U.S. patent application number 13/286920 was filed with the patent office on 2012-05-10 for multi-lumen instrument for providing radiation to a body cavity.
This patent application is currently assigned to Cytyc Corporation. Invention is credited to Timothy J. Patrick, Carribeth B. Ramey, Rance A. Winkler.
Application Number | 20120116146 13/286920 |
Document ID | / |
Family ID | 32393194 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120116146 |
Kind Code |
A1 |
Winkler; Rance A. ; et
al. |
May 10, 2012 |
Multi-lumen instrument for providing radiation to a body cavity
Abstract
A brachytherapy system for treating metastases on and around a
patient's spinous process is provided. The device generally
includes a catheter member having a proximal portion, a distal
portion, and at least one lumen extending therethrough. The distal
portion of the catheter member includes first and second branch
members that are adapted to be positioned on opposed sides of a
patient's spinous process. The device further includes first and
second elongate anchoring elements disposed on the first and second
branch members, and optionally can include at least one centering
mechanism disposed within each of the first and second anchoring
elements.
Inventors: |
Winkler; Rance A.; (Atlanta,
GA) ; Patrick; Timothy J.; (Alpharetta, GA) ;
Ramey; Carribeth B.; (Suwanee, GA) |
Assignee: |
Cytyc Corporation
Marlborough
MA
|
Family ID: |
32393194 |
Appl. No.: |
13/286920 |
Filed: |
November 1, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10867062 |
Jun 14, 2004 |
|
|
|
13286920 |
|
|
|
|
10365977 |
Feb 13, 2003 |
6749555 |
|
|
10867062 |
|
|
|
|
Current U.S.
Class: |
600/3 |
Current CPC
Class: |
A61N 2005/1021 20130101;
A61N 2005/1003 20130101; A61N 5/1027 20130101 |
Class at
Publication: |
600/3 |
International
Class: |
A61M 36/04 20060101
A61M036/04 |
Claims
1-43. (canceled)
44. A instrument for providing radiation to a desired region of
tissue surrounding an interstitial body cavity, the instrument
comprising: a catheter member having a proximal portion and a
distal portion, the distal portion including a branch member; and a
first lumen and a second lumen disposed within the catheter member
and extending from the proximal portion into the branch member,
wherein the first and second lumens are configured to receive a
radiation source.
45. The instrument of claim 44 wherein the distal portion has an
asymmetric configuration with respect to a longitudinal axis of the
instrument.
46. The instrument of claim 44 wherein the first lumen has an
asymmetric configuration with respect to a longitudinal axis of the
instrument.
47. The instrument of claim 44, wherein the radiation source
includes a first radioactive particle and a second radioactive
particle, and wherein the first lumen is configured so that the
first radioactive particle is farther from the longitudinal axis of
the instrument than the second radioactive particle.
48. The instrument of claim 44, wherein the branch member includes
a centering mechanism that comprising an inflatable balloon.
49. The instrument of claim 48, wherein the inflatable balloon has
a polymetric film wall.
50. The instrument of claim 44, wherein the first lumen is
configured to receive a solid radiation particle.
51. The instrument of claim 44, wherein the first lumen is
configured to receive a radioactive seed on a wire.
52. The instrument of claim 44, wherein at least part of the distal
portion is coated with a radio-opaque material.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to apparatus for use
in treating proliferative tissue disorders, and more particularly
to an apparatus for the treatment of such disorders in the body by
the application of radiation.
BACKGROUND OF THE INVENTION
[0002] Malignant tumors are often treated by surgical resection of
the tumor to remove as much of the tumor as possible. Infiltration
of the tumor cells into normal tissue surrounding the tumor,
however, can limit the therapeutic value of surgical resection
because the infiltration can be difficult or impossible to treat
surgically. Radiation therapy can be used to supplement surgical
resection by targeting the residual tumor margin after resection,
with the goal of reducing its size or stabilizing it. Radiation
therapy, or surgical excision followed by radiation therapy, is
commonly used to treat spinal metastases. Metastases are tumors
that have grown in a location that is remote from the site that the
tumor started, and spinal metastases result from the spread of
cancer cells into a patient's vertebral column.
