JP2520248B2 - How to create relational contour point data - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention extracts the contour point data of the skin and the contour point data of the bone from the CT image data of the head of the subject and relates them to each other. The present invention relates to a method of creating relational contour point data that enables

[Conventional technology]

Recently, for example, skin contour point data and bone contour point data are extracted from the CT image data of the subject, and the three-dimensional image of the subject's head, for example, is constructed and displayed by stacking the data. It's coming. In this case, conventionally, the contour point data of the skin and the contour point data of the bone are separately extracted as separate items and are not related to each other at all.

[Problems to be solved by the invention]

In such a three-dimensional image structure display, the contour point image of the skin and the contour point image of the bone are completely unrelated. Therefore, for example, in a surgery simulation of plastic surgery, for example, when the bone of the head is scraped to a certain shape, how the shape of the skin of that portion changes, or when the skin is shaved to have a certain shape, How to remove the bone in that part is not immediately displayed as a three-dimensional image in correlation with each other, but the contour point image of the skin and the contour point image of the bone are corrected and displayed by trial and error. I had to. From this,
The simulation in the surgery simulation of the plastic surgery is complicated and time-consuming, and the efficiency of the surgery simulation is reduced.

Therefore, the present invention provides a method of creating relational contour point data, which can extract contour point data of a part and contour point data of another part from CT image data of a target object and can correlate them with each other. The purpose is to

[Means for solving problems]

The means of the present invention for solving the above-mentioned problems is a CT of an object.
The contour point data of a part and the contour point data of another part different from this are extracted from the image data, and the distances from one contour point of one part to each contour point of the other part are calculated, respectively. The identification information indicating the coordinate position of the contour point of the other part which gives the distance is obtained, and the related contour point data is created by combining this identification information and the coordinate data of one contour point of the one part, and This is performed by repeatedly executing each contour point of one part and storing the obtained relational contour point data.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a flow chart showing the procedure of a method of creating relational contour point data according to the present invention. In this embodiment, as shown in FIG. 2, for example, skin contour point data Da and bone contour point data Db are extracted from CT image data collected on a tomographic plane having a head of a subject, A case of creating relational contour point data that correlates the two will be described. Here, the contour point data Da of the above skin
Is a number of contour points A ₁ , A ₂ , A ₃ , which represent the outline of the skin.
, And the coordinates of each contour point A ₁ , A ₂ , A ₃ , ... Are generally expressed as (Xn, Yn) (n = 1, 2, 3, ..., N). Further, the bone contour point data Db is composed of a large number of contour points representing the shape of the bone.
It consists of a set of B ₁ , B ₂ , B ₃ , ..., and each contour point B ₁ , B ₂ , B ₃ ,
The coordinates of ... are generally expressed as (xj, yj) (j = 1,2,3, ...,
j).

First, from the CT image data of the head collected in advance, the second
Skin contour point data Da and bone contour point data Db shown in the figure
(Step). Then, as shown in FIG. 3, each contour point A _{1 of} the extracted contour point data Da of the skin,
The coordinate data of A ₂ , A ₃ , ... Is recorded in the first memory 1, and the coordinate data of each contour point B ₁ , B ₂ , B ₃ , ... Of the bone contour point data Db is recorded in the second memory 2. Keep it. Next, one of the contour points of the skin, for example, the first contour point A ₁ is designated (step). That is, the contour points of the skin coordinates (Xn, Yn) as "1" to the serial number n in the extracts from the first memory 1 shown in FIG. 3 the (X _1, Y ₁₎ coordinate data. Next, from the first contour point A ₁ (X ₁ , Y ₂ ) of the skin to each contour point B ₁ , B ₂ , of the bone,
The distance R to B ₃ , ... Is calculated (step). Here, the coordinates of the contour points of the skin are generally expressed as (Xn, Yn), and the coordinates of the contour points of the bone are generally expressed as (xj, yj). The distance R to the contour point is expressed by the following equation.

