Chapter 7 Flashcards
Bony anatomy is always more reliable as a positioning criterion than what?
Soft tissue organs
The skeleton criteria for a particular of the body is shared by what?
Any procedures done in that area.
The bones of the lumbar spine and pelvis can be used to evaluate any abdominal position including what views?
IVP, cystogram, barium enema, upper GI, or a gallbladder series.
While attention to the projection of particular organs is sometimes important, by focusing primarily on the skeletal criteria we are able to what?
Simplify the rules of film critique.
All __________ procedures can be combined.
Thoracic
All abdominal and _______ views can be combined.
Pelvic
And most of the what can be discussed collectively in selecting criteria to evaluate positioning?
Spinal vertebrae
For the PA or AP view of the chest or bilateral ribs, the symmetry of what is typically recommended as the criterion for rotation?
Sternoclavicular joints
These 2 joints (sternoclavicular) should be equidistant from what and locates by what?
Equidistant from the midline if the spine and located by the teardrop-shaped spinous process, as shown in figure 76-A.
Figure 76-B although the sternoclavicular joints, are only slightly rotated, the base of the lungs in this view are what?
Are grossly asymmetrical in length along the diaphragm.
SC Joints only indicate what?
The shoulders.
It is possible to have the shoulders straight and the hips crooked, resulting in what?
Rotation only at the bases of the lungs.
For a perfectly straight view, costophrenic angles of the lungs should also appear what?
equidistant from the midline of the spine.
On normal patients, this is achieved by ensuring what?
That one foot is not placed in front of the other.
There is great variation in the distance from the mid-spine to the sternoclavidular joints, depending on what
The thickness and size of the patient.
On average, the SC joints are approximately how many inches?
3/4 of an inch to either side of the patient.
One quarter inch of sideways shift for these joints equates to what
About 5 degrees of rotation in the shoulders.
With 5 degrees of rotation, one SC joint would be about what?
A 1/2 inch from the spinous process, while the opposite joint would be an inch from the mid spine.
Ideally, the scapulae should be completely desuperimposed from what?
The lung fields for a PA chest projection.
This is accomplished by rotating the shoulders forward until what?
Until both are in contact with the table, chest board or cassette.
In practice, the medial borders of the scapulae may superimpose what?
The upper lateral lung fields along the inner borders of the ribs by a small amount.
When both shoulders are rotated forward equally, this helps what?
Helps to eliminate any rotation of the chest itself and the sternoclavicular joints will be symmetrical.
If one scapula overlaps the lung field more than the opposite one, then what??
Both shoulders were not rotated forward evenly.
Angulation and Flexion/Extension
Routine chest and rib views require what??
No angulation of the X-ray beam.
On the medial aspects of the 1st 3 posterior ribs will be demonstrated where?
Above the clavicles as shown in Figure 76-B.
On same patients the third rib will be what?
Partially covered by the clavicle as in Figure 76-A.
For intentional lordotic views of the chests proper angle of the X-ray beam or extension of the spine will produce what?
A view with the clavicles projected over the medial aspects of the 1st posterior ribs and completely above the apices of the lungs.
It is common when performing AP chest projections such as “stretcher chests” or portable chests, to obtain what?
Improper lordotic views from insufficient caudal angulation of the x-ray beam.
Such views will demonstrate the clavicles above the posterior third ribs and tend to cause a what?
A “straightened out” linear appearance to the posterior ribs from the distortion of their normal curvature.
This problem is avoided by ensuring that the central ray is angled sufficiently caudal to be what?
Perpendicular to the mid-axillary line of the patient rather than perpendicular to the film, bed or stretcher.
Small children’s skulls are much larger in proportion to their what?
Their bodies than those of adults.
It does not take very much flexion or extension of the neck to get the what?
To get the chin or the occipital bone of an infant over the apices of the lungs.
When lying an infant on it’s back, the large cranium resting against the table often forces what to happen
The chin into a flexed position, superimposing it over the lung fields.
To avoid this (as well as to avoid a lordotic projection) place a 10-15 degree angle sponge on top of the cassette to accomplish what?
With the thickest end under the baby’s shoulders, allowing the head to fall gently back onto the film.
