Radiography: External Landmarks and Oblique Projections

External Landmarks

• C1 corresponds with the mastoid tip.
• C2 and C3 correspond with the Gonion (angle of mandible).
• C3 and C4 corresponds with Hyoid bone.
• C5 corresponds with Thyroid cartilage.
• C7 and T1 corresponds with Vertebra prominens
• T1 About 2 inches (5 cm) above level of jugular notch.
• T2 and T3 is at the level of jugular notch.
• T4 and T5 is at the level of sternal angle.
• T7 is at the level of the inferior angles of the scapulae.
• T9 and T10 is at the level of the xiphoid process.
• L2, L3 corresponds with the inferior costal margin.
• L4 and L5 corresponds with the superiormost aspect of iliac crests.
• S1 and S2 corresponds with the level of the anterior superior iliac spine (ASIS).
• Coccyx corresponds with the level of the pubic symphysis and greater trochanters.

Atlanto-Occipital AP Oblique Projections

• Rotate head to 45-60 degrees from the side being examined.
• CR Perpendicular to 1 inch anterior to EAM (External Auditory Meatus).
• Demonstrates the atlanto-occipital articulation between the orbit and the ramus of the mandible.

Atlanto-Occipital Kasabach Method

• In the first exposure, the head is rotated 40-45 degrees to the right away from the side being examined.
• In the second exposure, the head is rotated 40-45 degrees to the left away from the side being examined.
• CR 10-15 degrees caudad to a point midway between the outer canthus and the EAM.
• Demonstrates an AP axial oblique projection of the dens.

Fuchs Method

• Patient is in a supine position.
• MML (Mentomeatal Line) should be perpendicular to the table.
• CR is parallel to the MML, directed towards the inferior tip of the mandible.
• Respiration should be suspended during exposure.
• Best demonstrates the odontoid process within the foramen magnum.
• An alternative projection for the dens when the upper half is not shown on the open-mouth projection.

PA (Posterior-Anterior) Judd Method

• Patient should be in prone position.
• The OML (Orbitomeatal Line) forms an angle of 37° to the plane of the IR (Image Receptor).
• MML (Mentomeatal Line) is perpendicular to the table.
• CR is parallel to the MML, directed to the inferior tip of the mandible.
• Best demonstrates the odontoid process within the foramen magnum.
• An alternative projection for the dens when the upper half is not shown on the open-mouth projection.

C1 and C2 AP Open-Mouth Projection

• CR is perpendicular to the center of the open mouth.
• SID (Source-to-Image Distance) of 30 inches (70 cm) is often used to increase the field of view of the odontoid area.
• Patient is asked to phonate "ah" softly during exposure.
• Lower margin of the upper incisor to the mastoid tip should be perpendicular to the base of the skull.
• Best demonstrates C1 and C2 free from superimposition.
• Best demonstrates the zygapophyseal joint of C1 and C2.
• Best demonstrates Odontoid and Jefferson's fractures.

Cervical Vertebra AP Axial Projection

• Occlusal plane should be perpendicular to the base of the skull.
• CR is angled 15°-20° cephalad, to enter at the lower margin of the thyroid cartilage to pass through C4.
• Respiration should be suspended during exposure.
• The projection shows the lower five cervical bodies and the upper two or three thoracic bodies.
• Also shows the presence or absence of cervical ribs.
• Best demonstrates the intervertebral disk space of C3-T2

Cervical Vertebra Upright Lateral Projection - Grandy Method

• Top of cassette should be about 1-2 inches above EAM (External Auditory Meatus).
• Adding 5-to 10 lbs. weights to each arm helps in pulling down the shoulders.
• SID of 72 inches (180 cm) compensates for increased OID (Object-to-Image Distance) and provides for less magnification.
• CR is horizontally directed to the upper margin of the thyroid cartilage (C4-C5).
• Best demonstrates cervical zygapophyseal joints.
• Most cervical injuries are best seen in lateral projection.
• 7 cervical vertebra are demonstrated.

