DE3437483A1 - Arrangement and method for producing three-dimensional models - Google Patents

Abstract

In medicine, there is a need before an operation, to make a bone model on which various methods of operation can be simulated. For this purpose, an arrangement for making three-dimensional bone models is described, the arrangement having an image generator, a converter, a processing machine and a fitting device. Using the image generator, primary data of the bone are obtained in the form of layer images which data are converted in the converter into model data representing the external circumferential lines of the individual layers. The model data feed a processing machine for producing discs which are stacked on top of one another on a fitting device which results in the bone model.

Description

•.

Arrangement and method for the production of three-dimensional models

The invention relates to an arrangement for manufacturing νon three-dimensional physical models of an organ (or a part thereof) of the human body, in particular for the production of bone models. The invention is also concerned with a method of manufacture of bone models.

There is a significant need in the medical field for the production of models of human organs, in order to be able to carry out an operation planning especially on a bone model before the surgeon carries out the actual operation on the patient himself.

With the current state of the art, one has limited oneself to to take x-rays of the bone to be operated on (for example a thigh fracture), ufli image the fracture and use the X-ray to make the diagnosis. In the further course of the A surgical procedure is selected based on the x-ray.

A next step then is to consider how to

-is- 3 A 3 7 A 8:

with the selected surgical procedure (ζ.B, plating) can best stabilize the particular fracture.

The two-dimensional X-ray image, however, leaves an exact one Do not prepare for surgery because it is three-dimensional Object "bones" only depicts two-dimensionally. Therefore, the surgeon can only be inadequate Forming ideas of the actual circumstances that exist and not his operational approach specify exactly. In particular, the implant dimension, the optimal implant position, length and position the required screws etc. are not optimally determined beforehand.

Since only parts of the fracture may be exposed during the operation, otherwise there is a risk of the fracture healing being impaired the surgeon can only provide an inadequate service, even in the actual operating phase Take a picture of the entire fracture. ,,

The difficulties outlined cannot be eliminated even with the aid of computer tomography. Though it is possible for the surgeon with some skill to get an idea based on the individual slice images of the object in its spatial

To make measurements, however, this conception is essential for the preparation of the operation and for its implementation not satisfying.

One could also consider the possibility of three-dimensional representation, which is known in research of a bone on the screen of a monitor when planning the operation. Even if through this a better spatial orientation or idea can be obtained, such is also sufficient spatial representation is not sufficient, for example, to select the optimal procedure from competing surgical procedures, because here, too, the surgeon lacks the opportunity to carry out a specific intervention on a model to be carried out on a trial basis beforehand.

in addition, there is the three-dimensional representation of an object on the screen of a monitor is only in the early stages of development. This technique namely requires extreme computing power that can only be managed by "very expensive large-scale computers". So is this solution is not practicable for reasons of cost.

The limited ability to assess the break by the surgeon requires in practice that the fracture must be further exposed during the operation, causing poor blood circulation and thus

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3Α37Α83

a poorer fracture healing is to be expected. In addition, X-ray checks are repeated during the operation required, which mean a radiation exposure for the patient and also for the operating steara.

Another disadvantage is that the operation time through the aforementioned x-ray controls, through further exposure of the fracture and through the certain Uncertainty on the part of the surgeon, who in coordination with the surgical team during the course of the operation Tries to create an ever clearer picture of how the bone fragments belong together and which ones the best possible fracture restoration is often extended by hours. It is not uncommon for such operations to be possible take up to 8 hours.

The disadvantageous circumstances described lead in some cases even to the fact that the operation once or also has to be repeated several times. In connection with the long duration of the operation mentioned above Finally it should be noted that the longer duration of the operation has the consequence that the patient because of the correspondingly longer exposure to anesthesia can be seriously endangered.

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This is where the invention comes in, on which the object is based is to enable an exact operation planning and to shorten the operation time.

This object is achieved in the arrangement mentioned in the preamble of claim 1 in that the Arrangement comprises the following components:

a) an image generator for generating a plurality of slice images (cross-sections) on different ones Locations of the organ, and thus for the generation of primary data characterizing the recorded layers of the organ,

b) a converter connected to it for converting the primary data into the external data Perimeter lines (boundary lines) of the individual layers representing (disc) Model data,

c) a processing machine fed by the model data with controllable tools for the production of sheets corresponding to the layers

_k ben made of a machinable material. plate, from which discs by stacking one on top of the other

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the physical model L can be produced, and

d) a registration device sum defined stacks of the discs.

With the arrangement according to the invention it is the first time possible in a closed, largely autonomous process from an organ of the human body or from a part of the organ a three-dimensional one to produce a physical model, so to speak, as a 1: 1 copy for experimental, exercise, planning and illustration purposes. The scale 1: 1 is only to be understood as an example; other size ratios are of course also possible possible.

It is also possible to interrupt the largely automatic process mentioned, if necessary, to control interactively in this way. For example, after each individual process, Intermediate step, call up the result data on computer graphics terminals. This can be used in computer graphics Apply the tried and tested method of "previewing" on fast and inexpensive devices before going on ' the slow and expensive manufacturing machines with the

plate (e.g. made of transparent plastic) panes
cut out, taking the perimeter of each slice of the
Perimeter of the slice of the X-rayed image,
ie the circumference of the relevant cross-section of the
, • X-rayed organ. Thus it is possible for

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data obtained passes over. Also the possibility of interactive graphic Correction is given here.

The starting point for the invention is next to the organ itself
an image generator for generating a plurality of slice images (cross-sections) at different points of the
Organs, ie for the production of the recorded layers
primary data characterizing the organ. I.

At this point, for example, the known

Use computed tomography, which is carried out by an organ U

Slice images (cross-sectional images) generated. |

With a converter, the primary data are converted into such (Schei-, §

ben) converted model data showing the outer circumference |

lines or the boundary lines of the respective layers' | ten represent.

Ii By means of a |. Fed from the model data obtained Processing machine can be made from a material,?

each of the slices is the eleventh assigned slice on cut out of the sheet of material so that a plurality of slices are obtained as a result.

