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Ch 11 - Positioning
skull/facial bones/sinuses/mandible/
| Question | Answer |
|---|---|
| name the three classifications of the skull and describe the differences. | A) dolichocephalic - 40' angle of petrous pyramids B) mesocephalic - 47' angle of petrous pyramids C) brachycephalic - 54' angle of petrous pyramids |
| CR angles and degrees of rotation are based on _____ (average) skull, which has an approximate angle of _____ between the midsagittal plane and the long axis of the petrous bone. | mesocephalic 47' |
| there is a _____ degree difference between the OML and IOML and ____ degrees between the OML and GAL | 7-8' 7-8' |
| What is the positioning term for the lateral junction of the eyelid. | Outer canthus |
| What is the positioning term for the posterior angle of the jaw. | gonion |
| What is the positioning term for the line between the IOM and the EAM? | IOML - infraorbitomeatal line |
| What is the positioning term for what corresponds to the highest "nuchal" line of the occipital bone? | Inion - occipital protruberance |
| What is the positioning term for the line between the glabella and the alveolar process of the maxilla? | glabelloalveolar line - GAL |
| What is the positioning term for the line between the mental point and the EAM? | MML - mentomeatal line |
| What is the positioning term for what is located at the junction of the two nasal bones and the frontal bone? | nasion |
| What is the positioning term for the small cartilaginous flap covering the ear opening? | tragus |
| What is the positioning term for what corresponds to the highest level of the facial bone mass? | supraorbital groove |
| What is the positioning term for the line between the midlateral orbital margin and the EAM? | OML - orbitomeatal line |
| What is the positioning term for the center point of the EAM? | auricular point |
| What is the positioning term for the positioning line primarily used for the modified Waters projection? | LML - lips-meatal line |
| What is the positioning term for the line used to ensure skull is in true lateral? | IPL - interpupillary line |
| What is the positioning term for what corresponds to the level of the petrous ridge? | TEA - top of ear attachment |
| What is the positioning term for the smooth, slightly depressed area between the eyebrows? | glabella |
| What are the most common errors made during skull radiography? | Tilt Rotation excessive flexion excessive extension incorrect CR angle |
| which two are the most common errors made during skull imaging? | TILT and ROTATION |
| Which imaging modality is the most common neuroimaging procedure performed for the cranium? | CT |
| Which imaging modality is commonly performed on neonates with a possible intracranial hemorrhage? | Ultrasound |
| Which imaging modality is commonly performed to evaluate patients for Alzheimer disease? | nuclear medicine |
| Describe a fracture that may produce an air-fluid level in the sphenoid sinus. | basal skull fracture |
| describe a destructive lesion with irregular margins | osteolytic neoplasm |
| Describe a ping-pong fracture. | depressed skull fracture |
| Describe a proliferative bony lesion of increased density. | osteoblastic neoplasm |
| Describe a tumor that may produce erosion of the sella turcica. | pituitary adenoma |
| Describe another term for osteitis deformans. | Paget's disease |
| Describe a bone tumor that originates in the bone marrow. | multiple myeloma |
| Which of the following clinical indications may require an increase in manual exposure factors? A) advanced Paget's disease B) metastatic neoplasm C) multiple myeloma D) basal skull fracture | A) advanced Paget's disease |
| Which cranial bone is best demonstrated with an AP Axial (Towne) projection of the skull? | occipital |
| When using a 30' caudad angle for the AP Axial (Towne) projection, which positioning line should be perpendicular to the IR? | OML |
| A properly positioned AP Axial (Towne) projection should place the dorsum sellae into the middle aspect of _____. | foramen magnum |
| A lack of symmetry of the petrous ridges during an AP axial (Towne) indicates what problem? | Rotation |
| If the patient cannot flex the head adequately for the AP Axial (Towne), what can the tech do? | Place the IOML perpendicular to the IR and increase the CR angle to 37' |
| What evidence on an AP Axial (Towne) image indicates whether the correct CR angle and head flexion were used? | dorsum sellae and posterior clinoids are visible centered within the foramen magnum |
| What CR angle should be used for the PA Axial (Haas)? | 25' cephalad |
| Where is the CR centered for a lateral projection of the skull? | 2" superior to the EAM (5cm) |
| What is the specific error if the mandibular rami are not superimposed on a lateral skull? | ROTATION |
| Where will the petrous ridges be projected with a 15' PA Axial (Caldwell) projection of the cranium? | in the lower 1/3 of the orbits |
