The Radiographic Examination: The Basics





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.





  • How did you decide?

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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