The sum of the won discs can be seen in a simpler way Way to make a model of the x-rayed To get organs. For this purpose, the individual slices can be numbered individually, and by stacking the individual discs in the correct order, the physical Build up the model, gluing the panes together for practical purposes.

For the production of the model by stacking the individual panes, it is necessary that the Slices are arranged relative to each other in such a local position, as the original or the assigned slice recordings corresponds. Therefore, the invention provides a fitting device to the individual To be able to stack panes in a defined manner. ,. In the subclaims several advantageous refinements are given for such a fitting device to realize in a simple way.

, So the basic idea of the invention is to an organ of the human body (i.e. the ori-

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3437 * 83

ginal) into a To divide a large number of cross-sections or slices, where the circumferential lines or the outer boundary lines of the individual slices.

In a further step, the mentioned disks are made or cut out of a machinable material. By stacking the slices produced in this way, one can use the method here called " the method called finite disks "constructs" the model of the organ.

The fidelity of the model that can be produced according to the invention depends, among other things, on the layer thickness of the generated discs. The thinner the layer thickness of the individual panes, the more precise the outer panes can be Forms of the original can be reproduced.

But it is also quite possible to use only a relatively small number of slices or slice images, and the » "Intermediate spaces" lying between two adjacent layers "to fill in" with the help of mathematical interpolation methods. A so-called "Expert knowledge" is used, for example, in the form of a database in which data from organs

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of the human body are stored on the basis of a large number of measurements.

In practice, a sufficient layer thickness of the

individual slices is now at 1, for example.

The advantages that can be achieved with the invention in the medical field can be described as revolutionary and represent a significant advance in medicine. Thus, with the arrangement according to the invention a skeletal section of a patient to undergo surgery in a fabricated Recreate a bone model. The bone model is a copy of the original. It is in shape and size identical to the original and realistically reproduces positional anomalies, fracture courses and fracture fragments again. The model is preferably made of a material that is identical to that used in bone surgery Instrument set is easy to edit.

On the manufactured with the arrangement according to the invention The planned surgical procedure can be simulated in all details in a bone model. Thus is before the optimal choice of implants during the operation, e.g. • size of a plate, length of the screws, etc. possible.

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3437A83

In addition, different Kiochen models can be used Surgical methods carried out and then by consulting several doctors with the help of the models the optimal surgical procedure can be determined on the basis of the "model operations".

For the doctor, this preoperative phase means an op · ^ optimal preparation for surgery, as it has not been possible until now. During the actual operation the operated model is itself sterilized (the surgeon can therefore use the model during the operation touch) on the operating table and is transferred specifically to the patient. Application of the invention in trauma surgery and orthopedics brings a fundamental

legendary improvement of the way of working for the benefit of the patient with himself.

Since the surgeon was able to plan and carry out the operation beforehand on the model, this results for the patient the advantage that the procedure can be carried out faster, more precisely and more safely. The surgeon is the invention already enables two, competing surgical procedures before the actual borrowed surgery on the patient himself in the special . To be able to compare cases with one another and to be able to choose the best surgical procedure.

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The success of the therapy is decisively improved by optimal operation planning. Fracture healing disorders are reduced and repeated surgical interventions are rarely required.

Another decisive advantage is that the operating times are shortened considerably, by up to 70 - 80%. The targeted approach that is made possible also reduces tissue damage and blood loss less. In addition, because of the shortened duration of the operation, the anesthetic burden is reduced in an advantageous manner for the patient.

The invention also makes the intraoperative x-ray controls - that is, the usual x-ray recordings during the operation itself - less often required, so that the radiation exposure for the patient and can also be significantly reduced for the surgical team.

The technical progress achieved with the invention is so significant that the use of the invention in the Trauma surgery and orthopedics will become as indispensable as, for example, dental technology for tooth preservation and dentures. Since the teeth and the oral

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cave are accessible for direct intervention, impressions can be taken here and seals can be sealed with their help and dentures are made. The production is successful in the dental laboratory and no longer requires attendance of the patient. The work on the patient then only consists of fine adjustments. This reference to Dental technology makes it clear that the invention also includes the skeletal system of a patient in a concrete model Makes editing accessible.

In addition to the mentioned field of application of copies as models For the first time, a bone substitute that is identical in terms of size and shape can also be used to plan operations which can be used in place of a bone (or part of it) on a patient must, because this is affected by a tumor, for example.

According to the previous state of the art, such bone replacements were only approximately manufactured manually on the basis of X-ray images, which in practice often “ leads to the bone replacement not fitting.

Overall, the surprising and novel combination of the features according to the invention are a • A number of advantages that were previously not considered possible

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create that on the medical Sebiet of more serious Meaning are.

It is already known in and of itself to feed a numerically controlled machine tool with data, to get out of one. Workpiece to manufacture an object, however, the corresponding data are obtained for the desired part, e.g. on the basis of a technical drawing .

Furthermore, it is already known to produce a tomography recording (tomogram) and the tomographed Object using a mathematical method in a rough approximation three-dimensionally static to be displayed on a screen, but the corresponding imaging process ends here.

The invention begins at the point where the above described procedure ends or fails. In a surprising way, EiB become connecting links, so to speak created between the X-ray or tomography image and the numerically controlled machine tool, by processing and converting the data from the imaging process into such data, with their Help with numerically controlled processing machines discs for the production of a three-dimensional body

model are compatible.

The invention offers the advantage that the models can be constructed as complex and finely as desired. Further Incidentally, it is also possible to produce cavity models (negative model).

Since the model in the invention is not made of one piece, but is made from many finite disks, can be achieved by parallelism of several machine tools In principle, any short production time can be achieved. The short production time is particularly then indispensable if operations have to be carried out immediately, e.g. after an accident.

