Image Evaluation: Cervical & Thoracic Vertebrae

What degree and direction of CR angulation are used for PA axial oblique cervical projections?

15-20 degrees caudally

What degree and direction of CR angulation are used for AP axial oblique cervical projections?

15-20 degrees cephalically

What CR angulation is used for an AP axial cervical projection in a supine patient?

15-degrees cephalad

Lateral Cervical Vertebrae Projection Analysis Criteria:

-Contrast and density are adequate to visualize the prevertebral fat stripe. -The anterior and posterior aspects of the right and left articular pillars and right and left zygapophyseal joints for each cervical vertebra are superimposed and the spinous processes are in profile. -The posterior arch of C1 and spinous process of C2 are in profile without posterior occiput superimposition, their bodies are seen without mandibular superimposition, the cranial cortices and the mandibular rami are superimposed, the superior and inferior aspects of the right and left articular pillars and the zygapophyseal joints of each cervical vertebra are superimposed, and the intervertebral disk spaces are open. -The long axis of the cervical vertebral column is aligned with the long axis of the expousre field.

PA/AP Axial Oblique Cervical Vertebrae Projection Analysis Criteria:

-The 2nd-7th intervertebral foramina are open, demonstrating uniform size and shape, the pedicles of interest are shown in profile, and the opposite pedicles are aligned with the anterior vertebral bodies. -The intervertebral disk spaces are open, the cervical bodies are seen as individual structures and are uniform in shape, and the posterior arch of the atlas is seen without foreshortening, demonstrating the vertebral foramen. -The inferior outline of the outer cranial cortices and the mandibular rami are seen without superimposition. -Oblique Cranium: The upper cervical vertebrae are seen with posterior occipital and mandibular superimposition. -Lateral Cranium: The upper cervical vertebrae are seen without occipital or mandibular superimposition, and the right and left posterior cortices of the cranium and the mandible are aligned.

Anteroposterior Cervical Atlas and Axis Projection Analysis Criteria:

-The atlas is symmetrically seated on the axis, with the atlas's lateral masses at equal distances from the dens. -The spinous processes of the axis is aligned with the midline of the axis's body, and the mandibular rami are visualized at equal distances from the lateral masses. -The upper incisors and base of the skull are seen superior to the dens and the atlantoaxial joint. -The atlantoaxial joint is open and the axis's spinous process is demonstrated in the midline and slightly inferior to the dens.

Lateral Cervicothoracic Vertebrae (Twining/Swimmer's) Projection Analysis Criteria:

-The humerus elevated above the patient's head is aligned with the vertebral column and the right and left cervical zygapophyseal joints, articular pillars, and posterior ribs are superimposed. -The intervertebral disk spaces are open, and the vertebral bodies are demonstrated without distortion.

AP Axial Cervical Vertebrae Projection Analysis Criteria:

-The spinous processes are aligned with the midline of the cervical bodies, the mandibular angles and mastoid tips are at equal distances from the cervical vertebrae, the articular pillars and pedicles are symmetrically visualized lateral to the cervical bodies, and the distance from the vertebral column to the medial clavicular ends is equal. -The intervertebral disk spaces are open, the vertebral bodies are demonstrated without distortion, and each vertebra's spinous process is visualized at the level of its inferior intervertebral disk space. -The third cervical vertebra is demonstrated in its entirety and the posterior occiput and mandibular mentum are superimposed. -The long axis of the cervical column is aligned with the long axis of the exposure field. -The fourth cervical vertebra is at the center of the exposure field -The 2nd-7th cervical vertebrae and the surrounding soft tissue are included within the collimated field.

Lateral Thoracic Vertebrae Projection Analysis Criteria:

-The thoracic vertebrae are seen through overlying lung and rib structures -The intervertebral foramina are clearly demonstrated, the pedicles are in profile, and the posterior surfaces of each vertebral body are superimposed, and no more than 1/2 inch of space is demonstrated between the posterior ribs. -The intervertebral disk spaces are open and the vertebral bodies are demonstrated without distortion.

AP Thoracic Vertebrae Projection Analysis Criteria:

-There is uniform density across the thoracic vertebrae -The spinous processes are aligned with the midline of the vertebral bodies and the distances from the vertebral column to the sternoclavicular ends and from the pedicles to the spinous processes are equal on the two sides. -The intervertebral disk spaces are open and the vertebral bodies are seen w/o foreshortening.

What are two advantages of aligning the long axis of the cervical column with the long axis of the collimated field for a lateral cervical projection?

1. Places the cervical vertebrae in a neutral position 2. Allows for tight transverse collimation

List two methods of confirming which is the first thoracic vertebra on a lateral thoracic projection

1. counting up from T12 2. locate the first vertebral prominens

It is often difficult to demonstrate C7 on a routine lateral cervical projection because of shoulder thickness. How should the patient be positioned to increase shoulder depression and improve C7 demonstration?

1. take image w/ patient in an upright position 2. have patient hold weights on each arm to depress shoulders 3. take exposure on suspended expiration

List two methods of confirming which is the 12th thoracic vertebra on a lateral thoracic projection.

1. the vertebra that has the last rib attached is T12 2. follow the posterior vertebral bodies of the lower thoracic and upper lumbar vertebrae, locating the subtle change from kyphotic to lordotic that takes place betweenT12 and L1

List two reasons why the patient's arms should be positioned at a 90-degree angle with the body for a lateral thoracic projection?

1. to prevent the humeri or their soft tissue from obscuring the thoracic vertebrae 2. so the inferior scapular angle can be used to locate T7

List two methods of achieving uniform projection density of the thoracic vertebrae on an AP projection?

1. use the anode heel effect 2. use a wedge-compensating filter

List 3 ways to reduce the amount of scatter radiation that reaches the IR when using the cervicothoracic projection.

1. use tight collimation 2. use a high-ratio grid 3. align a lead contact shield or apron along the posterior edge of the collimated field.

List two situations in which a cervicothoracic lateral projection would be indicated.

1. when the routine lateral cervical projection does not demonstrate C7 2. when the routine lateral cervical projection does not demonstrate the 1st-3rd thoracic vertebrae

What CR angulation is used for an AP axial cervical projection in an upright patient?

20-degrees cephalad

Which degree of body rotation is used for AP/PA axial oblique cervical projections?

45-degrees

How can rotation be identified on a lateral thoracic projection?

by evaluating the superimposition of the right and left posterior surfaces of the vertebral bodies and the degree of posterior rib superimposition

Describe the patient body form that demonstrates the greatest thoracic vertebral sagging when the patient is placed in a lateral projection.

A patient with wide hips and narrow waist

Describe how scoliosis can be distinguised from rotation on an AP thoracic projection.

A rotated thoracic image will demonstrate rotation of the thoracolumbar vertebrae and either the upper thoracic or lower lumbar vertebrae, whereas scoliosis will demonstrate rotation of the thoracolumbar vertebrae w/o corresponding rotation of the upper thoracic or lower lumbar vertebrae

Imaginary line connecting the point where the upper lip and nose meet with the external ear opening

Acanthiomeatal line

Describe how to determine the CR angulation to use for an AP atlas and axis projection on a trauma patient in a collar.

Align CR until it is aligned parallel with the infraorbitalmeatal line (IOML)

Describe how to position the IR beneath a trauma patient to demonstrate the right intervertebral foramina for an AP axial oblique cervical projection.

Align the left mastoid tip w/ the longitudinal axis of the IR and the right gonion with the transverse axis of the IR

How is the arm situated farther from the imaging table positioned?

Arm against patient's side and should be depressed

To obtain a cervicothoracic lateral projection, how is the arm adjacent to the imaging table positioned?

Arm elevated above patient's head as high as possible.

Which anatomic structures are included on oblique cervical projections with accurate positioning?

