Radiographic Techniques - Facial Bones and Sinuses

Radiographic Techniques - Facial Bones and Sinuses

• The lecture covers radiographic techniques for facial bones and sinuses.
• There are various projections with specific positioning for the patient and the image receptor for each projection.
• The occipito-mental (OM) projection shows the floor of the orbits, nasal region, maxillae, portions of the frontal bone and zygomatic bone.
• The purpose of the OM projection is to position the petrous portions of the temporal bone below the inferior part of the maxilla to avoid image noise.
• The patient should be positioned erect and facing the Bucky/receptor with the nose and chin in contact with the midline.
• The orbito-meatal baseline should be at a 45-degree angle to the Bucky/receptor.
• The horizontal central line should be at the level of the lower orbital margins.
• The median sagittal plane must be at right angles to the Bucky/receptor ensuring the outer canthus of eyes are equidistant.
• The collimated horizontal beam is centred with the Bucky/receptor, and the crosslines on the Bucky/receptor should align with the patient's anterior nasal spine.
• The petrous ridges should be inferior to the floor of the maxillary sinuses in the image.
• Rotation should be avoided. Distance from the lateral orbital wall to the outer skill margins should be equidistant on both sides.
• The 15-degree occipito-frontal projection is for demonstration of the frontal and ethmoid sinuses.
  • The patient position should be seated facing the vertical Bucky/skull unit cassette holder.
  • The median sagittal plane should be coincident with the midline.
  • The orbito-meatal baseline should be raised 15-degrees to the horizontal.
  • The nasion (bridge of the nose) should be centered in the Bucky.
• The central ray should be perpendicular to the vertical Bucky along the median sagittal plane, exiting at the nasion.
• The collimated field should encompass the ethmoid and frontal sinuses.
• Frontal sinus size may vary between individuals.
• Relevant sinuses need to be included in the image.
• Skull rotation needs to be avoided. The distance from a point in the midline of the skull to the lateral orbital margins should be equal on both sides.
• The lateral projection is used for specifically requested images, with a horizontal beam, for patient position erect or supine.
  • Erect position: patient sits facing a vertical Bucky/receptor, head rotated for the side under examination to be in contact with the Bucky/receptor.
  • The extended same-side arm provides stability for the head
  • The receptor height is adjusted so the centre is 2.5 cm inferior to the outer canthus of the eye.
  • Supine position: the patient lies on a trolley with their arms extended, the median sagittal plane vertical to the trolley cassette, and with the vertical CR supported against the side of examination.
  • The receptor centre is adjusted to be 2.5 cm inferior to the outer canthus.
  • The median sagittal plane must be parallel.
• The lateral image must include all facial bones and sinuses, especially the frontal sinus. Superimposition of lateral portions of the floor of the anterior cranial fossa should not occur in a true lateral view.
• The nasal bones projection uses an 18 x 24 cm cassette, with a vertical Bucky. The patient's head is rotated, with the median sagittal plane parallel to the image receptor and the interpupillary line perpendicular.
• Nose should coincide with the centre of the receptor.
• A horizontal central ray is directed through the centre of the nasal bones and collimated to include the nose. Nasal bones, soft tissue structures, the frontonasal suture, and the anterior nasal spine are demonstrated.
• The image should be free from rotation to accurately visualize the desired structures.
• Sufficient contrast and density (brightness) are needed to visualize the nasal structures with sharp bony structures to confirm no motion.

This quiz focuses on the radiographic techniques used for imaging the facial bones and sinuses. It covers the specific projections, patient positioning, and technical requirements for high-quality images, including the occipito-mental projection. Test your knowledge on the principles of anatomy and positioning that are critical in radiography.