5radiographicpositionsandprocedures2011skull

Radiographic positions and procedures


ByMr.souheil Barakat, Radiographic2011Contents

Basic terms,

Upper extremity, Skull.

Sella turcica.

Orbits.

Nasal bones.

Zygomatic arches.

Mandible.

Temporomandibular joints.

Panaromic tomography,

Paranasal sinuses,

Mastoids,


Basic terms1) Body positions: Body positions are the manner in which the patient is placed in relation to the surrounding space.

a) Decubitus : position assumed in lying down; the position assumed is described according to dependent body surface:

Dorsal decubitus: supine or lying on back.

Ventral decubitus: prone or lying face down

Right lateral decubitus: lying on right side Left lateral decubitus: lying on left side.

b) Standing position c) Seated position

2) Positioning terms:

a) Projection:

Projection usually describes the path of radiation as it goes from the x-ray tube through the patient to the image receptor.

b) View:

View describes the representation of an image as seen from the vantage of the image receptor.c) Method:Some radiologic procedures are named after individuals (for example, chassard-lapine or Towne) in recognition of their having developed a method to demonstrate a specific anatomic part.

3) Projection terminology: a) Frontal projections (AP or PA): AP (anteroposterior) projection :the x-ray beam is shown entering the front (anterior ) body surface and exiting the back (posterior) surface. PA (posteroanterior) projection:The central ray entering from the posterior body surface . b) Lateral projections: Lateral projections are always named by the side of the patient that is placed closest to the film (Right or left lateral projection). c) Oblique projections: The term oblique refers to a position in which the body part is rotated so that it does not produce a frontal ( AP or PA) or a lateral projection. Oblique projections could be :RAO or LAO in prone position and RPO/ LPO in supine . -In supine position : - LPO ( left anteroposterior oblique) : the patient is rotatd, So that the left side of the body is closest to the film . - RPO (right anteroposterior oblique) : the patient is rotated, So that the right

side of the body is closest to the film.

-In prone position: - RAO (right posteroanterior oblique) : the right side of the patient is closest to

the film.

- LAO (left posteroanterior oblique) : the left side of the patient is closest to the film.

d) Decubitus projections: Decubitus projections are so named to indicate that the patient is lying down. Similar to lateral and oblique position, decubitus positions are named by the body surface on which the patient is lying.

Dorsal decubitus : patient is lying on his back.

Ventral decubitus : patient is in prone position.

Right lateral decubitus : patient is lying on the right side of the body laterally.

Left lateral decubitus : patient is lying on the left side of the body laterally.

e) Tangential projection: A tangential projection is one in which the central ray skims between body parts to profile a bony structure and project it free of superimposition.

f) Axial projections: In an axial projection there is longitudinal angulation of the central ray with the long axis of the body part.4) Body movement: The following terms are used to describe movement related to the extremities: a) Abduction and adduction

Abduction :movement of a part away from central axis of body. Adduction : movement of a part toward central axis of body b) Flexion and extension

Extension :straightening of a joint; stretching of a part; also, a backward bending movement; opposite of flexion. Flexion : a bending movement of a joint whereby angle between contiguous bones is diminished; also , a forward bending movement; opposite of extension.

c) Inversion and eversion

Evert or eversion: movement of the foot when turned outward at the ankle joint.

Invert or inversion :movement of the foot when turned inward at the ankle joint. d) Pronate and supinate

Pronate: to turn arm so that palm of hand faces backward. Supinate: to turn arm so that palm of hand faces forward.5) Central ray : refers to the direction of the X-ray beam arising from tube toward patient (area of interest):a) Straight central ray: perpendicular , vertical or horizontal.

b) Angled central ray could be:

Cephalad : the central ray is oriented superiorly /proximally.

Caudad: the central ray is oriented inferiorly/distally or caudally. Medially: inside.

Laterally: outside

Anteriorly or posteriorly.

Skull

A) Skull landmarks and anatomy :

Acanthion : midpoint of the anterior nasal spine. Nasion : midpoint of the frontonasal suture.

Glabella : smooth elevation located between the superciliary arches.

Inion : midpoint of the external occipital protuberance.

Gonion: angle of the mandible.

Tragion : superior border of the tragus, located anteriorly and superiorly to the external acoustic meatus.

Mental point.

Midsagittal plane : midsagittal plane of skull, extending from the nasion to the inion.

Orbitomeatal line (OML) : it is perpendicular to the midsagittal plane, crossing through the nasion and both tragions.

Infraorbitomeatal line (IOML)

Acanthiomeatal line (AML)

External acoustic meatus (EAM)

Infraorbital margin.

Interpupillary line.

Outer canthus.

Inner canthus.

B) Lateral skull projection : 1) Position:

The patient may be placed either:

In the standing position.

In the seated position.

In the semiprone position.

In the supine position.

Adjust the patient's head so that the midsagittal plane is parallel to the plane of the cassette.

The interpupillary line is perpendicular to the film.

2) Central ray : Direct the central ray perpendicularly to a point located about 5 cm superior to the external acoustic meatus (EAM)

3) Evaluation criteria : Entire skull should be shown in a lateral projection without rotation or tilt. Superimposed orbital roofs and greater wings of sphenoid.

Superimposed mastoid regions and EAMs.

Superimposed temporomandibular joints.

Sella turcica seen in profile.

No overlap of cervical spine by mandible.

C) PA skull projection with zero degree central ray angulation:1) Position:

The patient is placed in either a prone or seated position, in a posteroanterior projection.

Rest the patient's forehead and nose on the table.

The OML plane should be perpendicular to the plane of the cassette

2) Central ray : Direct the central ray perpendicular to exit the nasion.

3) Evaluation criteria :

Entire cranial perimeter showing three distinct tables of squamous bone.

Frontal bone is well shown Equal distance from lateral border of skull to lateral border of orbit on both sides. Symmetric petrous ridges.

Petrous pyramids filling the orbits

D) PA skull projection : Caldwell method (with 15 degrees central ray angulation):1) Position:

Place the patient in either a prone or seated position. Rest the patient's forehead and nose on the table or against the upright bucky. The OML plane should be perpendicular to the plane of the cassette, in a posteroanterior projection.

2) Central ray :Direct the central ray to exit the nasion at an angle of 15 degrees caudad (in relation to the OML plane)


Entire cranial perimeter showing three distinct tables of squamous bone. Equal distance from lateral border of skull to lateral border of orbit on both sides.

Symmetric petrous ridges.

Petrous pyramids lying in lower third of orbit.

Penetration of frontal bone without excessive density at lateral borders of skull.

E) PA skull projection with 25 degrees central ray angulation : incidence face haute en appui front-nez in french:1) Position:

Place the patient in either a prone or seated position.

Rest the patient's forehead and nose on the table or against the upright bucky.

The OML plane should be perpendicular to the plane of the cassette, in a posteroanterior projection.2) Central ray : Direct the central ray to exit the nasion at an angle of 25 degrees caudad (in relation to the OML plane).

3) Evaluation criteria : Entire cranial perimeter showing three distinct tables of squamous bone. Equal distance from lateral border of skull to lateral border of orbit on both sides.


Petrous pyramids lying just below orbits.

Foramina rotundum are demonstrated.


F) AP skull projection with zero degree central ray angulation ( Petrous pyramids filling orbits view ) :Incidence face avec rochers dans les orbites in French : 1) Position :

Place the patient in the standing or supine position, in an anteroposterior projection. The midsagittal plane and OML are perpendicular to the cassette.

2) Central ray : - Direct the central ray perpendicularly to the nasion (zero degree central ray angulation in relation to the OML): incidence face, rochers dans les orbits in french " AP projection with petrous pyramids filling orbits"

3) Evaluation criteria and structures shown : Petrous pyramids are shown within orbits . Entire cranial perimeter showing three distinct areas of squamous bone.

Equal distance from lateral border of skull to lateral border of orbit on both sides.


G) AP skull projection with central ray angulation of 25 degrees cephalad: (incidence face haute en appui occipital , rayon vertical in french):

1) Position:

Place the patient in the supine position. Adjust the head in an anteroposterior projection with occipital support.

2) Central ray : The vertical central ray is directed to the nasion at an angle 25 degrees cephalad (in relation to the OML)

3) Evaluation criteria and structures shown :

This projection is often used in case of patient's trauma. Entire cranial perimeter showing three distinct areas of squamous bone.

Equal distance from lateral border of skull to lateral border of orbit on both sides.

Petrous pyramids lying just below orbits.


H)AP axial skull projection :Townes method: (incidence fronto-sous-occipitale semi-axiale, worms et Breton method in french):

1) Position : Place the patient in either a supine, seated or standing position, in an anteroposterior projection..Adjust the patient's head so that the midsagittal plane and OML are perpendicular to the plane of the cassette.

2) Central ray : The central ray enters about 6 cm above the glabella and passes through the midarea of the EAMs towards the foramen magnum at a caudal angle of 25 30 degrees to the OML..

3) Strutures shown and evaluation criteria :

Equal distance from lateral border of skull to lateral margin of foramen magnum on both sides, indicating no rotation. Symmetric petrous pyramids.

Dorsum sellae and posterior clinoid processes visible within foramen magnum.

