[Intl_DxMedPhys] rotation time artifact

[Idris Elbakri]

Dear colleagues,

I am curious to see if anyone has encountered a CT artifact that appears
when certain rotation times are used. This artifact started appearing a few
weeks ago on our head protocol on a Philips Spectral 7500. I investigated a
bit and found that the artifact appears when the rotation times are short
(0.33 and 0.4 seconds) and disappears at 0.5 sec or higher. Is the fast
rotation inducing some sort of vibration? Nothing in the protocol has
changed from a few weeks ago when there was no artifact.

Upon further ingestigation I also think the artifact appears in other
protocols, but is not as obvious, and its dependence on rotation time is
not evident. I still suspect some sort of mechanical effect.

I suspect the vendor will push back and say that there is nothing wrong
with the scanner as they have just completed a PM. I appreciate any insight
you can provide if you have seen something like this and how you might have
resolved it.

Cheers,

Idris Elbakri, PhD, MCCPM
PS. Figure from left to right: 0.33, 0.4, 0.5 and 0.75 sec rotation times.

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