| Which specific positioning error is present if the petrous ridges are projected higher in the orbits than expected for a 15' PA Axial? | excessive flexion of the head or insufficient CR angle |
| Which projection of the cranium produces an image of the frontal bone with little or no distortion? | 0' PA - posteroanterior skull |
| For a patient with possible trauma, what must be determined before performing the SMV skull? | rule out possible cervical fractures or subluxation |
| What positioning error has been committed if the EAMs are not superimposed with one more superior to the other on a lateral image? | TILT |
| Which skull positioning line is placed parallel to the plane of the IR for SMV? | IOML - infraorbitomeatal line |
| Which of the following projections best demonstrates the sella turcica in profile? | lateral |
| Which projection best demonstrates the foramen rotundum? | 25 - 30' PA Axial |
| Which of the following projections best demonstrates the clivus in profile? A) AP Axial B) 15' PA C) Lateral D) SMV | C) Lateral |
| Where does the CR exit for a PA axial (Haas)? | 1.5" superior to the nasion |
| Which imaging modality is best to differentiate between and epidural and subdural hemorrhage? | CT |
| An image of an AP Axial (Towne) skull shows the right petrous ridge is wider than the left. Which specific positioning error is present? | rotation of the patient's face to the left |
| An image of a 15' PA Axial (Caldwell) demonstrates the petrous ridges are projected at the inferior orbital margin. Which positioning error led to this outcome? | excessive CR angle or excessive extension of the head |
| An image of 15' PA Axial (Caldwell) demonstrates the distance between right midlateral orbital borders and lateral margin of the skull cortex is greater than the left side. Which positioning error led to this outcome? | rotation of the patient's face to the left |
| An image of an SMV Skull shows the mandibular condyles are within the petrous bone. Which specific positioning error led to the this problem? | excessive flexion, insufficient extension or CR not perpendicular to IOML/IR |
| An image of a lateral Skull shows orbital plates are not superimposed (one is slightly superior). What is the positioning error? | tilt |
| A lateral skull image demonstrates one mandibular ramus about .5cm more anterior than the other. What is the positioning error? | rotation |
| An AP axial (Towne) for skull demonstrates the dorsum sellae projected above the foramen magnum. What is the positioning error? | excessive extension of the skull or CR angle < 30' OML or 37' IOML |
| A patient comes to XRay with a possible tumor of the pituitary gland. Which projection would best demonstrate the bony involvement of the sella turcica? | lateral skull with collimation |
| A patient with possible linear fracture of right parietal bone comes to ED. Which single x-ray best demonstrates this fracture? | right lateral skull |
| A patient comes for a skull series, but cannot assume best position for either version of AP Axial (Towne) because of a very short neck and severe kyphosis. What can tech do to demonstrate the occipital bone? | should perform the PA version (Haas) |
| A patient with a possible basal skull fracture enters the emergency room. No CT is available. Which specific position may provide xray evidence of this fracture? | Dorsal decubitus (think trauma - supine lateral) will demonstrate the air/fluid levels in the sphenoid sinus |
| A neonate has a clinical history of craniosynostosis. Because of the age of the patient, Dr doesn't order an xray. What other imaging modality can be performed for this condition? | ultrasound |
| A patient with a clinical history of acoustic neuroma comes to x-ray. Which imaging modality can be performed for this pathology? | MRI or CT |
| An image of an AP Axial (Towne) projection shows the posterior arch of C1 is projected within the foramen magnum. The dorsum sellae is projected on the posterior arch as well. What is the positioning error? | excessive flexion of the neck or overangulation of the CR |
| An image of the AP Axial (Towne) for cranium shows the mid-to lower mandible is clipped. What should the tech do? | Nothing - the image is for the CRANIUM and because the mandible is elongated due to the CR angle, doesn't need to be included. |
| TRUE/FALSE Facial bone studies should always be performed recumbent when possible. | FALSE - erect preferred |
| TRUE/FALSE The common basic PA axial projection for the facial bones requires a 15' caudal angle, which projects the dense petrous pyramids into the lower 1/3 of the orbit. | TRUE |
| TRUE/FALSE An increase in kV of 25-30% (with manual techniques) is often required for the geriatric patient with advanced osteoporosis. | FALSE - a decrease is required due to bone loss |
| TRUE/FALSE CT is ideal for facial bone studies because it allows for visualization of bony structures as well as related soft tissue of facial bones. | TRUE |
| TRUE/FALSE Nuclear med is not helpful in diagnosing occult facial bone fractures. | FALSE Nuclear med is used for this |