- This projection is also used for tomographic studies of the ears, facial canal, jugular foramina and rotundum foramina.

I) Submentovertical skull base projection: incidence axiale de Hirtz in french:

1) Position:

Place the patient in the supine or the seated-upright position, in an anteroposterior projection.

The midsagittal plane should be perpendicular to the cassette.

Extend the patient's neck to the greatest as can be achieved, placing the IOML (infraorbitomeatal line) as parallel as possible to the cassette.

2) Central ray : The central ray enters the midsagittal plane of the throat between the angles of the mandible and passes through a point 2 cm anterior to the level of the EAMs .. the central ray should be horizontal in the seated-upright position, forming an angle of 105 degrees with the OML for Hirtz method.3) Structures shown: This projection of the cranial base demonstrates symmetric images of the petrosae, the mastoid processes, the foramina ovale and spinosum, the carotid canals , the sphenoidal and ethmoidal sinuses, the mandible , the bony nasal septum, the dens of the axis, and the occipital bone. The maxillary sinuses are superimposed over the mandible. This projection is also used for axial tomography of the orbits, optic canals, ethmoid bone, maxillary sinuses and mastoid processes.

The zygomatic arches are also well demonstrated.


Clearly visible structures of the cranial base Equal distance from lateral border of skull to mandibular condyles on both sides, indicating no rotation.

Superimposition of mental protuberance over anterior frontal bone, indicating full extension of neck.

Mandibular condyles anterior to petrous pyramids.

Symmetric petrosae.

SELLA TURCICAA) Lateral sella turcica projection:a) position : - A tightly collimated image fo the sella turcica is often requested in addition to the lateral projection of the entire skull.

- The patient may be placed in the seated erect or semiprone position.

- Adjust the rotation of the body so that the midsagittal plane is parallel to the plane of the film.

- Adjust the shoulders to lie in the same transverse plane.- The cassette is centered to the region of the sella turcica, a point 2 cm anterior and 2 cm superior to the external auditory meatus.

- Adjust the head in a true lateral position, so that the midsagittal plane is parallel with and the interpupillary line is perpendicular to the plane of the film.

- Adjust the head so that the infraorbitameatal line is parallel with the transverse axis of the film.

b) Central ray : Direct the central ray perpendicularly to the midpoint of the film.

c) Structures shown : A lateral projection of the sellar region of the cranium is seen.d) Evaluatin criteria :

- Sella trucica should not be rotated.- Anterior and posterior clinoid processes should be superimposed.

- Sella turcica should be in the center of the radiograph and in a lateral projection.- Close beam restriction needed of sellar region.

B) Sella turcica (dorsum sellae and posterior clinoid processes):

AP axial projection:a) Position of patient :

With the patient seated, standing or supine, center the midsagittal plane of the body to the midline of the grid. Place the patients arms along the sides of the body and adjust the shoulders to lie in the same transverse plane.

b) Position of part :

With the midsagittal plane centered to the midline of the grid, adjust the flexion of the head so that the infrorbitomeatal line is perpendicular to the plane of the film.

Adjust the film so that its midpoint will coincide with the central ray.

c) Central ray :

Direct the central ray to the midline of the film to a point that lies directly below the occlusal line at an angle of 30 or 37 degrees caudal according to the projection desired.

d) Structures shown:

An AP axial projection of the sellar region and the petrous pyramids is demonstrated.

A 30 degree angulation of the central ray will project the dorsum and tuberculum cellar and the anterior clinoid processes through the occipital bone above the level of the foramen magnum.

A 37-degree angulation will project the dorsum sellar and posterior clinoid processes within the shadow of the foramen magnum.

e) Evaluation criteria:

Sellar structures should be demonstrated within the foramen magnum with a 37-degree angulation and through the occipital bone with 30-degree angulation.

There should be no rotation of cranium.

Petrous pyramids should be symmetric.

Close beam restriction needed of sellar region.

ORBITS

Optic foramen, parieto-orbital oblique projection, Rhese method a) Position of patient : - Place the patient in the prone or seated erect position .- Place the arms in a comfortable position and adjust the shoulders to lie in the same transverse plane.b) Position of part : - Center the affected orbit to the unmasked half of the cassette and rest the head on the zygoma, the nose, and the chin.- Adjust the flexion of the head to place the acanthomeatal line perpendicular to the plane of the film.

- Adjust the rotation of the head so the midsagittal plane forms an angle of 53 degrees with the plane of the film.

- Check the position of the acanthomeatal line with one of the right-angle sides of the triangle.

c) Central ray : Direct the central ray perpendicularly to the midpoint of the film.

d) Evaluation criteria :- Optic foramen should lie in the lower outer quadrant of the orbit.

