 327 HCC patients, 41% were BCLC stage B, 20% stage C and 39% stage D.Corresponding median survival were 15 mo(IQR 5-26 mo), 5 mo(IQR 2-13 mo)and 3 mo(IQR 1-13 mo)(P < 0.0001), respectively. Among BCLC-B patients(n =135), 57% received TACE with a median number of 2 sessions(IQR 1-3 sessions).Survival was significantly better in BCLC-B patients treated with TACE HR =0.29(CI: 0.21-0.40) than those without TACE. After tumor reassessment by RECIST 1.1 criteria following the first TACE, patients with complete response achieved longer survival (HR = 0.15(CI: 0.04-0.56, P = 0.005))Eighty-two patients were treated with sorafenib, mostly BCLC-B and C(87.8%). However,12.2% were BCLC-D. Median survival with sorafenib was 4.5 mo(IQR 2.3-11.7 mo);which was lower among BCLC-D patients 3.2 mo(IQR 2.0-14.1 mo). A total of 36 BCLC-B patients presented tumor progression after TACE. In these patients,treatment with sorafenib presented better survival when compared to those patients who received sorafenib without prior TACE [HR = 0.26(CI: 0.09-0.71);P= 0.013].CONCLUSION In this real setting, our results were lower than expected. This highlights unmet needs in Argentina, prior to the introduction of new treatments for HCC.

Qualification of the ANET Code for Spallation Neutron Yield and Core Criticality in the KUCA ADS

Innovative nuclear reactor concepts such as the Accelerator Driven Systems (ADSs) have imposed extra requirements of simulation capabilities on the existing stochastic neutronics codes. The combination of an accelerator and a nuclear reactor in the ADS requires the simulation of both subsystems for an integrated system analysis. Therefore, a need arises for more advanced simulation tools, able to cover the broad neutron energy spectrum involved in these systems. ANET (Advanced Neutronics with Evolution and Thermal hydraulic feedback) is an under development stochastic code for simulating conventional and hybrid nuclear reactors. Successive testing applications performed throughout the ANET development have been utilized to verify and validate the new code capabilities. In this context, the ANET reliability in simulating the spallation reaction and the corresponding neutron yield as well as computing the multiplication factor of an operating ADS are here examined. More specifically, three cores of the Kyoto University Critical Assembly (KUCA) facility in Japan were analyzed focusing on the spallation neutron yield and the neutron multiplication factor. The ANET-produced results are compared with independent results obtained using the stochastic codes MCNP6.1 and MCNPX. Satisfactory agreement is found between the codes, confirming thus ANET’s capability to successfully estimate both the neutron yield of the spallation reaction and the keff of a realistic ADS.

生活在“高处”

圣经《新约·马太福音》中的一则寓言：“凡有的，还要加给他叫他多余；没有的，连他所有的也要夺过来。”这则寓言是著名的“马太效应”名字的出处。马太效应指强者愈强、弱者愈弱的现象，如果用它来解释“大卫塔”好像再贴切不过了。