MEDRADSC 2Y03 Lecture Notes - Lecture 4: Pubic Symphysis, The Sharper Image, Motion Blur
28 Jul 2019
School
Department
Course
Professor
Document Summary
Projection imaging relies on geometric principles to produce predictable results. Cr perpendicular to object; ir & object are parallel & should be in close proximity/touching. Distortion of image relative to the actual objects size, shape. Sid make sure it is exactly as it is prescribed. Focal spot; switch out ma or use what is prescribed. Patient will lay on their back (part is closest to ir); decreases oid. 10 caudal (towards feet) so that beam hits symphysis pubis, alters that part of image, but then coccyx becomes clear. Sides of altitudes (heights) of similar triangles are proportional a/a = b/b = c/c = h/h. When rays diverge depending on focal spot, will have a spot in the image called penumbra. Umbra: area most sharp; want more of this. Penumbra: area of unsharpness; want less of this. Influenced by focal spot size selected (ma); 800ma will have more penumbra than a 300 ma station; smaller ma = sharper image.
