Ribs - Oblique

Radiographic Positioning

Adult

Other related pages of interest Applied Radiography Radiographic Anatomy Radiographic Protocols

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 PACEMAN	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.