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From the past 10, 15 years, we see the influx of digital

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tomosynthesis.

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As you can see here, this is a three-dimensional breast shown as

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a two-dimensional image.

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There's a lot of tissue overlap,

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and then you don't know exactly where the structure is when it is compressed

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and try to see which level.

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And that is avoided to a large extent by what is called

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digital tomosynthesis. The

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methodology here is to create image, like thin

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slices, by taking an acquisition at a different time

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point.

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So the digital mammography's principle works as

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follows.

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The number of projection images is acquired of compressed

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breast while X-ray source rotates

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around a center of rotation closer or

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on detector surface, while detector is either static

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or rotates, depending on the system.

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So here is the breast held tightly.

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Now the X-ray tube system will rotate around the head here,

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the arc of 14 up to 20 slices, and at each of

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these things, you're acquiring an image, and all those image can

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be combined to create a regular mammography image.

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Or they can be individually viewed to utilize the structure

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because the overlapping of the structure is

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avoided. So for example, here,

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in this particular bottom, this is a digital detector, and now we are

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acquiring a breast with two different structure of interest,

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but now with A and B,

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with the A, we see these two object.

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With the B, we can see these two object.

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But with A plus B together, if there's only one thing,

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this cannot be differentiated at what depth that interest is.

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That's where the advantage of tomosynthesis comes into picture.

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The principle of tomosynthesis varies from manufacturer to manufacturers, depending

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on the number of projection, typically between 14 to 27

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projections. The way it's done is you have the incident X-rays.

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This is the breast with a different structure.

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You view it like a CT across the breast with multiple

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angles, and each of the angles are then reconstructed,

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so you can easily reconstruct it, and we can now

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decipher where the objects were.

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Same thing here. This is a compressed breast with various

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object. If it is a 2D only, they would all look like this.

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Whereas here, in this one, it position from slice to slice.

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So here is an image of a breast phantom with the

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ACR phantom placed on top of it,

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and this is to show

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the tomosynthesis image

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clearly showing all the structure on a single plane.

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In this, basically trying to show the advantage of tomosynthesis

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with respect to planar imaging.

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In a planar mammography,

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the three-dimensional object is now captured into a two dimension.

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So the object can be laying in different layers, but they all appear as

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one, as seen, and this is very difficulty.

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You can see some structure, but you don't know which depth it is

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aligned.

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On the other hand, with the tomosynthesis, the same objects are imaged

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from different angles. You can actually see the differences

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very clearly, and it help to diagnose the breast cancer at the

3:38

early stage.

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This is a projection image with the projections taking between plus

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seven and a half to minus seven and a half to 15-degree

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angle across the breast and reconstructed, and

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this recurrent image looks like a CT-like image, but they can be

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combined together and appear as a regular

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mammography image, too.

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So the images are reconstructed, and you

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can thumb through the images of all these tomosynthesis images.

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That way, this gives us a better picture where exactly is

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a particular object of interest exist, and you can go and biopsy

4:18

there or remove it.

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Finally,

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this is showing you as the digital mammography images.

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This is an MLO of a digital mammography image, and

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this is a synthetic mammography.

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Using the digital breast tomosynthesis, which you acquire different

4:36

slices, you can combine all together and create a synthetic

4:39

mammography,

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and this is a DVD style. So the idea here is basically,

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if the reader is used to the old type of a

4:49

viewing of an image, that can be still accommodated with the

4:53

tomosynthesis.

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Finally,

4:56

there is a strict requirement about the mammography, as I mentioned.

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This is regulated by MQSA Act passed in 1994.

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The full-field digital mammography system may be only used

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if it is FDA-approved and meets one of the following criteria.

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The FFDM unit must be accredited

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if a state accreditation body or with ACR has received FDA

5:21

approval to accredit same thing.

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In addition, MQSA-certified site must have the FDA

5:29

extend its screen-film certification to cover its

5:32

full-field digital mammography system.

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So this is what I want to share in this lecture on radiography, the

5:39

basic principle of physics, X-ray tube, X-ray output,

5:43

scatter radiation, Bucky factor, and then

5:48

the concept of digital radiography.

5:50

Under the digital radiography, there is the CR plates and

5:54

the indirect digital, which is most commonly used nowadays in

5:58

radiology, and amorphous selenium-based, which is used

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in mammography.

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And in mammography, we use a characteristic X-ray, while in all other

6:08

imaging, we use the Bremsstrahlung part of the radiation. Thank you.