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Challenge number two.

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So this is a patient in whom we have an enhancing lesion.

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We can see right here,

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but, so I just marked it here and now I'm scanning up.

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Still don't see a fiducial.

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Fiducial is starting to come in here.

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Middle of the fiduciary is here.

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So you can see when you look at this couple of things.

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One, our fiduciary, I left my star there,

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but we're clearly outta the plane of the li the image.

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We've come up three slices from there.

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Um, so we can see two things.

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One, that the tip of our fiduciary here

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is actually medial from our lesion.

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And because I was coming up with those slices,

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we're also above it.

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So the challenge here is when you do your first post

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fiducial placing view

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and you see that your tip

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of your fiducial is not right at that lesion.

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So where I wanted to go was here

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and where my cursor,

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my fiduciary ended up was four slices up here.

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So we gotta decide are we going to replace the fiducial

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or are we just going to biopsy in a different direction?

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So what do we do? In this case,

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we can do a couple of different things.

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What we need to decide is how close is the tip

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of off fiducial to the lesion?

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And the rough guide I use is about five to six millimeters.

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These vacuum assisted biopsy devices really will pull in

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quite a lot of tissue

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and so you can, um, you don't have to become

1:38

as absolutely spot on,

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but once you get over about five millimeters,

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it's probably not going to biopsy that area.

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So sort of six is my outside

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and if I'm out further than that in terms

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of the cranial cordal dimension, then I'm going to come out

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and I'm going to put the fiduciary in, in a new spot.

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And so to do that you're gonna have

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to retarget the lesion the same as you did the first time,

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get the new coordinates, work out the new grid position,

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so exactly the same as you did using your built-in software.

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However, that's done. Make a new skin nick

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and put the fiduciary back in and re-scan.

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Now if you are too deep

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or too shallow, you can just measure the distance from the

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tip of the fiducial to the lesion and you can pull back

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or go forward a bit.

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That's really pretty easy to do

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and I will do that to make sure I'm

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exactly where I want to be.

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If you are under six millimeters,

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but not quite on, it's the same

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as we were talking about when we were talking about coming

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in in the middle of the grid

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before you need to work out

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what direction you're gonna biopsy.

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So perhaps if the fiduciary was too inferior to the lesion,

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then you are going to say, okay,

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I'm gonna take all my biopsies instead of

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around 360 degrees, around 180 degrees,

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but I'm going to aim the chamber towards the patient's

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head and vice versa.

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If you are above the lesion, you may say, I'm

2:58

Just just gonna take my biopsies to 180 degrees, aiming

3:01

that biopsy cavity towards the feet.

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I'm just gonna draw this a little bit

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to make it a little bit more obvious to you.

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So let's say that our, um,

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we are looking at the patient lying down in the sca in the

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coil, that this is the head end up here,

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this is their foot end down here, here's your fiducial.

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And we know that the lesion is towards a patient's head.

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Then instead of doing it around your, um,

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360 degrees that you would usually biopsy, instead of that,

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you're gonna take it around 180 degrees.

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But I would make sure that you go back twice so

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that you cover that territory thoroughly

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and that you suck down as much tissue as possible.