C1-C7, T1, and surrounding soft tissue

Which anatomic structures are demonstrated on an AP axial cervical projection with accurate positioning?

C2-C7, T1, and surrounding soft tissue

Which anatomic structures are included on a lateral thoracic projection with accurate positioning?

C7, T1-T12, L1

Which anatomic structures are included on an AP thoracic projection with accurate positioning?

C7, T1-T12, L1, and 2.5" of the posterior ribs and mediastinum on each side of the vertebral column

Situation: The posteroinferior aspects of the cervical bodies are obscuring the interverebral disk spaces, the uncinate processes are enlongated, and each vertebra's spinous process is demonstrated within the inferior adjoining vertebral body.

CR angled too cephalically

Situation: The upper incisors are demonstrated approx. 1 inch inferior to the posterior occiptut's inferior edge, obscuring the dens and atlantoaxial joint, and the posterior occiput's inferior edge is demonstrated directly superior to the dens. The AML line was aligned perpendicular to the imaging table.

CR not angled 5-degrees cephalad

Situation: On a left PA axial oblique (LAO) projection, the intervertebral disk spaces are closed, the vertebral bodies are distorted, the posterior tubercles are demonstrated within the vertebral foramina, the C1 vertebral foramen is not demonstrated, and the inferior mandibular rami and the cranial cortices are demonstrated with superimpostion.

CR not angled enough caudally

Situation: The anteroinferior aspects of the cervical bodies are obsuring the intervertebral disk spaces, and each vertebra's spinous process is demonstrated within the vertebral body.

CR was not angled cephalically enough

How is the patient positioned to prevent rotation on a lateral cervicothoracic projection?

Cervical rotation: Position patient's head in a lateral projection Thoracic rotation: Position patient to superimpose the shoulders and inferior posterior ribs

If the 1st, 2nd, or 3rd thoracic vertebra is not included on a routine lateral thoracic projection, which supplementary position is used to demonstrate these vertebrae?

Cervicothoracic lateral (twining/swimmer's)

Situation: A portion of the 3rd cervical vertebra is superimposed over the posterior occipital bone.

Chin not adequately tucked, positioning the upper occlusal plane superior to the posterior occiput's inferior edge

Situation: The mandible is superimposed over a portion of the 3rd cervical vertebra.

Chin was overtucked, positioning the upper occlusal plane inferior to the base of the occiput

Slow shallowing breathing; used with a long exposure time to blur chest details

Costal breathing

Imaginary line connecting the inferior orbital margin and the external acoustic opening

IOML

How is a patient without upper teeth positioned for an AP projection of the atlas and axis?

Imagine where the occlusal plane would be if the patient had teeth, and position the patient using this imaginary line.

How should the CR be adjusted from the routinely used angle for a PA axial oblique cervical vertebrae projection in a patient who has severe kyphosis to demonstrate the lower cervical vertebrae better?

Increase the degree of CR angulation

Which special view can be taken to demonstate C7?

Lateral cervicothoracic (Twining method; Swimmer's technique)

Accurate CR centering on an AP atlas and axis projection is accomplished by centering the CR through the open mouth to the _____.

MSP

Situation: The articular pillars and zygapophyseal joints of one side of the patient are situated anterior to the opposite side's pillars and zygapophyseal joints.

MSP was not parallel with IR

Accurate CR centering on a PA axial oblique cervical projection is accomplished by centering the CR to the _____ plane at a level halfway between the ___ and _________.

MSP, EAM, jugular notch

Accurate CR centering on an AP thoracic projection is accomplished by centering the CR to the ______ plane at a level halfway between the _________ and _________.

MSP, jugular notch, xiphoid

Which body plane is positioned perpendicular to the IR for a lateral cervical projection?

Midcoronal

If the transversely collimated field is coned to a 6-inch field size, where is the marker placed to ensure that it will be within the collimated field?

