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Now, what is X-ray collimation? The way the X-ray collimation is

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achieved as follows. There are two sets of collimator

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blades generally present.

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One is called a round iris. It's like a camera

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eye closes, open. It confirms the X-ray beam to the

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image or intensifier field of view.

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You say nine inches, it'll adjust it, and in addition,

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collimation also have rectangular lead plates, which can be

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brought in to create more of a rectangular field.

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So this is the function of a collimation.

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Why is this important? Because for in order to

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reduce or keep the radiation dose only focused on the area of

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interest and reduce patient dose unnecessarily exposed on the

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healthy tissue, collimators should always be

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used with live fluoro and recording mode.

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I'm just showing here an example of a button which indicates which if you

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move in which direction, it'll either open up the X-ray field

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or closes it.

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One of the advantage of the proper collimation is it reduces

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scatter radiation. It reduces image quality.

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In this particular right side is a two image done on the pain clinic,

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where the first one is a pain clinic that's trying to

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do a location of the vertebral bodies, and this is the

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spine of the patient, and the field is completely open, and

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that should not be the way. You can see the fuzziness

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because of the large field. If we collimate to the area of

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interest, only to the area, immediately the image quality will increase,

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and the contrast is also increased.

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So in generally, the collimation reduces scatter

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radiation, improves image quality, and that's one of the reason

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why collimation is very essential, and learning about it is very

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essential during the practice.

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This is like my colleague usually call it buttonology, and

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we advise the user, such as the radiologist or the cardiologist,

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to become familiar with some of the buttons on the fluoroscopy

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system, especially in the interventional, where this is

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almost formed like a iPad dimension kept

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connected to the X-ray table. So you can see here, this is

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a three-mode fluoroscopy system, which can be set at three different

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dose level. That's why this is small, medium, and large.

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And then you have also image intensifier button showing plus and

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minus basically can go into magnify or not.

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These two buttons basically are adjusted, which will

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show you which direction the collimation blades are working,

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as you can see on both side, or you can see together collimate to

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the area of interest.

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Where do we need to do a collimation?

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Good example is

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by doing a proper collimation, the image quality improves.

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In fact, it increases the contrast

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and reduces image blooming.

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As shown here of a mobile C-arm image of a

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lumbar spine, it is because it is open

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completely, you have lot of averaging done, therefore, the image

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quality has poorer image contrast.

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On the other hand, by collimating to exactly to the region of interest

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and remove all this extraneous need for converting X-rays into

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light, the image becomes more clarified

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and higher image quality compared to the situation where

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the collimation is completely open.

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This is a busy slide basically toward showing various physics

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parameters and the comparison between radiography and

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fluoroscopy. I want to draw this patient's skin

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dose. This is 10 to 60 milligray per minute.

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This is a fluoroscopy. Whereas in radiography, when you take one X

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image, it range from 0.2 to 10 milligray.

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And that's why the radiation protection principle to minimize any

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risk is very essential. This particular one also shows

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the tube current has wide range. For pulse, it can go even

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higher. And here is the X-ray focal spot size

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and the duration.