The combination of passport software, prior knowledge - interpolation software, prior knowledge - database as well as existing ones Software components from the areas

1. Tomography (e.g. 2D reconstructions),

2. Image processing (e.g. skeletonization),

3. Computer-aided design IComputer-aided design; "CAD",

4. Computer-aided manufacturing "CAM",

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as well as interface software for converting data structures and- the format of one of the software components mentioned above is in the subsequent one surprisingly a solution for the production of bone models. The "plugging together" of this software ecomponents on the appropriate computers as well as imaging devices at the entrance and numerically controlled processing machines at the exit result in a producing "overall arrangement". In this combination is an essential basic idea of the invention, which leads to the numerous advantages mentioned leads.

In connection with the already mentioned and per se "known possibility of the three-dimensional Representation on the screen of a monitor should again be expressly pointed out that today's Computer power is not big enough to model human organs in sufficient size for medical purposes To illustrate dimensions on a screen. This is one reason the screen - if any - to be used only marginally. The second reason is that there is no comparable real one on the screen Operation planning and execution can be simulated.

• · t

At least when it comes to bone surgery, the (trauma) surgeon would like to have one with his usual instru ~ ~ ~ model to be physically processed. An essential aspect of the invention is therefore these tools will not be fully satisfactory even if there is sufficient technical development in the future only partially or marginally to be used and also components of the CAD of the CAM as well as of the NC production " to use. In principle, the invention can largely do without the previous visual area.

It is possible to make the physical models that are much more valuable to the surgeon. They convey the « one hundred percent and equally objective for everyone Illustration and offer the possibility of manipulation with usual means. To these advantages, which have already been explained in detail above, especially from a medical point of view, join them but still technical advantages.

With the invention it is

a) at the current state of the art and

b) in a sufficiently short time possible to manufacture one or more models that

c) ideally plan before the operation

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and have them rehearsed, as well

d) To represent the original during the operation in a way that cannot be beaten.

The invention also leads to significant cost advantages. Apart from the fact that the proposal according to an invention for the production of a bone model is to be regarded as completely new, this process is considerably more economical, as the unsuitable for the objective of the invention and also extremely expensive solution of the moving three-dimensional Representation on a screen.

Further, appropriate refinements and developments of the invention are specified in the subclaims and can be found in the drawing.

The invention is explained in more detail below by way of example with reference to the drawings. Show it:

Fig. 1. a principle block diagram ei

ner arrangement according to the invention,

Figs. 2 and 3 each show a perspective

Representation of a simplified model of a bone,

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4 shows an exploded view II Shape of several cross-sections 1-

ben of the bone according to FIG. 3,

Fig. 13 is a computer image showing the

Outlines several on top of one another
lying layers of a bone

Fig. 5-8 each a fitting frame, which

carries the individual disks according to FIG. 4 via webs,

Fig. 9 shows a fitting frame according to FIG

Clarification of the uninterrupted appearance

dens from a sheet of material, fj

Fig. 10 is a perspective view £

a pass chamber, W

f FIG. 11 a perspective illustration y

, - If

one of the disks according to FIG. ^1; 5-8 manufactured models,

12 shows a fitting device with fitting pins,

ten, ί |

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chens shows /

14 is a perspective view of a fitting housing,

15 shows a material plate with a plurality of fitting frames,

16 shows a further block diagram for the schematic explanation of the arrangement according to the invention,

Fig. 17 is another block diagram for

further explanation of the invention,

18 shows a further schematic principle block diagram,

19 shows one with the aid of a plotter on the basis of computer layer recordings Manufactured representation of individual layers, here in place of a square fitting frame Angle frames are used,

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Pig. 20 shows a representation according to FIG. 19 with further determined slices, which are held on angled rails via webs,

21 shows a shaped disk in which the outlines are used to generate serve a cavity,

22 and in each case three disks stacked one on top of the other for explanatory purposes a lateral bevel that is true to the contour, and

24 shows the basic diagram of another shaped disk with an annular one Cavity.

The graphic representation according to FIG. 1 shows in simpler form Form the basic idea of the invention. With animal reference number 10 is an example of an organ of the human Body designates a bone from which a model 18 is to be produced.

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With the aid of an imaging device 12 - e.g. a computer tomograph - slice recordings of cross sections are made generated at different locations of the bone 10, the detected layers of the bone 10 initially are characterized by primary data.

In a converter connected to the image generator 12 14, the primary data are converted into model data which contain the outer circumferential lines for each slice image of the respective cross-section. It happens differently than with the usual X-ray technology not here on the gray values at different To represent locations of the tomography; What is more important are the external dimensions of the individual Layers or cross-sections.

The arrangement in Fig. 1 further comprises a numerically controlled processing machine 16, which of the aforementioned Model data is fed. With the processing machine 16 can thus be made from a sheet of material Cut out slices, the outer circumferential lines of which correspond to the layers of the individual slices of the bone 10 correspond. If the panes produced in this way are "stacked" on top of one another in the correct order and with a precise fit, and the individual panes glued together, for example, the result is model 18. With the term

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"Precisely fitting" should be expressed:. that the individual discs relative to each other the local Take up the position that is assigned to them in the original. Suitable mating devices for this purpose are provided below explained in more detail.

The principle according to the invention can be described particularly clearly with the aid of FIGS. 2-10. The reference: Number 20 in Fig. 2 denotes an abstractly based bone, which has a simple shape. As a conceptual aid, an axis 30 shown in dashed lines is shown in the longitudinal direction through the bone 20.

In FIG. 3, the bone 20 according to FIG. 2 is shown again, with lines drawn in dashed lines an intellectual division into four parallel disks 22, 24, 26 and 28 is indicated here. These discs are intended to represent the cross-sections of the bone 20, which are sequentially generated with the aforementioned imager, be grasped, and from which the layer recordings are made.

The thickness or thickness of the disks 22, 24, 26 and 28 or the assigned slices for the individual slice recordings is in the graphic representation for better

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Clarification chosen deliberately to be relatively large; it should therefore be noted that the layer thicknesses in in practice are significantly lower. Today, a computer tomograph can be used to take slices Make at a distance of about 2 mm.