No more than 3" from the IR center

Situation: The dens is superimposed over the posterior occiput and the upper incisors are demonstrated approx. 2 inches superior to the posterior occiput's inferior edge.

Patient: Patient's chin not tucked enough to position the AML perpendicular to imaging table. CR: angled too cephalically

A patient wearing a collar and on a backboard is taken to the x-ray dept for a cervical vertebrae series. Should the collar be removed before the x-rays are taken?

No.

A patient wearing a collar and on a backboard is taken to the x-ray dept for a cervical vertebrae series. The patient's head is rotated. Should it be adjusted?

No.

Will rotation on an AP Axial cervical projection with poor positioning always be demonstrated throughout the entire cervical column? Defend your answer.

No. The upper and lower cervical vertebrae can move independently of one another.

Chewing surface of maxillary teeth

Occlusal plane

Situation: The distances from the atlas's lateral masses to the dens and from the mandibular rami to the dens are narrower on the right side of the patient than on the left side, and the axis's spinous process is shifted from the midline.

Patient's face rotated toward the left side.

Situation: The inferior cortices of the cranium and mandible are demonstrated without superimposition, and the vertebral foramen of C1 is demonstrated.

Patient's head and upper cervical vertebrae were tilted toward the IR.

Situation: Neither the posterior nor the anterior cortices of the cranium nor the mandible are superimposed.

Patient's head was rotated

Situation: The upper incisors are superimposed over the dens, and the posterior occiput's inferior edge is demonstrated superior to the dens and upper incisors. A 5-degree cephalic angulation was used to obtain this projection.

Patient: Patient's chin tucked more than needed to position the AML line perpendicular to imaging table. CR: angled too caudally

How must the patient's head be positioned for a lateral cervical projection to demonstrate the posterior arch of C1 and the spinous process of C2 in profile without posterior occiput superimposition and the bodies of C1 and C2 without mandibular rami superimposition?

Position the head's MSP parallel with the IR and the AML line parallel with the floor.

Which soft tissue structure found on a lateral cervical projection can be used to detect and localize cervical fractures or masses?

Prevertebral fat stripe

For the following AP/PA axial oblique cervical vertebrae projections, state whether the right or left intervertebral foramina will be demonstrated. RAO: ______ LAO:_______ LPO:_______ RPO:_______

RAO/LPO: right LAO/RPO: left *Anterior oblique (RAO/LAO)-closer to film *Posterior oblique (RPO/LPO)-farther from film

How is the patient positioned for an AP projection of the atlas and axis to demonstrate the upper incisor and posterior occiput superior to the dens and atlantoaxial joint?

Tuck the patient's chin until an imaginary line connecting the upper occlusal plane and the posterior occuiput's inferior edge is aligned perpendicular to the imaging table, or until the AML line is perpendicular to the imaging table, and have the patient open the mouth.

How can rotation be identified on a lateral cervical projection with poor positioning?

the articular right or left pillars and zygapophyseal joints will be demonstrated one anterior to the other.

How is the patient positioned for an AP Axial cervical projection to prevent rotation of the upper and lower cervical vertebrae?

UPPER: position mastoid tips and mandibular angles at equal distances from imaging table. LOWER: position shoulders at equal distances from the imaging table

Where is each vertebra's spinous process demonstrated if the CR angulation is too cephalad?

Within the inferior adjoining vertebral body

Which aspect of the positioning setup causes these cortices to be projected one superior to the other?

The angulation of the CR projects the mandible situated farther from the IR inferiorly on PA oblique projections and superiorly on AP oblique projections.

Which anatomic structures are included on an AP atlas and axis projection with accurate positioning?

The atlantoaxial and occipitoatlantal joints, atlas's lateral masses and transverse processes, and axis's dens and body.

How can one determine from an AP atlas or axis projection that the patient's neck was in extention for the projection?

The atlantoaxial joint will be closed and the axis's spinous process will demonstrate an increased inferior location to the dens.

How can one determine from an AP atlas or axis projection that the patient's neck was in flexion for the projection?