Cervical Vertebra Lateral Projection - Hyperflexion & Hyperextension

• Functional studies of the cervical vertebrae are performed to show normal AP movement or absence of movement resulting from trauma or disease.
• SID of 60-72 inches is recommended.
• MSP (Midsagittal Plane) should be parallel with the plane of the IR.
• CR is horizontal and perpendicular to C4.
• The images show the motility of the cervical spine when hyperflexed and hyperextended.

Hyperflexion

• Ask the patient to drop the head forward and then draw the chin as close as possible to the chest, so that the cervical vertebrae are placed in a position of hyperflexion for the first exposure.
• The body of the mandible is almost horizontal in a normal patient.
• All seven spinous processes are in profile, depressed, and closely spaced.

Hyperextension

• Ask the patient to elevate the chin as much as possible so that the cervical vertebrae are placed in a position of hyperextension for the second exposure.
• Body of the mandible is almost horizontal in a normal patient.
• All seven spinous processes are in profile, depressed, and closely spaced.

Cervical Vertebra AP Axial Oblique Projections RPO and LPO Positions

• First described by Barsóny and Koppenstein.
• Both sides are examined for comparison.
• Rotate body and head 45°.
• CR is angled 15°-20° cephalad towards C4.
• Best demonstrates the intervertebral foramina and pedicles farthest from the image receptor.

Cervical Vertebra PA Oblique Projections RAO and LAO Positions

• Rotate body and head 45°.
• CR is angled 15°-20° caudad towards C4.
• Best demonstrates the intervertebral foramina and pedicles nearest to the image receptor.

Cervical Vertebra AP Wagging Jaw Projection - Ottonello Method

• CR is perpendicular to C4.
• Have the patient open and close the mouth during exposure to blur out the mandible.
• Use low mA and long exposure time (minimum of 1 second).
• The lower margin of the upper incisors to the base of the skull should be perpendicular to the table.
• The entire cervical column is demonstrated, with the mandible blurred or obliterated.

Cervical Vertebra Vertebral Arch (Pillars) AP Axial Projection

• Patient is in a supine position with hyperextended neck.
• CR is angled 25 degrees caudad to C7 (range 20°-30°caudad).
• Referred to as the PILLAR OR LATERAL MASS PROJECTIONS.
• Demonstrates the posterior elements of the cervical vertebra.
• Demonstrates Pathology involving the posterior vertebral arch (particularly the pillars) of C4 to C7.

Vertebral Arch (Pillars) AP Axial Oblique Projection

• Right and Left Head Rotations - CR 35° caudad to spinous process of C7 (Range of CR 30°-40°).
• Rotate the patient's head 45-50 degrees from the side of interest.
• Rotation of 45°-50° demonstrates the articular process of the C2-C7 and T1.
• Rotation of 60°-70° demonstrates the processes of C6 and T1-T4.
• Demonstrates the vertebral arches or pillars when the patient cannot hyperextend the neck for the AP or PA axial projection.

Cervicothoracic Swimmers Lateral Twinning Method

• Patient is in an erect position.
• Perpendicular if the shoulder is well depressed.
• Angle the CR 5° caudad if the shoulder is not depressed.
• The regional part is the interdisk space of C7 and T1
• A compensating filter may or may not be used.
• Best projection to demonstrate C7 to T1 when not shown on a cervical lateral projection.
• Good projection to demonstrate the upper thoracic vertebrae (T1-T4) when not shown on a thoracic lateral projection.
• Performed as a swimmers lateral upright method

Cervicothoracic Swimmers Lateral Pawlow Method

• Patient is in a lateral recumbent position.
• Pawlow Method: CR is angled 3°-5° caudad to the interdisk of C7 and T1.
• Modified Pawlow: CR is angled 5°-15° cephalad.
• This is a good projection when C7 to T1 is not visualized on the lateral cervical spine or when the upper thoracic vertebrae are of special interest on a lateral thoracic spine.

Thoracic Vertebra AP (Anteroposterior) Projection

• Top of cassette should be about 1 to 1 1/2 inches, or 3 to 5 cm, above the level of the shoulder.
• CR is perpendicular to T7.
• Thoracic vertebral bodies, intervertebral joint spaces, spinous and transverse processes, posterior ribs, and costovertebral articulations should be visible.
• HEEL EFFECT: Position the Cathode End of Tube towards the Feet.
• Anode End of the Tube should be positioned towards the Head.

Thoracic Vertebra Lateral Projection

• Patient is allowed to continue breathing during exposure to blur out unwanted rib and lung markings overlying the thoracic vertebra.
• Use at least 2 seconds exposure time.
• CR is perpendicular to T7, entering the posterior half of the thorax.
• Male: CR angled 15° cephalad.
• Female: CR angled 10° cephalad.
• If vertebral column is not horizontal, support not placed under lower thoracic.
• CR demonstrates thoracic vertebral bodies in lateral profile and intervertebral joint spaces and foramina.

Thoracic Vertebra Oblique Projections AP and PA Oblique Projections

• Rotate the body 20° from true lateral so that the midcoronal plane forms an angle of 70° from the plane of the image receptor.
• CR is perpendicular to T7.
• Posterior Oblique Position best demonstrates the zygapophyseal joint farthest from the image receptor.
• Anterior Oblique Position best demonstrates zygapophyseal joint closest to image receptor.

Lumbar Vertebra AP (Anteroposterior) Projection

• Patient should be in a supine position with knees flexed.
• Flexing the knees helps to decrease the lordotic curve of the lumbar spine.
• PA PROJECTION: reduces patient dose and sometimes used for upright studies of the lumbar spine; it is also the preferred position for patients who has excruciating pain to reduce physical discomfort.

Lumbar Vertebra AP (Anteroposterior) Projection - Central Ray

• When Perpendicular at the level of the iliac crest for lumbosacral studies.
• When perpendicular to L3 for Lumbar study.
• The erect position is useful to demonstrate the natural weight-bearing stance of the spine.
• CR best Demonstrates the lumbar bodies, intervertebral disk spaces.

Lumbar Vertebra Lateral Projection

• Flex the knees to straighten the spine and help open the intervertebral disk spaces.
• The lumbar Spine may or may not be horizontal to table. If horizontal table, Central Ray is at lumbar spine; if not,
  • 1. Perpendicular at the level of the iliac crest for lumbosacral studies.
  • 2. Perpendicular to L3 for Lumbar study.
• Male - CR angled 5 degrees caudad.
• Female - CR angled 8 degrees caudad.
• Demonstrates lumbar bodies, intervertebral disk spaces, and transverse process
• Best demonstrates the intervertebral foramina.
• Good projection for demonstrating compression fractures.

Lumbar Vertebra Oblique Projections

• Rotate the body 45 degrees
• 30° rotation is for L5 to S1 to best demonstrate the lumbosacral processes
• A 50° oblique from plane of tabletop to best visualizes the zygapophyseal joints at L1 to L2 is needed.
• CR should be perpendicular to 1-1 1/2 inches above iliac crest (L3)
• Demonstrates the scotty dog.
• Best demonstrates the zygapophyseal joint.
• Neck - Pars Interarticularis, Ear - Superior articular process, Eye - Pedicle, Nose - Transverse process, Front legs - Inferior articular process Body - Lamina.
• Posterior Oblique position Best visualize zygapophyseal joint nearest to image receptor and Anterior Oblique position Best visualize zygapophyseal joint farthest to image receptor.

Lateral L5 to S1 - Francis Method

• Patient is in lateral position, locate both iliac crest.
• An imaginary line is drawn between the interiliac plane
• CR angulation is adjusted to be parallel with the interiliac line.
• CR 5°-8° caudad to 1 inch inferior to iliac crest and 1 inch is anterior to the posterior surface of the body.
• An alternate technique to demonstrate the L5-S1 junction when the spine is not horizontal .
• Good projection for ruling out Spondylolisthesis.

