Basics Of Ct And Mri Pdf
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There are several types of these imaging tests that help the doctor make an accurate diagnosis and choose the ideal treatment plan. Each imaging test uses different technology to create images that help your doctor identify certain medical complications. Three common types of imaging devices are x-rays, computed tomography CT scans and magnetic resonance imaging MRIs tests. Your physician may order one test or multiple tests. You might be anxious about having these tests performed, but diagnostic imaging scans are generally painless and non-invasive. Still, it can be helpful to get an understanding of how they each work and their common uses.
Computed tomography CT scanning is an extremely common imaging modality in modern medicine. With advancements in technology, it is rapidly replacing many diagnostic radiographic procedures. In this article, we will outline the basic science behind CT scans, describe the principles of interpretation , and highlight their advantages and drawbacks compared to other imaging techniques. The scanner emits x-rays towards the patient from a variety of angles — and the detectors in the scanner measure the difference between the x-rays that are absorbed by the body, and x-rays that are transmitted through the body. This is called attenuation.
CT Scan vs. MRI
CT scans and MRIs are both used to capture images within your body. The biggest difference is that MRIs magnetic resonance imaging use radio waves and CT computed tomography scans use X-rays. While both are relatively low risk, there are differences that may make each one a better option depending on the circumstances. A constant magnetic field and radio frequencies bounce off of the fat and water molecules in your body. Radio waves are transmitted to a receiver in the machine which is translated into an image of the body that can be used to diagnose issues.
X-Ray vs. CT vs. MRI
These slices are called tomographic images and contain more detailed information than conventional x-rays. Unlike a conventional x-ray—which uses a fixed x-ray tube—a CT scanner uses a motorized x-ray source that rotates around the circular opening of a donut-shaped structure called a gantry. During a CT scan, the patient lies on a bed that slowly moves through the gantry while the x-ray tube rotates around the patient, shooting narrow beams of x-rays through the body. Instead of film, CT scanners use special digital x-ray detectors, which are located directly opposite the x-ray source.
Cross-sections are reconstructed from measurements of attenuation coefficients of x-ray beams in the volume of the object studied. CT is based on the fundamental principle that the density of the tissue passed by the x-ray beam can be measured from the calculation of the attenuation coefficient. Using this principle, CT allows the reconstruction of the density of the body, by two-dimensional section perpendicular to the axis of the acquisition system.
A computerized tomography CT or computerized axial tomography CAT scan combines data from several X-rays to produce a detailed image of structures inside the body. A CT scan can be compared to looking at one slice of bread within a whole loaf. This is different from an X-ray machine, which sends just one radiation beam. The CT scan produces a more detailed final picture than an X-ray image. It can see tissues within a solid organ.
Computed Tomography (CT) Scanning
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