| TRUE/FALSE MRI is an excellent imaging modality for detection of small metal foreign bodies in the eye. | FALSE Patient must be cleared of all metallic foreign bodies before going to MRI |
| What is the name of the fracture that results from a direct blow to the orbit leading to disruption of the inferior orbital margin? | Blow-out fracture |
| A free floating zygomatic bone is the frequent result of a _____ fracture. | Tripod fracture |
| What is the major disadvantage of performing a straight PA projection for facial bones, with no CR angulation or neck extension, as compared with other facial bone projections? | Dense petrous pyramids superimpose facial bone structures, such as orbits, obscuring details |
| Where is the CR centered for a lateral position for the facial bones? | Zygoma |
| What is the proper name method for the parietoacanthial projection of the facial bones? | Waters method |
| Which facial bone structures are best seen with a parietoacanthial projection? | orbits including infraorbital rims, bony nasal septum, maxillae, zygomatic bones, and arches |
| What CR angle must be used to project the petrous pyramids just below the orbital floor with the PA Axial (Caldwell)? | 30' caudad |
| Which structures specifically are better visualized on the modified parietoacanthial (Waters) projection as compared with the basic Waters projection? | a less distorted view of the orbital rims Orbital rims/floors |
| Give two reasons why projections of the facial bones are performed PA rather than AP when possible. | - (OID) less magnification/distortion because bones are close to IR. - (ALARA) reduces patient dose to thyroid/facial structures (eyes) |
| What are two differences between the lateral projections of the cranium and lateral projection for the facial bones? | - centering (zygoma for FB, 2" superior to EAM for cranium) - IR is placed portrait for facial bones, crosswise for cranium |
| The PA Waters for facial bones has the _____ line perpendicular to the IR, which places the OML at _____ angle to tabletop/IR? | MML 37' |
| Where does the CR exit for a parietoacanthial (Waters) facial bones? | acanthion |
| Where does the CR exit for a 15' PA axial (Caldwell) facial bones? | nasion |
| The modified PA (waters) requires the _____ line is perpendicular to the IR, which places the OML at a _____ angle to tabletop and image receptor. | LML - lips-meatal line 55' |
| TRUE/FALSE Lateral projections for the nasal bones are generally taken bilaterally for comparison. | TRUE |
| TRUE/FALSE The oblique inferosuperior (tangential) projections for the zygomatic arch requires the skull be rotated and tilted 15' away from affected side. | FALSE must be TOWARD affected side |
| TRUE/FALSE Both oblique inferosuperior (tangential) projections for the zygomatic arch are taken for comparison. | TRUE |
| For a PA Waters, the petrous ridges should be projected directly below the _____; and projected into the lower half of the maxillary sinuses or below the _____ for a modified Waters projection. | maxillary sinuses infraorbital rims |
| Which specific facial bone structures (other than the mandible) are best demonstrated with SMV if correct exposure factors are used (soft tissue technique) | zygomatic arches |
| Where is the CR centered for an AP axial for the zygomatic arches? | 1" superior to nasion |
| List the proper method name and common descriptive name for the parieto-orbital oblique projection for the optic foramen. | Rhese three point landing (cheek, nose, chin) |
| What is the final angle of the midsagittal plane and the IR for the Rhese? Where is the optic foramina visible in the final image? | 53' in the lower outer quadrant of the orbit |
| Which projection best demonstrates fractures of the orbital floors (blowout fractures)? | Modified Waters |
| Which projection best demonstrates the optic foramen? | parieto-orbital oblique (Rhese) |
| Which projection best demonstrates a view of the single zygomatic arch? | oblique inferosuperior projection |
| Which projection best demonstrates profile image of nasal bones and nasal septum? | lateral (nasal bones) |
| Which projection best demonstrates bilateral zygomatic arches? | submentovertical (SMV) |
| Which projection best demonstrates the inferior orbital rim, maxillae, nasal septum, nasal spine, zygomatic bone and arches? | parietoacanthial projection |
| TRUE/FALSE The PA Axial of the mandible produces an elongated view of the condyloid process. | TRUE |
| Which projection of the mandible projects the opposite half of the mandible away from the side of interest? | axiolateral oblique |
| What must be done to prevent the ramus of the mandible from being superimposed over the cervical spine with an axiolateral oblique projection of the mandible? | extend the neck/chin slightly |
| How much skull rotation from lateral toward IR is required with an axiolateral oblique projection of the body of the mandible? | 30' |
| How much skull rotation from lateral toward IR is required with an axiolateral oblique projection of the mentum of the mandible? | 45' |