[0003] Radiation therapy can be administered through one of several
methods, or a combination of methods, including external-beam
radiation, stereotactic radiosurgery, and permanent or temporary
interstitial brachytherapy. The term "brachytherapy," as used
herein, refers to radiation therapy delivered by a spatially
confined radioactive material inserted into the body at or near a
tumor or other proliferative tissue disease site. Owing to the
proximity of the radiation source, brachytherapy offers the
advantage of delivering a more localized dose to the target tissue
region.
[0004] For example, brachytherapy is performed by implanting
radiation sources directly into the tissue to be treated.
Brachytherapy is most appropriate where 1) malignant tumor regrowth
occurs locally, within 2 or 3 cm of the original boundary of the
primary tumor site; 2) radiation therapy is a proven treatment for
controlling the growth of the malignant tumor; and 3) there is a
radiation dose-response relationship for the malignant tumor, but
the dose that can be given safely with conventional external beam
radiotherapy is limited by the tolerance of normal tissue. In
brachytherapy, radiation doses are highest in close proximity to
the radiotherapeutic source, providing a high tumor dose while
sparing surrounding normal tissue. Interstitial brachytherapy is
useful for treating malignant brain and breast tumors, among
others.
[0005] While devices exist for delivering radiation to treat
metastases, there is still a need for instruments which can be used
to provide brachytherapy to target tissue within specific areas of
a human body, such as within a patient's spine. In particular, a
number of cancers, including spinal cancers as well as other
thoracic cancers, can proliferate into a patient's spine. At
present, there are no devices configured for treatment of such
proliferation, especially where the proliferation extends through
more than one vertebra within the spine.
SUMMARY OF THE INVENTION
[0006] The present invention generally provides a brachytherapy
system for treating metastases on and around a patient's spinous
process. In one embodiment, a brachytherapy device is provided
having a catheter member including a proximal portion, a distal
portion, and at least one lumen extending therethrough. The distal
portion of the catheter member includes first and second branch
members that are adapted to be positioned on opposed sides of at
least one of a patient's spinous process. The device further
includes first and second elongate anchoring elements disposed on
the first and second branch members. The device is adapted to
receive a radiation source through the at least one lumen in the
catheter to the first and second branch members for delivering
radiation to tissue surrounding the at least one spinous process.
The device can also optionally include at least one centering
mechanism disposed on each of the first and second branch members.
Each centering mechanism is effective to maintain symmetry of the
first and second branch members with respect to a patient's spinal
column, and/or to receive a radiation source and to deliver the
source to a treatment site.
[0007] The first and second anchoring elements are preferably
adapted to be positioned between a spinous process and transverse
process of at least one vertebral body, and to extend along a
length of a patient's spinal column, such that the first and second
anchoring elements, when expanded, engage and anchor the first and
second branch members between the spinous process and transverse
process of at least one vertebral body. In an exemplary embodiment,
the first and second elongate anchoring elements each have a length
adapted to span a plurality of vertebrae.
[0008] In another embodiment, the first and second anchoring
elements can be first and second outer expandable balloons, and
each centering mechanism can be an inner expandable balloon. Each
inner expandable balloon preferably has a size adapted to receive a
predetermined amount of a fluid radiation source such that varying
doses of radiation can be delivered along a length of the outer
expandable balloon. More preferably, each inner expandable balloon
is effective to position a radiation source at a predetermined
distance apart from the first and second outer expandable balloon
to provide a minimum absorbed dose for delivering radiation to
tissue adjacent to the outer expandable balloons.
[0009] In yet another embodiment, a brachytherapy device is
provided including an elongate catheter member having a proximal
portion, a distal portion, an inflation lumen, and at least one
source lumen. A plurality of inner centering mechanisms are
disposed around the catheter member and are in communication with a
source lumen. In use, the device is adapted to receive a radiation
source to deliver radiation to tissue surrounding the device. The
device can also optionally include an outer anchoring member
disposed around the distal portion of the catheter member and in
communication with the inflation lumen. The outer anchoring member
is adapted to anchor the catheter member between a spinous process
and transverse process of at least one vertebral body, and to
extend along a length of a patient's spinal column. The plurality
of centering mechanisms are preferably disposed within the outer
anchoring member and are effective to maintain symmetry along a
length of the distal portion of the elongate catheter member.