Now, in the above formula (1), n = 1 and j = 1,
The coordinate data of the contour points B ₁ , B ₂ , B ₃ , ... of the bone are sequentially fetched from the second memory 2 shown in Fig. 3 and substituted as 2, 3, ..., j, and the distances are calculated as shown in Fig. 2. R ₁ , R ₂ , R ₃ , ... Are calculated in sequence. Next, the distances R ₁ , R ₂ , R ₃ , ...
And the identification information j indicating the coordinate position of the contour point of the bone giving the minimum distance is obtained (step). For example, in Fig. ₂ , the distance to the second contour point B ₂ (x ₂ , y ₂ ) of the bone
If R ₂ is the minimum, j = 2 is used as the identification information, and this value is set as J ₁ . Next, the identification information j thus obtained,
The coordinate data (Xn, Yn) of the specified contour points of the skin is combined to create the relevant contour point data (j, Xn, Yn) (step). Now, the value of the identification information j is J ₁ , and the contour point of the designated skin is the first contour point A ₁ (X ₁ , Y ₂ ).
Therefore, the relational contour point data in this case is (J ₁ ,
X ₁ , Y ₁ ). Then, the relational contour point data (J ₁ , X ₁ , Y ₁ ) thus created is used as the first relational contour point data D ₁
Is recorded in the third memory 3 as shown in FIG.

Next, the designation of the contour points of the skin is advanced by one (step). That is, at the coordinates (Xn, Yn) of the contour point of the skin, the serial number n is incremented by 1 to be "2", and the second contour point A ₂ (X ₂ , Y ₂ )
Is specified. Then, the coordinate data of (X ₂ , Y ₂ ) is taken out from the first memory 1 shown in FIG. Next, it is judged whether or not all the contour points A ₁ , A ₂ , A ₃ , ... Of the skin have been completed (step). For now, we have only finished about the first contour point A ₁ and proceeded to the second contour point A ₂ , so
The step proceeds to the “NO” side and returns to the front of the step.
Then, the steps → → → → are repeated to sequentially advance the contour points of the skin to A ₃ , A ₄ , ..., and the distance R is calculated each time, and the coordinate position of the contour point of the bone giving the minimum distance R is determined. The identification information j shown is obtained, and the related contour point data (j, X
n, yn) will be created. In this way, the contour points of the skin
When all of A ₁ , A ₂ , A ₃ , ... Are completed, the step exits to the “YES” side. At this time, as shown in FIG.
In the third memory 3, n pieces of relational contour point data D ₁ , D ₂ , ... Dn
Is recorded. Then, the relational contour point data D ₁ , D ₂ , ... Dn obtained as described above are stored in, for example, the magnetic disk 5 as shown in FIG. 3 (step).

According to the relational contour point data (j, Xn, Yn) thus created, the skin contour point data and the bone contour point data are associated with each other. For example, regarding the first relational contour point data D ₁ (J ₁ , X ₁ , Y ₁ ), the identification information j
The value J ₁ (= 2) of represents the serial number j attached to the coordinates (xj, yj) of the bone contour point, and the first contour point A ₁ (X ₁ , Y ₁ ) of the skin It is shown that the closest distance among the contour points B ₁ , B ₂ , B ₃ , ... Is the second contour point B ₂ (x ₂ , y ₂ ) of j = J ₁ = 2. There is. Second relation contour point data D ₂ (J ₂ ,
The relationship between X ₂ and Y ₂ ) and below can be similarly determined.

Next, the relational contour point data (j, Xn, Y
How to use n) will be described with reference to FIG. For example, the contour point data of the skin and the contour point data of the bone are extracted from the CT image data of the head of the subject, and these are stacked to display the three-dimensional image of the head of the subject. When performing a surgical simulation of plastic surgery using, for example, scraping a part of bone is
This corresponds to changing the coordinates of the contour point of the bone corresponding to the location. Furthermore, when the bone is scraped off as described above, the skin at that portion is also dented, so the coordinates of the contour points of the skin corresponding to that portion must also be changed. Now the 4th
In the figure, in the second memory 2, coordinate data of each contour point B ₁ , B ₂ , B ₃ , ... Of the extracted contour point data Db of the bone is recorded. Here, it is assumed that the part of the second contour point B ₂ of the bone is appropriately cut off and its coordinates (x ₂ , y ₂ ) are changed to (x ₂ ′, y ₂ ′). Then, the coordinate data of the contour points B ₁ , B ₂ ′, B ₃ ′, ... Of the bone corrected in this way are recorded in the fourth memory 4 as shown in FIG.

