First experimental time-of-flight-based proton radiography using low gain avalanche diodes.

Objective.Ion computed tomography (iCT) is an imaging modality for the direct determination of the relative stopping power (RSP) distribution within a patient's body. Usually, this is done by estimating the path and energy loss of ions traversing the scanned volume utilising a tracking system and a separate residual energy detector. This study, on the other hand, introduces the first experimental study of a novel iCT approach based on time-of-flight (TOF) measurements, the so-called Sandwich TOF-iCT concept, which in contrast to any other iCT systems, does not require a residual energy detector for the RSP determination.Approach.A small Sandwich TOF-iCT demonstrator was built based on low gain avalanche diodes (LGADs), which are 4D-tracking detectors that allow to simultaneously measure the particle position and time-of-arrival with a precision better than 100µm and 100 ps, respectively. Using this demonstrator, the material and energy-dependent TOF was measured for several homogeneous PMMA slabs in order to calibrate the acquired TOF against the corresponding water equivalent thickness (WET). With this calibration, two proton radiographs (pRads) of a small aluminium stair phantom were recorded at MedAustron using 83 MeV and 100.4 MeV protons.Main results.Due to the simplified WET calibration models used in this very first experimental study of this novel approach, the difference between the measured and theoretical WET ranged between 37.09% and 51.12%. Nevertheless, the first TOF-based pRad was successfully recorded showing that LGADs are suitable detector candidates for Sandwich TOF-iCT.Significance.While the system parameters and WET estimation algorithms require further optimization, this work was an important first step to realize Sandwich TOF-iCT. Due to its compact and cost-efficient design, Sandwich TOF-iCT has the potential to make iCT more feasible and attractive for clinical application, which, eventually, could enhance the treatment planning quality.

Cardiolipin-Targeted NIR-II Fluorophore Causes "Avalanche Effects" for Re-Engaging Cancer Apoptosis and Inhibiting Metastasis.

Restoring innate apoptosis and simultaneously inhibiting metastasis by a molecular drug is an effective cancer therapeutic approach. Herein, a large rigid and V-shaped NIR-II dye, DUT850, is rationally designed for potential cardiolipin (CL)-targeted chemo-phototheranostic application. DUT850 displays moderate NIR-II fluorescence, excellent photodynamic therapy (PDT) and photothermal therapy (PTT) performance, and ultra-high photostability. More importantly, the unique rigid V-shaped backbone, positive charge, and lipophilicity of DUT850 afford its specific recognition and efficient binding to CL; such an interaction of DUT850-CL induced a spectrum of physiological disruptions, including translocation of cytochrome c, Ca2+ overload, reactive oxygen species burst, and ATP depletion, which not only activated cancer cell apoptosis but also inhibited tumor metastasis both in vitro and in vivo. Furthermore, the tight binding of DUT850-CL improves the phototoxicity of DUT850 toward cancer cells (IC50 as low as 90 nM) under safe 808 nm laser irradiation (330 mW cm-2). Upon encapsulation into bovine serum albumin (BSA), DUT850@BSA exerted a synergetic chemo-PDT-PTT effect on the 4T1 tumor mouse model, eventually leading to solid tumor annihilation and metastasis inhibition, which could be followed in real time with the NIR-II fluorescence of DUT850. This work contributed a promising approach for simultaneously re-engaging cancer cell apoptotic networks and activating the anti-metastasis pathway by targeting a pivotal upstream effector, which will bring a medical boon for inhibition of tumor proliferation and metastasis.

CPR with restricted patient access using alternative rescuer positions: a randomised cross-over manikin study simulating the CPR scenario after avalanche burial.

BACKGROUND: The aim of this manikin study was to evaluate the quality of cardiopulmonary resuscitation (CPR) with restricted patient access during simulated avalanche rescue using over-the-head and straddle position as compared to standard position. METHODS: In this prospective, randomised cross-over study, 25 medical students (64% male, mean age 24) performed single-rescuer CPR with restricted patient access in over-the-head and straddle position using mouth-to-mouth ventilation or pocket mask ventilation. Chest compression depth, rate, hand position, recoil, compression/decompression ratio, hands-off times, tidal volume of ventilation and gastric insufflation were compared to CPR with unrestricted patient access in standard position. RESULTS: Only 28% of all tidal volumes conformed to the guidelines (400-800 ml), 59% were below 400 ml and 13% were above 800 ml. There was no significant difference in ventilation parameters when comparing standard to atypical rescuer positions. Participants performed sufficient chest compressions depth in 98.1%, a minimum rate in 94.7%, correct compression recoil in 43.8% and correct hand position in 97.3% with no difference between standard and atypical rescuer positions. In 36.9% hands-off times were longer than 9 s. CONCLUSIONS: Efficacy of CPR from an atypical rescuer position with restricted patient access is comparable to CPR in standard rescuer position. Our data suggest to start basic life-support before complete extrication in order to reduce the duration of untreated cardiac arrest in avalanche rescue. Ventilation quality provided by lay rescuers may be a limiting factor in resuscitation situations where rescue ventilation is considered essential.