[0010] In yet another embodiment of the present invention, a method
for treating spinal metastases is provided. The method includes the
step of providing at least one brachytherapy apparatus for
delivering radioactive emissions. The apparatus has a catheter
member having proximal and distal ends and at least one lumen
extending therethrough, at least one anchoring element disposed
proximate to the distal end of the catheter, and a radiation source
disposable through the at least one lumen in the catheter for
delivering radiation to the tissue surrounding the anchoring
element. The method further includes the steps of intraoperatively
placing at least one brachytherapy apparatus between a spinous
process and transverse process of at least one vertebral body along
a length of the patient's spinal column, providing a controlled
dose of radiation to tissue surrounding the apparatus, and removing
the brachytherapy apparatus. The radiation source is preferably
placed into the brachytherapy apparatus after placement of the
apparatus between the spinous process and transverse process of at
least one vertebral body, and is removed from the apparatus before
removal of the apparatus.
DESCRIPTION OF THE DRAWINGS
[0011] The foregoing features, objects and advantages of the
invention will become apparent to those skilled in the art from the
following detailed description of a preferred embodiment,
especially when considered in conjunction with the accompanying
drawings in which:
[0012] FIG. 1 is perspective view illustration of one embodiment of
a brachytherapy system for proliferative tissue disorders in a
patient's spinal column;
[0013] FIG. 2 is a perspective view illustration of another
embodiment of a brachytherapy system for proliferative tissue
disorders in a patient's spinal column;
[0014] FIG. 3 is a diagram illustrating one embodiment of a branch
member for use with the system of the present invention;
[0015] FIG. 4 is an illustration of a brachytherapy system
according to the present invention positioned between a patient's
spinous process and transverse process of several adjacent
vertebrae.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] The present invention generally provides a radiotherapy
system, and preferably a brachytherapy system, for delivering
radiation to tissue and/or bone. While the system can be used for a
variety of purposes, the system is preferably used to treat spinal
metastases, and more particularly, to treat metastases on and
around a patient's spinous process. FIG. 1 illustrates one
embodiment of the device which generally includes a catheter member
10 having a proximal portion 12, a distal portion 14, and at least
one lumen extending therethrough. As shown in FIG. 1, the catheter
member 10 includes first and second lumens 16, 18 extending through
the proximal and distal portions 12, 14. The distal portion 14 of
the catheter 10 includes first and second branch members 20, 22
which are preferably adapted to be positioned on opposed sides of a
patient's spinous process. Each branch member 20, 22 includes an
anchoring element 24, 26 disposed on at least a portion thereof for
anchoring the branch members 20, 22 at the treatment site. The
first and second branch members 20, 22 can also be adapted to
receive a radiation source through at least one of the lumens 16,
18 (or another lumen) formed in the catheter 10. The radiation
source can generally be provided as a solid radiation source which
can be loaded into the lumen using a conventional afterloader or as
a liquid radiation source which can be loaded, for example, into
anchoring elements 24, 26 using the lumen or lumens. The device is
particularly advantageous in that it allows radiation to be
delivered to specific regions of a patient's spine and surrounding
tissue. Moreover, the treatment can be tailored depending on the
intended treatment site.
[0017] The catheter member 10 can have a variety of configurations,
but is preferably a semi-flexible or flexible elongate member
having a proximal portion 12 and a distal portion 14 having first
and second branch members 20, 22. Flexibility (or semi-flexibility)
in catheter member 10 can allow the catheter member to be adapted
to the curvature of a particular patient's spine. The catheter 10
further includes at least one lumen formed therein that extends
through the proximal portion 12 and the first and second branch
members 20, 22 of the distal portion 14. In an exemplary
embodiment, a first lumen 16 extends through the proximal portion
12 and the first branch member 20, and a second, separate lumen 18
extends through the proximal portion 12 and the second branch
member 22. The lumens 16, 18 can each terminate at a distal port
34, 36 formed in the first and second branch members 20, 22,
respectively.
[0018] The branch members 20, 22 can be integrally formed with the
proximal portion 12 of the catheter 10, or alternatively can be
mated to the proximal portion 12 using a variety of mating
techniques. As shown in FIG. 1, the first and second branch members
20, 22 are mated to the proximal portion 12 of the catheter 10 via
a Y-shaped connector element 32. The Y-shaped connector element 32
includes a proximal end 32a that can be fixedly or removably mated
to the proximal portion 12 of the catheter 10, and first and second
distal ends 32b, 32c. The first distal end 32b can be fixedly or
removably mated to the first branch member 20, and the second
distal end 32c can be fixedly or removably mated to the second
branch member 22. A variety of mating techniques can be used for
mating the proximal portion 12 and the first and second branch
members 20, 22 of the catheter 10 to the connector 32 including,
for example, a threaded engagement, a twist lock engagement, a
snap-fit engagement, and any other mechanical and/or electrical
engagement mechanism. A person having ordinary skill in the art
will appreciate that while a Y-shaped connector 32 is shown, a
variety of connectors can be used to mate the first and second
branch members 20, 22 to the proximal portion 12 of the catheter
10.
[0019] Each branch member 20, 22 can have a variety of shapes and
sizes, but preferably each branch member 20, 22 has a generally
elongate shape and is adapted to be positioned on opposed sides of
a patient's spinous process, preferably between the spinous process
and the transverse process, across one or more of the patient's
vertebrae. As shown in FIG. 1, the first and second branch members
20, 22 each have a generally elongate shape and extend in a
direction substantially parallel to a longitudinal axis A of the
device. The branch members 20, 22 can be substantially rigid, but
are preferably substantially flexible to facilitate insertion of
the branch members 20, 22 between the spinous process and
transverse process of one or more vertebrae in various portions of
the patient's spine which may have differing curvatures. In an
exemplary embodiment, the branch members 20, 22 are sufficiently
flexible to allow the shape of each branch member 20, 22 to be
adjusted during use of the device 10 to conform to the curvature of
the portion of the patient's spine being treated. In addition,
anchoring members 24, 26 are preferably sufficiently malleable (or
can be placed in a sufficiently malleable state) to allow for
placement of branch members 20, 22 in irregular spaces between
vertebral processes or to adapt to spinal curvature.
[0020] While two branch members 20, 22 are shown, a person having
ordinary skill in the art will appreciate that the catheter 10 can
have a single branch member, or any number of branch members.
However, for treatment of cancerous proliferation in a patient's
spine by fitting branch members 20, 22 to a patient's spinal
process or processes, a person of ordinary skill in the art will
recognize that either two or one branches will be preferred and
that, for dosing symmetry purposes, under certain circumstances two
branches will be preferred.
[0021] The length L of each branch member 20, 22 can also vary
depending on the intended use, but preferably each branch member
20, 22 has a length L that is sufficient to allow the branch
members 20, 22 to extend along a plurality of vertebrae. In an
exemplary embodiment, each branch member 20, 22 has a length L
between about 4 cm and 12 cm. As previously stated, the branch
members 20, 22 can be removably mated to the connector 32. Thus,
the catheter 10 can be provided as a kit having several branch
members with varying lengths to allow the appropriately sized
branch members to be selected.
[0022] Each branch member 20, 22 further includes first and second
anchoring members 24, 26 disposed thereon. The anchoring members
24, 26 can have a variety of configurations and are preferably
effective to engage and anchor each branch member 20, 22 between
the spinous process and the transverse process of at least one
vertebral body. As shown in FIG. 1, each anchoring member 24, 26 is
an expandable balloon member that is primarily sealed around the
branch member 20, 22 and is in communication with one of the lumens
16, 18. The port 34 that is in communication with the first lumen
16 is disposed within the first anchoring member 24 for expanding
the first anchoring element, and the port 36 that is in
communication with the second lumen 18 is disposed within the
second anchoring element 26 for expanding the second anchoring
element.