- Optic foramen should be seen enface at the end of the sphenoid ridge.

- Entire orbital shadow should be included.

- Close beam restriction needed of the orbital region.

Orbits : lateral projection

a) Technique:

With the patient either semiprone or seated erect, the outer canthus of the affected eye is placed adjacent to and centered over the midpoint of the film. The head is adjusted to place the midsagittal plane parallel with the plane of the film.

The central ray is directed perpendicularly through the outer acanthi.

The patient is instructed to look straight ahead for the exposure.

b) Evaluation criteria:

Density and contrast should permit optimal visibility of the orbit and eye for foreign bodies.

Orbital roofs should be superimposed.

Sella turcica should not be rotated.

Close beam restriction needed and centered to the orbital region.

Orbits : PA axial projection

a) Technique :

The head is rested on the forehead and nose, and the film holder is centered inch distal to the nasion. Adjust the head so that the midsagittal plane and the orbitomeatal line are perpendicular to the plane of the film.

Direct the central ray through the center of the orbits at a caudal angulation of 25 degrees. This angulation is used to project the petrous portions of the temporal bones below the inferior margin of the orbits .

The patient is asked to close the eyes and to concentrate on holding them still for the exposure.

b) Evaluation criteria:

Petrous pyramids should lie below the orbital shadows.

There should be no rotation of the cranium.

Close beam restriction needed and centered to the orbital region.

Nasal bones: lateral projection

a) Position of patient :

Although the patient may be seated erect before a vertical grid device, the recumbent ( lying ) position facilitates placement of the small films used in lateral examination of the nasal bones.

With the patient in a semiprone position, adjust the rotation of the body so that the midsagittal plane of the head is approximately horizontal . Place the arms in a comfortable position and adjust the shoulders to lie the same transverse plane.


Adjust the head so that the midsagittal plane is parallel with, and the interpupillary line is perpendicular to, the tabletop. Adjust the flexion of the head so that the infraorbitomeatal line is parallel with the transverse axis of the cassette . c) Central ray :

Direct the central ray perpendicularly to the bridge of the nose at a point inch distal to the nasion.d) Structures shown:

A lateral projection of the nasal bone is demonstrated, showing the detail of the side nearer the film and of the soft structures of the nose . Both sides are examined for comparison.


Nasal bone and soft tissue should be demonstrated without rotation.

Anterior nasal spine and frontonasal suture should be visualized.

Nasal bones : tangential projectiona) Technique :-Use the larger film placed under the chin, so that the plane of the film is perpendicular to the glabelloalveolar .-Place the patient in prone position, so that the chin can be rested on a sandbag or on an inclined cassette for support.-Extraoral film: Elevate the side of the cassette adjacent to the patient on a small sandbag or a folded towel. Rest the head on the fully extended chin and center the film to the midsagittal plane just anterior to the chin. Adjust the inclination of the cassette so that its plane is perpendicular to the glabelloalveolar line. Adjust the head so that the midsagittal plane is perpendicular to the plane of the film. Immobilize the head and instruct the patient to suspend respiration for the exposure.

b) Central ray: Direct the central ray along the glabelloalveolar line perpendicularly to the plane of the film.

c) Structures shown:

An axial projection of only a portion of the nasal bones that extend beyond the glabelloalveolar line is shown .

This projection is primarily used to demonstrate any medial or lateral displacement of fragments in fractures.d) Evaluation criteria:

Nasal bones should be demonstrated with minimal superimposition unless the patient has a prominent forehead, recessed nose, or protruding upper teeth.

There should be no rotation of the nose.

Soft tissue should be visualized.

Zygomatic arches: tangential (submentovertical) projection

a) technique :

The patient may be placed in either the seated erect or the supine position. When the supine position is used, elevate the trunk on several firm pillows or a suitable pad to allow complete extension of the head and flex the knees to relax the abdominal muscles. Center the midsagittal plane of the body to the midline of the vertical grid device or the table. Place the arms in a comfortable position and adjust the shoulders to lie in the same transverse plane.

-Extend the patients head completely so that the infraorbitomeatal line, which passes through the long axis of the zygomatic arches, is as nearly parallel with the plane of the film as possible.-Rest the head on the vertex and adjust it so that the midsagittal plane is perpendicular to the plane of the film.

-Respiration is suspended for the exposure.

-Adjust the cassette position so that the midpoint of the film will coincide with the central ray.

-Direct the central ray perpendicularly to the infraorbitomeatal line and center it midway between the zygomatic arches. It passes through a coronal plane lying approximately 1 inch posterior to the outer acanthi.

b) Structures shown: A symmetric axial projection of the zygomatic arches is shown, projected free of superimposed structures .

