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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a device for treatment through hyperthermia,
allowing to heat a diseased area of a patient through dissipation of an
electrical energy applied according to an electrical field through of
unipolar electrodes disposed adjacent to the diseased area or within said
area. The invention is of particular interest in that it allows to
considerably reduce the effects traumatizing for the patient, produced by
using such treatments.
2. Summary of the Prior Art
Hyperthermia is a known process, which consists in heating living
biological tissues to temperatures substantially higher than their normal
temperature, and which is utilized in the treatment of various illnesses
and especially in cancerotherapy. In the example of this latter
application, it is desirable to heat the tissues to be treated to
temperatures of about 44.degree. C. to 45.degree. C., while avoiding, as
much as possible any substantially increase in temperature of the healthy
surrounding tissues.
This condition raises a problem which resides in the correct localization
of the heated area. In certain configurations which the diseased tissues
can present, this correct localization of the heating is impossible to
obtain with electrodes situated outside the patient's body. Therefore, in
numerous cases, treatment by hyperthermia is carried out through using
electrodes directly implanted in or around the area to be treated, so as
to more closely confine the area heated.
Such probes can be either of the bipolar or the unipolar type. In the case
of bipolar probes, the high frequency electric energy supplied by a
generator, in the form of a voltage, can be applied to a single probe of
this type, to heat the area in which it is implanted. In the case of
unipolar probes, the high or average frequency voltage supplied by the
generator is applied to two separate unipolar probes, each of these two
probes being connected to one of the output poles of the generator, the
heated zone thus being mainly established between two unipolar probes of
the type that can be implanted.
The implantation of a bipolar or unipolar probe in a diseased area
represents for a patient an operation that can be accompanied by acute
pain, and which is particularly traumatizing for treatments by
hyperthermia for a given zone to be treated, must generally be repeated at
variable frequencies and over periods of time comprised between several
days and several tens of days.
Another painful or at least disagreeable effect for the patient is
associated with the particular sensibility of cutaneous tissues to high
temperatures. In fact, experiments have shown that it is not generally
possible for the patient's comfort, to maintain, without an anaesthetic, a
temperature of about 43.degree. with respect to the skin during periods of
about 1 hour.
Another source of considerable inconvenience for the patient, during
treatment, is associated to the mechanical rigidity of the probes,
especially unipolar probes. These latter are generally constituted by
metal needles, that are relatively rigid and which can, even after they
have been placed in position, constitute a source of pain or ache more
particularly while passing through the skin.
A general object of the present invention is to produce a structure for
implanting unipolar or bipolar probes allowing to reduce as such as
possible the disagreeable effects to which the patient is subjected.
More specifically, one of the objects of the invention is to suppress the
disagreeable effects caused by repeatedly implanting the probes.
Another object of the invention is to suppress the heating of the skin
during treatment by hyperthermia of the cutaneous tissues.
Similarly, another object of the invention is to suppress or attenuate the
disagreeable effects to the skin caused by the rigidity of the probes.
It is to be noted furthermore that during treatment, certain tissues of the
area to be treated can undergo different rises in temperature, this being
able to lead during treatment to modifying the implantation of the probes.
Therefore, one of the objects of the invention is also to allow to modify
the configuration of the heated area, without requiring that the
implantation of the probes be modified.
SUMMARY OF THE INVENTION
According to the invention, a device for treatment through hyperthermia is
provided, which comprises, at least one generator supplying an alternating
electric power, the said electric power being applied, according to an
electric field, to an area to be treated of a patient through unipolar
electrodes connected to the said generator, at least one of the said
unipolar electrodes being an implantable unipolar probe, said device
comprising furthermore at least one vector tube intended to be implanted
permanently in the area to be treated by crossing through the patient's
skin and containing the said unipolar probe during a hyperthermia session
the said vector tube comprising at least one tubular end formed of an
insulating material and extended by a metallic tube, the said metallic
tube being adapted to contain at least partially the said unipolar probe
and to be in contact with the said area to be treated, and the said
tubular end being intended to be situated at the level of the skin, the
said unipolar probe being introduced through the said tubular end into the
said metallic tube with which the said unipolar probe is in electrical
contact.
By the expression "placed permanently" is meant with respect to the vector
tube a period of time, for example, several days, during which time
several hyperthermia sessions are scheduled for which the placing in
position of the electrodes or unipolar probes is carried out by their
introduction into a vector tube.
