Computed Tomography An Increasing Source of Radiation Exposure Free Essay Example, 1500 words

While tube current is varied cyclically in relation to the starting tube current value in angular tube current modulation, longitudinal tube current modulation aims to produce uniform noise levels across various regions. For this, the operator uses the following manufacturer-specific methods: the reference noise index (GE Healthcare Technologies, Waukesha, Wis), reference image acquisition (Philips Medical Systems, Best, the Netherlands), reference tube current-time product value (Siemens Medical Solutions, Forchheim, Germany), or reference standard deviation or image quality level (Toshiba Medical Systems, Tokyo, Japan). This gives the operator the required level of image quality for input to the algorithm (McCollough, Bruesewitz, and Kofler 2006.)c. Angular-longitudinal tube current modulation-this involves the simultaneous combination of angular and longitudinal (x-, y-, and z-axis) tube current modulation. The tube current is varied during both gantry rotation and along the z-ax is of the patient (i. e., from the anteroposterior direction to the lateral direction, and from the shoulders to the abdomen). As before, the operator uses the manufacturer-specific methods to indicate the desired level of image quality. Since the x-ray dose is adjusted according to the patient-specific attenuation in all three planes, this method is the most comprehensive approach to dose reduction (McCollough, Bruesewitz, and Kofler 2006)d. We will write a custom essay sample on Computed Tomography: An Increasing Source of Radiation Exposure or any topic specifically for you Only $17.96 $11.86/pageorder now Automatic exposure control (AEC)-while the operator determines the image quality requirements, the CT system determines the right tube current-time product. However, it may not be that easy to determine the image quality requirements for the various patient age groups and CT examination types. Depending on the diagnostic task, the operator can make a choice between low noise and a low dose to get the required image quality. Based on this, the CT system will make adjustments to the tube current during the gantry rotation, during movement along the z-axis, or during movement in all three dimensions (McCollough, Bruesewitz, and Kofler 2006).

Whats Going Wrong in Public School - 1743 Words

What is going wrong with schools? There is a lot wrong with schools, and easier question these days is, Whats right with schools? Sadly the list would be shorter. The public school system in America today is sadly lacking, not just in the field of academic achievement. Children are, in effect, risking their lives by attending school. Critical attacks from disturbed students are spreading like a plague. Every year, there is increase in the number of students who give up education after high school and start working in minimum wage jobs/unskilled jobs. Stereotypes between smart and dumb students and racism are the biggest issues student faces in school education system. The public education system always gives priority to students who†¦show more content†¦The education gap in the U.S. between different races is growing wider and wider, and equal education opportunity is being undermined. Although free universal public education was adopted early in U.S. history, equal oppor tunity has never been realized. In the movie Escalante stated that those (AP Calculus) scores would have never been questioned if my kids did not have Spanish surnames and come from barrio schools. You know that When ethnicity and culture are made indistinguishable, schools become full with stereotypes. The school which supposes to teach students that we are all equal is the cause of racism. Moore argued in his essay saying that students learn stuff which they are forced to learn. Also, students tend to learn more from the environment where they spend most of their time in. They learn that to rock the boat could get them rocked right out of the school. Dont question authority. Do as youre told. Dont think, just do as I say(Moore 168). Both movie and Moores essay illustrates that how racism is followed by various grop od people, directly and indirectly. Most of the time in past and at some point in present, racism have been mainly practiced by teachers and they are the one tell thei r students to follow it. Racism has its roots in the belief that some people are superior because they belong to a particular race, ethnic or national group. In any measures, racism weakens childrens self-esteem and grind down the educational process. TheShow MoreRelatedPublic Schools Should Not Be The Place For Religious Practices1601 Words   |  7 Pagesimmediately conflicts arose between religions, and their belief systems. No problems seem to arise with teaching religion to children in school until the 1900 s. That is when the courts decided religious instructions in public schools would be deemed unconstitutional. Court cases started around the country with people fighting against religious instruction in public schools, many accusing teachers of putting their beliefs in their teachings. 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3 Most Important Events in World History free essay sample

3 Most Important Events in World History Many events have shaped the world to what it is today. Events such as the writing of the Communist Manifesto, the Black Death, and World War II were very important in history and their effects can still be seen today. If not for these monumental events the world would be a very different place. The first one of these to occur was the Black Death. The Black Death is believed to have been spread from Asia, originating in Europe in Italy. It was a horrible disease with a mortality rate of seventy-five percent. The first effect it had on Europe was that t annihilated most of the European population. Out of fear or due to death, farmers abandoned their farms. This caused a food shortage and caused even more deaths than the plague had already. This caused prices of food to sky rocket and not return to normal prices until long after the plague had passed. We will write a custom essay sample on 3 Most Important Events in World History or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page It also redistributed the population and wealth among Europeans and almost reset the credit system in Europe because most debtors and creditors had died. This had a profound effect on future generations, giving them a fresh start. The second one of these was the writing of the Communist Manifesto. Written in the mid eighteen-hundreds by Karl Marx and Friedrich Engels, it was the start of Marxism which in turn spawned communism. Communism is one of the great world ideas, and is a very powerful idea. Communist ideas have done many great and important things. The first effect they had was inspiring the Bolshevik Revolution. This created the first communist state and sparked a wildfire of red. The fallout of Soviet Russia included, but isnt limited to the Cold War and the Cuban Missile Crisis. It gave rise to great powers like Lenin, Stalin, and Castro, and still impacts the Worlds olitical climate today. The third important occurrence was World War II. In the aftermath of World War II, Europe was in ruins. After the allies were declared victorious, the boundaries of Europe were redrawn, and it was left up to the allied powers to rebuild the areas of high conflict. World War II also created the superpowers of the United States and the Soviet Union. This created a world which seemed predominantly ruled by these two powerful countries and in many ways it was. Also due to World War II, nuclear warfare was introduced to the worlds mind, and the threat of nuclear exchange was large contributing factor to the Cold War, another major event in World History. Perhaps the most daunting effect of World War II however was the Holocaust and the discovery of its final death count. The Holocaust is what most people consider to be one of the worst crimes man has ever committed, and it must be of grave importance to us if we wish not to repeat it. In reality more than Just these three events shaped the world. These however are the ones I found most important. These events were incredibly important and had great impact. It could truly be wondered what the world would be like if these events had never occurred.