Corresponding to the layer recordings, the processing machine 16 already mentioned in FIG individual disks 22,24,26 and 28 made from a sheet of material cut out. In Fig. 4, the disks 22, 24, 26 and 28 are arranged one above the other, with the axis 30 shows that the four disks 22, 24, 26 and 28 are already in the correct relative positions to one another are located, i.e. they are already correct or

shown in perfect fit.

If the disks 22-28 were simply cut out from a sheet of material, they would be stacked on top of each other the precisely fitting arrangement is not possible without special aids. Therefore, in a first pre- ,, ferred embodiment of the invention provided that the individual panes 22-28 are each held within a fitting frame 32-38 via webs 50-56.

By this measure it can be achieved that the individual Discs 22 - 28 within the fitting frame 32 -

related to the original bone 20 or here also related take the local position on the axis 30, which corresponds to the original. The individual passport frames 32-38 represent the individual. Discs 22-28 each represent the reference point.

:: In the example described, the processing machine 16 controlled by the model data in such a way that from the material plate (cf. FIG. 15), for example the fitting frame 32 with the disk 22 and the webs 50 cut in one piece in one operation will. Each fitting frame 32-38 has continuous interruptions on two opposite frame sides 46 and 48, while the other two frame sides open into the webs 50 and 52. Furthermore are In the inner corners of each fitting frame 32-38 there are notches 40 which - as well as the interruptions 46 and 48 - facilitate a mechanical breaking off of the fitting frame in an operation to be explained further below should.

In an advantageous embodiment of the invention, a cutting tool for the machine tool 16 can be used Use a laser beam, which can cut out the required parts from a • wooden panel. As shown in Fig. 9

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is clear, the Schneidbai runs in the laser beam So ₁ that an interruption of the cutting process is not necessary, ie the passport frame 32 with the disc 22 and the webs 50 is cut out in one piece ix a single operation. The start of the cutting path is designated by point A, and arrows B clearly show the cutting path running without interruptions to starting point A.

After in the assumed example of the abstract bone 20, the four fitting frames 32-38 with the respective Disks 22-28 are cut out, the fitting frame in a fitting chamber 58 shown in FIG. 10 in the direction of arrow C inserted in the correct order (so the first step is the fitting frame 38 with the lower Disc 28 taken). Although the location of each disc 22-28 defines within the mating frames 32-38 is established, this assignment is not yet sufficient in the present case. Rather, it has to be for that Care must be taken that the individual fitting frames 32 -> 38 can be inserted into the fitting chamber 58 even in a clearly defined position.

The individual fitting frames 32-38 therefore each have a phase 42 and 44, and on two adjacent edges

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the fitting chamber 58 has corresponding edges 60 on the inside
and 62 on. As a result, the required unambiguous assignment of the local position of the passport frames * 32 - 38 at
Stacking one on top of the other within the passport holders 58 ensures.

After the first lower fitting frame 38 into the fitting chamber
58 is inserted, the disc 28 is secured with an adhesive
and then the next one arrives
Fitting frame 36 in the fitting chamber, with the disc 26 on
their upper side also coated with an adhesive
will etc.

It is important that only the individual;. ·;

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Discs 22 - 28 are glued together, whereby the |! consisting here of four locating frame stack zusammenge- m

will hold, and that the webs 50 - 56 and the frame $ j widen the fitting frame 32-38 not glued together

will.

The through the interconnected disks 22-28
The staple held together will then be restored from j $

of the mating chamber 58 and around that shown in FIG te model consisting of the disks 22 - 28

.hold, the frame sides and the bars are marked with a $

% iach mechanical breaking removed. In this to- | *

In connection with this, the above-mentioned interruptions 46 and 48 as well as the incisions 40 are important, which make it easier to break off the frame sides and the webs, so that this is then shown in FIG. 11 *; ¹ physical model remains. It should also be mentioned that the webs 50-56 are cut out correspondingly thin at their transition points to the individual disks 22-28 in order to ensure easy breaking off.

A comparison with the template of the bone 20 in FIG. 1 shows that the model produced according to FIG. 11 does not match the bone 20 identically, but it must be taken into account that, for reasons of better illustration, only four slices or slices are used here became. It is readily apparent that with an increased number of very much thinner slices, an almost identical model can be produced in the manner described above. Accordingly, the invention also works with a large _{number A of} individual thin disks.

Regarding the fitting device necessary in the invention, another embodiment is shown in FIG. 12 ₍ . In which several - here two fitting pins 66 and 68 are used on a base 64. The simplicity

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For the sake of this, square disks 7 5 - 78 are used as a basis.

To correct the individual disks 70 - 78 in the sense of the For stacking originals on top of one another, bores 80 and 82 are provided within each disc. The location of the Bores 80 and 82 to each other corresponds to the position of the stationary dowel pins 66 and 68. If therefore the disk 78 in Fig. 12 in the direction of arrow D on the underlying disc 76 is placed, the dowel pins 66 and 68 through the holes 80 and are performed, the local position of the disc 68 is exactly defined. Moreover, in the embodiment according to FIG. 12, too, the individual disks are connected to one another

glued together, and the stack obtained in this way can then be removed from the base 64. The one before mentioned fitting frames are not required in this embodiment.

For a better understanding of the invention, FIG. 13 shows a drawing produced by means of a computer A multiplicity of outlines of superimposed layers of an actual bone of a human Body. At the same time, this illustration makes it clear that one can determine the number and also the location of the dowel pins

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or the bores 86 so that all slices produced on the basis of the layer recordings are within of the respective disc area are detected. For the rest, FIG. 13 conveys with the one above the other shown circumferential lines 84 of the individual layers a certain spatial impression (seen perpendicular to the plane of the drawing) of the bone.

Another possibility for the defined stacking of the panes is shown in FIG a mating housing 90 with a front slot 92 shows. The disk 94 is on a connecting web 96 on a Fastened fitting plate 98, which here, so to speak, replaces the fitting frame explained at the beginning (see. Fig. 5-8). The fitting plate 98, the web 96 and the disc are in turn composed of one part by means of a Cutting tool cut out of a sheet of material. Several fitting plates 98 with the associated disks 94 can be inserted in the direction of arrow E into the fitting housing, the connecting web 96 in the slot, ^ is led.

