Note: Descriptions are shown in the official language in which they were submitted.
106S~135
'~ethod of cinematographic display of layers of
three-dimensional objects"
The invention relates to a method of cinematographic
display of layer images recorded in optical images, of moving
three-dimensional objects.
The principal field of application is the X-ray technique,
~herein images of a three-dimensional object are formed, by the
cyclic pulsing of various X-ray sources in rapid succession from
different directions by means of an X-ray image intensifier.
Various methods of making laminographs are known in the
X-ray technique, for example, from United States Patent Specifica-
tion 3,499,146 which issued on March 3, 1970 to Albert G. Richards.
Furthermore, the magazine "Der Radiologe", 9 (1969), page 37 and
further mentions the possibility of displaying, using a series of
electronically stored X-ray images, a large number of discrete
laminographs adjacently on a storage tube. Using a system compris-
ing a plurality of object lenses or after prior image reduction by
means of a single wide-angle lens, the X-ray images can also be
summed; see, for example, American Journal of Rontgenology 105
tl969), page 903. Steplessly adjustable display of the lamino-
graphs is thus possible. Other methods have demonstrated that
similar results can be achieved also by means of holography.
These methods have a common aspect in that the X-ray images are
holographically stored, i.e. such that during the reconstruction
a three-dimensional image of the object is produced by integra-
tion.
However, the methods described thus far do not enable
cinematographic display of layer images. The invention has
for its ob;ect to record movement processes in the body
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and to enable during cinematographic display, for example, during tomography,
the position and the direction of the layer to be changed, the object being
passed through quasi-three dimensionally, the layers being found and display-
ed in direct succession.
These layers can be recorded either cyclically one after the
other by means of a fast film camera and subsequently be used for lamino-
graphy by reconstruction, or on-line recording and display can be applied,
or both procedures can be followed.
According to the present invention, there is provided a method
for cinematographic display of layer images of a three-dimensional object
comprising the steps of: cyclically successively irradiating a three-
dimensional object with penetrating radiation from a plurality of fixed
X-ray sources positioned spaced apart on one side of the object to produce
with a single fixed X-ray image-intensifier positioned on the other side
of the object corresponding series of perspective images of the three-
dimensional object and successively superimposing the different images from
each repetitive series of images to form a laminograph of the object.
In this manner cinematographic laminographs having the quality
of the conventional tomosynthesis method can be achieved.
The method according to the invention will be described in detail
hereinafter for the X-ray technique with reerencc to the drawings.
Fig. 1 shows a diagram for the cinematographic di.splay of X-ray
exposures from different perspectives.
Fig. 2 illustrates the prinicple.
Figs. 3a to 3d show embodiments for the on-line processing of
recordings in perspective into laminographs of the irradiated object.
Fig. 4 diagrammatically shows a device for making on-line lamino-
graphs.
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Figure 5 sho~s the principle.
Figure 6 diagrammatically shows the subsequent production and
cinematographic display of laminographs.
For making X-ray recordings from different perspectives according
to Figure 1, a series of X-ray sources are used which are preferably arranged
in one plane. For example, in Figure 1 the X-ray sources 1, 2 and 3 are
diagrammatically shown (usually N X-ray sources are used, N being an integer,
preferably between 10 and 50). These X-ray sources - numbered from 1 to N,-
cyclically flash one after the other by electrical or electronic control, the
flash duration each time being, for example, 1 ms, so that, for example, in
the case N = 20, each X-ray source flashes 25 times per second, taking into
account an interval of 1 ms between flashes.
According to Figure 1, the X-ray images are formed by means of an
X-ray image intensifier 4, so that on the output screen 5 of this X-ray image
intensifier the images Bl, B2, ... Bn of the object 6, corresponding to the
X-ray sources 1 to N, appear in rapid succession. These cyclical image series
are shaped as ...Bl, B2, ..., BN, B 1' B 2' ~ N
etc. representing the images from the same perspective at later instants.
This total series is taken over by the output screen of the X-ray image in-
tensifier or is directly processed into laminographs. Using, ~or example, a
partly transparent mirror, both processes ~film recording and direct further
processing) can also b0 performed in parallel.
In accordance with Figure 1, the object 6 is positioned on an ad-
justable table 7 and can be shifted along the optical axis of the system.
Figure 2 shows the principle of real-time processing of output
screen images of the X-ray image intensifier. First these output screen
images are corrected. This is effected, for example, in that the output
images are projected by the screen 8 ~5 in Figure 1) onto a surface 9 re-
sembling the input screen 4' (Figure 1~, the output images being subsequently
3a geometrically-optically imaged in the plane 10 while maintaining the original
rec~rding geometrr. In the case of real-time processing, it must be ensured
that, ~hen a given output image (for example Bl) appears in 8, only the
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correct, associated beam path from 8 to 10 is opened, and that all other beam
paths remain closed. This can be achieved, for example, by means of fast
shutters, so that when a given X-ray source flashes, each time the correct
shutter (for example, for Bl, at the objective 11) opens.