Unless they are very flat or are traumatically depressed, the arches, being farther from the film, are projected beyond the prominent parietal eminences.

c) Evaluation criteria:

Zygomatic arches should be free from overlying structures.

Zygomatic arches should be symmetric and without foreshortening.

There should be no rotation of the head.

Mandibular rami : (PA and PA axial projections)


Examine the patient in the prone position or seated before a vertical grid device. Place the arms in a comfortable position ad adjust the shoulders to lie in the same transverse plane.b) Position of part :

Films may be taken with or without a grid. In either case , rest the patient s head on the forehead and nose, and (1) for a general projection of the mandibular rami, center the tip of the nose to the midpoint of the film, or (2) for the demonstration of the condylar processes, center the glabellas to the midpoint of the film. The film is adjusted so that the midpoint will coincide with the central ray.

With the head resting on the forehead and nose and centered to the midline of the table, or with the desired region centered to the cassette , adjust the head so that the midsagittal plane is perpendicular to the plane of the film.

Immobilize the head and instruct the patient to suspend respiration for the exposure.

c) Central ray : For a general surgery projection, direct the central ray perpendicularly to the lips .. For the condylar processes, direct the central ray 20 or 25 degrees cephalad


A PA projection shows the mandibular body and rami.

The central part of the body is not well shown because of the superimposed shadow of the spine. This projection is usually employed to demonstrate any medial or lateral displacement of fragments in fractures of the rami.


Mandibular body and rami should be symmetric on each side.

Condylar processes should be demonstrated when the central ray is angled cephalad.

Entire mandible should be included.

Mandible : Axiolateral projection


Place the patient in the prone position or seated so that the head can be adjusted on a horizontally placed cassette.

When the patient is in the prone position, oblique the body slightly and have the patient support the body on the opposite hand and forearm.

b) Central ray :

Direct the central ray to the midpoint of the film at an angle of 25 degrees cephalad.

c) Structures shown:

An axiolateral projection demonstrates the body of the mandible from the angle to the region of the canine.

d) Evaluation criteria :

Mandible body to the canine tooth should be demonstrated.

Opposite side of the mandible should not overlap mandibular body.

Mandible: submentovertical projection


Examine the patient before a vertical grid device or place in the supine position. In the latter case , elevate the trunk 7 or 8 inches on firm pillows or on a suitable pad to permit complete extension of the head and flex the patients knees to relax the abdominal muscles and thus relieve strain on the neck muscles. Center the midsagittal plane of the body to the midline of the table or the vertical grid device. Place the arms in a comfortable position and adjust the shoulders to lie in the same transverse plane.b) Position of part :

With the head fully extended, rest it on the vertex and adjust it so that the midsagittal plane is vertical . when the head cannot be extended enough so that the infraorbitomeatal line is horizontal when the patient is in the supine position, the cassette should be inclined caudally.


Adjust the cassette so that its midpoint will concede with the central ray.

c) Central ray :

Direct the central ray perpendicularly to the infraorbitomeatal line and center it midway between the external auditory meatuses.


An axial projection of the mandibular body is demonstrated, showing the coronoid and condyloid processes of the rami.


Distance between the outer border of the skull and the mandible should be equal on both sides.

Condyles of the mandible should be anterior to the petrosae.

Symphysis should extend almost to the anterior border of the face so the mandible is not foreshortened.

Temporomandibular joints: AP axial projection

a) Position of patient : Place the patient in the supine or seated erect position.


Center the cassette to the midsagittal plane of the patients neck at a point directly below the temporomandibular joints. Place the arms in a comfortable position and adjust the shoulders to lie in the same transverse plane.

Adjust the head so that the midsagittal plane is vertical . Flex the head enough so that the orbitomeatal line is perpendicular to the plane of the film.

Instruct the patient to suspend respiration for the exposure.

c) Central ray :

Direct the central ray at a caudal angle of 35 degrees. Center it midway between the temporomandibular joints. It enters at a point approximately 3 inches above the nasion.

One film is exposed with the mouth closed, and, when not contraindicated, one is exposed with the mouth open.


This projection presents an axial image of the condyloid processes of the mandible and of the mandibular fossae of the temporal bones.

c) Evaluation criteria :

No rotation of the head.

Only minimal superimposition by the petrosa on the condyle in the closed mouth examination.

Condyle and temporomandibular articulation should be demonstratd below the petrosa in the open-mouth position.

Temporomandibular joints : lateral transcranial projection


Place the patient in a semiprone position of seated before a vertical grid device.

In examinations of the temporomandibular joints (TMJs), it is common practice to make one radiograph with the mouth closed and, when not contraindicated, one with the mouth open. b) Position of part :

Center a point inch anterior to the external auditory meatus to the cassette and rest the patients head on the cheek. Adjust the flexion of the head so the acanthomeatal line is parallel with the transverse axis of the film. Immobilize the head and instruct the patient to suspend respiration for the exposure.

After making the exposure with the mouth closed, change the cassette and instruct the patient to open the mouth side. Recheck the position of the acanthomeatal line and make the second exposure.

c) Central ray : Direct the central ray 15 degrees caudal, exiting through the dependent TMJ.d) Structures shown :

The open- and closed-mouth projections demonstrate the condyles and necks of the condylar processes. The projections also show the relation between the mandibular fossa and the condyle. The open mouth projection demonstrates the mandibular fossa and the inferior and anterior excursion of the condyle. Both sides are examined for comparison.

The closed-mouth position of this method is employed for the demonstration of fractures of the neck and condyle of the ramus.e) Evaluation criteria :

Temporomandibular articulation should be clearly visualized.

Condyle should lie in the mandibular fossa in the closed-mouth examination.

Condyle should lie below the particular tubercle in the open-mouth projection if the patient is normal and able to open the mouth wide.

Panoramic tomography : mandible

a) Pathology demonstrated : Fracturs of the mandible and TMJ pathology. Dental pathology.

b) Technical factors :

IR size 23 x 30 cm (9 x 12 inches) crosswise.

Curved nongrid cassette.

70 80 kV range.

c) Unit preparation :

Atach image receptor to panoramic unit.

Position tube and image receptor at starting position.

Raise chin rest to approximately same level as patient's chin.

d) Shieldging : wrap vest-type lead apron around patient.

e) patient position :

Remove all metal , plastic , and other removalble objects from head and neck.

Explain to patient how tube and image receptor rotate and the time span needed for exposure.

Guide patient into unit, resting patient's chin on bite block.

Position patient's body, head , and neck properly. Do not allow head and neck to stretch foreward but have paitent stand in close, with spine straight and hips forward.

f) Part position :

Adjust height of chin rest until IOML is aliged parallel with floor.

The occlusal plane (plane of biting surface of teeth) declines 10o from posterior to anterior.

Align midsagittal plane with the vertical center line of the chin rest.

Position bite block between patient' s front teeth.

Instruct patient to place lips together and position tongue on roof of mouth.

g) Central ray : X-ray beam direction is fixed and directed slightly cephalic to project anatomic structures, positioned at the same height, on top of one another. Fixed SID, per panoramic unit.

h) collination : A narrow, vertical-slit diaphragm is attached to tube, providing collimation.

i) Structure shown : A single image of the teeth, mandible TMJs , nasal fossae, maxillary sinus, zygomatic arches, and maxillae is shown. j) Evaluatin criteria :

The mandible visualized without rotation or tilging is indicated by the following : TMJs on the same horizontal plane in the image.

Rami and posterior teeth equally magnified on each side of the image.

Anterior and posterior teeth sharply visualized with uniform magnification . Correct positioning of the patient is indicated by the following : Mandibular symphysis projected slightly below the mandibular angles, mandible oval in shape.

Occlusal plane parallel with the long axis of the image.

Upper and lower teeth positioned slightly apart with no superimposition.

The mandible is located in the center of the image. Density of mandible and teeth is uniform across entire image. No density loss is evident in the center .

No artifacts are superimposed on the image.

Note : When the TMJs are of interest, additional panoramic images are taken ( lateral panoramic view for eath TMJ with the mouth open and closed ).

Maxillary sinuses: waters method ( Blondeau method in french)


Place the patient in the PA position, preferably seated erect. Center the midsagittal plane of the body ot the midline of the grid device or table. Place the arms in a comfortable position and adjust the shoulders to lie in the same transverse plane.


Extend the patients head to approximately the correct position and then center the cassette or cassette-changing tunnel to the anterior nasal spine (acanthion). Rest the head on the chin and adjust it so that the midsagittal plane is perpendicular to the plane of the film. Using a protractor as a guide, adjust the head so that the orbitomeatal line forms an angle of 37 degrees from the plane of the film.


c) Central ray :

Direct the central ray perpendicularly to the midpoint of the film . it enters the vertex and emerges at the anterior nasal spine.


The maxillary sinuses (antra) are demonstrated with the shadows of the petrous pyramids lying below the antra floors. The frontal and ethmoid sinuses are distorted in this position, and the sphenoid sinuses are not shown.

The Waters position is also used to demonstrate the rotundum foramina, the images of which are seen, one on each side, just below the medial aspect of the orbital floor and above the roof of the maxillary sinuses.


Petrous pyramids should lie immediately below the floor of the maxillary sinuses.

Distance between the lateral border of the skull and the outer border of the orbit should be equal on both sides.

Orbits and maxillary sinuses should be symmetric on each side.

Maxillary sinuses should be visualized clearly.

Close beam restriction needed of the sinus area.

Frontal and anterior ethmoid sinuses: PA axial projection, Caldwell method

a) Technique :

With the patient in the preferred upright position, center the midsagittal plane of the body to the midline of the grid. Place the patients arms in a comfortable position and adjust the shoulders to lie in the same transverse plane.b) Position of part :

When the angulation of the vertical grid device cannot be adjusted. The patient may be positioned as follows, (it must be realized that in this method, the central ray is not horizontal)

Center the nasion to the cassette.

Rest the patient's head on the forehead and nose and adjust both the midsagittal plane and the orbitomeatal line perpendicular to the plane of the film. Immobilize the head and instruct the patient to suspend respiration for the exposure.

Direct the central ray to the nasion at an angle of 15 degrees caudal to the orbitomeatal line, which is also 15 degrees to the place of the film (identical angulation is achieved by directing the central ray 23 degrees caudal to the glabellomeatal line)

c) Structures shown :

This method demonstrates the frontal sinuses, lying above the frontonasal suture; the anterior ethmoid cells, lying on each side of the nasal fossae and immediately below the frontal sinuses.

The sphenoid sinuses, projected through the nasal fossae and immediately below the frontal sinuses; and the sphenoid sinuses, projected through the nasal fossae just below or between the shadows of the ethmoid sinuses.

The shadows of the dense petrosae extend from the lower third of the orbital shadows inferiorly to obscure the upper third of the antral shadows. This projection is used primarily for the demostration of the frontal sinuses and the anterior ethmoid cells.

d) Evaluation criteria:

Distance between the lateral border of the skull and the outer border of the orbits should be equal.

Petrous ridge should be symmetric on both sides.

Petrous ridge should lie in the lower third of the orbit.

Frontal sinuses should lie above the frontonasal suture and the anterior ethmoid air cells above the petrous ridges.

Frontal and anterior ethmoid sinuses should be visualized clearly.

Close beam restriction needed of the sinus area.

Paranasal sinuses : lateral projection


Seat the patient before a vertical grid device with the body placed so that the head can be adjusted in a true lateral position.

b) Position of part:

Center the cassette approximately to 1 inch posterior to the adjacent outer cantus.

Rest the patients head on the parietal eminence and adjust it in a true lateral position. The midsagittal plane is parallel with the plane of the film, and the interpupillary line is perpendicular to the plane of the film.

Immobilize the head and suspend respiration for the exposure.

c) Central ray:

Direct the central ray perpendicularly to the midpoint of the film; it enters the patients head to 1 inch posterior to the outer acanthus remote from the film.


A lateral projection shows the AP and superoinferior dimensions of the paranasal sinuses, their relationship to surrounding structures, and the thickness of the outer table of the frontal bone.


All four groups should be included; sphenoid sinus is of primary importance.

Sella turcica should not be rotated.

Orbital roofs should be superimposed.

Mandibular rami should be superimposed.

Sinuses should be visualized clearly.

Mastoid process and petrous portions, Schuller method

a) Position of paitent :

Place the patient in the prone position, or preferably, seated before a vertical grid device.


A mark may be made on each mastoid process at the junction of the auricle and the head immediately behind the external auditory meatus. When the mastoid cells are the point of interest, the auricles may be taped forward.

Place the patients head in the true lateral position with the midsagittal plane parallel with and the interpupillary line perpendicular to the plane of the film. Adjust the flexion of the head so that the infraorbitomeatal line is parallel with the transverse axis of the film.

c) Central ray :

The central ray is directed through the dependent external auditory meatus at the caudal angle 25 degrees.


The Schuller 25-degree projection demonstrates the pneumatic structure of the mastoid process, the mastoid antrum, the tegument tympani, the internal and external auditory meatuses, the sinus and dural plates, and, when present, the mastoid emissary vessel.e) Evaluation criteria:

Mastoid and petrous regions should be in the center of the radiograph.

Mastoid air cells should lie posterior to the petrous region.

Temporomandibulr joint should lie anterior to the petrous region.

Opposite mastoid and petrous region should not superimpose the side of interest.

Close beam restriction needed of the mastoid and petrous region.

PA projection: transorbital method (Guillen method in french)


Place the patient in either the prone or the seated erect position and center the midsagittal plane of the body to the midline of the table or vertical grid device.

Flex the patients elbows, place the arms in a comfortable position, and adjust the shoulders to lie in the same transverse plane.

b) Position of part:

Rest the patients head on the forehead and nose, with the midsagittal plane perpendicular to the midline of the table. Adjust the flexion of the head so the orbitomeatal line is perpendicular to the plane of the film. With the cassette in the Bucky tray, center it at the level of the nasion. The x-ray beam must be very tightly collimated to reduce scatter radiation.


c) Central ray :

Direct the central ray perpendicular to the nasion. Because of variations in the shape of the patients skull, the central ray may need to be angled approximately 15 degrees caudal .


The PA transorbital radiograph demonstrates the internal auditory canals projected through the shadow of the orbits. The distance between the floor and roof of each internal auditory canal should be equal . e) Evaluation criteria:

Petrous ridges should be projected below the superior margin of the orbits.

There should be no sagittal rotation as evidenced by an equal distance between the lateral margins of the skull and the orbital shadows.

Close collimation should be seen enabling visualization of the internal auditory canals.

Posterior profile projection stenvers method

a) Position of patient : Place the patient in the prone position or seated before a vertical grid device.

b) Position of part : A mark may be made on each cheek at a point 1 inch directly anterior to the external auditory meatus. When the head is correctly adjusted, this point will be inferior to the arcuate eminence. Center the localization point to the midpoint of the cassette and rest the head on the forehead, the nose, and the zygoma.

Adjust the flexion of the head so the infraorbitomeatal line is parallel with the tranverse axis of the film.

Adjust the head so that the midsagittal plane forms an angle of 45o with the plane of the film.

c) Centra ray : Direct the central ray to the midpoint of the film at an agnle of 12 degrees cephalad.

d) Structures shown:- The Stenvers method shows a profile image of the pars petrosa.- The petrous ridge, mastoid cells, mastoid antrum, area of the tympanic cavity, bony labyrinth , internal auditory canal, and the cellular structure of the petrous apex are shown.

e) Evaluation criteria :

- Petrosa should be demonstrated in profile without distortion. - Outer border of the skull to the lateral border of the orbit should be included.

- Petrous ridge should extend to a point approximately two thirds of the way up

lateral border of the orbit . - Mastoid process should be demonstrated in profile below the margin of the

cranium . - Posterior margin of mandibular ramus should superimpose lateral border of cervical column. - Mandibular condyle will be projected over the first cervical vertebra - Close beam restriction needed to the petrosa and mastoid region.

Acttic-Aditus-antral areas: Chauss III method a) Position of patient :

Place the patient in either the supine or the seated erect position.


Rotate the head, from the AP position, 15 degrees away from the side being examined and then adjust the position of the patient or the film so that a point 1 inch medial to the tragus is centered to the midline of the film. When using non-Bucky technique, center the film inch distal to the tragus.

Adjust the flexion of the head so the orbitomeatal line is parallel with the transverse axis of the film.Recheck for rotation and immobilize the head.

c) Central ray :

Direct the central ray to a point midway between the outer margin of the orbit and the tragus at an angle of 20 degrees caudal. The central ray parallels a line passing through the external auditory meatus.d) Structures shown:

A slightly oblique view of the petrosa, demonstrating the attic-aditus-antral areas is shown.


Attic-aditus-antral area should be demonstrated near the lateral margin of the orbit.

Skull should be only slightly obliqued.

Petrous ridge should extend to the uppermost margin of the orbit.

Entire petrosal region should be included.

Close beam restriction needed of the petrous region.

Auditory ossicles and attic-aditus-antrum areas axiolateral oblique projection , mayer method :

) Position of patient : Place the patient in the supine position or seated laterally before a vertical grid device

a) Position of part : The auricles may be taped forward.

When the patient is examined in the supine position the outer side of the cassette should be elevatd so that the closet possible part-film relationship can be obtained .

This requires that the opposite side of the cassette be braced with a sandbag to prevent slipping and to elevated and support the head for accurate centering of the part ot the film.

With the ear that is being examined adjacent to the film, adjust the head at the angle of 45 degrees and then center the localization point behind the auricle to the cassette. b) Central ray : Direct the central ray through the dependent external auditory meatus at an angle of 45 degrees caudad.

c) Structures shown: An axial oblique projection of the petrossa in the direction of its long axis demonstrating the external auditory meatus, the tympanic cavity and ossicles, the epitympanic recess (attic ) , the aditus , and the mastoid antrum.d) Evaluation criteria :

Petrosa should be demonstrated inferior to the mastoid air cells. External auditory meatus should be visualized adjacent and anterior to the petrosa. Temporomandibular joint should be seen anterior to the external auditory meatus.

Auricle of the ear should not superimpose the ptrosa or mastoid air cells.

Close beam restriction needed of the petrosal region.

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