It is to be noted that one considerable advantage provided by the invention
is to enable to associate easily a treatment by radiotherapy to a
hyperthermia treatment; the save vector tubes can be used:
a--to introduce the radioactive needles (polonium or the like) for the
radiotherapy sessions;
b--to introduce unipolar probes, for the hyperthermia sessions.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will become more apparent from the following description,
given by way of non-limitative illustration, with reference to the four
appended drawings in which:
FIG. 1 illustrates the implanting of unipolar probes in a zone to be
treated, with a first version of a device for treatment by hyperthermia
according to the invention;
FIG. 2 shows details of a vector tube intended according to the present
invention to contain a unipolar probe;
FIG. 3 schematically shows a second version, with several generators, of a
treatment device according to the invention allowing easily to modify the
distribution of the currents in the zone to be treated;
FIG. 4 schematically illustrates a distribution of the currents as modified
with respect to FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a hyperthermia treatment device 1 according to the
invention, and an example of implantation of unipolar probes S1, S2.
The treatment device comprises a generator G1 of the type operating at
average or high frequency (in the range of 100 KHz to several MHz), and
average power (in the range of several tens of Watt to several hundreds of
Watt). The generator G1 supplies, across a first and a second output
terminal 4, 5 an alternating electric energy intended to be dissipated
within the body 6 (partially represented) of a patient, in order to raise
the temperature of an area 8 to be treated by hyperthermia. The electric
energy supplied by the generator G1, in the form of a voltage (not
represented) for example, is applied to the unipolar probes S1, S2, the
first unipolar probe S1 being for this purpose connected to the first
output terminal 4 and the second unipolar probe S2 being connected to the
second output terminal 5. In the non-limitative example described, the
unipolar probes S1, S2 are both of the implantable type, i.e. constituted
by a metallic needle 10, one end 11 of which is connected to a
conventional electrically conductive wire 12 through which they are
connected to the generator G1; but it is also known in the prior art, and
this can also be applied when carrying out the invention, to use a single
implantable probe S1, S2 of the unipolar type cooperating with a unipolar
electrode (not represented) adapted to be placed inside the patient's body
6.
According to the prior art, as explained in the preamble of the present
description, implantable unipolar probes are directly implanted in the
tissues to be treated at each hyperthermia session, contrary to the
possibilities offered by the present invention.
In fact, according to the present invention, the treatment device 1
furthermore comprises vector tube V1, V2 provided so as to be implanted in
the zone 8 to be treated or adjacent thereto, as represented in the
nonlimitative example of FIG. 1, and to be left there permanently, i.e.
over a period of time during which several sessions of treatment by
hyperthermia are performed. The vector tubes V1, V2 are adapted to
receive, during each treatment session, a unipolar probe S1, S2 introduce
into a vector tube V1, V2 through a first or a second end 17, 18 of this
latter, at least one of these ends 17, 18 having to be a placed for this
purpose outside the patient's body 6, i.e. protruding with respect to the
patient's skin 20.
FIG. 2 shows more clearly, by way of non-limitative example, a vector tube
V1 and a unipolar probe S1. The first and second ends 17, 18 of the vector
tube V1, at least one of which is necessary, are produced, according to
one characteristic of the invention, from an electrically insulating
material, and according to another characteristic of the invention, this
material should furthermore be flexible, these characteristics both
contributing to the comfort of the patient as will be described
herein-below. These conditions are met by using materials, such as for
example a polyamide known under the trademark "Nylon.RTM." or a
polytetrafluoroethylene known under the name of TEFLON.RTM.. The first
tubular end 17 is extended by a metallic tube 23, communicating with the
tubular end 17, so that a unipolar probe S1 can be introduced in the
direction shown by the first arrow 25, for example, up to within the
metallic tube 23. In the non-limitative example described, the metallic
needle 10 of the unipolar probe S1 has a diameter DI substantially smaller
than the internal diameter D2 of the metallic tube 23; this allows to
ensure in a simple way an electrical contact between the metallic needle
10 and the metallic tube 23 when the needle is introduced at least
partially into this latter. Supposing that the needle 10 has in a
conventional way a diameter D1 of about 0.8 mm, and that the internal
diameter D2 of the metallic tube 23 is about 0.9 to 1 mm for example, in
order to allow the passage of the needle 10 and to ensure the electrical
contact and that, on the other hand, the wall 24 of the metallic tube 23
comprises a thickness E of about 0.1 to 0.15 mm, the external diameter D2
of the metallic tube 23 will be about 1.1 to 1.2 mm. The assembly of the
metallic tube 23 and the tubular ends 17, 18, can be carried out by those
skilled in the art in different ways, as, for example, represented in FIG.
2; as shown there, the metallic tube 23 comprises next to its Junction J
with the tubular ends 17, 18 an end part 3 where the wall 24 has a smaller
thickness E1, so that the tubular end 17 can be sunk on this end part 3
without creating any significant overthickness with respect to the
external diameter D3; the end part 3 thus comprises an electrically
insulating oversheathing 16.
The implantation of the vector tube V1 in the area 8 to be treated can be
carried out by using a hollow needle (not represented) of the type called
vector cradle, for example, the use of which in the medical field is
current, especially for the implantation of various probes in living
tissue; said vector cradle is also described in French patent published
under No. 2 421 628. The vector tube V1 can be placed in the vector
cradle, which is thereafter introduced at the desired site into the zone 8
to be treated; the vector cradle is thereafter withdrawn with care by
causing to it to slide on the vector tube V1 which remains in place.
Referring again to FIG. 1, the vector tubes V1, V2 being placed in position
each unipolar probe S1, S2 is introduced into a vector tube V1, V2. The
unipolar probe S1, S2 being connected to the generator G1, and said
generator operating, an electrical field represented on FIG. 1 by field
lines I.sub.1, I.sub.2 . . . I.sub.n is established between the unipolar
probes S1, S2 through the intermediary of the vector V1, V2 in order to
produce a rise in temperature of the area to be treated 8 subjected to the
electrical field. One advantage of this disposition resides in the fact
that it allows to confer upon vector tubes V1, V2 active lengths
respectively L1, L2 between which is established an electrical field,
independently from the lengths L3 of the unipolar probes S1, S2, this
allowing to confine more accurately the zone 8 subjected to the electrical
field. In fact for frequencies lower than several MHz, thicknesses of
insulating materials of about 0.10 mm are sufficient to prevent the
establishment of the electric current. In the non-limitative example
described, the active lengths L1, L2 correspond to the length of the
metallic tubes 23 exposed, i.e. not sheathed by the tubular ends 17, 18 of
insulating material. This allows in particular to confer active lengths
L1, L2 of possibly different dimensions, compatible with the geometry of
the zone 8 to be treated, while using unipolar probes S1, S2 having
metallic needles 10 of identical lengths L3.
The tubular ends 17, 18 ensure furthermore protection with respect to the
skin 20, which is particularly sensitive to rises in temperature. Thus,
for example, in the case where on unipolar probe, the second unipolar
probe S2 for example is situated at the level of the skin 20, not being
for example entirely fitted into the second vector tube V2; the end 11 of
the needle 10 connected to the wire 12 thus being situated outside the
patient's body 6, at a location 11' marked for example, the presence of
the tubular end 17 prevents the establishment of the electrical field at
the level of the skin 20 and thus prevents the burning sensations felt by
the patient in such a case. This possibility of withdrawal of a unipolar
probe S1, S2 is the more important as it allows to release in the vector
tube V1, V2 a zone Z opposite to the first end 17, into which can be
introduced through the second end 18, a needle made of a radioactive
material (not represented) of a conventional type. This allows to carry
out simultaneously a treatment by hyperthermia and a treatment by
radiotherapy.
Another very important advantage for the patient's comfort is contributed
by the flexibility of the tubular ends 17, 18 which allows relative
movements thereof with respect to a longitudinal axis 28 of the IO
unipolar probes S1, S2 this flexibility allowing them to follow the
movements of the skin due for example to slight movements of the patient,
thus allowing to avoid that the patient experiences painful sensations.
In the non-limitative example represented in FIG. 1, two vector tubes V1,
V2 have been represented but a greater number n of these vector tubes V1,
V2 . . . Vn can be implanted permanently in the case, for example, where a
greater number of unipolar probes S1, S2 are used with for example several
generators (not represented on FIG. 1) or again in the case where the
practitioner desires to modify the heating configuration of a treated zone
8. Such a modification can be desirable from one hyperthermia session to
another, or even during the same session, in the case for example where
the tissues (not represented) of one zone to be treated 8 have different
sensitivies to the electrical field.
FIG. 3 schematically illustrates a second version of the treatment device 1
according to the invention, which allows to carry out modifications of the
heated area such as mentioned herein-above, without requiring modification
of the implantation position of the vector tubes V1, V2 . . . already
implanted (not represented on FIG. 5 for enhanced clarity). It is to be
noted that this version of the invention can also be applied in the case
of a conventional utilization of implantable unipolar probes, i.e. without
vector tubes V1, V2 . . . V3.
In this second version, the treatment device 1 should comprise, further to
the first generator G1, at least one supplementary generator G2, i.e. at
least two frequency synchronized generators G1, G2.
Therefore, in the non-limitative example described, the treatment device
comprises, in addition to the first generator G1, a second and a third
generator G1 substantially of the same type as the first generator G1, a
number N of generators, higher than 3 can also be used. In the
non-limitative example described, the treatment device 1 comprises
furthermore a main oscillator 30 connected by connections 31 to each of
the generators G1, G2, G3 in order that these latter operate at a single
frequency F1 and according to a single phase.
The area 8 to be treated is represented on FIG. 3 by a cross-sectional view
in a plane perpendicular to the longitudinal axis 28 shown in FIG. 1. In
the example described, six unipolar probes S1, S2 . . . S6 are either
implanted directly in the area 8 to be treated, or each is placed as in
the previous example, in a previously implanted vector tube, the unipolar
probes S1, . . . S6 being shown in cross-section, they are represented on
FIG. 3 by circles. In the non-limitative example described, the unipolar
probes S1, . . . S6 are disposed in an area 8 to be treated substantially
on a circle 16 having a centre 0, through which pass three axes 33, 34, 35
forming between them an angle alpha of about 30.degree.; two unipolar
probes S1, . . . S6 connected to the save generator G1, G2, G3 in the
non-limitative example described, disposed on a single axis 33, 34, 35 but
opposite with respect to the center 0. Each of the probes S1, . . . S6 is
connected by an electric conductor 12 to one of the output terminals B1,
B2 . . . B6 of a generator GI, G2, G3:
the first and the second probes S1, S2 disposed on the first axis 33 are
connected respectively to the first and the second terminal B1, B2 of the
first generator G1;
the third and fourth probes S3, S4 disposed on the second axis 34, are
connected respectively to a third and fourth output terminal B3, B4 of the
second generator G2;
the fifth and sixth probes S5, S6 disposed on the third axis 35, are
connected respectively to a fifth and a sixth terminal B5, B6 of the third
generator G3.
The three generators G1, G2, G3 operate at an idetnical frequency F1, and
thus, by determining the polarities +,- (for a given instant) of the
output terminals B1, B2 and B3, B4 and B5, B6 corresponding to each of the
enerators G1, G2, G3, it is possible to place unipolar probes S1 to S6
corresponding to a desired position in the area 8 to be treated, such as
for example shown on FIG. 3, so as to establish the electrical field
between these unipolar probes S1 to S6 according to a desired arrangement;
this positioning of the probes can be carried out through direct
implantation or by placing each probe in a vector tube as explained
herein-above.
Supposing that the first, third and fifth output terminals B1, B3, B5 have
a positive polarity +, the second, fourth and sixth output terminals B2,
B4, B6 will have a negative polarity -, these +,- polarities appearing
respectively at the unipolar probes S1, S3, S5 and S2, S4, S6.
The electrical field represented by the field lines I.sub.1 to I.sub.n will
be in these conditions established in the whole of the area 8 to be
treated.
As mentioned herein-above, it can be desirable to modify the distribution
of the electrical field, i.e. the configuration of the heated area. This
is possible according to the invention, without causing any supplementary
discomfort to the patient, either by substituting the unipolar probes S1,
. . . S6 between one another, with respect to the vector tubes, in the
case where the latter are used, or by modifying the respective +,-
polarity of the probes S1, to S6 by acting on the generators G1, G2, G3 as
well in the case where the unipolar probes S1 to S6 are directly implanted
in the area 8 to be treated, as in the case where they are disposed in the
vector tubes. For this purpose, each of the generators G1, G2, G3
comprises an inverter device respectively 41, 42, 43 allowing to invert
the polarity between two output terminals B1, B2 and B3, B4 and B5, B6 of
any single generator G1, G2, G3. The commutation devices 41, 42, 43 can
consist of conventional commutating means allowing for example for the
first generator G1 to invert the connections (not represented) established
between the output terminals B1, B2 and the amplifiers (not represented)
conventionally provided on each generator G1, G2, G3. Such an inversion of
polarities can be carried out in different ways, all of which are within
the scope of those skilled in the art, and can also consists in an
inversion of the conducting wires 12 connected to the output terminals B1,
B2.
It is also possible through modifying the polarity of the probes S1 to S6,
to obtain modification of the distribution of the electrical field, as
form example represented in FIG. 4.
FIG. 4 represents the area 8 to be treated according to a view analog to
that of FIG. 3, i.e. taken in a plane perpendicular to the longitudinal
axis 28 shown on FIG. 1, the unipolar probes S1 to S6 occupy the same
position as FIG. 3, but comprise different +,- polarities, so that these
polarities are successively positive +and negative -. The electrical field
represented by the field lines I.sub.1, . . . I.sub.n established between
the adjacent probes in +,- polarities thus corresponds substantially to a
circular distribution around the circumference of circle 16, i.e. around
the center 0 which in this configuration is not subjected to the
electrical field.
Other heating configurations of the area 8 to be treated can be obtained,
by modifying either the distribution of the probes S1, . . . S6 in the
vector tubes V1, V2 . . . or by modifying the positive + or negative -
polarity conferred upon each of the probes.
The present description constitutes a non-limitative example of a treatment
device 1 by hyperthermia according to the invention, in which n tubes
vector V1, V2 . . . Vn adapted to be implanted permanently allow to
suppress the causes of the discomfort felt by the patient with treatment
appliances according to the prior art; a treatment device 1 according to
the invention allows furthermore to carry out an appropriate heating of
the area 8 to be treated, with much more flexibility than in the prior art
.
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