In this way, the change in the coordinates of the skin contour point due to the change in the coordinates of the bone contour point is obtained by approximation as follows. That is, in FIG. 4, when the value J ₁ of the identification information j of the first relational contour point data D ₁ recorded in the third memory 3 is “2”, the first contour point A ₁ of the skin is It can be seen that the closest bone contour point to (X ₁ , Y ₁ ) is the second contour point B ₂ (x ₂ , y ₂ ). However, the second contour point B ₂ of this bone
Since (x ₂ , y ₂ ) is cut as described above and changed to B ₂ ′ (x ₂ ′, y ₂ ′), the change amount of the coordinates is Δx = x ₂ − in the X direction.
x ₂ ′, and Δy = y ₂ −y ₂ ′ in the Y direction. Therefore,
The coordinates of the first contour point A ₁ (X ₁ , Y ₁ ) of the skin may be changed in accordance with the amount of change in the coordinates of the second contour point B ₂ of the bone. Therefore, the coordinate data (x ₂ , y ₂ ) of the second contour point B ₂ of the bone before change is read from the second memory 2 and the second contour point of the bone after change is read from the fourth memory 4.
The coordinate data (x ₂ ′, y ₂ ′) of B ₂ ′ is read out, and the amount of change Δx = x ₂ −x ₂ ′, Δy = y ₂ −y ₂ ′ of the coordinate is calculated. Only the coordinates (X ₁ , Y ₁ ) of the first contour point A ₁ of the skin should be changed. Therefore, the coordinates of the first contour point A ₁ of the changed skin are X ₁ −Δx = X ₁ − (x ₂ , x ₂ ′) (2) in the X direction and Y ₁ −Δy in the Y direction. = Y ₁ − (y ₂ , y ₂ ′) (3) As a result, a new first relational contour point data D ₁ is created from the value J ₁ of the identification information j and the values of the equations (2) and (3), and as shown in FIG. It is recorded in the third memory 3. Even when the coordinates of other parts of the contour points of the bone are changed, new relation contour point data is created in the same manner as above.

In the steps of the flowchart shown in FIG. 1, all distances R from one contour point of the skin to each contour point (xj, yj) of the bone are calculated even after the second time. Is not limited to this, and if the identification information j is obtained in the previous step, in the next step, the distance is only around the bone contour point (xj, yj) indicated by the identification information j, for example, about 10 points before and after that. R may be calculated. For that purpose, a small processing loop that operates after the second time may be formed in the step. In this case, the calculation process of the distance R is performed in a short time, and the identification information j can be obtained at high speed in step.

Further, in the above explanation, as shown in FIG. 2, the skin contour points A ₁ , A ₂ , A ₃ , ... To the bone contour points B ₁ , B ₂ , B ₃ ,
... was decided to calculate the distance R to the present invention is not limited to this, contour points of the bone B ₁ Conversely, B _2, B _3, contour points of the skin from _{... A 1, A 2, A} 3 The distance to, ... May be calculated.

Furthermore, the contour point data extracted from the CT image data is
Not limited to skin and bone, contour point data of other parts may be used.

〔The invention's effect〕

Since the present invention is configured as described above, it is possible to correlate a part composed of CT image data of an object, for example, contour point data of skin and another part, for example, contour point data of bone, and to correlate the two. it can. Therefore, for example, even if the coordinates of a contour point of a part of the contour point data of the bone are changed,
With respect to the skin contour point data corresponding to this, it is possible to easily obtain an approximate value of the change in the coordinates of the contour point of the part. From this, in surgery simulation of plastic surgery performed by displaying a three-dimensional image, for example, when the bone of the head is scraped to a certain shape, how the shape of the skin of the part changes will be mutually compared. It is possible to associate and immediately display the composition as a three-dimensional image. Therefore, the simulation in the surgery simulation of the plastic surgery can be performed easily and quickly, and the efficiency of the surgery simulation can be improved.

[Brief description of drawings]

FIG. 1 is a flow chart showing a procedure of a method for creating relational contour point data according to the present invention, and FIG. 2 is an explanatory view showing skin contour point data and bone contour point data extracted from CT image data of the head. FIG. 3 is an explanatory diagram showing a recording state of the related contour point data in the memory, and FIG. 4 is an explanatory diagram showing a coordinate change state of the related contour point data. Da ... skin contour point data, Db ... bone contour point data, A ₁ ,
A _{2 to} An ... skin contour points, B ₁ , B _{2 to} Bj ... bone contour points, R ₁ ,
R _2, R ₃ ... distance, J _1, J ₂ ~Jn ... value of the identification information, D _1, D ₂ ~Dn
... relevant contour point data, 5 ... magnetic disk.

Claims (1)

(57) [Claims] 1. Contour point data of a part and contour point data of another part different from this are extracted from CT image data of an object, and one contour point of one part to each contour point of the other part. To calculate identification information indicating the coordinate position of the contour point of the other part that gives the minimum distance,
This identification information is combined with the coordinate data of one contour point of the one part to create relational contour point data, which is repeatedly executed for each contour point of one part, and the obtained relational contour point data is stored. A method of creating relational contour point data, characterized by: