The Lateral View of the Skull is a foundational projection included in almost all standard cranial series. It evaluates the lateral calvarium, the anterior/middle/posterior cranial fossae, the sella turcica in profile, and the relationship between the inner and outer cortical tables.
1. Clinical Indications & Contraindications
Detailed Indications:
- Cranial Vault & Base Trauma: Detection of linear, depressed, or comminuted fractures of the parietal, temporal, frontal, or occipital bones.
- Sella Turcica Pathologies: Assessment of sellar enlargement, erosion, or destruction due to pituitary adenomas, craniopharyngiomas, or “Empty Sella” syndrome.
- Intracranial Air & Fluid Levels (Cross-Table Lateral):
- Sphenoid sinus air-fluid levels indicative of a basilar skull fracture and cerebrospinal fluid (CSF) leakage.
- Pneumocephalus (intracranial air collection) following traumatic dural tears.
- Neoplastic & Osteolytic Lesions: Evaluation of “punched-out” lytic lesions in Multiple Myeloma, osteolytic metastases, eosinophilic granuloma, and epidermoid cysts.
- Metabolic & Bone Remodeling Diseases: Diagnosis of Paget’s disease (cotton-wool appearance, basilar invagination), fibrous dysplasia, hyperparathyroidism, and osteopetrosis.
- Pediatric Assessment & Suture Alignment: Evaluation of coronal, squamosal, and lambdoid sutures; detection of scaphocephaly, oxycephaly, or other craniosynostoses.
- Vascular & Normal Anatomical Calcifications: Identification of middle meningeal artery grooves, pacchionian (arachnoid) granulations, pineal gland calcification, and choroid plexus calcification.
Contraindications & Limitations:
- Unstable Cervical Spine Trauma (Standard Position): Patients with suspected or unconfirmed C-spine injuries must not have their heads turned or rotated into a standard lateral position. A Cross-Table (Horizontal Beam) Lateral must be performed in the true supine position with no neck movement.
- Bilateral Superimposition (Inherent Limitation): Left and right cranial structures superimpose over each other. Accurate localization of a small cortical lesion to a specific side often requires an orthogonal AP/PA view or tangential projections.
2. Technical Factors
| Parameter | Recommended Specification | Radiographic Rationale |
| Image Receptor (IR) | 24 × 30 cm (10 ×12 inches) | Landscape / Horizontal orientation |
| Source-to-Image Distance (SID) | 100 to 115 cm (40 to 44 inches) | Standard focal distance to balance beam diverge and sharpness |
| Grid Ratio | 8:1 to 12: 1 Essen focused grid | Essential to absorb scatter from cranial structures |
| Tube Potential (kVp) | 70 – 80 kVp | Lower kVp compared to AP/PA due to reduced lateral cranial thickness |
| mAs Range | 15 – 25 mAs | Calibrated based on lateral thickness; center AEC cell active |
| Focal Spot | Small (0.6 mm) | High spatial resolution needed for fine sellar margins and vascular grooves |
| Marker | “R” or “L” lead marker | Placed anteriorly to indicate which side is closer to the IR |
| Breathing | Suspended respiration | Eliminates respiratory and muscle movement blur |
3. Step-by-Step Patient & Part Positioning
Lateral Skull / Cranium: Patient Positioning
True Lateral View
Central Ray: 0° Perpendicular
Enters 2″ (5 cm) Superior to EAM
Enters 2″ (5 cm) Superior to EAM
▼
IOML // Transverse Axis of Table / IR
(Infraorbitomeatal line parallel)
(Infraorbitomeatal line parallel)
Interpupillary Line (IPL) ⟂ IR (90°)
(Perpendicular alignment prevents tilt)
(Perpendicular alignment prevents tilt)
Mid-Sagittal Plane (MSP) // IR
(Parallel alignment prevents head rotation)
(Parallel alignment prevents head rotation)
▼
[ Image Receptor Surface ]
Affected lateral cranium flat against Bucky
Affected lateral cranium flat against Bucky
1
Centering (2″ Superior to EAM)
Directs the perpendicular beam through the center of the cranial vault and sella turcica.
2
MSP Parallel (// IR)
Mid-sagittal plane is aligned parallel to the IR to eliminate rotation of mandibular angles and orbital plates.
