ORBITS POSITIONING

ORBITS

are cone-shaped, bony-walled cavities situated on each side of the midsagittal plane of the head.

frontal, ethmoid, and sphenoid) and the face (lacrimal, palatine, maxillary, and zygomatic)

Orbits are formed by the seven bones of the cranium:

a roof, a medial wall, a lateral wall, and a floor

Each orbit has;

base

The easily palpable, quadrilateral-shaped anterior circumference of the orbit is called its

optic foramen

The apex of the orbit corresponds to the ____

37 degrees; 30 degrees

The long axis of each orbit is directed obliquely, posteriorly. and medially at an average angle of ____ to the midsagittal plane of the head and also superiorly at an angle of about ___ from the OML.

ORBITS

serve primarily as bony sockets for the eyeballs and the structures associated with them, but they also contain blood vessels and nerves that pass-through openings in their walls to other regions.

optic foramina; superior and inferior orbital sulci.

The major and frequently radiographed openings are the previously described ___ and the ___

farcture

Because the walls of the orbits are thin, they are subject to ___

blow-out

____ fractures may be demonstrated using any combination of radiographs obtained with the patient positioned for parietoacanthial projections (Waters method), radiographic tomography, and/or CT.

- Use of small focal spot to lessen the penumbral shadow.
- Use of close collimation to reduce scatter radiation
- Immobilization of eyeballs by letting the patient gaze steadily at a fixed object.
- Use of clean cassettes and screens to avoid appearance of artifacts that resemble the foreign body.

In order to acquire fine-detail film quality for detection and localization of minute foreign body particles, the technologist must follow the following:

SCOUT RADIOGRAPH

is taken to determine whether the foreign body can be demonstrated in radiography.

lateral, PA Axial and Bone-free studies

A scout radiograph is taken to determine whether the foreign body can be demonstrated in radiography. • Projections include:

seated erect or recumbent

SCOUT RADIOGRAPH IN ORBITS Positions can be;

lateral position

For the ___, the patient can be semiprone or seated erect with the outer canthus of the affected eye placed adjacent to the cassette and centered. MSP should be parallel and IPL perpendicular to IR. The patient is asked to look straight ahead with the CR perpendicular to the outer canthus.

outer canthus.

For the lateral position, the patient can be semiprone or seated erect with the outer canthus of the affected eye placed adjacent to the cassette and centered. MSP should be parallel and IPL perpendicular to IR. The patient is asked to look straight ahead with the CR perpendicular to the ____

- Density and contrast should permit optimal visibility of the eye and orbit for foreign bodies Orbital roofs should be superimposed
-Sella turcica should not be rotated o -- Spot view is needed a centered to the orbital region.

For the lateral position, The image should appear as follows:

PA Axial position

For the____, the forehead and nose is placed in contact with the IR. IR is centered 3⁄4 in or 1.9 cm distal to the nasion. MSP and OML are perpendicular to IR. CR is then centered to the orbits using a 30- degree caudal angulation. This should project the petrous pyramids below the inferior margin of the orbits. The patient is asked to close their eyes and hold them still for the exposure.

3⁄4 in or 1.9 cm; 30- degree caudal

For the PA Axial position, the forehead and nose is placed in contact with the IR. IR is centered ___ distal to the nasion. MSP and OML are perpendicular to IR. CR is then centered to the orbits using a ___ angulation. This should project the petrous pyramids below the inferior margin of the orbits. The patient is asked to close their eyes and hold them still for the exposure.

- Petrous pyramids should appear below the orbital shadows
- No rotation of the cranium
- Spot view centered to the orbital region

For the PA Axial position, The image should appear as follows:

Additional: Modified Waters method

In this projection, the petrous portions are displaced by part position and not through CR angulation. Nose and chin should rest on the IR with the MSP perpendicular to IR.

25-37-degree

Additional: Modified Waters method: Flexion of the neck allows the orbitomeatal line to form a ___ angle with the IR. CR is perpendicular to the midorbits. The patient is asked to close their eyes and hold them still for the exposure.

- Petrous pyramids should appear below the orbital shadows
- No rotation of the cranium
- Spot view centered to the orbital region

Additional: Modified Waters method, The image should appear as follows:

Vogt-Bone Free positions

These positions are used to detect small or low-density foreign particles located in the anterior segment of the eyeball or in the eyelids.

Vogt-Bone Free positions

The projections include, latermedial and superoinferior if the eyeball is not deep-seated with the use of peri-apical or occlusal films.

Vogt-Bone Free positions

In the __, eyes may be directed straight forward and/or in different positions.

vertical movement

Vogt-Bone Free positions; For ___ images, in the first exposure, the patient looks up as much as possible and the second exposure involves the patient to look down as much as possible.

horizontal movement

Vogt-Bone Free positions: For ___ images, the first exposure is made by letting the patient look on the extreme right and the second one on the extreme left. These images are taken in a superoinferior projection if the eye is not deeply seated.

lateral position

Vogt-Bone Free positions; In the ___, the film is curved back to avoid discomfort caused by the pressure of the sharp edge. The film should be parallel with the MSP. The patient should apply steady pressure on the film during the exposure.

Vogt-Bone Free positions

The CR is directed horizontally through the outer and inner canthi.

Anterior segment of the eyeball should demonstrate soft tissue The zygoma should not overlap the anterior segment of the eyeball

Vogt-Bone Free positions, The image should appear as follows:

superoinferior projection

Vogt-Bone Free positions: For the ___, the film is placed against the lower eyelid between the inferior margin of the orbit and the eyeball. Firm pressure should be applied during the exposure. The film may be placed diagonally for better placement.

superoinferior projection

Vogt-Bone Free positions: CR is vertically centered just anterior to the superior margin of the orbit and between the canthi.

