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Questions and Answers
What is the significance of the outer canthus of the eye in radiographic positioning?
What is the significance of the outer canthus of the eye in radiographic positioning?
- It is used as a reference point for the interpupillary line. (correct)
- It defines the lowest point of the orbit.
- It indicates the highest point of the skull.
- It serves as a location for the external auditory meatus.
Which anatomical landmark is considered the highest point of the skull?
Which anatomical landmark is considered the highest point of the skull?
- Nasion
- Glabella
- External occipital protuberance
- Vertex (correct)
What does the infraorbital margin point refer to?
What does the infraorbital margin point refer to?
- The midpoint of the eye sockets.
- The lowest point of the nasal bone.
- The superior rim of the orbit.
- The lowest point of the inferior rim of the orbit. (correct)
Which line is defined as extending from the outer canthus of the eye to the center of the external auditory meatus?
Which line is defined as extending from the outer canthus of the eye to the center of the external auditory meatus?
Where is the external occipital protuberance located?
Where is the external occipital protuberance located?
What does the anthropological baseline connect?
What does the anthropological baseline connect?
Which landmark is associated with the junction of the nasal and frontal bones?
Which landmark is associated with the junction of the nasal and frontal bones?
What is the angle of the mandible commonly referred to as?
What is the angle of the mandible commonly referred to as?
How is a lateral projection defined?
How is a lateral projection defined?
What determines the naming of an oblique projection?
What determines the naming of an oblique projection?
In a right lateral projection, where does the central ray enter the skull?
In a right lateral projection, where does the central ray enter the skull?
What is an example of a complex oblique projection?
What is an example of a complex oblique projection?
In a fifty-five degree right anterior oblique projection with caudal angulation, what does the term 'caudal' refer to?
In a fifty-five degree right anterior oblique projection with caudal angulation, what does the term 'caudal' refer to?
What additional angle might be added to an oblique projection?
What additional angle might be added to an oblique projection?
When performing an oblique projection, what should you ensure about the central ray?
When performing an oblique projection, what should you ensure about the central ray?
What is the significance of angling the X-ray tube during complex oblique projections?
What is the significance of angling the X-ray tube during complex oblique projections?
What does the median sagittal plane do?
What does the median sagittal plane do?
Which landmark is located posteriorly on the median sagittal plane?
Which landmark is located posteriorly on the median sagittal plane?
What kind of projection is indicated by the central ray entering through the occipital bone and exiting through the frontal bone?
What kind of projection is indicated by the central ray entering through the occipital bone and exiting through the frontal bone?
In what situation would cranial angulation be indicated in imaging?
In what situation would cranial angulation be indicated in imaging?
What does the term 'FO30°↓' indicate in a radiographic projection?
What does the term 'FO30°↓' indicate in a radiographic projection?
Which statement is true about coronal planes in relation to the median sagittal plane?
Which statement is true about coronal planes in relation to the median sagittal plane?
What is the anthropological plane?
What is the anthropological plane?
What describes the relationship between the median sagittal, anthropological, and coronal planes?
What describes the relationship between the median sagittal, anthropological, and coronal planes?
Which landmark is immediately superior to the nasion?
Which landmark is immediately superior to the nasion?
What is the primary function of the infraorbital line in skull radiography?
What is the primary function of the infraorbital line in skull radiography?
Which of the following landmarks is associated with the ear?
Which of the following landmarks is associated with the ear?
The median sagittal plane is best described as which of the following?
The median sagittal plane is best described as which of the following?
What does the term 'angle of the mandible' refer to?
What does the term 'angle of the mandible' refer to?
Which line connects the centers of the two pupils in radiographic positioning?
Which line connects the centers of the two pupils in radiographic positioning?
What is the significance of the vertex in skull anatomy?
What is the significance of the vertex in skull anatomy?
What does the anthropological baseline connect?
What does the anthropological baseline connect?
What does the median sagittal plane do?
What does the median sagittal plane do?
Which of the following correctly describes a coronal plane?
Which of the following correctly describes a coronal plane?
What is defined as an occipto-frontal projection?
What is defined as an occipto-frontal projection?
In radiographic terminology, what does angling the beam caudally mean?
In radiographic terminology, what does angling the beam caudally mean?
What is contained within the anthropological plane?
What is contained within the anthropological plane?
What would the abbreviation 'FO30°↓' indicate in radiographic projection?
What would the abbreviation 'FO30°↓' indicate in radiographic projection?
Which planes are at right-angles to each other?
Which planes are at right-angles to each other?
What defines a central ray in radiographic positioning?
What defines a central ray in radiographic positioning?