3
IPL Perpendicular (90° ⟂ IR)
Interpupillary line is kept strictly perpendicular to the IR to eliminate lateral head tilt.
4
IOML Parallel Alignment
Infraorbitomeatal line is aligned parallel to the transverse edge of the cassette to standardize vertical pitch.
- Patient Preparation: Remove all radiopaque materials from the head and cervical area (hairpins, clips, spectacles, earrings, dentures, necklaces, and hearing aids).
- General Posture Options:
- Semi-Prone (Swimmer’s/Stenvers Stance – Preferred for Table): Patient lies semi-prone on the table. The side of interest is placed in contact with the table/bucky. The ipsilateral arm is placed by the side, while the contralateral arm and flexed knee elevate the opposite side for stability.
- Erect (Seated/Standing): Patient sits facing the upright Bucky, turning their head and torso laterally so the side of interest rests flat against the receptor.
- Alignment of Reference Lines & Planes:
- Mid-Sagittal Plane (MSP): Must be strictly parallel to the plane of the image receptor. (Verify that the nose and face are not pointed down toward the table or tilted upward).
- Interpupillary Line (IPL): Must be strictly perpendicular to the plane of the image receptor. A small sponge placed under the mandible or nose helps maintain this perpendicularity.
- Infraorbitomeatal Line (IOML): Must be parallel to the long/transverse axis of the image receptor (ensuring no flexed “chin-down” or extended “chin-up” tilt).
4. Central Ray (CR) & Collimation
- Central Ray (CR) Angle: 0⁰ (Perpendicular to the image receptor).
- CR Entry Point: Directed to a point 5 cm (2 inches) superior to the External Auditory Meatus (EAM) (or midway between the glabella and inion). This directly centers the beam over the sella turcica and sphenoid bone.
- Collimation: Four-sided collimation to the outer margins of the skull vault (vertex superiorly, base of skull/C1-C2 inferiorly, and anterior/posterior skin lines).
5. Positioning Errors & Diagnostic Artifacts
| Error Type | Visual Indicator on Radiograph | How to Correct |
| Rotation (Twisting) | Anterior and posterior separation of the bilateral orbital roofs, mandibular rami, and EAMs. | Realign the Mid-Sagittal Plane (MSP) to be strictly parallel to the IR. |
| Tilt (Lateral Leaning) | Superior and inferior separation of the orbital roofs and mandibular angles. | Adjust the Interpupillary Line (IPL) to be strictly perpendicular to the IR. |
| Pitch (Flexion/Extension) | Sella turcica appears angled; occipital base overlaps upper cervical vertebrae excessively. | Realign the IOML parallel to the plane/edge of the IR. |
6. Radiographic Anatomy & Quality Evaluation Criteria
Lateral Cranium: Anatomical Evaluation
Diagnostic Quality Criteria
True Lateral Projection (Superimposition Verification)
1
Sella Turcica in True Profile
Anterior and posterior clinoid processes and dorsum sellae visualized without dual-contour distortion.
2
Superimposed Orbital Roofs
Superimposition of the orbital plates confirms the absence of lateral head tilt (IPL was perpendicular).
3
Superimposed Mandibular Rami & EAM
Bilateral acoustic canals and rami superimpose directly, verifying no head rotation (MSP was parallel).
4
Cranial Vault & Sphenoid Sinus
Entire calvarium including vertex to base included; sphenoid sinus clearly aerated beneath the sella.
- Superimposition Criteria:
- True lateral position is confirmed by the complete superimposition of the orbital roofs (plates) and the greater wings of the sphenoid.
- Bilateral mandibular rami and external auditory meatuses (EAMs) superimpose precisely.
- Sella Turcica in Profile: Anterior and posterior clinoid processes, dorsum sellae, and hypophyseal fossa are visualized sharply in profile without dual borders or distortion.
- Bone Detail & Contrast:
- Clear visualization of the diploic space between the inner and outer tables of the cranial vault.
- Clearly defined middle meningeal vascular grooves and cranial sutures (coronal, lambdoid, squamosal).
- Field of Coverage: Entire cranium from the superior vertex to the upper cervical spine (C1-C2 atlantoaxial junction) included without motion blur.