The atlantoaxial joint will be closed and the axis's spinous processes will demonstrate an increased superior location to the dens.

Situation: The atlas and its posterior arch are obscured. The inferior cranial cortices demonstrate more than 1/4 inch of distance between them, and the inferior cortices of the mandibular rami demonstrate more than 1/2 of distance between them.

The head and upper cervical vertebrae were tilted away from the IR.

The 3rd cervical vertebra is demonstrated in its entirety on an AP axial cervical projection with accurate positioning. How was the patient positioned to accomplish this demonstration.

The patient's chin adjusted until an imaginary line connecting the upper occlusal plane and the posterior occiput's inferior edge was aligned perpendicular to the table or until the acanthiomeatal line was aligned perpendicular to the imaging table.

Why is a long source-image receptor distance (SID) used for the lateral cervical vertebral projection?

To decrease the OID created between the cervical vertebrae and IR

Does too much or too little cephalad angulation cause elongation of the uncinate processes on an AP axial cervical projection?

Too much

How do the intervertebral disk spaces slant on the cervical vertebrae?

Upwardly, anteriorly to posteriorly

Why is it not necessary to use a grid, even though a high kVp level is used for AP axial oblique cervical projections?

When a long OID is used, causing scatter radiation to be diverged away from the IR and decreasing the amount of scatter radiation that reaches the IR. (Air gap technique)

When should a 5-degree caudal CR angulation be used with the cervicothoracic lateral projection?

When the patient is unable to depress the shoulder positioned farther from the IR

Which anatomic structures are aligned with the IR to prevent rotation when positioning the patient for a lateral cervical projection?

align the shoulders, mastoid tips, and mandibular rami

How is the patient positioned to prevent rotation on a lateral thoracic projection?

align the shoulders, posterior ribs, and posterior pelvic wings on top of each other

State how the CR can be adjusted to offset the thoracic vertebral sagging from a patient with wide hips and a narrow waist.

angle the CR 10-15 degrees cephalically

State where the radiolucent sponge is positioned to offset the thoracic vertebral sagging from a patient with wide hips and a narrow waist.

between the patient's lateral body surface and the imaging table, just superior to the iliac crest

Situation: The posterior surfaces of the vertebral bodies are demonstrated without superimposition and the posterior ribs are superimposed.

the elevated side of the thorax was rotated anteriorly

If the CR angulation is not adequately angled for an AP axial cervical projection, the intervertebral disk spaces are ________ and each vertebra's spinous process is demonstrated within ________________.

closed, it's vertebral body

When rotation is present on an AP thoracic projection, the side demonstrating the greater distance between the spinous processes and pedicles will be ______ the IR.

closer to

When the patient and cervical vertabrae are rotated away from the AP Axial projection, the vertebral bodies will move toward the side positioned __________ the IR, and the spinous processes will move toward the side positioned _________the IR.

closer to, farther from

How is the CR angled and positioned for an AP axial oblique cervical projection?

direct it 45-degrees medially and 15-degrees cephalically;center it to the right side of the patient's neck halfway between the AP surfaces of the neck at the level of the thyroid cartilage.

What respiration is used for the cervicothoracic lateral projection?

expiration

What is the cause for the difference in CR angulation for a supine or upright patient?

gravitational pull on vertebrae when patient is supine

Is the degree of slant higher when the patient is upright or supine?

higher when upright

How is the patient positioned for a lateral cervicothoracic projection to demonstrate open intervertebral disk spaces and undistorted vertebral bodies?

the cervical and vertebral column should be positioned parallel with the IR

Accurate CR centering on a lateral thoracic vertebral projection is accomplished by centering the CR to the __________ when the patient's arm is positioned at a 90-degree angle with the body.

inferior scapular angle

How is patient positioning adjusted from a neutral lateral cervical projection to achieve an extended lateral projection?

instruct patient to extend the chin up and backward as far as possible.

