OBJECTIVE: The biological characteristics of schizophrenia are often studied by using functional imaging techniques. However, since volunteers with schizophrenia routinely fail to perform as accurately or as quickly as healthy volunteers, it is difficult to ascertain whether a particular deficit in blood flow to a brain region is due to behavior or to the underlying illness. In this report, investigators used an auditory recognition task to assess brain blood flow patterns and behavioral correlates of schizophrenic patient volunteers trained on the task. METHOD: Twelve healthy volunteers and 18 volunteers with schizophrenia were trained to make tone frequency recognitions. Accuracy and stimuli were matched between groups. Participants were required to press a button to indicate whether a briefly presented tone was the high-frequency (1500 Hz) reference tone or one of a lower frequency level (level chosen to elicit an 80% accuracy score). Subjects underwent bolus [(15)O]H(2)O blood flow positron emission tomography during inactive rest, a sensory motor control condition, and the decision task. Blood flow patterns were assessed between conditions and between groups. RESULTS: As a group, the patients with schizophrenia (who performed as quickly and accurately as the comparison subjects) exhibited significantly less change in regional cerebral blood flow (rCBF) to the anterior cingulate and supplementary motor cortices when switching from the sensory motor control to the decision condition. There were also marked between-group differences in correlations between rCBF and response time. Whereas the comparison subjects exhibited progressively greater blood flow to the frontal cortex in association with longer response times, the schizophrenic patients exhibited progressively lower blood flow in conjunction with extended response times. CONCLUSIONS: The failure to appropriately enhance cingulate activity when engaged in a demanding task and the progressive, time-dependent decline in frontal blood flow suggest that patients with schizophrenia are unable to make optimal use of frontocingulate systems when maximally engaged in high-error tasks. 相似文献
In 1798, President John Adams signed the bill creating the Marine Hospital Service to medically care for U.S. merchant seamen. That agency is known today as the U.S. Public Health Service (PHS). In 1918, the PHS Commissioned Corps commissioned sanitary engineers in the Reserve Corps, and in 1930, President Herbert Hoover signed the Parker Act authorizing sanitary engineers to be part of the regular Commissioned Corps. During the world war years, PHS engineers were detailed to improve sanitation for military bases in the United States and abroad. In the 1960s, most PHS engineers served in the Indian Health Service, upgrading sanitation facilities for American Indians and Alaskan Natives. During the 1970s, PHS engineers were involved in providing an integrated and coordinated attack on environmental issues. Today, PHS engineers are involved with many aspects of public health protection and have been detailed around the world to provide emergency assistance in the wake of disasters. 相似文献
: The measurement of complex dose distributions (those created by irradiation through multiple beams, multiple sources, or multiple source dwell positions) requires a dosimeter that can integrate the dose during a complete treatment. Integrating dosimeter devices generally are capable of measuring only dose at a point (ion chamber, diode, TLD) or in a plane (film). With increasing use of conformal dose distributions requiring shaped, noncoplanar beams, there will be an increased requirement for a dosimeter that can record and display a 3D dose distribution. The use of a 3D dosimeter will be required to confirm the accuracy of treatment plans produced by the current generation of 3D treatment-planning computers.
: The use of a Fricke-infused gel and magnetic resonance imaging (MRI) to demonstrate the localization of stereotactic beams has been demonstrated (11). The recently developed BANG polymer gel dosimetry system (MGS Research, Inc., Guilford, CT), based on radiation-induced chain polymerization of acrylic monomers dispersed in a tissue-equivalent gel, surpasses ther Fricke-gel method by providing accurate, quantitative dose distribution data that do not deteriorate with time (6, 9). The improved BANG2 formulation contains 3% N,N′-methylene-bisacrylamide, 3% acrylic acid, 1% sodium hydroxide, 5% gelatin, and 88% water, where all percentage are by weight. The gel was poured into volumetric flasks, of dimensions comparable to a human head. The gels were irradiated with complex beam arrangements, similar to those used for conformal radiation therapy. Images of the gels were acquired using a Siemens 1.5T imager and a Hahn spin-echo pulse sequence (90°-τ-180°-τ-acquire, for different values of τ). The images were transferred via network to a Macintosh computer for which a data analysis and display program was written. The program calculates R2 maps on the basis of multiple TE images, using a monoexponential nonlinear least-squares fit based on the Levenberg-Marquardt algorithm. The program also creates a dose-to-R2 calibration function by fitting a polynomial to a set of dose and R2 data points, obtained from gels irradiated in test tubes to known doses. This function can then be applied to any other R2 map, so that a dose map can be computed and displayed.
