WK 3 Facial bones

kvp and mas:

PA/AP: 70-80 kVp, 20-30 mAs

Lateral: 70-75 kVp, 10-15 mAs

Concerns: dose to orbits

Projections

PA caldwell face 25 degree caudal

  • petrous ridges below inferior orbital margin

  • forehead and nose against bucky

  • OML perpendicular to bucky

  • CR exit point nasion

  • trauma for fluid levels - straight tube

  • greater caudal tilt = further projection of petrous ridges

  • Collimation: superior to superior orbital margins, inferior to include mandible, lateral to include skin margin

  • Radiolucent eyebrow sign - air in the facial cavity

Intraorbital air - fractures

OM Waters

  • mentum of chin touching bucky and OML raised 45 degrees

  • CR at acanthion

  • straight tube

  • petrous ridges below maxillary sinuses

  • demonstrates zygoma and zygomatic arch

  • mc-grigor campbell lines assess facial symmetry and fractures

  • close collimation to outer margins of skull

Extended waters OM 30 deg

  • OML 45 degrees from horizontal

  • 30 deg caudal tube angle to see infraorbital canals - infraorbital nerve, artery and veins run through those canals

  • CR exits at acanthion

  • elongated zygomatic arches

  • 70-80 kvp and 20-30 mas

Lateral face

  • less exposure to capture soft tissue and facial bones

  • IOML parallel to floor

  • Centre at zygoma - midway btw EAM and outer canthus of the eye

  • collimate to facial bones - posterior eam, superior frontal sinus, anterior skin margin and inferior to chin

Paranasal sinuses imaging

  • frontal, maxillary, ethmoidal and sphenoidal sinuses

  • use straight tube for all - to see fluid levels

PA caldwell 15-20 deg

  • patient nose on IR - OML 20 deg from horizontal

  • straight tube

  • petrous ridges in the lower third of the orbits

  • CR at the level of the nasion

  • frontal and anterior ethmoid sinus

Waters OM

  • mentum of chin touching the bucky - OML raised 45 deg from horizontal

  • Open mouth of patient to see sphenoidal sinus

  • straight tube

  • CR exits at acanthion

  • can see frontal, ethmoidal and maxillary sinus - sphenoid sinus seen with open mouth

Lateral sinus

  • IOML parallel to floor

  • centre to zygoma

  • all 4 sinuses demonstrated

  • straight tube