[0023] In use, the anchoring elements 24, 26 are movable between a
deflated position to allow positioning of the first and second
branch members 20, 22 between the spinous process and transverse
process of one or more vertebral bodies, and an inflated position,
as shown, wherein air or fluid is delivered through the lumen 16,
18 and the port 34, 36 in each of the first and second branch
members 20, 22 to inflate the anchoring elements 24, 26 and thereby
anchor the first and second branch members 20, 22 between the
spinous process and transverse process.
[0024] The anchoring elements 24, 26 can have any shape and size,
but preferably each element 24, 26 has a predetermined shape in its
expanded form, as shown in FIG. 1, such that, when inflated, the
anchoring elements 24, 26 are adapted to securely fit between the
spinous process and the transverse process to positively locate the
branch members 20, 22 with respect to the target tissue to be dosed
with radiation. While the size of the anchoring elements 24, 26 can
be predetermined, the size can be selectable during treatment by
inflating the anchoring elements 24, 26 to a desired level. In an
alternative embodiment (not shown), each anchoring element 24, 26
can be an expandable cage member, and the catheter 10 can
optionally include a control lever or similar mechanism for moving
the expandable cage members between a contracted position and an
expanded position. This configuration, as well as a number of
inflatable balloon, double balloon, and other expandable surface
member anchoring members as well as their operation and association
with one or more lumens within device 10 is described in more
detail in U.S. Pat. No. 6,413,204, issued Jul. 2, 2002, and
entitled "Interstitial Brachytherapy Apparatus and Method for
Treatment of Proliferative Tissue Diseases," which is incorporated
herein by reference. A person having ordinary skill in the art will
appreciate that a variety of anchoring elements can be used with
the present invention.
[0025] FIG. 2 illustrates another embodiment of a catheter 40
according to the present invention. The catheter 40 is similar to
catheter 10 in that it includes a proximal portion 42, a distal
portion 44 having first and second branch members 46, 48, and a
connector 50 disposed therebetween. The catheter 40 also includes
first and second anchoring elements 52, 54 disposed on the first
and second branch members 46, 48 and effective to anchor the branch
members 46, 48 between a spinous process and transverse process of
at least one vertebral body. First and second lumens 56, 58 extend
through the catheter 40 and include distal portions (not shown) in
communication with the first and second anchoring elements 52, 54
for inflating the anchoring elements 52, 54.
[0026] While the catheter 40 is very similar to catheter 10 shown
in FIG. 1, the connector 50 differs in shape. As shown, the
connector 50, rather than having a Y-shape, has a substantially
straight portion 60 that extends between the proximal portion 42
and the second branch member 48, and a side-arm 62 that extends
outward from the straight portion 60 and mates to the first branch
member 46. This configuration allows the second branch member 54 to
be positioned along one side of the spinous process and the first
branch member 52 to extend around and along the other side of the
spinous process.
[0027] Catheter member 40 further includes at least one centering
mechanism 64, 66 disposed within each of the first and second
anchoring elements 52, 54. The centering mechanisms 64, 66 can have
a variety of configurations, and can be effective to maintain
symmetry of the first and second branch members with respect to the
patient's spinal column, and/or to receive a radiation source and
to deliver the source uniformly to a treatment site. As shown in
FIG. 2, the centering mechanisms 64, 66 are expandable balloon
members that are adapted to fit within the outer anchoring element
52, 54. When inflated, the centering mechanisms 64, 66 can be
spaced a predetermined distance apart from the outer anchoring
element 52, 54 and/or each other, or alternatively the centering
mechanism 64, 66 can engage the anchoring elements 52, 54 upon
inflation. Each centering mechanism 64, 66 can also vary in shape
and size, depending on the intended use. The size can, however, be
selectable during treatment by inflating each centering mechanism
64, 66 to a desired level. The number of centering mechanism 64, 66
used can also vary depending on the intended use and on the length
of the first and second branch members 46, 48. In an exemplary
embodiment, branch members 46, 48 that have a length adapted to
extend across several vertebrae include one or more centering
mechanisms 64, 66 to assist in positioning each branch member
between the spinous process and transverse process of each
vertebra.