Performance of a low gain avalanche detector in a medical linac and characterisation of the beam profile.

Low gain avalanche detectors can measure charged particle fluences with high speed and spatial precision, and are a promising technology for radiation monitoring and dosimetry. A detector has been tested in a medical linac where single particles were observed with a time resolution of 50 ps. The integrated response is similar to a standard ionising chamber but with a spatial precision twenty times finer, and a temporal precision over 100 million times better, with the capability to measure the charge deposited by a single linac pulse. The unprecedented resolving power allows the structure of the ∼3 µs linac pulses to be viewed and the 350 ps sub-pulses in the train to be observed.

Risk Factors for Posttraumatic Stress Symptoms Among Avalanche Survivors: A 16-Year Follow-Up.

Few natural disaster studies have assessed factors associated with posttraumatic stress disorder (PTSD) beyond a decade after trauma. Using North's disaster model as a framework, the aim of this study was to identify factors associated with clinically significant posttraumatic stress symptoms (CS-PTSDS) in avalanche survivors (n = 399) 16 years after the disaster. Completed self-report questionnaires were received from 286 (72%) survivors. CS-PTSDS were assessed with the Posttraumatic Diagnostic Scale. Predictors of CS-PTSDS in a multivariate analysis were secondary sequelae factors of lack of social support (adjusted relative risk [RR], 2.90; 95% confidence interval [CI], 1.37-6.13) and financial hardship in the aftermath of the trauma (adjusted RR, 2.47; 95% CI, 1.16-5.26). In addition, the community factor of providing assistance in the aftermath of the avalanche (adjusted RR, 1.95; 95% CI, 1.04-3.64) was inversely associated with CS-PTSDS. Screening for these factors may be useful in identifying those most vulnerable to developing chronic PTSD after this unique type of disaster.

[Management of severe accidental hypothermia]. / Manejo de la hipotermia accidental severa.

Accidental hypothermia is an environmental condition with basic principles of classification and resuscitation that apply to mountain, sea or urban scenarios. Along with coagulopathy and acidosis, hypothermia belongs to the lethal triad of trauma victims requiring critical care. A customized healthcare chain is involved in its management, extending from on site assistance to intensive care, cardiac surgery and/or the extracorporeal circulation protocols. A good classification of the degree of hypothermia preceding admission contributes to improve management and avoids inappropriate referrals between hospitals. The most important issue is to admit hypothermia victims in asystolia or ventricular fibrillation to those hospitals equipped with the medical technology which these special clinical scenarios require. This study attempts to establish the foundations for optimum management of accidental hypothermia from first emergency care on site to treatment in hospital including, resuscitation and rewarming with extracorporeal circulation.

ETNOGRAFÍAS SOCIO-TERRITORIALES DE LA MIGRACIÓN Y LA MOVILIDAD EN EL MAGDALENA MEDIO: Los casos de la avalancha de Armero, la Reserva de Mariquita y la gentrificación de Honda / SOCIAL-TERRITORIAL ETHNOGRAPHIES OF MIGRATION AND MOBILITY IN THE MID MAGDALENA RIVER BASIN: The cases of Armero Avalanche, Mariquita Reservoir, and Honda Gentrification

Este artículo trata de ciertos tipos de migración y movilidad en Mariquita, Armero-Guayabal y Honda, municipios del Magdalena Medio caldense y tolimense. El problema que se planeta es cómo la migración y la movilidad no son procesos unívocos, ni se pueden estudiar a partir de una sola dinámica; por el contrario, se entrecruzan circunstancias no sólo de causa de estos fenómenos, sino también de implicaciones en los lugares de llegada o acogida que, en su conjunto (causas e implicaciones), dan explicación a la existencia de la migración y la movilidad de personas, bienes y servicios. La metodología que se sigue es la de multiplanos etnográficos, tomando como discurso de referencia las voces directas de los narradores que fueron entrevistados en distintos momentos y escenarios de sus propios municipios durante los años 2008 y 2009.

This article describes certain types of migration and mobility in Mariquita, Armero-Guayabal and Honda, municipalities belonging to the mid Magdalena River basin in Caldas and Tolima (Colombia). The problem presented is how migration and mobility are neither univocal processes nor they can they be studied from a unique dynamic; on the contrary, they crosslink circumstances not only of the causes of this phenomena but also of the implications in the arrival or reception places which, together (causes and implications) explain the existence of people, goods and services migrations and mobility. The methodology used was the ethnographic multi-plane method taking as a reference discourse the live voices of the narrators which were interviewed at different times and sceneries of their own municipalities during 2008 and 2009.