Here, too, the stacked panes are glued together, and then the individual Web 96 broken off from the stack, so that the model (stack of discs) remains.

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In Fig. 15 is a section of a material plate shown, in which already a large number of fitting frames with the associated webs by means of a laser and the respective disks located therein are molded or cut. To later eir.; E correct To be adhered to when stacking, the individual frames are numbered. By breaking it off easily can be removed from the entire material plate 88, the individual fitting frames and then within the already mentioned pass chamber are stacked.

To explain the invention, FIG. 16 shows a basic block diagram refined in five stages or lines shown. The “black box” 100 is, quite generally, an arrangement for producing three-dimensional models 18 from an original 10 designated.

In the second line it can be seen that the "black box" 100 consists of four components, namely one Imager 12, a computer 102, a numerically controlled processing machine 16 and a registration device 104.

In an imaging process, the image generator 12 generates primary data from the bone 10 which characterize the bone 10. As secondary data (Mon-

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delldaten) can be two-dimensional gray value image matrix data can be output as images on a monitor or on photographic material. These images can also be "on-line" via a remote data transmission link or "off-line" are transmitted on magnetic data carriers to the further processing computer 102.

With a software chain shown on the computer in the third line in FIG. 16 from the areas "Pattern Recognition "PR (reference number 106)," Computer Aided Design " CAD (reference number 108), "Computer Aided Manufacturing" CAM (reference number 110) and "Computer Graphics" CG (reference number 112), the secondary data are processed in such a way that supplemented and converted that at the output of the computer 102 there are data that are directly into the numerically controlled processing machine 16 can be fed and are sufficient for production of disks stacked in the register 104 - result in a true-to-original model of the bone 10.

In the fourth line of the illustration according to FIG. 16 it can be seen that from the area “Pattern Recognition” 106 a known raster-line-conversion algorithm R / L (ref. 114) is used. Line outlines (and not grid outlines) that support the tomography

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layers are the basis for the sitfh subsequent composition from the two-dimensional Outlines of "three-dimensional" computer models.

These models are also called 2 1/2 D ode £ in the CAD context "Wire Frame Models" called WFM. In this modeling, the "expert knowledge" already mentioned above may be used. ; betw. "Prior knowledge" should be included, \ Jas is identified here by the addition "Expert", so that in FIG. 16 in the fourth line with the reference number 1iii an "Expert Wire Frame Modeller" EWFM is called, which not only algorithmically interpolates intermediate layers generated, but also through the inclusion of data from standard bones from a reserved

nen database.

Expert knowledge (statistical data from medical measurements) is stored on such a database. In practice, it is often necessary to produce a large number of model slices from a few tomography slices (for example 10) Generate ben (for example 100O). An interpolation alone - of whatever kind - would possibly be used here for general purposes in the field of modeling biomedical objects - whereupon the invention aims - deliver only rough model equivalence with the original.

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Following the "Expert Wire Frame Modeling" EWFM 116 are in the computer - as required - as required thin model slices generated so that one conceptually with infinitely thin, but also infinitely many slices, could produce any smooth models. In in practice, however, instead of the infinite (infinite) thin slices finitely strong and thus only finitely many slices the invention also as an arrangement and method for the production of three-dimensional models using the finlte method Designate disks which form a core point of the invention.

With the help of the finite disks, the original can be constructed into a model kept in the computer. at So it is the "Expert Wire Frame Modeller" 116 an example from the field of computer-aided design = Computer Aided Design CAD 108.

As previously already explained, the finite number of slices for subsequent processing are on or th ausgeschnit from a sheet of material 88 (see Figure 15 This fitting frame 32, for example -... 38 provided so that the individual discs later on a _t the processing machine 16 downstream device shift-free and defined to a three-dimensional

I V "J I · <· ■ ·

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sional model 18 can be stacked on top of one another.

So that this can happen automatically, according to the fourth line of the illustration in FIG. 16, the “Expert Wire Frame Modeller” 116 eir, “Fitting and Layout Software Module” 118 is connected, which generates the corresponding paths to be cut. This is alio a "path finding software". For this, the "Computer Aided Manufacturing" CAM area can be used 110 generally seen to familiarize such problems is concerned, and for which can stand for present purposes, the Fit and layout software as an example.

From the "Computer Graphics" area 112, according to FIG fourth line in FIG. 16, a two-dimensional basic graphic 120 is used, with which the in the course of can depict models and drawings of the process chain on the computer but can also be used here in an effective way as a link to the numerically controlled processing machine 16, which is an essential element of the invention.

In the bottom line of FIG. 16, the software components mentioned above are shown for a better understanding broken down in more detail.

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The outlines obtained from the raster images contain for the subsequent links in the process chain (Interpolation algorithms, laser path) there may be too many interpolation points. You will therefore use the re-segmentation algorithm according to "Reumann / Witkam (Proceedings o £ (the International Computing Symposium 1973, Davos, Switzerland September 4-7 Ί973) with a Generalizer G 122.

In a subsequent Z-component 124, the tomography slices present from the imaging method 12 are produced Composed internally into a 2 1/2 D model. The Z-Componer 124 can be regarded as a storage device, which stores the outlines with x, y values in a memory for each slice in the Z direction.

The 2 1/2 D model, which contains only a relatively small number of layers (e.g. 10 layers), is generated in a Z1 / Z2 generator, 126 intermediate layers, with the inclusion of standard data of the biomedical object, so that a total of 100 * layers is then created.

In a following Z2 / Z3 generator 128, further intermediate layers are created with the aid of known spline || , or similar procedures are interpolated so that the

Model 18 then consists of, for example, 100 layers.

- -50 -

From the relatively few outlines - namely Z1 pieces in x, y planes emerging from the device of the imaging process 12 are delivered, so in the "Wire Frame Modeller" 116 in the third, the Z-Dimerision Z3. Layers generated. A ratio of Z3 / Z1 = 100 would result in 1000 output layers from the ten input layers to generate. 100 neighboring layers must then be generated from one layer, for example a practical value for a 50 cm long bone model generated from 1/2 mm thick slices is.

