1 / 10

Resident Physics Lectures

Christensen, Chapter 7 X-Ray Beam Restrictors. Resident Physics Lectures. George David Associate Professor Department of Radiology Medical College of Georgia. Aperture Diaphragms Cones and Cylinders Collimators. Restrictors Types. Lead sheet with hole in center simple

jelani-underwood
Download Presentation

Resident Physics Lectures

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Christensen, Chapter 7 X-Ray Beam Restrictors Resident Physics Lectures George David Associate Professor Department of Radiology Medical College of Georgia

  2. Aperture Diaphragms • Cones and Cylinders • Collimators Restrictors Types

  3. Lead sheet with hole in center • simple • large penumbra (shadow) • Lead close to focal spot Focal Spot Aperture Diaphragms Penumbra Film

  4. Focal Spot Focal Spot Film Film Cones & Cylinders With cone angle as above, this functions as an aperture Reduced Penumbra

  5. Advantages • Provides adjustable rectangular field • fluoro may also have circular field • light beam indicates x-ray field • Configuration • two sets of shutters • longitudinal • transverse • sets may actually have two pairs of shutters operating together Collimators One set; two pairs

  6. Focal Spot Filter Lamp Mirror Shutters (only 1 set shown) • Generally include filter & light Collimators

  7. Numerical field size indicators • Field size is SID dependent 8 10 12 14 17 40” 8 10 12 14 17 Collimator Features

  8. Field center indicator (crosshairs) • plastic sheet attached to bottom of collimator • two black lines drawn on it • light projects field center on patient Shutters Crosshairs Collimator Features Bottom of Collimator

  9. senses film size, orientation, & SID • source - image distance • limits x-ray field to size of film • No longer required • PBL does not insure tube & bucky are aligned! Positive Beam Limitation(PBL or Automatic Collimation) Cassette

  10. X-Ray / Light Field alignment • Alignment of x-ray field to bucky • Field Size Indicator accuracy • PBL accuracy Collimator Checks

More Related