| How much skull rotation from lateral toward IR is required with an axiolateral oblique projection of the ramus of the mandible? | 0' - true lateral |
| How much skull rotation from lateral toward IR is required with an axiolateral oblique projection of the general survey of the mandible? | 10-15' |
| What is the maximum angle of the CR for an axiolateral oblique projection of the mandible? | 25' cephalad |
| What specific positioning error has been committed if both sides of the mandible are superimposed with an axiolateral oblique projection? | insufficient cephalic CR angle or skull tilt |
| Where should the CR exit for a PA axial projection of the mandible? | acanthion or lips (PA projection) |
| Which cranial positioning line is placed perpendicular to the IR for a PA or PA axial projection of the mandible? | OML |
| TRUE/FALSE For a true PA of the mandibular body, the AML should be perpendicular to the IR. | TRUE |
| TRUE/FALSE the CR should be angled 20-25' caudad for a PA axial of the mandible. | FALSE cephalad |
| Which aspect of the mandible is best demonstrated with an AP axial projection? | condyloid process |
| What CR angle is required for AP axial of the mandible if OML is perpendicular to IR? What angle is required if the IOML is perpendicular? | 35' caudad or 42' caudad |
| Where is the CR centered for an AP Axial projection of the mandible? | 1" superior to the glabella |
| Which projection of the mandible demonstrates the entire mandible, including the coronoid and condyloid processes? | SMV |
| Which imaging system provides a single, frontal perspective of the entire mandible? | orthopantomography (panoramic tomography) |
| What device provides inherent collimation during an orthopantomographic procedure? | narrow, vertical slit diaphragm |
| Which cranial line is placed parallel to the floor for the orthopantomography of the mandible? | IOML |
| What type of image receptor must be used with analog orthopantomography? | curved, non-grid 9x12 IR |
| TRUE/FALSE The modified Law method provides a bilateral and functional study of the TMJ. | TRUE |
| TRUE/FALSE The mandibular condyles move anteriorly as the mouth is opened. | TRUE |
| Which projection of the TMJ requires the skull be kept in true lateral position? | Schuller axiolateral projection TMJ |
| The axiolateral (Schuller) projection for TMJ requires a CR angle of _____ and which direction _____? | 25 - 30' caudad |
| The axiolateral oblique TMJ is commonly referred to as the _____ method, which requires a _____ degree head rotation from lateral and a _____ degree caudad angle. | modified Law 15' (oblique) 15' (caudad) |
| If the area of interest is the temporomandibular fossae, angle the CR _____ to the OML for AP Axial (towne) to reduce superimposition of the TM fossae and mastoid portions of the temporal bone. | 40' caudad |
| Aligning the _____ plane perpendicular to the IR prevents rotation of either a PA or an AP axial mandible. | GAL/ MSP |
| What digital kV should be should used for sinus radiography? | 75-85 kV |
| To demonstrate any possible air or fluid levels within the sinuses, it is important to _____ and _____ | perform erect if possible use a horizontal beam |
| TRUE/FALSE Secondary osteomyelitis is often caused by tumor invasion. | FALSE |
| TRUE/FALSE Ultrasound exams of the maxillary sinuses to rule out sinusitis are possible. | TRUE |
| TRUE/FALSE MRI is the preferred modality to study soft tissue changes and masses within the sinuses. | TRUE |
| List the four most commonly performed routine projections for paranasal sinuses. | Parietoacanthial Waters Lateral FB PA axial Caldwell SMV |
| Which single projection for a paranasal sinus routine provides and image of all four sinus groups? | Lateral |
| If the patient cannot stand/sit for the lateral paranasal sinuses exam, the projection should be taken with _____. | horizontal beam |
| Which paranasal sinuses are best demonstrated with a PA Caldwell projection? | frontal and anterior ethmoid |
| To avoid angling the CR for erect PA axial Caldwell sinus, the head should be adjusted so that the OML is _____ degrees from horizontal. | 15' |
| Which group of paranasal sinuses is best demonstrated with a parietoacanthial projection? The OML forms a _____ angle with the IR. | maxillary 37' |
| Which positioning line is placed perpendicular to the IR for a parietoacanthial projection? | MML |
| Where are the petrous ridges located on a well-positioned parietoacanthial projection? | just below the maxillary sinuses |
| Which paranasal sinuses are demonstrated with an SMV projection of the paranasal sinuses? | sphenoid, ethmoid, and maxillary sinuses |
| Where should the CR exit for both the parietoacanthial Waters and PA transoral (open-mouth Waters)? | acanthion |
| What is the one major difference in positioning between the parietoacanthial and PA axial transoral projections? | opening the mouth for the PA axial transoral |
| Which sinuses are projected through the oral cavity with the PA axial transoral projection? | sphenoid |