The fitting and layout software module 118 located in the fourth line in FIG. 16 can also be referred to as a so-called "Path Finder", and in the "Path Finder" the passport information (bars and frames) and panel grid information windows are added to the individual outlines. In a "fitter" F 130, for example, the outlines of the fitting frames 32-38 or PdB holes (cf. the bores 80, 82 and 86 in FIG. 12 and _A 13) are added. A numbering can also be used here? of the individual slices. In the “layouter” L 132, the individual panes - depending on their number - are placed on one or more material plates 88 in accordance with the illustration in FIG. The disks are then made from the material plates, from which

- si - 3Α37Λ83

the desired model is created by stacking them on top of each other .

Depending on the desired material, it can be different Give layout requirements. In Fig. 15 is an example a possible laser path for a material plate 88 made of wood is shown. With the disks shown, which are "lasered out" from the plate 88 is at With a plate thickness of e.g. 2 mm, a bone model of about 31.2 cm in length is produced if 156 slices is based on.

This number can be set automatically without operator intervention and using the maximum (laser) machine speed be cut out. The use of the maximum possible speed is for practice of crucial importance, since the models are often made in hours at most and not in days must be.

For the individual case you can find the laser paths ~ - that is, the Cutting paths for the laser beam - preferably interactive graphically. In the case of a mass, those found in this way can Prototype paths are also algorithmized so that the human-machine interaction in favor of full automation is replaced. The graphic interaction

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is conveniently carried out with a graphical editor. Such an editor arises from, for example a slight extension of the "graphic core system" GKS (DIN 66252, ISO / DIS 7942), which is shown in Fig. 16 in the bottom line is designated by the reference number 134.

The direct connection of production machines to conventional plot systems or to the graphic core system 134 is another important element of the invention. For this purpose only a "device driver" NC ;? 136, but not a costly or development-intensive one Special CAM system required.

Fig. 17 shows in the top line once again summarized the above-described, comprising twelve members existing process chain, which is covered by the "black box" 100 in FIG.

In the second line in FIG. 17 are the individual blocks or boxes are shown again, and arrows with the numbers 1 ... 8 indicate individual process steps led out and fed to the graphic element GKS 160. This representation is intended to indicate that an .Each point of the chain within the dashed line computer 102 with a view to production

- 53 - "3437 <> 83

advanced images are produced which can be viewed on devices via a computer graphics system - such as a graphics screen 138 (DIS) or a plotter 140 (PL) can make visible. Just like these devices through one Driver, for example connected to the graphics system 134, can also be a numerically controlled one Processing machine 16 are coupled. It is then, as it were, another terminal of a graphics system to grasp.

The graphics system is therefore of central importance in the invention. On the one hand you can use it in everyone Procedural stage images are displayed. This is an advantage, among other things, because it results in a There is a quick control possibility before the final output on a comparatively slow production machine he follows. For clarification, reference is made to FIG. 15, which shows, for example, a detail enlargement created with a graphics editor.

On the other hand, the graphics system represents the invention represents a link between the CAM element (see 110 in FIG. 16) and the production machine 16.

The importance of the graphics system is also clear from FIG. 18, which from an EDP point of view

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is sketched.

In the “shell model ¹¹ according to FIG. 18, imaging methods (BV) 12, computer-aided design (CAD; 108 and computer-aided manufacturing (CAH) 110 are used. Computer-aided design 108 typically includes a database with problem-specific content (here Nprmdaten Plotters 140 and screens 138 come into consideration as the end device of the graphics system 112. It has been demonstrated within the scope of the invention that numerically controlled machines 16 can be coupled in analogy for the purpose pursued here of producing models.

In addition to the above description and explanation of Fig. 5-9 should also be noted that in the event that the two phases 42 and 44 are of the same design, a clear assignment for the stacking within the fitting chamber 58 is not yet guaranteed is because the individual fitting frames 32 - 38 then both with their front «and the back facing" up in the pass chamber 58 can be inserted. The desired clarity can be achieved here by that the individual fitting frames are numbered on their one surface and that the pages with the numbers always point upwards.

• It ··! ·

But it is of course also possible to use the two; ' To develop phases of different sizes or with different inclinations, whereby the \ -

Uniqueness is guaranteed.

The intended breaking points, which are intended to facilitate the breaking off of the webs 50 - 56 from the panes 22 - 28, can incidentally by provided at the transition point between the webs and the discs. Holes or It can also be sufficient to make the connection area correspondingly narrow.

To _Fig.% '15 it should be noted additionally that, according to the local representation fall out each locating frame according to the Sehneidvorgang for example by means of a cutter from the material plate 88. However, it is also possible to leave enough space between the adjacent fitting frames to prevent falling out, and so that the individual fitting frames can be broken out.

The representations according to FIGS. 19 and 20 are based on a plotter drawing made on the basis of computer tomography recordings and the subsequent computer chain are made by means of a computer. Instead of

• ·

• ·

- 56 -

The square fitting frames mentioned above are provided here with angular frames 142, a. \ which the individual respective panes are again held by webs. A "cell-shaped Leuen" in FIG. 19 and the figure shows how the individual cross-sectional shapes of the disks located one above the other in the original change.

In the previous explanation of the invention it was always assumed that the desired physical model by stacking individual slices assigned to the slice images of a computed tomogram. However, the basic concept according to the invention is not limited to this aspect.

At. With reference to FIG. 21, it is explained below that within the scope of the invention it is also possible to provide cavity models or "negative models" in order to produce a physical model of the original. In this solution, the outline 148 of the individual _A slices is again taken as a basis, however, the outline 148 here delimits a cut-out cavity within associated molded disks 144.

When stacking a large number of such shaped disks on top of one another 144 is created - comparable to the casting technique

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- 57 -

- a cavity, the wall of which the contours of the original This cavity 150 can then - as known per se from casting technology - to be filled or potted with a potting compound in order to sin To get a model, which here, however, not from individual panes, but through the solidified potting compound is formed.