Dropping the head off of the sponge and film or using a thicker sponge may do what?
Hyperextend the head and injure the child.
Normal frontal views of the chest on adult patients should be on full inspiration, with what showing?
Ten posterior ribs showing in the lung fields
To consider a rib as being in the lung field, at leas what must appear?
The medial one half of the posterior rib should appear above the diaphragm.
This same rule applies for what?
the above-the-diaphragm projections of the ribs
Figure 80 is an example of inadequate inspiration, and shows how to count what?
The ribs
For infants in general, how many ribs above the diaphragm is adequate?
Nine.
For premature and newborn infants, how many ribs above the diaphragm is adequate?
Eight.
When adequate penetration is used for chest radiography, details of the thoracic spine and medial ribs will be what?
Just visible through the heart shadow, as in Figure 76.
Proper density will then also demonstrate the what?
Soft tissue markings in the lung fields.
A chest radiograph is repeatable any time what happens?
Any time that the mediastinal structures are obliterated by inadequate penetration or density, leaving the heart and spine area with a white or clear appearance.
The lateral view of the chest has no what?
No pairs of reliable anatomy close to the central ray.
In assessing rotation, we are limited to using what?
Using anatomy along the back of the chest, which is less variable than the anterior chest wall.
The right and left posterior ribs should be what?
Superimposed directly on top of each other, and the right and left costophrenic angles should also superimpose each other.
Figure 82 shows that when the lateral chest view is rotated what appears?
A space of lung field will appear between the sets of ribs, usually with one set of ribs showing the circular on end appearance from looking down at them.
As a rule of thumb, if this space is more than what?
Two finger-breadths wide, the view should be repeated.
On lateral views, one inch of shift between the ribs indicates what?
About 5 degrees of rotation, since one side shifts forward by 1/2 inch and the opposite side shifts backward 1/2 inch
The posterior costophrenic angles in figure 82 are shifted by the same amount as what?
As the ribs, and are reliable indicators of rotation.
Note that there is a normal long space that lies behind what?
Lies behind the spine, between it and the posterior ribs.
Some patients have very curved ribs so that this space is large, an appearance that can be mistaken for what?
Rotation even though the posterior ribs are exactly superimposed, figure 83.
Be careful not to mistake this normal space behind as what?
A space between two sets of ribs.
During lateral chest projections, a common error is what?
To fold the patient’s hands on top of his head, rather than his arms.
Views like that in figure 83 can result in what?
With arm tissue superimposing the lateral lung field.
Whenever possible, the patients forearms should be what.
Crossed over his head.
Asking the patient to keep his chin up also helps him what?
Stand straight, and on large patients this can make a difference in fitting the lung fields on the film.
In figure 84 a large patient’s anterior costophrenic angles were clipped off when he did what.
When he leaned back upon taking a deep breath, extending the spine.
The same rule used for the PA chest, of demonstrating ten ribs above the diaphragm, also applies to what?
The evaluation of adequate inspiration on the lateral chest view.
One must observe the position of the uppermost peak of what?
The dome of the diaphragm and count the number of posterior ribs which lie above that point.
When a proper 45 degree oblique view is taken of the chest or ribs, the posterior ribs on one side will appear to be what?
One half as long as those on the opposite side as in figure 85
Also, the sternum will be shifted so that there is a what?
A 2-3 inch space between it and the spine.
When the rotation is too shallow, the space between the sternum and spine will be less than what?
Two inches and the foreshortened lung will not yet be reduced to one-half.
When the rotation is too steep, the foreshortened lung will be reduced to less than what?
One half the width of the opposite lung, and the view will begin to take on a distinct rotated lateral appearance
For coned down oblique views of the right or left ribs, the posterior ribs on the side of interest are what?
Laid out roughly parallel to the film, so that they appear long and somewhat straightened, while those on the opposite side are foreshortened and very curved.
For posterior oblique positions, the side of interest is the downside.
For anterior oblique positions, the side of interest is the upside.
Ideally on the side of interest the heads of most of the ribs dont what?
Do not superimpose the bodies of the vertebrae. If they do, the position is too steep.