In this manner series of images cyclically appear in the plane 10
on the locations which are correct according to perspective. So as to ob-
tain laminographs, these perspective images must be superimposed. For this
purpose a large number of possibilities exist. Figure 2 shows one possibility:
using a number of objectives 12, the individual images in 10 are imaged in the
plane 13 where they are superimposed. In the case of a fixed transfer from
10 to 13 via the objectives 12, a permanently adjusted layer of the object 6
(Figure 1) is sharply focussed in 13.
Figures 3a - d shows further possibilities of superimposing perspec-
tive images so as to form laminographs. For example in Figure 3a the images
(14) in the plane 10 are imaged on the output face 17 by way of a fibre optic
15 or 16, the said face 17 possibly also being formed by a frosted surface 18.
Prom this location they are successively displayed in the plane 20 in the
recording sequence by the associated objective 19, a lamlnograph then being
produced by image integration of all individual images.
For the superimposition of the images ~for example 21), the use of
a scatter disc 22 is then sufficient, if the scatter cone thereof is directed
in the direction of the objective (in this case 23).
In Pigure 3b the images in the plane 10 are collected by means of
grid structures. For example the Fresnel lens 24 or the hologram (also 24)
acting as a lens serves to focus the light coming from the curved surface 9
roughly in the direction of the point 25. The second Fresnel lens (for ex-
ample, 26) or the hologram (also 26) acting as the lens serves to focus the
beam path additionally on the objective 27. Any image disturbing patterns
occurring, caused by the superimposition o~ the images by means of the grid
structures, can be avoided by fast movement of the grid structures with re-
spect to each other. The superimposition of the images so as to ~btain the
laminated image 28 in the plane 29 is effected by means of a number of objec-
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tives in the plane 30.
An opto-electronic superimposition possibility is shown in Figure
3c. The images produced in rapid succession in the plane 10 (for example 31)
are recorded by means of television camera tubes 32, are bundled in an elec-
tronic installation 33 and are subsequently displayed as a laminograph on a
monitor 34. The electronic installation 33 may be, for example, a modified
electronic tomosynthesis installation as described in the article "Computer
controlled synthesis to Tomograms by means of TV-Storage Tube", IEEEE Tr. on
Biomedical Engineering, Vol. BME-21, No. 3, May 1974. However, an advantage
exists in that the individual images from the various perspectives (for ex-
ample 31) and hence the three-dimensional information of the object, can be
electronically stored during a single phase of the movement process of this
object, the laminograph and the laminograph depth adjustment being additional-
ly electronically adjustable.
Contrary to the Figures 3a - 3c, in Figure 3d the image superim-
position is effected without intermediate imaging. The output images of the
image intensifier projected on the curved surface 9 are successively imaged
in the plane 37 by means of a series of objectives 35 in the plane 36. The
field lens 38 or the hologram 39, acting as the field lens only causes a beam
deflection, so that the individual images in the plane 37 constitute a complete
image and hence a laminograph.
Figure 4 shows the combined device according to the Figures 1 and 2
for the direct further processing of the images produced on the output screen
of the X-ray image intensifier into laminographs. This device enables the
roentgenological display of a layer which is specific to the apparatus on a
display screen, for example, the luminescent screen of a television monitor
(see Figure 2). During this fixed display of a layer which is specific to the
apparatus, the object can be arbitrarily moved through this fixed layer which
is specific to the apparatus, so that in the superimposition plane of the
reconstructed in~ividual images always the layer of the object is sharply
imaged w~i~hcorresponds exactly to the layer specific to the apparatus.
Figure 4 furthermore shows in detail: the X-ray sources 40 in the
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plane 48 successively irradiate the object 41; the point a in the plane X
is displayed, for example in the points ai of the image intensifier 42 and,
v a correction unit, on one of the output surfaces 43 of the screen corres-
ponding to the image intensifier, successively in dif~erent locations a'i.
Simultaneously, the images appearing on the output screen 75 can be recorded
and stored, by means of a fact, commercially available film camera 77, and be
subsequently displayed on the surface 44 by means of a projection unit 77' and
a mirror 76' for further processing. ~pon reconstruction of the individual
beam paths in the positions 40' of the plane 45, corresponding to the positions
of the X-ray sources in the X-ray source plane 48, the plane X' just before
the curved surface 44 corresponds to the plane X of the layer which is specific
to the apparatus, and the same is applicable to the points a and a'.
