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Патент USA US3086133

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April 16, 1963
Filed April 27, 1959
4.1¢@ 37A ‘ ATTORNEYv
United States Patent O
Patented Apr. 16, 1963
modiñed at will, in particular by the insertion in the
utilization circuit of one, two or three filters of the
Henri Maurice Marchal, 12 Rue Jacques Bingen,
Paris, France
Filed Apr. 27, 1959, Ser. No. 809,181
Claims priority, application France Apr. 30, 1958
1 Claim. (Cl. Z50-_227)
double T type connected in series for the calibration of
cine-densiographic recordings relating respectively to an
examination of the heart, to an examination of arterioles
of the lung or of the arterioles of the liver.
The invention is more particularly directed to a certain
method of application (that for which it is applic-d to
radiological examination) and also to certain forms of
embodiment of the said arrangements; it is also directed
still more particularly, by way of new industrial products,
to apparatus of the kind referred to embodying the ap~
plications of these same arrangements, together with the
special elements and tools adapted to -their preparation,
The present invention relates to apparatus used in
radiology and especially in local densiography, following
the technique of which the variations are recorded in the
luminosity of a small liuorescent screen on to which falls
a beam of rays, X-rays or other, after having passed
through an obstacle a small zone of which it is desired to
and the assembled units, especially radiological installa#
study, the said variations being a function of the variations
of opacity and therefore of the density of the said zone.
Since it is in these cases that its application would appear
to oifer the greatest advantage, the invention is more
tions, which are equipped with such apparatus.
The invention will be understood more clearly by
reference to the descriptive text which follows below, to
variations of transparence and/or the movements are
view, an essential part of an apparatus for localized
gether with the accompanying drawings, it being under
particularly concerned, amongst this type of apparatus, 20 stood that this description and these drawings are only
with those used in medical radiology for the purposes of
given by way of indication and without any implied
diagnosis, and in particular for the local examination of
small zones of organs or of small organs, of which the
FIG. 1 of the drawings shows diagrammatically in plan
relatively rapid, for example for the examination of 25 medical densiography, constructed in accordance with the
members subjected to pulsations of the blood, such as the
arterioles which irrigate the lungs of a patient (this
technique being sometimes known by the name of cine»
FIGS. 2 and 3 are views on a l-arger scale of one of the
members of the same apparatus, with portions broken
away, the views being respectively in elevation and end~
densiography) .
It has especially for its object to make these apparatus 30
better adapted than they have been up to the present
FIG. 4 shows a portion of the image observed on the
time, to the various requirements of practice, especially
large radioscopic screen of this apparatus.
in that they enable the small region studied to be posi
tioned and located with a greater degree of precision.
According to the invention, an apparatus for derisio
FIGS. 5 and 6 show respectively, in horizontal cross
section along the line V-V of FIG. 6, and in vertical
cross-section along the line VI-VI of FIG. 5, an essen
Vtial part of an alternative form of an apparatus for
localized medical densiography in accordance with the
present invention.
graphic examination enabling the variations of intensity
of a main radiation flux (X, gamma or other rays) to be
observed and recorded after its passage through an ob
stacle of variable opacity to be examined, comprising es
‘ FIG. 7 shows diagrammatically `an essential part of a
sentially a surface element of small dimensions irradiated 40 further alternative form of an apparatus of the same kind
by a portion of the said flux and a device adapted to con
similarly constructed.
vert the variations of intensity of the radiation emitted by
FIGS. 8 and 9 show in detail two elements of the device
Ithe said element to variations of a readily usable elec
illustrated in FIGS. 2 and 3.
trical parameter, in which the said surface element is
And ñnally, FIG/10 shows the form of the calibrated
disposed at the edge of said device and preferably at a 45 recorded curves in accordance with a preferred method
certain distance from said edge, said distance being con
of application of the invention.A
sidered at right angles to the general direction of the main
In accordance with the invention, and more especially
flux of rays, at least a part of the immediate vicinity of
in accordance with that of its methods of application and
said surface element being composed only of material
the methods of construction of its various parts to which
which is transparent to said main radiation, whereby, on 50 preference should apparently be given, use is made of a
the radioscopic image formed by said radiation beyond
source of radiation l, the radiation produced by this
said surface element, the image formed by said element
source being passed through the subject 2 with the object
is not submerged in the shadow cast by the said device,
for example of studying the variations of opacity of a
but is disengaged, at least in part, from said shadow.