What characteristic defines a lateral projection?
What characteristic defines a lateral projection?
Which factor is NOT considered when naming an oblique projection?
Which factor is NOT considered when naming an oblique projection?
In a 40 degree left anterior oblique projection, which statement is true?
In a 40 degree left anterior oblique projection, which statement is true?
How is a complex oblique projection achieved?
How is a complex oblique projection achieved?
In a fifty-five degree right anterior oblique projection, what does the term 'anterior' indicate?
In a fifty-five degree right anterior oblique projection, what does the term 'anterior' indicate?
What does a 35° caudal angulation typically affect in a projection?
What does a 35° caudal angulation typically affect in a projection?
What happens in an oblique projection when more complex angles are introduced?
What happens in an oblique projection when more complex angles are introduced?
In lateral projections, which side of the head is closer to the image receptor?
In lateral projections, which side of the head is closer to the image receptor?
Which landmark corresponds to the lowest point of the inferior rim of the orbit?
Which landmark corresponds to the lowest point of the inferior rim of the orbit?
What is the primary function of the interpupillary line in radiographic positioning?
What is the primary function of the interpupillary line in radiographic positioning?
What does the term 'gonial angle' refer to in craniofacial anatomy?
What does the term 'gonial angle' refer to in craniofacial anatomy?
In the context of skull anatomy, what is the significance of the external occipital protuberance?
In the context of skull anatomy, what is the significance of the external occipital protuberance?
Which line is defined as passing from the infraorbital point to the upper border of the external auditory meatus?
Which line is defined as passing from the infraorbital point to the upper border of the external auditory meatus?
Identify the landmark that is found at the junction of the nasal and frontal bones.
Identify the landmark that is found at the junction of the nasal and frontal bones.
What does the term 'orbito-meatal baseline' specifically refer to in radiographic terms?
What does the term 'orbito-meatal baseline' specifically refer to in radiographic terms?
Which of the following landmarks is situated laterally at the highest point of the skull in the median sagittal plane?
Which of the following landmarks is situated laterally at the highest point of the skull in the median sagittal plane?
What anatomical feature is typically the reference point for the anthropological plane?
What anatomical feature is typically the reference point for the anthropological plane?
Which plane is perpendicular to the anthropological plane?
Which plane is perpendicular to the anthropological plane?
What is the primary function of the occipto-frontal projection in skull radiography?
What is the primary function of the occipto-frontal projection in skull radiography?
In which projection does the central ray exit through the occipital bone?
In which projection does the central ray exit through the occipital bone?
What does a cranial angulation of the central ray indicate?
What does a cranial angulation of the central ray indicate?
For which projection is the angulation typically expressed after the name of the projection?
For which projection is the angulation typically expressed after the name of the projection?
When referring to beam angulation, what does an angle described as '↑' mean?
When referring to beam angulation, what does an angle described as '↑' mean?
What do the initials 'FO30°↓' specifically indicate in imaging procedures?
What do the initials 'FO30°↓' specifically indicate in imaging procedures?
What does the term 'coronal plane' refer to in the context of lateral projections?
What does the term 'coronal plane' refer to in the context of lateral projections?
In identifying an oblique projection, what are the two primary factors considered?
In identifying an oblique projection, what are the two primary factors considered?
What additional considerations might come into play when performing complex oblique projections?
What additional considerations might come into play when performing complex oblique projections?
When comparing lateral and oblique projections, what is a significant difference in how they are defined?
When comparing lateral and oblique projections, what is a significant difference in how they are defined?
What is the implication of the term '55°RAO35°↓' used in radiographic projections?
What is the implication of the term '55°RAO35°↓' used in radiographic projections?
Which statement regarding the positioning of the central ray in lateral projections is accurate?
Which statement regarding the positioning of the central ray in lateral projections is accurate?
What is the role of the angle created by the patient's position and the receptor in producing an oblique projection?
What is the role of the angle created by the patient's position and the receptor in producing an oblique projection?
In a 40 degree left anterior oblique projection, which aspect influences where the image receptor is placed?
In a 40 degree left anterior oblique projection, which aspect influences where the image receptor is placed?
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Study Notes
Skull Radiography Landmarks
- Outer canthus of the eye: The lateral point where the upper and lower eyelids meet.
- Infraorbital margin/point: The lowest point of the inferior rim of the orbit.
- Nasion: The articulation between the nasal and frontal bones.
- Glabella: A bony prominence found on the frontal bone immediately superior to the nasion.
- Vertex: The highest point of the skull in the median sagittal plane.
- External occipital protuberance (inion): A bony prominence found on the occipital bone, usually coincident with the median sagittal plane.
