Some Stumbling Points
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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In 15 years of being an RT, I’ve never seen PA obliques of c-spine or l-s spine done on a real patient. But I guess you still have to learn what they demonstrate!
Tim » These aren’t PA obliques. They are AP oblique projections but posterior oblique positions…
John - the tip I taught myself was…….in the lumbar spine, the ’scotty dog’ looks to the side of the posterior oblique.
Hope thats of some help, but i’m sure you have the issue well sorted out anyway.
BTW…just checked your blog again tonite, after a long time………very very impressed, on many levels.
When are you going to post again on DPC?
I took this topic up with a Radiologist doing our
wet reads today. He brought up and interesting point
about postions and distance.
As you see in Merrills’ images ARE more or less the same. BUT to counter air-gap and optimise detail
it’s recommended your SID of 72 inches. As a habit
I like patients to be sitting and stable usually in a wheeled chair for postioning reason. So my method
has been PA obliques. Patient postion R/L AO.
Otherwise I need to dig a hole in the floor to get the 15 to 20 degree tube angle that is recommended. Of course if you prefer your exam patient standing
this is all muted.
Bottom line “Keep your eye on the prize” cause……..
image IS everything!!!!!