region of this subject, the said region being of small di
In addition to this principal arrangement, the apparatus 55 mensions in the `direction at right angles to the iiux of
of the invention comprises certain other arrangements
which are preferably employed at the same time (but
It should first of all be stated that the recording of such
which could however be used separately, when so re
variations is already known: to this end, a small íiuores
quired) and which will be described in greater detail
cent screen is placed in the field of the X-rays after they
60 have passed through the subject, this screen being ar
below, in particular:
A second device having two main features, the first of `
ranged to face a photo-electric cell (or other similar de
which comprises the use, for the calibration of the curves
vice such as a photo-multiplier) which is capable of
recorded by cine-densiography, of the ratio between the
transforming the luminosity of this Screen to an electric
amplitudes of the oscillations `recorded corresponding
to the oscillations of the radiation employed at a rela
tively high frequency (due to a uniform modulation, at
100 cycles per second for example) and at a relatively
In order to locate the position of this small screen
with respect to the subject, there is arranged beyond the
cell on the path of the X-rays, a normal radioscopic screen
low frequency respectively (corresponding to the pulsa
constituted for example by a lead glass having its face
tion of the blood), íiltering means being employed so as
which is turned towards the subject covered by a layerto eliminate the inst-mentioned oscillations from the re 70 of plastic material coated with a product which gives a
corded curve. The second feature consists in arranging
the said filtering means so that their time-constant can be
" visible iiuorescence to X-rays (examples of such products
being calcium tungstate or zinc sulphide).
3,085, es
Unfortunately, with this arrangement, since the cell
The image then formed on the radioscopic screen 4
is composed on the one hand of shadows 17 (FIG. 4)
is opaque to X-rays it casts a substantial shadow on the
screen: the portion of this shadow which corresponds
which are more or less dark, corresponding to the organs
of the subject traversed by the X-rays, and on the other
hand, two dark shadows, one 18 corresponding to the
shadow of the cell 5 andthe other 19 of the small screen
11. This latter shadow may be framed at least partially
by an opaque line 29 which is the image formed by a
wire of lead or other material opaque to Y-rays, sur
to the small screen is thus badly defined; in addition, this
shadow hides the immediate vicinity of the zone to be
studied, and this cannot therefore be located with pre
cision, especially `by radiography.
ln order to overcome these drawbacks, in accordance
with the present invention at least one portion of the
immediate vicinity of the small screen is made trans
rounding the screen 11 when the said screen is trans
parent to X-rays, which is the preferred case of utiliza
tion. In this case in fact, it is possible to examine and
parent to X-rays.
In the form of embodiment shown in FIGS. l to 3,
the source 11 is arranged behind the patient 2, the latter
to define, either by radioscopy or by radiography, the
exact part of the member which corresponds to the
being placed behind a frame 3 which supports a radio
scopic screen 4 at right angles to the axis of the beam
densiographic recording.
of X-rays.
A protective screen 21 (FiG. l) for example of wood
or other material transparent to Xsrays, may be inter
The frame 3 carries known means enabling a photo
multiplier cell 5 to be displaced in any desired manner.
These means may be constituted by small remote-com
posed between the patient and the cell 5.
In the form of embodiment which has just been de
scribed, the shadow 1S is considerable and may still be
trolled motors, independent of each other and adapted
to control respectively the vertical and horizontal dis
placements and the angular movements of the cell in
its vertical plane; or alternatively the frame may be
a source of diiñculty in certain examinations.
actly facing the aperture of the cell and directing this
11, the luminosity of which is transmitted through them
to the photo-cathode ‘14.
In order to avoid all loss of light, it is advisable to
surround them by a sheath 23 which is opaque to light
but transparent to X-rays, for example of aluminium, the
This drawback can be removed by employing the alter
native form of apparatus illustrated in FIGS. 5 and 6, in
accordance with which the cell 5 is mounted outside the
articulated about a horizontal shaft 6 on a support 7
which can be moved vertically along a column S which 25 ilux of X-rays, on the uprights of the frame 3.
