Skull - PA (Caldwell) 0°

Radiographic Positioning

Adult

Other related pages of interest Applied Radiography Radiographic Anatomy Radiographic Protocols

Name of projection	Skull - PA (Caldwell) 0°
Area Covered	Frontal bone, crista galli, internal auditory canals, frontal and anterior ethmoid sinuses, petrous ridges, greater and lesser wings of sphenoid and dorsum sellae
Pathology shown	Fractures of the skull (medial and lateral displacement), neoplastic processes and Pagets disease
Radiographic Anatomy	Skull Radiographic Anatomy
IR Size & Orientation	24 x 30 cm Portrait
Film / Screen Combination	Regular (CR and DR as recommended by manufacturer)
Bucky / Grid	Moving or Stationary Grid
Filter	No
Exposure	75 kVp 20 mAs
FFD / SID	100 cm
Central Ray	CR is perpendicular to IR (parrallel to OML) and centred to exit glabella
Collimation	Outer skin margins of the skull
Markers	Inferior and Lateral Marker orientation PA
Shielding	Gonadal (check your department's policy guidelines)
Respiration	Suspended
Positioning	Erect Patient is standing or sitting facing the upright bucky Forehead and nose are touching the bucky The radiographic baseline (OrbitoMeatal Line) is perpendicular to the bucky The midsaggital plane is also perpendicular to the bucky The interpupillary line is parallel to the floor Ensure no rotation of the head by checking that the EAMs are the same distance from bucky CR directed to exit at the level of the nasion CR is perpendicular to IR (parrallel to OML) and centred to exit glabella Prone Rest patients nose and forehead against table/bucky Flex neck aligning OML perpendicular to IR Align midsagittal plane perpendicular to midline of table/bucky Ensure no rotation of the head by checking that the EAMs are the same distance from bucky CR is perpendicular to IR (parrallel to OML) and centred to exit glabella
Critique PACEMAN	Positioning petrous ridges fill the orbits No rotation is evidenced by The lateral borders of the orbits to the lateral borders of the skull are equidistant on both sides. (see note below) No tilt is evidenced by The petrous ridges are horizontal Area Covered Skull vault, maxilla Collimation Centre: Glabella Shutter A: Open to include the lateral skin margins of the skull Shutter B: Open to include the entire skull superiorly, and the maxilla inferiorly Exposure Assess for adequate penetration of the thickest part of the skull, the frontal bone Bony trabecular patterns and cortical outlines are sharply defined Soft tissues are visualised
Special Notes	Effect of 0-5 degree caudal central ray angulation Petrous ridges will be seen within the orbits The central ray will parallel to the radiographic baseline (OML) Effect of 15 degree caudal central ray angulation Petrous ridges will be seen in the lower third of the orbits The supraorbital rim will be seen Effect of 20 degree caudal central ray angulation Petrous ridges are completely clear of the orbits Often used in facial bone series Determining the direction of head rotation The distance from the lateral border of the orbit to the lateral border of the skull on one side will be decreased on the side the patient is looking to. That is, in a PA position, if the patient is rotated to the left, then the distance will be smaller on this side when compared with the right side of the skull.)