Road to Radiography

I felt cheated after this morning’s written test on spinal positioning.  I’m so used to seeing questions worded in ways that are designed to trip us up, I read too far into one of my questions and got it wrong. 

The question was:  What is the transverse centering position for the posterior oblique lumbar spine x-ray?

The interesting part of this was that I had just done a LPO lumbar in my physical positioning test in lab an hour earlier.  I’m fully aware that the proper CR centering point for this exam is 2″ medial to the upside ASIS.  No problem… Easy answer…

I can’t remember what all four of my multiple choice options were, but two of them were as follows:

A. 2″ medial to upside ASIS
B. ASIS

I chose B.  The reason I chose B is because of the way the question was worded.  Why were we asked for the TRANSVERSE centering position?  The plane on which the ASIS is found is a transverse plane of the human body.  When you introduce the fact of a point 2″ medial to the upside ASIS, you have introduced the intersection of a transverse plane and a sagittal plane.  I made an assumption that the question wording was designed to make me pick the obvious answer rather than the correct one, and I was wrong. 

Oh well… I made a 92.8 on the test, but this question kept me just below the level of an A…

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Tags: 2nd Semester, RAD-112 by John Setzler
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I have encountered a few points of ‘distress’ in studying for my spinal series tests that come up later this morning. I’m not sure why I can’t wrap my mind around these concepts, but I’m having one hell of a time sorting out oblique x-rays of the spine. Our text book doesn’t seem to clarify this very well, but when I’m looking at a radiograph of an oblique cervical spine, how can I tell if I’m viewing an LPO, RPO, LAO, or RAO position?

Shortly after I started this program, I decided that I wanted to get a copy of the Merrill’s Atlas of Radiographic Positioning as a supplementary text since we weren’t using it in my program. We use Bontrager’s Textbook of Radiographic Positioning and Related Anatomy. I decided to pull out the Merrill’s Atlas to see what it had to offer for my current problem. What I discovered is that the RAO and LPO views look very similar and the RPO and LAO views look similar as well. The differentiation between the two is which side of the spine you are viewing. The oblique view of the cervical spine shows the intervertebral foramina. The anterior obliques show the foramina closest to the image receptor while the posterior obliques show the foramina farthest away from the IR.

• RPO - shows patient’s left-side cervical spine intervertebral foramina
• LPO - shows patient’s right-side cervical spine intervertebral foramina
• RAO - shows patient’s right side cervical spine intervertebral foramina
• LAO - shows patient’s left side cervical spine intervertebral foramina

In the thoracic spine obliques, the same should hold true.  In the oblique views of the thoracic spine, we are looking for the zygapophyseal joints. 

• RPO - shows patient’s left side thoracic spine zygapophyseal joints
• LPO - shows patient’s right side thoracic spine zygapophyseal joints
• RAO - shows patient’s right side thoracic spine zygapophyseal joints
• LAO - shows patient’s left side thoracic spine zygapophyseal joints

This situation takes a twist when we get down to the lumbar spine.  The lumbar obliques also show zygapophyseal joints.

• RPO - shows patient’s right side lumbar spine zygapophyseal joints
• LPO - shows patient’s left side lumbar spine zygapophyseal joints
• RAO - shows patient’s left side lumbar spine zygapophyseal joints
• LAO - shows patient’s right side lumbar spine zygapophyseal joints

The Merrill’s Atlas has markers on the radiographs that demonstrate the patient position.  The Bontrager book seems to avoid that.  The Bontrager book just tags the image as ‘oblique’ rather than giving a right or left indicator for some reason.  I’m finding things l like and dislike about each of these books as we progress.  Having both sets is handy.  I still cant’ seem to identify a radiograph as one position or the other without an extra set of clues.  In our radiograph reviews, it will state ‘prone’ or ’supine’ which tells us if it’s a posterior or anterior oblique.  I guess I’ll try to sort it out in the morning before the test…

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Tags: 2nd Semester, Important Concepts, RAD-112 by John Setzler
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