How is patient positioning adjusted from a neutral lateral cervical projection to achieve a flexed lateral projection?

instruct patient to tuck the chin against the chest as tightly as possible

What advantage does using a breathing technique over a nonbreathing technique have when imaging the thoracic vertebrae in the lateral projection?

it will blur the ribs and lung markings

What type of curvature does the thoracic vertebral column demonstrate?

kyphotic

Which cranial and mandibular cortices will be demonstrated inferiorly on a left AP axial oblique (LPO) cervical projection?

left

Which cranial and mandibular cortices will be demonstrated inferiorly on a right PA axial oblique (RAO) cervical projection?

left

What is the curvature of the cervical vertebral column?

lordotic

Which body plane is used to set up the degree of obliquity?

midcoronal

Accurate CR centering on a lateral cervicothoracic projection is accomplished by centering a perpendicular CR to the ________ plane at a level ______ superior to the _________ or at the level of the ______________.

midcoronal, 1 inch, jugular notch, vertebra prominens

Accurate CR centering on a lateral cervical projection is accomplished by centering the CR to the _______ plane at a level halfway between the _____ and ___________.

midcoronal, EAM, jugular notch

Accurate CR centering on an AP axial cervical projection is obtained by placing the CR at the patient's _________ plane at a level halfway between the ________ and _________.

midsagittal, EAM, jugular notch

Situation: A left PA axial oblique (LAO) projection, obtained with the patient's head in an oblique position, demonstrates obscured pedicles and intervertebral foramina, and the vertebral column is superimposed over a portion of the left sternoclavicular joint and medial clavicular end.

patient rotated less than 45-degrees

Why should the clivus be included on all lateral cervical projections?

the clivus with the dens can be used to evaluate cervical injury

Situation: A right PA axial oblique (RAO) projection, obtained with the patient's head in a lateral position, demonstrates the intervertebral foramina, the right pedicles (although they are not in true profile), the left pedicles in the midline of the vertebral bodies, and the right zygapophyseal joints.

patient rotated more than 45-degrees

Situation: The upper cervical vertebra is tilted toward the left side.

patient's head and upper cervical vertebrae's MSP were not aligned with the lower cervical vertebrae.

Situation: The upper cervical vertebrae are obscured by the patient's cranium and mandible.

patient's head not turned to a lateral direction

Situation: The upper thoracic vertebrae was overexposed and the lower thoracic vertebrae demonstrate adequate density

patient's head was positioned at the cathode end of the tube, and a compensating filter was not positioned over the upper thoracic vertebrae

Situation: The spinous processes are not aligned with the midline of the cervical bodies and the pedicles and articular pillars are not symmetrically demonstrated lateral to the vertebral bodies. The right mandibular angle is visible, the left mandibular angle is superimposed over the cervical vertebrae, and the medial end of the right clavicle is demonstrated without vertebral column superimposition.

patient's head was turned and torso rotated toward the right side

Situation: The intervertebral disk spaces are closed and the vertebral bodies are distorted

patient's vertebral column not positioned parallel with the IR

How can the patient be positoined with respect to the x-ray tube for an AP thoracic projection to take advantage of the anode heel effect?

position patient's head and upper thoracic vertebrae at the anode end and lower thoracic vertebrae at cathode end

How can the patient be positioned to reduce the kyphotic curvature and better align the x-ray beams with the intervertebral disk spaces?

position patient's head on a thin pillow and bend their knees, placing the feet flat against the imaging table

How must the patient's head be positioned for a lateral cervical projection to demonstate superimposed inferior cranial and mandibular cortices and to obtain open superior intervertebral disk spaces?

position the MSP parallel with the IR and the IPL perpendicular to the IR

How is the patient positioned to obtain an AP projection of the atlas and axis without rotation?

position the patient's shoulders, mandibular angles, and mastoid tips at equal distances from the imaging table

How should the patient be positioned to demonstrate the alignment of the right and left posterior cranium and mandible cortices and to demonstrate the upper cervical vertebrae without occipital or mandibular superimpostion for an AP/PA axial oblique cervical projection?

position the skull's MSP parallel with the IR and the AML parallel with the floor.