- External auditory meatus (EAM): The opening within the ear that leads into the external auditory canal.
- Angle of the mandible (gonial angle): Located at the posterior border at the junction of the lower border of the ramus of the mandible.
Skull Radiography Lines
- Interpupillary (interorbital) line: Joins the centre of the two orbits or the centre of the two pupils when the eyes are looking straight forward.
- Infraorbital line: Joins the two inferior infraorbital points.
- Anthropological baseline: Passes from the infraorbital point to the upper border of the EAM.
- Orbito-meatal baseline (radiographic baseline): Extends from the outer canthus of the eye to the centre of the EAM. This line is angled approximately 10° to the anthropological baseline.
Skull Radiography Planes
- Median sagittal plane: Divides the skull into right and left halves. Landmarks on this plane are the nasion anteriorly and the external occipital protuberance (inion) posteriorly.
- Coronal planes: At right-angles to the median sagittal plane and divide the head into anterior and posterior parts.
- Anthropological plane: A horizontal plane containing the two anthropological baselines and the infraorbital line. It is an example of an axial plane.
- Auricular plane: Perpendicular to the anthropological plane and passes through the centre of the two EAMs. It is an example of a coronal plane. The median sagittal, anthropological and coronal planes are at right-angles.
Skull Radiography Terminology
- Occipto-frontal (OF) projection: Central ray enters the skull through the occipital bone and exits through the frontal bone.
- Frontal-Occipto (FO) projection: Central ray enters the skull through the frontal bone and exits through the occipital bone.
- Cranial angulation: Beam directed up the body towards the head (↑).
- Caudal angulation: Beam angled toward the feet (↓).
- Lateral projection: Collimated central ray passes along a coronal plane at right-angles to the median sagittal plane. Named according to the side of the head closest to the image receptor.
- Oblique projection: Central ray is at some angle to the median sagittal plane and the coronal plane. Named according to the anterior or posterior portion of the head in contact with the receptor, and the left or right side of the head in contact with the receptor.
Skull Radiography Projections
- Forty degree left anterior oblique (40°LAO): Head rotated to the left with the median sagittal plane 40° to the image receptor and the left side of the head in contact with the image receptor.
- Fifty five degree right anterior oblique with 35°caudal angulation (55°RAO35°↓): Head is rotated with the right side of the face in contact with the receptor and the median sagittal plane makes an angle of 55° with the image receptor. Central ray has a 35° caudal angulation.
Radiographic Techniques - Skull
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Radiographic positioning of the skull relies on landmarks and lines.
-
Landmarks
- Outer Canthus of the eye: The lateral point where the upper and lower eyelids meet
- Infraorbital margin/point: The lowest point of the inferior rim of the orbit
- Nasion: The articulation between the nasal and frontal bones
- Glabella: A bony prominence on the frontal bone, superior to the nasion
- Vertex: The highest point of the skull in the median sagittal plane
- External occipital protuberance (inion): A bony prominence on the occipital bone, coincident with the median sagittal plane
- External auditory meatus (EAM): The opening within the ear leading to the external auditory canal
- Angle of the mandible (gonial angle): Located at the posterior border at the junction of the lower border of the ramus of the mandible
-
Lines:
- Interpupillary (interorbital) line: Joins the center of the two orbits or pupils when the eyes are looking straight forward
- Infraorbital line: Joins the two inferior infraorbital points
- Anthropological baseline: Passes from the infraorbital point to the upper border of the EAM
- Orbitomeatal baseline (radiographic baseline): Extends from the outer canthus of the eye to the center of the EAM. Angled 10° to the anthropological baseline
-
Planes:
- Median sagittal plane: Divides the skull into right and left halves. Landmarks include the nasion anteriorly and the external occipital protuberance posteriorly.
- Coronal planes: At right angles to the median sagittal plane, dividing the head into anterior and posterior parts.
- Anthropological plane: A horizontal plane containing the two anthropological baselines and the infraorbital line. An example of an axial plane.
- Auricular plane: Perpendicular to the anthropological plane, passes through the center of the two EAMs. An example of a coronal plane.
Positioning Terminology
- Skull projections are described by stating the relative positions of the skull planes to the image receptor, the central ray relative to skull planes/image receptor, and the centring point/area to be included in the collimated X-ray beam.
Occipto-frontal Projection
- The central ray enters the skull through the occipital bone and exits through the frontal bone.
- This is an occipto-frontal (OF) projection.
Frontal-Occipto Projection
- The central ray enters the skull through the frontal bone and exits through the occipital bone.
- This is a fronto-occipital (FO) projection.
Beam Angulation
- Many OF or FO projections require the central ray to pass along the sagittal plane at some angle to the orbital-meatal plane.
- The degree and direction of angulation are stated after the projection name.
- Cranial angulation involves the beam directed up the body toward the head (↑).
- Caudal angulation involves the beam directed toward the feet (↓).
(FO30°↓) FO 30° Caudal Projection
- The central ray enters the skull through the frontal bone and exits through the occipital bone with a 30° caudal angulation.
Lateral Projection
- The collimated central ray passes along a coronal plane at right angles to the median sagittal plane.
- Named according to the side of the head closest to the image receptor/cassette.
Oblique Projections
- Obtained when the central ray is at an angle to the median sagittal plane and the coronal plane.
- Named based on whether the anterior or posterior portion of the head is in contact with the receptor/cassette, and whether the left or right side of the head is in contact with the receptor/cassette.
Forty Degree Left Anterior Oblique (40°LAO)
- The head is rotated to the left such that the median sagittal plane is 40° to the image receptor and the left side of the head is in contact with the image receptor.
Complex Oblique Projections
- An oblique projection with an additional caudal or cranial angulation relative to a specified baseline.
- This angulation is usually achieved by raising or lowering the chin, or angling the X-ray tube, or both.
Fifty Five Degree Right Anterior Oblique with 35°caudal angulation (55°RAO35°↓)
- The head is rotated such that the right side of the face is in contact with the receptor/cassette and the median sagittal plane makes a 55° angle with the image receptor.
- The central ray has a 35° caudal angulation.
55 Right Anterior Oblique With 35°caudal angulation
- This projection can be achieved with a combination of tube and orbital-meatal plane angulation.
Skull Radiography Landmarks
- Outer Canthus of the Eye: The lateral point where the upper and lower eyelids meet.
- Infraorbital Margin/Point: The lowest point of the inferior rim of the orbit.
- Nasion: The articulation between the nasal and frontal bones.
- Glabella: A bony prominence on the frontal bone, superior to the nasion.
- Vertex: The highest point of the skull in the median sagittal plane.
- External Occipital Protuberance (Inion): A bony prominence on the occipital bone, usually in the median sagittal plane.
- External Auditory Meatus (EAM): The opening within the ear that leads into the external auditory canal.
- Angle of the Mandible: Located at the posterior border of the ramus of the mandible, where it joins the lower border.
Skull Radiography Lines
- Interpupillary (Interorbital) Line: Joins the centers of the two orbits or the pupils when looking straight ahead.
- Infraorbital Line: Joins the two inferior infraorbital points.
- Anthropological Baseline: Extends from the infraorbital point to the upper border of the EAM.
- Orbito-meatal Baseline (Radiographic Baseline): Extends from the outer canthus of the eye to the center of the EAM. This line is angled approximately 10° to the anthropological baseline.
Skull Radiography Planes
- Median Sagittal Plane: Divides the skull into right and left halves. It includes the nasion anteriorly and the external occipital protuberance posteriorly.
- Coronal Planes: Perpendicular to the median sagittal plane, dividing the head into anterior and posterior parts.
- Anthropological Plane: A horizontal plane containing the two anthropological baselines and the infraorbital line. It's an example of an axial plane.
- Auricular Plane: Perpendicular to the anthropological plane, passing through the center of the two EAMs. It's an example of a coronal plane.
Radiographic Positioning Terminology
- Occipto-frontal (OF) Projection: Central ray enters the skull through the occipital bone and exits through the frontal bone.
- Frontal-occipital (FO) Projection: Central ray enters the skull through the frontal bone and exits through the occipital bone.
- Beam Angulation:
- Cranial: Beam angled upward towards the head (↑).
- Caudal: Beam angled downward towards the feet (↓).
Standard Skull Projections
- Lateral Projection: Collimated central ray passes along a coronal plane at right angles to the median sagittal plane. Named according to the side of the head closest to the image receptor.
- Oblique Projection: Central ray at an angle to the median sagittal plane and the coronal plane. Named based on whether the anterior or posterior portion of the head is in contact with the receptor and the left or right side of the head is in contact with the receptor.
- Forty Degree Left Anterior Oblique (40° LAO): Head rotated left, with the left side of the head in contact with the receptor.
- Complex Oblique Projections: May include caudal or cranial angulation in relation to a specified baseline.
- Fifty Five Degree Right Anterior Oblique with 35° Caudal angulation (55° RAO35°↓): Head rotated right, with the right side of the face in contact with the receptor. Central ray has a 35° caudal angulation.
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