MIRA3004 Lecture Notes - Lecture 1: Colloid, Gastrointestinal Perforation, Barium
5 Aug 2018
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Document Summary
Different tissues within the body attenuate x-ray beam to different degrees. The number of x-ray photons in the beam which exits the patient depends upon the: thickness of part being examined, physical density of the part, atomic numbers of the part, exposure factors used. The ratio of the x-ray intensity emerging from one part of an object to the intensity emerging from a more absorbing adjacent part. Where there is considerable difference between the physical densities of two organs e. g. heart and lungs. Outlines of structures can be visualised on a radiograph because of the subject contrast. If there is a difference between the average atomic numbers of two tissues such as soft tissue and bone then the structures can be seen because of subject contrast. Barium oesophagus (ap and lat), stomach, enema. Positive cm (increases both the atomic number and the physical density of the area to be examined) Extremely insoluable in water and acids (safe)