The subsequent optical and electronic superimposition of the inter-
mediate individual images, for example, in the plane 46, has already been
described with reference to some examples. The superimposition is effected
such that the points a' appearing in different locations on the screen 44
coincide in the plane x", so as to form the point a", i.e. the plane X is
imaged in the plane X".
The position of the layer plane X in the object can be changed in
2Q two ways. One possibility, already described consists in the moving of the
object with respect to the layer X. However, a second possibility exists in
the changing of the position of the layer which is specific to the apparatus,
in that the imaging between the planes 46 and X" is varied, so that a point a
on the optical axis before or behind the plane corresponds to the point a" on
the optical axis 49 in X".
Por the postponed cinematographic laminated display of three-
dimensional objects, based on stored images, two display methods are in
principle possible.
The first display technique, illustrated by the Figures 2 and 4, is
based on one output plane which resembles the output plane of the image inten-
sifier, for example, 9 in Pigure 2 or 44 in Pigure 4. The cyclical image
l~ 2 ... BN, B l~ B 2 ... B'N; B"l ... etc. are successively projected
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in time on the output surface, and are further processed as described with
reference to the Figures 2 and 4.
The second display technique offers the advantage that the light
intensity is higher, and is in principle illustrated by Figure 5. According
to this technique, all N images are simultaneously processed by a recording
cycle Bl to BN. Subsequently, the image series of the next recording cycle
B'l to B'N is realized. To this end, contrary to the first display technique,
N separate output surfaces are required. According to Figure 5, the in- ,
dividual images, for example, Bl to B4 are displayed at high light intensity,
either by means of geometrical-optical imaging techniques (referred to as
52) or by means of image-transporting light fibres, (denoted by 53) in given
positions B~l to B~4 in the plane 54, wherefrom they are projected, for
example, using one of the said methods, for corrections each time on a curved
surface 55. The images B~ thus produced are subsequently optically or elec-
tronically superimposed in one plane. It is of decisive importance that the
points 58, whereby the output surface images B~ are imaged in the plane 59,
correspond to the locations of the X-ray sources, for example, 40 in Figure
4, whilst the plane 59 corresponds to the layer X specific to the apparatus
in Figure 4. The imaging is optically effected by means of a suitable
imaging objective 56 in the plane 57. Electronically the output surface
images B~x are either projected via objectives 60 Oll image pick-up tubes 61
or th~ images B~ are directly imaged on the image pick-up tubes 63 by fibre
optics. To this end, the beam cone produced by the fibre optic 62 should
intersect the virtual point 58. The images electronically recorded for ex-
ample, in the planes 64 or 65, are bundled, like in Figure 3c, in an elec-
tronic installation and are subsequently displayed on a monitor as a lamino-
graph. According to the first display method, based on one output surface,
the individual images of the television installation are applied in rapid
succession, whilst according to the second display method, requiring separate
output surfaces, all images are simultaneously applied to the television
installation for an arbitrary duration.
Whilst the three-dimensional display of the object during the
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optical processing is obtained by adequate masking of the diaphragms 66, for
the electronic processing either the pick-up tubes 61 or 63 can be shifted
with respect to each other in a defined manner, thus layers of various depths
being produced~ or the shifting of the individual images with respect to each
other can be effected by electronic means.
In order to make optimum use of the light for all geometrical-optical
display methods, the light coming from the output surface 55 can be directed
such that the imaging lens, for example, 56 or 60, is optimally used. Figure
5 shows one possibility by utilizing the directional properties of a fibre
optic 67; however, other possibilities of directing rays can also be used for
the method according to the invention.
Figure 6 diagrammatically shows the experimental construction of
the real-time method in a plan view, the cinematographic laminated display of
three-dimensionel objects being effected by simultaneous superimposition of
all N images of a recording cycle. The images, for example, B5 to B7 and BN,
are exposed at high light intensity and are intermediately optically displayed
in accurately defined locations 72 to 74 and 70 (behind the plane of the
drawing, each time denoted by 69). From these locations they are projected
onto curved surfaces 71 ~see also 55 in Figure 5) which correspond to the
curvature of the input screen of the image intensifier, and are subsequently,
as described in Figure 5, processed into laminographs using ~ superimposition
method. The distribution of the N output surfaces (diagrammatically repre-
sented by 71) in the defined positions 72 to 74 and 70 should be chosen such
that by means of a lens matrix, for example, in the plane 57 in Figure 5, all
individual output surface images and the associated perspectives are imaged
in one plane ~59 in Figure 5), so that a laminograph is produced by integration
of all N images.