The screen 11 is housed between two strips 22 (FIGS.
can be displaced horizontally along two slides 9 by caus
5 and 6) of a substance such as quartz which is trans
ing it to rotate about its axis, two cables 10 stretched
parent to X-rays and capable of transmitting in an al
horizontally between the two =uprights of the frame 3
most complete manner, the light which it receives.
ybeing each wound several times round this column.
These strips are sufliciently rigid to support the screen
Instead of arranging the small ñuorescent screen ex
aperture towards the subject as in the known types of
apparatus, this small screen 11 is mounted on the edge
of the cell, in the immediate proximity of its aperture
12, or preferably at a certain distance from this aperture,
considered parallel to the screen 4, and the arrangement
inner face of this sheath being preferably reflecting.
It will be understood that any suitable means may be
provided for displacing the cell and the Strips.
does not coincide with a portion of the shadow cast by
It may ybe an advantage to articulate the strips on the
the cell.
Fluorescent screens are generally formed with a sup
The use of these strips enables the thickness between
port which is opaque or translucent but not transparent,
the protective plate 21 and the screen 4 to be considerably
this support being coated with the fluorescent substance.
reduced, `and in particular it enables the latter to be
It is an advantage to use a screen having a tluorescence
is such that the shadow which it casts on the screen 4
completely disengaged so that, apart from the shadows
which can be utilized on both its faces.
To this end, for example, the small screen 11 is formed 45 corresponding to the organs to Ibe examined, there ap
pears only that corresponding to the small screen 11
in the following manner:
(and/or to its `frame).
The iluorescent substance is coated on a support 13
By way of indication, it may be stated that the strips
(FIG. 3) which is transparent to visible light and which
22 can have a straight semi-cylindrical form having a
may or may not be rigid. The support may for example
50 diameter of the order of l centimeter and a length of
be made of methyl poly-methacrylate (a material known
about 2O` centimeters.
by the commercial name of “Plexiglas”), or a flexible
They may also be elbowed.
plastic material.
In accordance with an alternative form of embodiment,
In addition, the liuorescent coating 29 (FIG. 8)
whieh may be composed of a number of separate coat
ings transmitting their activation from one to the other
a ilexible light-guide may be formed over at least a part
55 of the distance between the screen and the cell, by plac
ing pieces of quartz 24 (FIG. 7) separated from each
is preferably covered by a second plate 3d* for the pur
other in a deformable sheath of a material transparent
poses of protection, this plate being either rigid or flexible
to X-rays, the spaces between two successive pieces 24
and transparent to light and to X-rays.
The support 13 is arranged parallel to the screen 4 60 being filled with a liquid 26 which is transparent to light
and has the same index of refraction as quartz.
at a few millimeters or a few centimeters above the aper
Means such as those shown diagrammatically at 27
ture 12 of the lead-protected cell, the photo-cathode of
enable the free extremity of this flexible tube, which car
which is shown diagrammatically at 14. Mirrors 1S,
which may be plane or otherwise, are arranged on each
side of the small screen 11 so as to reflect towards the 65
aperture 12 the light which it emits under the impact of
the X-r-ays.
The assembly formed by the mirrors 15 and the sup
ries the screen 11, to be moved with respect to the cell 5.
The light sent to the cell 5 must be modulated in a
strictly stable manner, and in certain cases the use of the
town mains supply or of X-radiation produced by the
usual types of generator is not satisfactory for the re
spective reasons of the indifferent stability of the mains
porting means for these mirrors and of the support l13
(means which form a kind of `closed box 16 entirely 70 supply and of the parasites inherent with the said gen
opaque to light and coupled in a light-tight manner to
the protective casing of the cell, which is itself opaque to
In accordance with an advantageous arrangement of
X-rays and to light) is composed of materials trans
the invention, a continuous beam of X-rays is first gen
parent to X-rays such as aluminium, glass coated with
aluminium or silver, etc.
erated following the usual method, for example by the
75 adjunction of an assembly of condensers which can be
shunted to earth when so required, after ywhich an opaque
screen is periodically interposed on the path of this beam
close to its source, for example by causing the periph
eral zone of a perforated disc to pass in a continuous
manner across the beam at regular intervals, the disc
being rotated at a well-defined constant speed about its
axis, or by the use of a screen oscillating at a constant
frequency, for example in front of a slot.