The stacked mold disks 1 <': 4 are held together by molding box pins 152 and in one here Inserted fitting housing, not shown.

In order to clearly introduce the shaped disks 144 into a fitting housing, they have different designs Phases 151 and 153. Furthermore, predetermined breaking lines 146 are provided approximately in the middle. After the The cavity 150 is cast and the casting compound has cooled down, the molded disks 144 stacked on top of one another can are individually separated from one another at the predetermined breaking lines 146, so that the "cavity" filled with the potting compound 150, now the physical model, remains.

Both according to the method described above and according to the oten method of the Finite disk model has at its

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Outer wall discrete gradations due to the finite slice thickness used.

Particularly on the basis of the finite disks, reference should be made 22 and 23 explain how an adaptation to the conditions of the original is possible here is.

22 shows three disks 154 lying on top of one another 156 and 158. The gradation between the individual panes can be clearly seen.

Within the computer chain implemented with the aid of computers, a program can easily determine the angle cC at which two adjacent corner points of two successive panes - here the panes 154 and 156 - are located. When cutting out the respective disk or disks from a sheet of material, the cutting tool - for example a laser beam - can be controlled during the cutting out in such a way that the cutting does not take place perpendicular to the plane of the sheet of material, but at a respective angle OC. The inclination of the cutting tool in relation to the material plate is thus changed during the cutting process /, and in FIG. 23 it can be seen that such a "smoothed" or adapted outer shape of the

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stacked discs 154, 156/158 existing Model can be achieved.

A particularly advantageous embodiment of the invention, which is based on the preceding Hard of Fig. 21 explained basic idea of the "Negativmocell" is based, will be explained below with reference to FIG. The starting point here is the consideration for the surgeon to create a plastic model of the bone in question within the human Body shows.

As an example, assume, according to FIG. 24, a model of a human leg (contour line 168) with the one in it located bone (discs 162) to produce. The outlines 168 as well as the outlines of the individual Slices 162 can in turn be defined with slice images.

In the plan view of a _{shaped disk 160 in FIG. 24λ} , one can see that a hollow space 166, which is annular here, is cut out again, delimited by the outlines 168 of the human leg assumed here. The annular cavity 166 is only interrupted by connecting webs 164, which the

- 60 -

Hold the disks 162 on the shaped disks 160.

If, in accordance with the individual slice images, a plurality of shaped disks 160 are placed in a fitting housing stacked one on top of the other, in this case too there is a "Casting mold" (cavity 166) here with one preferably

transparent potting compound is filled. The on- |

stacked discs 162 practically represent the fs

Core that is not filled with a potting compound

will. Ö

Similarly, as described previously with reference to FIG. 21, \ Ä have the form of discs 160 rupture lines 170, so that the individual halves of the mold plates can be removed by breaking off after solidification of the transparent encapsulant 160 is left then limited by the contour lines 168 and in the area of the cavity 166 a transparent model, which reveals the bone formed from stacked disks 162 within the leg. The web 164 remaining in the finished model produced in this way can be made relatively narrow so that it is no longer disruptive.

Overall, the present invention thus offers one Variety of practical use cases corresponding to the

Surgeons who need a model to plan and prepare their surgery are of great help.

Claims (1)