Vogt-Bone Free positions; superoinferior projection

Anterior segment of the eyeball should demonstrate soft tissue The superior margin of the orbit should not overlap the anterior segment of the eyeball

Parallax Motion method

This method is used to determine the presence of foreign body within the eyeball.

Richards

Parallax Motion method: ___ describes the method using two lateral exposures and two PA exposures with the eyeball in different positions.

Anteriorly and posteriorly

Parallax Motion method: ____ intralocularly displaced foreign bodies move with the eyeballs whereas centrally located foreign bodies do not move.

Parallax Motion method

Foreign bodies lodged in the extrinsic muscles or in the fascial sheath of the bulb also move with the eyeball but for this reason the method is used for preliminary check and not as a precision localization procedure.

PA Axial position

Parallax Motion method: For the____, the patient places the nose and chin in the IR with the MSP perpendicular to IR.

Parallax Motion method

One exposure is taken with patient looking in the extreme right and the other exposure on the extreme left.

Parallax Motion method

CR is perpendicular to the midorbits.

Parallax Motion method

The images appear as follows: Demonstration of the orbits without rotation of the cranium Petrous pyramids should lie below the floor of the orbits

lateral position

Parallax Motion method: For the _____, the patient's head is rested on the IR with the outer canthus of the affected eye adjacent and centered to the IR, MSP should be parallel to IR.

One

Parallax Motion method: ___ exposure is made with the eye looking up as far as possible and another exposure looking down as far as possible.

Parallax Motion method: lateral position

Parallax Motion method: CR is directed perpendicular to the canthi.

Parallax Motion method: lateral position

Parallax Motion method- The images appear as follows: Density should provide optimal visualization of the eye and orbit. Orbital roofs should be superimposed o Sella turcica should not be rotated.

Sweet method

This method determines the exact location of the foreign body by the use of geometric calculations

8x10

Sweet method: A device that has a localizer device and an ___ inch film tunnel with two markers with known relationship and position is required.

Sweet method

The patient lies in the lateral recumbent position lying on the affected side.

Sweet method

In this method an indicator placed 10 mm. in front of the vertex corneae is included in two radiographs (CR perpendicular,

Sweet method

CR 15-25 degrees cephalad), taken with different directions of the rays, from which the position of the foreign body is determined with the aid of a graphic localizing chart.

Sweet method

The image should appear as follows: o The direct lateral position demonstrates the depth of the foreign body with the device's ball and cone and orbital roofs superimposed

Sweet method

The image should appear as follows: o The angled lateral position demonstrates the position of the foreign body with the device's ball and cone not superimposed

Pfeiffer-Comberg method

A leaded contact lens is used for this method which is placed directly over the cornea. The foreign bodies are then localized in relation to the corneoscleral junction and the limbus of the eye

Pfeiffer-Comberg method

A film holder with a vertical (2 sighting apertures and a bite bar) and horizontal tunnel, and a contact lens with 4 markers separated in 90 degree angles, is used for this procedure.

PA projection

Pfeiffer-Comberg method: For ____, the patient is placed on the film holder laterally and CR is directed horizontally on the lowermost sighting aperture - the position occupied by the affected eye. The sterile contact lenses are then applied after applying anesthesia to the eye. The neck is then extended.

PA projection

Pfeiffer-Comberg method: The MSP should be parallel to the horizontal tunnel and perpendicular to the vertical tunnel. The teeth are closed in the bite bar.

PA projection

Pfeiffer-Comberg method: The patient is then asked to look ahead and fix his/her gaze. The film is placed in the vertical tunnel for this position.

lateral projection

Pfeiffer-Comberg method: For the ___, the tube is then move so that the CR is directed to the outer canthus. The film is then placed on the horizontal tunnel.

PA projection

Pfeiffer-Comberg method: The ___ shows the location of the foreign body with reference to the center of the contact lens. The image shows no rotation of the skull and pars petrosa below the orbital floors.

lateral projection

Pfeiffer-Comberg method: The ___ shows the depth of the foreign body penetrated. The image also shows the orbital roofs superimposed.

Parietoorbital Oblique Projection of the Optic Canal and Foramen: Rhese Method

Patient is either semiprone or seated.

Parietoorbital Oblique Projection of the Optic Canal and Foramen: Rhese Method

CR is perpendicular, entering approximately 1 inch (2.5 cm) superior and posterior to the upside TEA. The central ray exits through the affected orbit closest to the IR.

Parietoorbital Oblique Projection of the Optic Canal and Foramen: Rhese Method

This projection demonstrates the optic canal "on end" and the optic foramen lying in the inferior and lateral quadrant of the projected orbit. Any lateral deviation of this location indicates incorrect rotation of the head. Any longitudinal deviation indicates incorrect angulation of the AML.

Orbitoparietal Oblique Projection of the Optic Canal and Foramen: Rhese Method

Patient is either supine or seated upright.

Orbitoparietal Oblique Projection of the Optic Canal and Foramen: Rhese Method

CR is perpendicular to enter the uppermost orbit at its inferior and lateral quadrant.

Orbitoparietal Oblique Projection of the Optic Canal and Foramen: Rhese Method

Greater radiation exposure to the lens of the eye occurs with the orbitoparietal oblique projection than with the parietoorbital oblique projection.

Orbitoparietal Oblique Projection of the Optic Canal and Foramen: Rhese Method

This projection should be used for patients who cannot be turned to the prone position. However, placing the patient supine results in a certain degree of magnification on the radiograph because of the increased OID.