The X-radiation is then modulated in a stable manner
or be put into circuit, which corresponded to the portion
35 of the said curve (end of recording).
A circuit arrangement of this kind does not enable
the absolute value of the reference a to be modified as
a function of the pulsatility of the organ studied, which
can vary to a very considerable extent from one organ
to another.
In order to overcome this drawback, according to an
advantageous arrangement of the invention, a number of
(for example at 420 cycles per second) which removes 10 successive filters, preferably of the double T type, are
connected in the amplifying chain in such manner that
the drawbacks inherently due to parasitic or irregular fre
it is possible to use at will one of these filters only, or
quencies during the amplification which is necessary to
two, or more, depending on the pulsatility of the organ
use the data received by the cell.
examined. These lilters are connected either in series or
In accordance with a particularly advantageous form
of ‘this arrangement, the periodic interruption is not 15 in parallel, and can be put into service at will by means
of at least one change-over switch.
applied to the X-radiation, but to the light radiation
For example, if a series of three filters is available:
transmitted according to the invention, Whether by reflec
tion or by refraction, from the small screen 11 to the
One only is used for the examination of a shadow
corresponding to a very high pulsatility, such as the
aperture 12, as is shown diagrammatically by the disc 28
represented in chain-dotted lines on FIG. 5.
20 cardiac shadow, which has a large depth of modulation
and only requires a low gain before recording: if the
The'said periodic interruption may -be effected with
filtering system were too extensive, the residual amplitude
advantage b-y means of a rotating disc 31 (FIGS. 3 and
corresponding to the rapid modulation (100 cycles)
9) provided with ra-dial or other perforations, rotating
would- be too small to be measured with accuracy, and
in front of a diaphragm 33, fixed or not fixed, provided
with corresponding perforations and mounted at the input 25 would be for example of the order of 2 mm. only;
For the examination of shadows corresponding to the
of the cell.
arterials of the lungs, which have a low pulsatility, the
In the form of embodiment shown in FIGS. l> to 3,
it may be an advantage to arrange the oscillating screen
gain should be increased and two of the iilters are em
ployed, connected in series;
or the perforated disc in the interior of the box 16, in
An-d for the examination of shadows corresponding
order to reduce the overall size of the unit.
to the arterioles of the liver, the pulsatility of which is
The modulation of the beam which has just been
very small, the gain of the amplifying chain must be
described is particularly well adapted to the form of
considerable and the filtering must be more powerful
embodiment in which the source of Iradiation is not a
than in the preceding cases. In this case therefore the
This is the case of radio-active thulium 35 whole of the three available filters will be employed.
more or less continuous source of X-rays, but is a source
of gamma rays.
170, the half-life of which is of the order of 4 months
The quotient of the quantities b and a can be effected
and which emits a perfectly stabilised gamma radiation,
the energy of ywhich (of the order of 85 kev.) is com
in any desired manner, and especially in an automatic
manner, for example by means of electronic apparatus
equipped with quotient-meters in known manner, which
patible with the means of protection generally provided
in the equipment of radiology installations. It will of 40 would kbe mounted in parallel to the amplifying chain.
course be understood that in the case of use of a source
of this kind, it would be necessary to replace the ñuores
In addition, means such as an oscillograph adapted
for recording are preferably provided for recording the
value of the ratio b/a or “index” thus calculated, while
at the same time the densiographic record is made and
In order to apply the results recorded on the cine 45 preferably also an electro-cardiogram.
It should be noted -that for the -calibration referred to
densiographic curves under the best conditions, it is an
above, it is of particular advantage to effect a rapid and
advantage to be able to calibrate the curves obtained
uniform modulation of the radiation employed by a
in an independent manner, especially independently of
cent screen yby a suitable detector such as a scintillator
crystal of Sodium iodide activatedby thallium.
periodic interruption of the light or X-radiation effected
50 by the movement of opaque screens in the manner
density of the organ examined.
described above, for example a-t 420 cycles; the curve
To this end, it has already been proposed to record
corresponding to this rapid modulation is in fact much
on the same negative the variations of intensity of the
the amplifying chain employed and of the radiological
light radiation employed due on the one hand to the
modulation of -this radiation at a relatively high uniform
more accurate and faithful than that obtained by modu
frequency (for example of 100 cycles) and on the other 55
It will be understood that any filtering means may be
provided in order to elimina-te oscillations of stray or
hand to the more or less considera-ble interception of the
said radiation by the organ studied by reason of the
lating mains supply current at 100 cycles.
parasitic frequencies.
