Ribs - ObliqueThis is a featured page

Radiographic Positioning


Adult
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Name of projection Ribs - Oblique (Posterior or Anterior Obliques)
Area Covered Upper Ribs view shows ribs 1 through to 10
Lower Ribs view shows rib 8 through to 12
Pathology shown Fractures, benign and malignant tumours, rib notching, congenital abnormalities
Radiographic Anatomy Ribs Radiographic Anatomy
IR Size & Orientation 35 x 43 cm
Portrait
Film / Screen Combination Regular
(CR and DR as recommended by manufacturer)
Bucky / Grid Moving or Stationary Grid
Filter No
Exposure 66 kVp, 16 mAs for Upper Ribs
75 kVp, 30 mAs for Lower Ribs (to penetrate the abdomen)
(can use long exposure time on table bucky)
FFD / SID 100 cm
Central Ray Posterior Obliques
Directed to the centre of the IR, in line with the mid-clavicular line and so that the top of the IR is approximately 4 cm above the patient's shoulder
Perpendicular to the IR

Anterior Obliques
Directed to the centre of the IR, to the point midway between the vertebral bodies and the lateral rib margins and so that the bottom of the IR is at the level of the Iliac Crest.
Perpendicular to the IR
Collimation Upper Ribs
Centre: Halfway between jugular notch and xiphoid sternum, approximately 1/4 of the way across from the midline towards the lateral rib margin
Shutter A: Open to include from the vertebral bodies to the lateral rib margin
Shutter B: Open to the film size superiorly and inferiorly

Lower Ribs
Centre: Place the lower margin of the IR at the level of the Iliac Crest, approximately 1/4 of the way across the patient from the midline to towards the lateral rib margin
Shutter A: Open to include from the vertebral bodies to the lateral rib margin
Shutter B: Open to the film size superiorly and inferiorly
Markers Posterior Obliques
Superior and Lateral
Indicate the side closest to the bucky (which is the affected side)
Marker orientation is AP

Anterior Obliques
Superior and Lateral
Indicate the side closest to the bucky (which is the affected side)
Marker orientation is PA
Shielding Gonadal (check your department's policy guidelines)
Respiration Upper Ribs on suspended inspiration
Lower Ribs on suspended expiration
Positioning Posterior Oblique view
  • Position the patient so that their back is against the bucky
  • Rotate the patient so they are angled 45° with the affected side touching the bucky (use a 45 degree sponge for support if the patient is supine)
  • Position the arm on the affected side so that it is away from the area of interest (either out to the side, over the patient's head, or resting on top of the bucky)
  • Align the mid-clavicular line of the side being imaged to the midline of the IR

Anterior Oblique view
  • Position the patient so that they are facing the bucky
  • Rotate the patient so they are angled 45° with the affected side away from the bucky and the non affected side touching the bucky
  • Position the arm on the affected side so that is away from the area of interest (either out to the side, over the patient's head, or resting on top of the bucky)
  • Align the patient so that mid-clavicular line of the side being imaged (between the lateral rib margin and the spine) to the midline of the IR
Critique

Positioning
Assessment of correct patient obliquity
  • The tip of the xiphoid sternum is midway between the spine and the lateral rib margin
Area Covered
  • Upper ribs: Ribs 1 through to approximately 10 may be seen above the diaphragm providing the image was taken while the patient suspended breathing on maximum inspiration.
  • Lower ribs: Ribs 12 through to approximately 8 may be seen below the diaphragm providing the image was taken while the patient suspended breathing on maximum expiration.
Collimation
Upper Ribs
Centre: This will be approximately at the level of the 7th rib
Shutter A: Open to include the vertebral bodies to the lateral rib margin
Shutter B: Open to include the 1st rib at the top of the film

Lower Ribs
Centre: This will be approximately at the level of the 10th rib
Shutter A: Open to include the vertebral bodies to the lateral rib margin
Shutter B: Open to include the 12th rib on the bottom of the film

Exposure
There should be adequate exposure so that
  • the cortical outlines and bony trabeculation of the ribs are seen
Special Notes Collimation
Take care with collimation, especially while imaging upper ribs, as the rib cage expands on inspiration

Determining how to fix incorrect obliquity
If the person is not obliqued enough
  • they are closer to being in an AP position
  • the xiphoid sternum will be closer to the thoracic spine than to the lateral rib margin
  • the pedicles of the vertebrae seen will be almost equidistant from the vertebral body edges (as they are shown in an AP view of the spine)
If the person is too obliqued
  • they are closer to being in a Lateral position
  • the xiphoid sternum will be closer to the lateral rib margin than to the thoracic spine
  • the intervertebral foramen of the thoracic vertebrae will be almost open (as they are shown in a lateral thoracic spine view)
Posterior vs Anterior Oblique views Posterior Obliques will show the axillary ribs more clearly and less magnified than the Anterior Oblique views.



AndyC
AndyC
Latest page update: made by AndyC , Jun 19 2011, 9:36 AM EDT (about this update About This Update AndyC Edited by AndyC

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