: Through exposure to known doses of radiation, the gel has been shown to respond linearly with dose in the range of 0 to 10 Gy, and its response is independent of the beam energy or modality. Dose distributions have been imaged in orthogonal planes, and can be displayed in a convenient form for comparison with isodose plans. The response of the gel is stable; the gel can be irradiated at any time after its manufacture, and imaging can be conducted any time following a brief interval after irradiation.
: The polymer gel dosimeter has been shown to be a valuable device for displaying three-dimensional dose distributions. The imaged dose distribution can be compared easily with calculated dose distributions, to validate a treatment planning system. In the future, gels may be prepared in anthropomorphic phantoms, to confirm unique patient dose distributions. 相似文献
We have previously reported that children receive significantly less radiation exposure after abdominal and/or pelvis computed tomography (CT) scanning for acute appendicitis when performed at our children's hospital (CH) rather than at outside hospitals (OH). In this study, we compare the amount of radiation children receive from head CTs for trauma done at OH versus those at our CH.
Methods
A retrospective chart review was performed on all children transferred to our hospital after receiving a head CT for trauma at an OH between July 2012 and December 2012. These children were then blindly case matched based on date, age, and gender to children at our CH.
Results
There were 50 children who underwent head CT scans for trauma at 28 OH. There were 21 females and 29 males in each group. Average age was 7.01 ± 0.5 y at the OH and 7.14 ± 6.07 at our CH (P = 0.92). Average weight was 30.81 ± 4.69 kg at the OH and 32.69 ± 27.21 kg at our CH (P = 0.81). Radiation measures included dose length product (671.21 ± 22.6 mGycm at OH versus 786.28 ± 246.3 mGycm at CH, P = 0.11) and CT dose index (53.4 ± 2.26 mGy at OH versus 49.2 ± 12.94 mGy at CH, P = 0.56).
Conclusions
There is no significant difference between radiation exposure secondary to head CTs for traumatic injuries performed at OH and those at a dedicated CH. 相似文献
Background and Aim: Little is known about the causes of overt obscure gastrointestinal bleeding (OGIB) in patients using anti‐thrombotic therapy. We aimed to describe video capsule endoscopy (VCE) findings and to identify factors associated with positive findings in these patients. Methods: We carried out a retrospective study of 56 patients who underwent VCE for evaluation of previous overt OGIB during anti‐thrombotic therapy. VCE studies were re‐evaluated by a gastroenterologist blinded to clinical details. Clinical data included in the multivariate analysis were sex, age, indication for and type of anti‐thrombotic therapy, hemodynamic instability on admission, type of blood loss, hemoglobin on admission, use of a proton pump inhibitor, NSAID use, time between bleeding episodes and VCE, and whether or not anti‐thrombotic therapy was resumed before the VCE study. Results: A probable cause for gastrointestinal bleeding was identified in 28 (50%) of the 56 studies. Angiodysplasia was found in 19 patients. Twenty‐two studies showed a possible cause in the small bowel. Multivariate logistic regression analysis showed that reinstitution of anti‐thrombotic therapy before VCE was carried out was the only independent predictor of positive VCE findings (OR: 8.61, 95% CI: 1.20–60.42, P = 0.032). Conclusions: Small intestinal angiodysplasia was the most common cause for overt OGIB. Reinstitution of withdrawn anti‐thrombotic drugs before the VCE examination was carried out was associated with positive VCE findings in multivariate analysis. 相似文献
During a multiple-casualty incident, a large casualty caseload adversely affects the quality of trauma care given to individual patients. From a trauma care perspective, the goal of the hospital emergency plan is to provide severely injured patients with a level of care that approximates the care given to similar patients under normal conditions. Therefore, the realistic admitting capacity of the hospital is determined primarily by the number of trauma teams that the hospital can recruit. Effective triage of these casualties is often not straightforward, with high overtriage rates. Simplified triage algorithms may be a practical alternative to more elaborate schemes. The concept of minimal acceptable care is the key to a staged management approach during a mass-casualty incident. Discrete-event computer simulation and war game tabletop exercises for key personnel are 2 new modalities that are supplementing the traditional mock disaster drill as effective planning and training tools. 相似文献