On head rotation, the atlas pivots around the dens. This results in the lateral mass located on the side toward which the face is turned being displaced __________ and the side away from which the face is turned being displaced _________.

posteriorly, anteriorly

Which patient condition can simulate rotation on an AP thoracic projection?

scoliosis

If patient motion cannot be avoided on a lateral thoracic projection when using a breathing technique, what respiration should be used?

suspended expiration

What patient respiration is used for an AP thoracic projection to demonstrate the vertebrae and posterior ribs?

suspended respiration

Which anatomic structures are included on a lateral cervicothoracic projection with accurate positioning?

the 5th-7th cervical vertebrae and the 1st-4th thoracic vertebrae

Situation: The posterior surfaces of the vertebral bodies are demonstrated without superimposition and more than 1/2 inch of space is demonstrated between the posterior ribs.

the elevated side of the thorax was rotated posteriorly

Situation: The distance from the left pedicles to the spinous processes is greater than the distance from the right pedicles to the spinous processes

the left side of the patient was positioned closer to the IR than was the right side (LPO)

Situation: The lower thoracic intervertebral disk spaces are obscured and the vertebral bodies are distorted

the patient's legs were extended

How can scoliosis be distinguished from rotation on a lateral thoracic projection?

the posterior ribs demonstrate differing degrees of rotation

How can rotation be identified on a lateral cervicothoracic projection?

the right and left articular pillars, posterior ribs, and zygapophyseal joints will be demonstrated w/o superimpostion

Which anatomic structures are included on a lateral cervical projection with accurate positioning?

the sella turcica, clivus, 1st-7th cervical vertebrae, superior half of T1, and surrounding soft tissue

Situation: The right and left articular pillars, zygapophyseal joints, and posterior ribs are demonstrated w/o superimposition. The humerus that was raised and situated closer to the IR is demonstrated posterior to the vertebral column.

the shoulder that was depressed and positioned farther from the IR was rotated anteriorly

Situation: The right and left articular pillars, zygapophyseal joints, and posterior ribs are demonstrated w/o superimposition. The humerus demonstrating the lesser amount of magnification is situated anterior to the vertebral column.

the shoulder that was depressed and positioned farther from the IR was rotated posteriorly

Situation: The 8th-12th thoracic intervertebral disk spaces are obscured and the vertebral bodies are distorted.

the thoracic vertebral column was not aligned parallel with the imaging table

How is the patient positioned to obtain open intervertebral disk spaces on a lateral thoracic projection?

the vertebral column should be positioned parallel with the IR

Describe how to position the compensating filter for an AP thoracic projection accurately.

thin edge of filter at the inferior sternum, where it begins to decline; thick end toward cervical vertebrae

How tightly can one transversely collimate on an AP projection of the thoracic vertebrae?

to an 8" transverse field size

Why are lateral flexion and extension projections of the cervical vertebrae obtained?

to demonstrate AP vertebral mobility

Why is it necessary to use a 5-degree cephalic CR angulation on an AP atlas and axis projection?

to offset the magnification of the upper incisors caused by the long OID

Why is a long SID used for AP axial oblique cervical projections?

to offset the magnification that would result because of the long OID used for the examination.

Why is it necessary to use an angled CR for AP/PA axial oblique cervical projections?

to open the intervertebral disk spaces and demonstrate undistored vertebral bodies

How is the patient positioned to ensure that rotation will not be demonstrated on an AP thoracic projection?

with the shoulders and anterior superior iliac spines at equal distances from the imaging table

When the thoracic vertebrae are in a lateral projection, the posterior ribs are positioned on top of each other. Why does the resulting projection demonstrate the posterior ribs without superimposition?

x-ray divergence will cause the posterior ribs situated farther from the IR to demonstrate more magnification than those situated closer to the IR