Physics:Focal spot blooming

From HandWiki

Focal spot blooming is the unwanted change in the focal spot size of an X-ray tube during change in exposure.[1]

Cause

Focal spot blooming is caused due to increased mAs. When high exposure setting are used, the electron beam from the cathode fail to focus on a particular point because of electrostatic repulsion.[2]

References

  1. Fosbinder, Robert; Orth, Denise (2011-02-16) (in en). Essentials of Radiologic Science. Lippincott Williams & Wilkins. ISBN 978-0-7817-7554-0. https://books.google.com/books?id=jRVg5ilM1UEC&dq=focal+spot+blooming&pg=PA66. 
  2. Pettersson, Holger; Allison, David J. (1998) (in en). The Encyclopaedia of Medical Imaging. Taylor & Francis. pp. 159. ISBN 978-82-91942-00-1. https://books.google.com/books?id=xhzOGs0XJlcC&dq=focal+spot+blooming&pg=PA159.