In the result, and whatever form of embodiment may
pulsations of the blood at a relatively low frequency, to
`be adopted, there is finally available an apparatus for
which this organ is subjected.
The amplitude of the tirst oscillations is represented 60 radiological examination enabling densiography to be
utilized, and having Va large number of advantages as
by a in FIG. l0, and that of the second by b in the
compared with those existing up to the present time, in
same figure.
particular, having an increased accuracy in respect of
Experience has shown that the radio b/a of these
the positioning and the location of the small zone studied,
amplitudes does not depend, for a given source of
on the one hand, and on the other hand the iidelity of
X-radiation, either on the gain of the amplifier~ or on the 65 the result collected at the output of the device which
radiological density of the organ traversed, but only on
converts the variations of density of the organ studied to
the amplitude of the variations of that density. This
variations of electric current.
ratio, which is sometimes known as the “index of pul
llt will of course be understood, and this follows further
satility,” is thus a faithful image of the pulsatility of the 70 more from the foregoing description, the invention is not
said organ.
in any Way limited to its forms of application described,
Up to the present time, a double T filter was used,
nor is it limited to the forms of embodiment of its various
parts which have been more particularly dealt with; on
which could either be put out of circuit, corresponding
to the recording of a portion of curve similar to that
the contrary, it includes all the alternative forms, espe
shown at 34 in FIG. l0 (beginning of the recording), 75 cially:
Those in which the apparatus is equipped with a num
ber of small screens 11 associated with the same number
0f cells, in order to permit a more convenient scanning
of ti e whole of the organs irradiated;
Those in which the stabilization of the flux of X-rays
and/or a variable calibration is employed for densio
element being disposed in a plane intersecting said beam
graphic studies, independently of the disengagement of
between said object and said observation means, means
for positioning said element in said plane to intersect
a small section of said beam at any desired point, a
cell sensitive to light disposed with respect to said ele
ment and said beam for receiving light as directed from
said element and to avoid simultaneously intersecting
that section of the beam intersected at any time by said
the image corresponding to the small screen 11;
Those in which the device which delivers an electric
element, a flexible sheath forming a duct extending be
current as a function of the intensity of the beam of 10 tween said element and said cell, said sheath being made
X-rays which has passed through the subject, is directly
of a material transparent to X-rays, a plurality of quartz
pieces located in said sheath and a liquid transparent to
sensitive to that intensity (Geiger counter, ionization
light and having the same index of refraction as quartz
chamber, etc.) instead of being indirectly affected through
the intermediary ot the small screens 11;
Those in which the small screen 11 is essentially con
stituted, not by a substance which becomes fluorescent
under the impact of X-rays, but by a scintillator crystal
capable of transforming to light the radiant energy which
it receives (produced by X-rays or other radiations), the
light emitted by this crystal being capable of being trans
mitted to the cell by quartz strips such as those described
above, with an excellent efficiency which may attain 80%
for strips of 1 metre in length.
What I claim is:
`Densiography apparatus for use with radioscopic ap 25
paratus including means for generating a ilux of X-rays,
means for directing a beam of said rays through an object
of examination, and means beyond said object for ob
filling the spaces in said sheath between said quartz pieces,
whereby light is directed from said element to said cell. '
References Cited in the tile of this patent
Schepker ____________ __ Nov. 30, 1954
Armistead ____________ __ June 12, 1956
Schultz ______________ __ Oct. 23, 1956
Ball et al _____________ __ June 18, 1957
Untermyer ____________ __ July 2, 1957
Ball et al. ____________ __ Oct. 15, 1957
Lee _________________ __ N'ov. 12, 1957
Godbarsen ___________ __ June 24, 1958
serving a radioscopic image formed by said beam after
passing through said object, a surface element of relatively 30
Clark _______________ __ Aug. 26, 1958
Stava et al ___________ __ Aug. 25, 1959
small area which emits light in response to X-rays, said
Germany ____________ __ Aug. 13, 1956
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