Lumbosacral Junction and Sacroiliac Joints AP Axial and PA Axial Projection

• Central Ray used during the projection
• MALE 30°cephalad
• FEMALE 35°cephalad at the level of the ASIS
• Demonstrates an open L5-S1 intervertebral disk space.
• PA AXIAL: MALE 30°caudad /FEMALE 35°caudad at the level of the ASIS

5th Lumbar PA Axial Oblique Projection - Kovacs Method

• Rotate the pelvis 30 degrees anteriorly from the lateral position.
• CR should be 15-30 degrees caudal to the superior edge of the upside iliac crest.
• Best demonstrates the L5 intervertebral foramen

Sacroiliac Joints AP Oblique Projections

• CR should be perpendicular to 1 inch medial to elevated ASIS
• The patients body is rotated 25-30 degrees away from the side being examined.
• Demonstrates the sacroiliac joint farthest from the image receptor.
• AP Axial Oblique: Same position as AP oblique but employs a CR of 20-25 degrees cephalad entering 1 inch medial and 1 ½ inches distal to the elevated ASIS.

Sacroiliac Joints PA Oblique Projections:

• The patients body is rotated 25-30 degrees towards the side being examined.
• PA Axial Oblique: Same position as PA oblique but employs a CR of 20-25 degrees caudad entering 1 inch medial and 1 ½ inches distal to the elevated ASIS. Demonstrates the sacroiliac joint closest to the image receptor.

PA Projections, Chamberlain Method

• CENTRAL RAY: Perpendicular to the symphysis pubis
• Demonstrates abnormal change in the normal relation of the pubic symphysis to each other.
• Used for abnormal sacroiliac motion (SI joint slippage or relaxation).

Sacrum and coccyx

• Wowel preparation maybe be needed.
• Central Ray
  • (AP) 10°CAUDAD
  • (PA) 10°CEPHALAD
    • to a point 2 inches superior to the symphysis pubis.
• SACRUM
  • (AP) 15°CEPHALAD
  • (PA) 15°CAUDAD
    • To a point 2 inches superior to the symphysis pubis.

Sacrum and coccyx, Lateral Projections

• Interiliac plane perpendicular to the level of the ASIS with a point 3 ½ inches posterior.

Sacral Vertebra Canal and Sacroiliac Joints Axial Projection / Nolke Method

• Patient sitting on the end of the table.
• The patient leanes forward so that the vertical canal is vertical.
• CR perpendicular to the long axis of the sacrum.
• Demonstrates the lower sacral vertebral canal, the junction of the sacrum and the coccyx and the last lumbar vertebra.

Lumbar Intervertebral Disk; Weight Bearing Method

• When standing, the patient CR should perpendicular to L3 or 15°20° caudad projected through the L4-L5 or L5-S1 interspaces.
• Demonstrates bending PA projections of the lower thoracic region and lumbar region
• Demonstrates mobility of the intervertebral joints.

Scoliosis Radiography PA and Lateral Projections

• Demonstrates the amount or degree lateral curvature
• LATERAL: Demonstrate spondylolisthesis and exaggerated degree of kyphosis or lordosis curve.
• Demonstrates the degree and severity of scoliosis - Ferguson Method:
• Patient in facing the VCH with an upright position
• 1 inch bellow the iliac crest the lower margin of IR Used to demonstrate primary from secondary curve

AP Projection

• Used in patients with early scoliosis lateral flexion
• CR perpendicular to the level of L3
• Demonstrates structural change with maximum right bending And maximum left bending

Spinal Fusion Series Lateral Projection; Hyperflexion and Hyperextension

CR perpendicular to the spinal fusion area or L3. Projection assesses mobility at spinal fusion site. 1st flexion & 2nd extension radiographs