تعليمات الوقاية التعرض من الأشعة في دائرة ألاشعة
تعليمات الوقاية التعرض من الأشعة في دائرة الأشعةRadiation Safety Instructions in Radiology Department
Artifact In CT
Artifact In CT Artifact Origins Physics Based Beam hardening Partial volume effect. Photon starvation. Under sampling. Patient Based Metal. Patient motion Inadequate scan field. Scanner Based Detector sensitivity Spiral Artifacts in MSCT 3D and MPR artifacts: Stair step artifacts. Zebra artifact Windmill artifact. Cone beam artifact Physics Based Beam Hardening Causes The average energy of the X-ray beam becomes greater (Harder) as it passes through tissue. Because the attenuation of bone is greater than tissue, bone causes more beam Hardening than soft tissue. The beam hardening occurs artifacts in CT because rays from some projection angle are hardened to a differing extent than rays from other angles, confusing the reconstruction algorithm. Beam hardening cause broad dark or streaks artifacts. (1) Physics Based Beam Hardening Correction Prefilter the X-ray beam near the focus ( bowtie) Avoid highly absorbing bony regions by patient positioning or gantry tilt. Algorithms. Beam harde
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