Low dose rate γ-ray detection using a MAPS camera under a neutron radiation environment.

We present γ-ray radiation detection in a neutron radiation environment using a monolithic active pixel sensor (MAPS) camera without conversion or shielding layers. The measured output signal is the sum of the pedestal value, noise, and real radiation response signal. The sensor response shows that the MAPS camera is sensitive to neutrons and can capture a single photon. The number of pixels with a signal exceeding 100 exhibits a strong dependence on the dose rate and is the best indicator of this value. Therefore, a MAPS camera can be efficiently used as a radiation detection sensor in a robotic system, further limiting human errors in performing radiation detection in complex nuclear radiation environments.

Using SEMAC at 3 T MR to evaluate spinal metallic implants and peripheral soft tissue lesions.

We aimed to assess the usefulness of slice-encoding metal artifact correction (SEMAC) for the evaluation of spinal metallic implants and peripheral soft tissue lesions at 3T magnetic resonance.Twenty-seven patients with spinal metal implants underwent both SEMAC and high bandwidth (HiBW) based sequences scanning for reduction artifacts. The area size and maximum longitude of artifacts, the peri-prosthetic soft tissue, and metal visualization were assessed by 2 independent doctors, as well as the lesions signs were reviewed by 2 senior readers. A paired 2-tailed t-test and McNemar test were used for statistical analysis.The size of artifacts on SEMAC images decreased by 37% and 24%, and the scores are higher than that on HiBW images. T1 weighted (T1W)-SEMAC acquired the highest score in metal prosthesis visualization, while short tau inversion recovery SEMAC showed more signs of lesions than clinical HiBW group.SEMAC effectively reduces the metal artifacts and is useful for assessing soft tissue lesions.

[Beneficial effect of thyrotropin-releasing hormone in combination with HSD on hemorrhagic shock with pulmonary edema at high altitude in the rat].

OBJECTIVE: To study the effects of thyrotropin-releasing hormone (TRH) in combination with hypertonic saline/dextran (7.5% NaCl + 6% Dextran 40, HSD ) on hemorrhagic shock with pulmonary edema in the rats which were recently brought to high altitude. METHODS: Forty-nine SD rats, transported to Lasa, Tibet, which was 3,760 meters above the sea level, were anesthetized one week later with sodium pentobarbital (30 mg/kg, intraperitoneal). Hemorrhagic shock with pulmonary edema was induced by hemorrhage (50 mm Hg maintained for 1 hour,1 mm Hg=0.133 kPa) plus intravenous injection of oleic acid (50 microl/kg). They were equally divided into seven groups (n=7): normal control, hemorrhagic shock, hemorrhagic shock with pulmonary edema (HSPE), HSPE plus TRH (5 mg/kg), HSPE plus HSD (4 ml/kg), and HEPE plus TRH and HSD in combination. Hemodynamic parameters including mean arterial blood pressure(MAP), left intraventricular systolic pressure (LVSP) and the maximal change rate of intraventricular pressure rise or decline (+/- dp/dt max) were observed at 15, 30, 60 and 120 minutes, blood gases were analyzed at 30 and 120 minutes, and the water content of lung and brain was determined at 120 minutes after drug administration. RESULTS: TRH or HSD used alone or in combination significantly increased MAP, LVSP and +/- dp/dt max (P<0.05 or P<0.01 ), ameliorated acid-base imbalance, and decreased the water content of lung and brain. The effect of the two in combination was superior to either drug used alone. CONCLUSION: TRH in combination with HSD can be used in the treatment of hemorrhagic shock with pulmonary edema at high altitude.

[Effect of different volumes of fluid resuscitation on hemorrhagic shock with pulmonary edema at high altitude in the unacclimated rat].

OBJECTIVE: To study the effects of different volumes of fluid resuscitation on hemorrhagic shock with pulmonary edema at high altitude in the unacclimated rat. METHODS: One hundred and twenty-six SD rats transported to Lasa, Tibet, 3 760 meters above the sea level, were anesthetized one week later with sodium pentobarbital (30 mg/kg, intraperitoneal). Hemorrhagic shock with pulmonary edema model was induced by hemorrhage (50 mm Hg for 1 hour, 1 mmHg=0.133 kPa) plus intravenous injection of oleic acid (50 microl/kg). Experiments were then conducted in two parts. Sixty-three rats in part I were equally divided into nine groups (n=7): normal control, hemorrhagic shock control, hemorrhagic shock with pulmonary edema (HSPE) without fluid infusion, HSPE plus infusing lactated Ringer's solution (LR) with 0.5-, 1-, 1.5-, 2- or 3- fold volume shed blood, and 1 volume of LR plus mannitol (10 ml/kg). Hemodynamic parameters including mean arterial blood pressure (MAP), left intraventricular systolic pressure (LVSP) and the maximal change rate of intraventricular pressure rise or decline (+/- dp/dt max) were observed at 15, 30, 60 and 120 minutes after infusion, blood gases were measured at 30 and 120 minutes after infusion and the water content of lung and brain was determined at 120 minutes after infusion. In part II, additional 63 rats were used to observe the effect of different volumes of fluid resuscitation on survival time of HSPE rats. RESULTS: 0.5 volume of LR infusion significantly improved MAP, LVSP and +/- dp/dt max, prolonged the survival time of HSPE animals (all P<0.01), while it did not increase the water content of lung and brain and had no marked influence on blood gases. One volume of LR infusion slightly improved hemodynamic parameters, prolonged the survival time and increased the water content of lung. More than 1 volume of LR infusion including 1.5-, 2- and 3- fold volume LR deteriorated the hemodynamic parameters and decreased the survival time of shocked animal, meanwhile they apparently increased the water content of lung. One volume of LR plus mannitol (10 ml/kg) infusion did not improve the hemodynamic parameters and blood gases; also it did not decrease the water content of lung. CONCLUSION: The tolerance to fluid infusion for the unacclimated animal subjected to hemorrhagic shock with pulmonary edema at high altitude is significantly decreased. 0.5-1 volume of LR infusion appears to be beneficial effect on resuscitation at high altitude, while over 1 volume of LR infusion would aggravate pulmonary edema and exacerbate fluid resuscitation effect.