![]() We offer this Site AS IS and without any warranties. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. MedHelp is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. To learn more about CT service and maintenance, check out our CT blogs or any of our free resources.The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. Whether you simply need service on your CT scanner or if you're ready to upgrade your CT capabilities, we can help answer your questions. If your reconstruction techniques and reduction software are current and your radiologist is scanning with the highest kV they are comfortable with and streak artifacts are still appearing, it's probably time to call in a service engineer to diagnose underlying causes. However, there is a tradeoff in that the higher kV will reduce the tissue contrast of the scan 2. A radiologist can also try scanning at a higher kV in order to get a harder X-ray beam and thus, fewer beam hardening artifacts. Streak artifacts can be reduced using newer reconstruction techniques or metal artifact reduction software. For example, if a metal implant blocks all photons, then the corresponding detector element will only detect scattered photons 2. The biggest problem is when scattered photons end up in a detector that would usually have very few photons. This means photons could end up in a different detector than they should be in. Basically, scatter causes X-ray photons to change direction and change energy. The other big issue that causes streak artifacts is something called Compton scatter. In the same way, X-rays lose their energy, or "harden", more quickly as they pass through metal or bone than as they pass through muscles or organs. And if I’m swimming through water, I expend less energy than if I were swimming through, say, Jell-o. As I swim, I lose energy as I cross the pool I’m more tired the further I go. ![]() Here's an analogy to help understand beam hardening: P retend I’m swimming across a pool. I am an X-ray beam and the pool is the part of the body being scanned. See an example of an artifact caused by beam hardening below. Bright streaks are seen adjacent to the dark streaks 2. These phenomena produce dark streaks between metal, bone, iodinated contrast, barium, and other high-attenuation materials. Most streak artifacts occur near materials such as metal or bone, primarily as a result of beam hardening and scatter. The name should suffice to tell you what a streak artifact looks like, but the causes bear some explanation. In spite of this, CT is commonly susceptible to a number of image anomalies 1, including streak artifacts. The technology is a mainstay in the imaging stables of most hospitals. Generally, images produced by CT scanners are accurate representations of the scanned object.
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