Thursday, September 21, 2006

Creating the arch and other concerns

Like Matt Kroona I sometimes ponder what I am doing, more correctly if my doing is correct.
1)I want to know what the criteria is for creating the arch for the "oblique" view (pano). I recently had a mandibular canal large enough to drive a truck through and was playing around with creating the "best" visionary of the canal with regards to the pano. I started to wonder if showing the canal vs keeping the perpendicular for the cross sections conflicted. When I am creating the arch for the (pano) I try to keep the perpendicular as close to 90 degrees without losing the canal but what if your losing the canal by keeping the perpendicular?
2)On another tangent. I am checking each scan for movement; by using a technique suggested last iCAT meeting. This entails going to the raw data, rotating the skull then bringing the cursor to the symphisis and rolling the ball from 366 to 1. I am finding that many times there is a contrast change from the 366 to 1 giving the "impression" that there is patient movement. I recently started using the velcro strap across the patients forehead and it seems to help.
3)Lastly, does anyone check the success of the calibration by taking a scout view and seeing how the "white screen" appears? Arun had made a comment one day, when I was sharing my computer with him, that he could see that I needed to do another calibration because the screen was not uniformed, too much saturation. You can actually look at the center of your screen and it appears as though there is a vertebre running down the center and the outer borders have a greyish look.
OK folks, I haven't gone over the Matt's or Eric's script but I am close.


Blogger Amnon said...

Devery, your orientation MUST be Cross sections perpendicular to the arch turn on the hush marks it helps visually.
You can always take a second Pano with a thinner layer to show the canal & remember to mark which one refers to the cross sections!!
We do it sometimes, mostly when there is anomalies of the canal.

The reason I tend not to give this canal orientated pano is that you see only a thin layer(very deceptive), and Docs tend to have bone height impression & even measure on panos(an old habit).

Our final movement test are the cross sections actually if they are acceptable!
As long as they are only a bit blurred it's ok If I get a double contour (cortical) then bad news.

8:04 AM  
Blogger Matt Kroona said...

You used my name twice in the same posting. Do I get a sucker or a sticker or something?;-)

Whether it correct or not, I try to set up the arch so that it shows the canal as clearly as possible on the pan view. If you look at the pan Eric posted recently, it is fairly thin and show the canal nicely. That's my goal. I also try to set my arch so that the anterior cross sections are centered in the window.

As far as movement goes, I'm with Amon. The cross sections are the real movement test. I had a patient last week that swallowed in the middle of the scan and actually opened and closed his teeth. I saw him swallow but when I checked the raw data it showed no change between the first and last frame. The swallow was evident when I scrolled through the raw data but if I had released the patient with only a raw data test, I would have regretted it. I always check the cross sections before I release a patient. Cheap insurance.

2:43 PM  
Blogger Eric Iwamoto said...

This blog format does not allow photographs in the comment section. Review my answer under new posting "Multiple Oblique Images".

4:04 PM  

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