Last week I went under the knife to correct a large kink in my nasal septum. While they were in there my surgeon also decided to trim my inferior turbinates, all with the hope that one day I'll finally be able to breathe properly - can't wait to see what it's like! So far I'm 8 days post op, and what a lousy 8 days it has been. Who would have thought that such a small operation can cause so much pain and discomfort?
Anyway I'm not here to burden you with my woes. What I want to do is use my CT scan as a teaching case.
I used the following scanning parameters for this protocol:
- Pitch = 0.5:1
- Beam Collimation = 20mm
- kVp = 100
- mA = 60
- Rotation Speed = 0.5sec
- TOTAL DLP = 28 mGy.cm
My aim with these settings was the get the lowest dose possible (30 mAs), while still trying to maximise both spatial resolution (by keeping pitch and collimation low) and contrast resolution (by keeping kVp low).
For post processing, I used a wide window (4000/800) and a sharp kernel. I increased the iterative reconstruction to 80% which dramatically reduced the image noise. The trade-off here is that it can make the images look rather "plastic", but I'm happy to sacrifice this to keep dose and noise down. 1 mm slices provide enough spatial resolution to visualise the small and subtle structures within the nasal cavity, but I didn't want to go any lower because it would have increased image noise too much.
All of these factors combined give us the image below. Enjoy!
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