The chest x-ray and computed tomography (CT) are part of every physician’s practice. You should have a basic understanding of the anatomy and pathologic findings visible on these images. In just 12 short, interactive (and occasionally humorous) chapters, you will learn a systematic approach to reading the normal anatomy of the thorax and the basic patterns of lung disease.
1
Let’s start with the standard frontal view of the chest, the posteroanterior (PA) radiograph, or the “PA chest.” The terms posterior and anterior refer to the direction of the x-ray beam, which in this case traverses the patient from _____________.
A.
front to back
B.
back to front
1
B. back (posterior) to front (anterior)—international standard
2
By convention, the routine frontal view is taken with the patient upright and in full inspiration. The x-ray beam is horizontal, and the x-ray tube is 6 feet from the film or detector. This is what you get when you order a _____________ view.
A.
front
B.
back
C.
PA
D.
AP
2
C. PA (posteroanterior) chest—direction of beam
3
The PA view is taken at a distance of _____________ feet to reduce magnification and enhance sharpness.
A.
6
B.
5
C.
4
D.
3
3
A. 6
Placing the part to be x-rayed close to the image receptor also reduces magnification and increases sharpness. See for yourself: Place your hand, palm down, 3 or 4 inches from a desktop, preferably under a desk lamp (bulb type). Observe the shadow. Flex your middle finger only. Its shadow gets narrower and appears sharper. That finger also appears foreshortened.
If the light source (i.e., x-ray tube) moves further away, the finger would appear _____________.
A.
smaller and less sharp
B.
smaller and sharper
C.
larger and sharper
D.
larger and less sharp
B.
smaller and sharper: the further the source, the less the magnification and penumbra.
4
To reduce the magnification and increase image sharpness, the patient should be as _____________ the x-ray receptor as possible.
A.
close to
B.
far from
4
A. close to
The x-ray tube should be as _____________ the imaging receptor as practical.
A.
close to
B.
far from
B.
far from
Similar to optics
5
The anteroposterior (AP) view is usually made with a portable x-ray unit on very sick patients who are unable to stand, and on infants. The patient is supine or sitting in bed. In this instance, the x-ray beam passes through the patient from _____________.
A.
front to back
B.
back to front
5
A. front (anterior) to back (posterior)
The AP view is taken supine or sitting in bed rather than prone (PA) because it is easier for a sick patient; an infant usually fusses less when he or she can see what’s happening.
6
Portable units are less powerful and bedside space is tight. Therefore AP portable views use a shorter tube-to-detector distance. Compared with the PA radiograph, the AP radiograph has more magnification, and the anatomy appears _____________ sharp.
A.
sharper
B.
less sharp
C.
equally sharp
6
B. less sharp
The heart is an anterior structure. It would seem larger on a(n) _____________ image. Why?
A.
AP
B.
PA
A.
AP
The heart is further from detector (film)
The PA upright is preferred to the AP supine view because (1) there is less magnification; (2) the image is sharper; (3) the erect patient inspires more deeply, showing more lung; and (4) pleural air and fluid shift with gravity and are easier to detect on the erect film.
7
Figures 1-1A and 1-1B are two images of the same patient, the PA image is _____________.
Sharper edges, less magnification, deeper inspiration
Frontal radiographs, AP or PA, are viewed as if you were facing the patient from the front. In Figure 1-1A and B , and in all x-rays, the patient’s left is to your right. The heart is on the left. Right?
8
The other routine view is the lateral ( Figure 1-2 ). By convention, the left side of the chest is held against the x-ray receptor. This is called a(n) _____________ view.
A.
side
B.
erect
C.
2nd
D.
lateral
Figure 1-2
8
D. lateral
Similar to the PA view, it is also taken at _____________ feet.
A.
6
B.
5
C.
4
D.
3
A.
6 feet
If we were consistent, we would call it a right-left lateral, but “a foolish consistency is the hobgoblin of little minds” (Emerson). We just call it a lateral view.
9
It is often difficult to detect a lesion located behind the heart, near the mediastinum, or near the diaphragm on the PA view. The _____________ view often shows such a lesion, so we use it routinely.
A.
erect
B.
AP
C.
lateral
D.
PA
9
C. lateral
Figures 1-3A and 1-3B demonstrate the value of the lateral image. The lateral view shows a focal density (white) over a lower vertebral body (arrow). This pneumonia is almost invisible behind the heart on the frontal view.
10
On the lateral, which is routinely taken with the left side against the cassette, a right-sided nodule appears _____________ than an identical left-sided nodule.
A.
larger
B.
smaller
10
A. larger (magnified)
Its margins will be _____________.
A.
sharper
B.
less sharp
B.
less sharp
Further away: more magnification and penumbra.
11
In Figure 1-4A , the patient is in the right anterior oblique position. His _____________ chest is against the cassette.
A.
left
B.
right
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