PATENT ADVOCATE. .... _: . ··. . ·· .: DIPL.-ING. UWE THÖM £ N.:. ^: .J EUROPEAN PATENT ATTORNEY Dipl.-Ing. Karsten Reumann 420/1 Claims 1. Arrangement for the production of three-dimensional physical models of an organ (or a part thereof) of the human body, in particular for the production of bone models, characterized in that the arrangement comprises the following components: a) an image generator (12) for generating a plurality of slice images (cross-sections) at different points of the organ (10), and thus for the generation of the detected Primary data characterizing layers of the organ (10), b) 'an adjoining converter (14) for converting the primary data into the outer circumferential lines (boundary lines) of the individual layers re. presenting (target) model data / c) a processing machine (16) fed by the model data with controllable Tools for the production of discs corresponding to the rails (22-28; 70-78) from a machinable sheet of material (88), from which slices are stacked the physical model (18) can be produced, and d) a fitting device (58; 66,68) to the defined Stack the discs (22-28; 70-78). 2. Arrangement according to claim 1, characterized in that the image generator (12) is a tomography device from which the primary data are derived. 3. Arrangement according to claim 1, characterized in that the image generator (12) is formed by an X-ray apparatus, and that the primary data from the X-ray images are derived. 4. Arrangement according to claim 1, characterized in that the converter (14) consists of a computer | or several computers with a program chain for generating the (target) model data. 5; Arrangement according to Claim 1 / characterized / that the processing machine (16) is formed by a numerically controlled machine, and that the controlled tool includes a cutting tool for cutting the disks (22-28; 70-78) from the material plate (88). 6. 'Arrangement according to claim 5, characterized in that the cutting tool is formed by a laser beam. 7. Arrangement according to one of the preceding claims 1-6, characterized in that each disc (22-28; 70-78) is arranged by means of webs (50-56) in ' a fitting frame (32-38), and that the fitting frame (32-38) have identical dimensions. .8th. Arrangement according to one of the preceding claims 1-7, characterized in that the disc _ ₄ _ 3 * 4374 (22-28; 70-78), the webs (50-56) and the fitting frame (32-38) are formed in one piece. 9. Arrangement according to one of the preceding. Claims 1-8, characterized in that the disc (22-28; 70-78) can be separated from the webs (50-56) at a predetermined breaking point at its transition point. 10. Arrangement according to one of the preceding claims 1-9, characterized in that two opposite frame sides of the fitting frame (32-38) are separated approximately in their middle by an interruption (46). 11. Arrangement according to one of the preceding claims 1-10, characterized in that in each of the inner corners of the fitting frame (32-38) a notch (40) is provided as a predetermined breaking point. 12. Arrangement according to one of the preceding claims 1-11, characterized in that the fitting device by an upwardly open fitting chamber (58) is formed, the internal dimensions of which for inclusion the fitting frames supporting the panes (22-28) are formed. 13. The arrangement according to claim 12, characterized in that the fitting frame (Γ2-38) has a phase (42,44) at at least one corner, and that the fitting chamber (58) has correspondingly filled edges (60,62) on the inside, so that the fitting frame (32-38) can only be introduced into the fitting chamber (58) in a single defined position. 14. Arrangement according to one of the preceding claims 1-6, characterized in that the fitting device comprises at least two dowel pins (66,68) arranged vertically on a base (64), and that the disks (70-78) with corresponding bores (80 -82) are provided for receiving the dowel pins (66,68) so that the local positions of the stacked panes (70-78) are defined by the fixedly arranged dowel pins (66,68). - 15. Arrangement according to one of the preceding claims 1-6, characterized in that the fitting device is formed by an upwardly open fitting housing (ipO), one side wall of which is separated by a continuous slot (92), and that the disc (94) via a connecting web (96), the width of which corresponds to the width of the slot (92) speaks, is allied with a fitting plate (98), Deren / ^ measurement the inside dimensions of the passport housing (90) corresponds, and that the .Scheibe (94), the connecting web (96) and the fitting plate (98). are cut in one piece from the material plate (88). 16. The arrangement according to claim 15, characterized in that the disc (94) at the connection point with the connecting web (96) (predetermined breaking point) can be broken off from this. 17. Arrangement according to one of the preceding claims 1-16, characterized in that the material plate (88) consists of plywood. 18. Arrangement according to one of the preceding claims 1-16, characterized in that the material plate (88) consists of transparent material. ;, 19. A method for the production of a three-dimensional physical model of an organ (or a part thereof) of the human body, in particular for the production of bone models, characterized by the following process stages: a) an imaging process for the production of individual layers of the organ (10) characterizing primary data, b) a computer process chain for the mathematical generation of the outer circumferential lines (Boundary lines) of the individual layers representing (pane) model data, c) a numerically controlled machining method (16) for machining a sheet of material (88) in order to cut out disks (22-28; 70-78), the contours of which correspond to the circumferential lines (84) of the Layers of the organ (10) correspond, and d) a registration process to locate the disc (22-28; 70-78) in a registration device (58; 66,68; 90) corresponding to the assigned layer of the organ (10) to be defined in a defined manner. • 20th Method according to claim 19, characterized in that * 4 β - · ο "" 2T43U83 draws that computer tomography is used as an imaging process. 21. The method according to claim 19, characterized in that sonography is used as the imaging method. 22. The method according to claim 19, characterized in that the nuclear spin resonance method is used as the imaging method. 23. The method according to claim 19, characterized in - \ i i is characterized in that as an imaging method, the conventional 5 $ Partial X-ray technology is used. _ £ j 24. The method according to claim 19, characterized in - | indicates that as part of the computer process chain S Algorithms from the field of image processing differ | j be turned. | ty 25. The method according to claim 19, characterized in that - f \ indicates that as part of the computer process chain U i <Λ Algorithms from the field of computer graphics $ be used. U a 26. The method according to claim 19, characterized in that algorithms from the field of "computer-aided design" (CAD) are used. 27. The method according to claim 19, characterized in that algorithms from the field of "computer-aided manufacturing" (CAM) are used as part of the numerically controlled machining process. 28. The method according to claim 19, characterized in that norm data are obtained from the organ on the basis of a collective of patients, and that these data are made available in a memory ready for retrieval and are included in the computer process chain in the course of a mathematical interpolation process. 29. The method according to any one of the preceding claims 19-28, characterized in that a laser cutting machine is used as the numerically controlled processing machine (16). 30. The method according to any one of the preceding claims 19-28, characterized in that the numerically controlled processing machine (16) is a . -λ * ■; ■> - »- - Milling machine is used. 31. The method according to any one of the preceding claims 19-28, characterized in that as. numerically controlled machining aschine (16) a flame cutting machine is used. 32. The method according to any one of the preceding claims 19-28, characterized in that a water jet cutting machine is used as the numerically controlled processing machine (16). 33. The method according to any one of the preceding claims 19-28, characterized in that a saw is used as the numerically controlled processing machine (16). 34. The method according to any one of the preceding claims 19-33, characterized in that the discs (22-28) together with a fitting frame (32 ~ 38), and the discs (22-28) holding stage (50-56) in one piece the material plate (88) are cut out and then stacked in a fitting chamber (58). - 11 - 44 44 44 44 * 4 3437433 35. The method according to claim 34, characterized in that the discs (22-28) are glued to one another. 36. The method according to claim 35, characterized in that the discs (22-28) are screwed together. 37. The method according to claim 36, characterized in that the stacked fitting frames (32-38), the inner panes (22-28) of which are glued together, are removed from the fitting chamber (58), and that the fitting frames (32-38) and the webs (50-56) are separated from the bonded panes (22-28). 38. The method according to claim 37, characterized in that the separation of the fitting frames (32-38) and the webs (50-56) from the panes (22-28) takes place by breaking off individually per fitting frame or per pane 39. Method (and arrangement) for manufacturing a three-dimensional physical model of an organ (or part of it) of the human body, , -in particular for the production of bone models, characterized by the following process stages: a) an imaging process for the production of individual layers of the organ (10) characterizing primary data, b) a computer process chain for the η athematic generation of the outer circumferential lines (Boundary lines) of the individual layers representing (pane) model data, c) a numerically controlled machining method (16) for machining a sheet of material, in order to cut out cavities (150; 166), the contours of which correspond to the circumferential lines correspond to the layers of the organ (10), and d) a fitting process in order to define the local position of the cavities (150; 166) in a fitting device corresponding to the assigned * layer of the organ (10). 40. The method according to claim 39, characterized in that the cavities (150; 166) are cut out of shaped disks (142; 160) which are marked with a predetermined breaking line (146; 170) - 13 -, 3 4 3 7> 8 3 are provided so that they broke apart in half can be. 41. The method according to claim 40, characterized in that the shaped disks (142; 160) are stacked on top of one another in a fitting device, and that the cavity (150; 166) formed thereby is filled with a casting compound.