| What anatomy does the lateral sinus projection best demonstrate? | all four paranasal sinuses |
| What anatomy does the parietoacanthial sinus projection best demonstrate? | best view of maxillary sinuses |
| What anatomy does the PA axial Caldwell sinus projection best demonstrate? | frontal and anterior ethmoid |
| What anatomy does the PA transoral sinus projection best demonstrate? | sphenoid sinus in oral cavity |
| What anatomy does the SMV sinus projection best demonstrate? | inferosuperior view of sphenoid and ethmoid sinus |
| An image of a lateral facial bones shows the mandibular rami are not superimposed. What positioning error led to this error? | rotation |
| An image of a parietoacanthial Waters shows the petrous ridges are projected within the maxillary sinuses. Is this acceptable? If not, what must be done to correct? | NO, not acceptable ensure the MML is perpendicular to the IR (insufficient extension) and that CR is perpendicular to exit at acanthion |
| An image of a PA Waters shows the distance between the lateral margins of the orbits and the lateral aspect of the cranial cortex is not equal. What type of positioning error is this? | rotation |
| An image of a 30' PA axial projection facial bones shows the petrous ridges are projected at the level of the infraorbital margins. Is this acceptable? If not, what must be done to improve the next image? | Yes, this is acceptable |
| An image of a superoinferior projection of the nasal bones shows the glabella is superimposed over the nasal bones. What positioning error led to this outcome? How does the tech correct it? | excessive flexion incorrect CR angulation |
| A lateral image of the facial bones demonstrates the bodies of the mandibles are not superimposed. One is about 1cm superior to the other. How to correct? | Tilt ensure the GAL is parallel to the IR. |
| A parieto-orbital oblique (Rhese) shows the optic foramen is located in the upper outer quadrant of the orbit. Is this acceptable? how to fix? | NO, not acceptable increase extension of head/neck |
| An image of an axiolateral oblique mandible shows the body of the mandible is severely foreshortened, although it is the area of interest. What positioning error led to this outcome? | insufficient rotation of the skull towards the IR |
| A patient with a possible fracture of the nasal bones enters the ER. Dr is concerned about deviation of the bony nasal septum along with possible fractures. What routine would be best? | R and L Lateral Nasal bones parietoacanthial Waters |
| A possible blowout fracture of the right orbit enters the ER. In addition to the normal FB routine, what single projection would best demonstrate this type of injury? | parietoacanthial axial (modified Waters) |
| A patient w/possible fracture of left zygomatic arch comes in. Neither the AP axial nor the SMV demonstrates left side well. Radiologist is indecisive as to whether arch is fractured. What other projections can the tech provide to better define this area? | Oblique inferosuperior (tangential); bilateral projections for comparison |
| Tech attempts to perform an SMV for zygomatic arches but because of the size of the patient's shoulders, the patient cannot flex his neck enough to place IOML parallel to IR. What can tech do to work around this? | place CR perpendicular to IOML, then angle IR to be perpendicular to CR and IOML |
| PA Caldwell sinus image shows petrous pyramids are projected into lower half of orbits, obscuring the ethmoid sinuses. Tech uses a horizontal beam for these projections. Skull was positioned placing OML 15' angle from horizontal plane. How fix? | extend head/neck more to move the petrous pyramids down |
| an image of a parietoacanthial projection shows the distance between the MSP and outer orbital margin is not equal. What positioning error? | rotation |
| an image of an SMV sinus shows the distance between the mandibular condyles and lateral border of the skull is not equal. What positioning error? | tilt |
| A PA transoral image shows the sphenoid sinus is superimposed over the upper teeth and nasal cavity. How adjust position to fix? | increase extension of head/neck (MML must be perpendicular) |
| In a PA Waters, the petrous ridges are projected below the maxillary sinuses. What positioning error (if any) is present? | nothing is wrong |
| A patient with a clinical history of sinusitis comes for a sinus study. The patient is quadriplegic and cannot be placed erect. Which single projection demonstrates any possible air fluid levels in the sinuses? | horizontal beam lateral |
| Need to rule out a possible polyp in the sphenoid sinus. What routine or special projection provides the best assessment for this patient? | Lateral PA Caldwell parietoacanthial SMV PA transoral |
| patient with clinical history of deviated bony nasal septum. Which facial bone projections best demonstrate the degree of deviation? | PA PA axial parietoacanthial Waters |
Created by:
Larobbins
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