[0028] In use, each centering mechanism 64, 66 is in communication
with a lumen in the catheter 40 for inflating the centering
mechanisms 64, 66. Preferably, the catheter 40 includes four lumens
56, 57, 58, 59. The first and second lumens 56, 58 include one or
more ports (not shown) that communicate with the first and second
anchoring elements 52, 54, respectively. The third lumen 57 can
include a port (not shown) disposed within each centering mechanism
64 in the first branch member 46, and the fourth lumen 59 can
include a port (not shown) disposed within each centering mechanism
66 in the second branch member 48. By way of non-limiting example,
FIG. 3 illustrates the second branch member 48 having inner lumen
58 (shown in FIG. 2) in communication with port 55 disposed within
anchoring element 54. FIG. 3 further illustrates each centering
mechanism 66 having a port 67 disposed therein. A person having
ordinary skill in the art will appreciate that a variety of
configurations can be provided for inflating the anchoring elements
52, 54 and the centering mechanisms 64, 66. In addition, centering
mechanisms 64, 66 can be separately expandable or inflatable by,
for example, providing separate lumens to each centering mechanism
to allow for selective inflation. Where centering mechanisms 64, 66
are inflated with a radioactive treatment fluid to treat the target
proliferative tissue, this configuration can allow selective
treatment (by providing differing doses from the centering
mechanisms) along the lengths of branch members 46 and 48 as well.
Still further, centering mechanisms 64, 66 can, in one embodiment,
perform the function of anchoring elements 52, 54, thus obviating
the need to have separate anchoring elements.
[0029] With no limitation intended, anchoring elements and the
centering mechanisms can be formed from a polymeric film wall,
which may comprise a biocompatible, radiation resistant polymer.
Suitable polymers include, for example, silastic rubbers,
polyurethanes, polyethylene, polypropylene, polyester, and PVC.
Still further, the centering mechanisms can be formed according to
the balloon and/or expandable surface elements described in U.S.
Pat. No. 6,413,204, issued Jul. 2, 2002, and entitled "Interstitial
Brachytherapy Apparatus and Method for Treatment of Proliferative
Tissue Diseases," which has been incorporated herein by reference
above.
[0030] The present invention also provides a method for treating
spinal metastases. FIG. 4 illustrates one embodiment of a spinous
process catheter 80 having a single branch member 82. A person
having ordinary skill in the art will appreciate that a variety of
catheters can be used, and that the catheter can have any number of
branch members for providing radiation to various portions of a
patient's spinal column. As shown, a surgeon intra-operatively
places the branch member 82 of the catheter 80 into a patient's
spinal column and guides it between the spinous process 84 and
transverse process 86 of one or more vertebrae. Preferably, where
two branch members are used, a first branch member is positioned on
one side of the spinous process, and a second branch member is
positioned on the second side of a patient's spinous process. The
anchoring element 88 can then be inflated with air or other fluids,
such as saline or a radiation absorbing fluid such as a contrast
media used in angiography. Where centering mechanisms are provided,
one or more of the centering mechanisms can optionally also be
inflated with air or other fluids.
[0031] The catheter 80 can be pre-loaded with a radioactive source,
or alternatively the radioactive source can be inserted into the
catheter 80 via one of the lumens (not shown). In one embodiment,
one or more solid radioactive seeds may form the radioactive
source. The seed or seeds can be located within a lumen in branch
member 82 by locating the seed or seeds on a wire that can be moved
into, caused to dwell in, then be removed from the lumen using an
afterloader such as those commonly found in hospitals in which
radiotherapy is applied. The radioactive source, especially where
the radioactive source is provided in the form of a liquid, can be
disposed within one or more of the centering mechanism or within
the anchoring element 88. Preferably, the radioactive source dwells
in each centering mechanism until the prescribed dose of
radiotherapy is delivered, or the radioactive source can be
inserted for prescribed amounts of time on a daily or other
scheduled basis until the prescribed dosage has been achieved. The
radioactive source is then retrieved and the catheter 80 is
removed. The application of radiotherapy using a radioactive source
within catheter 80 can also be performed according to the many
descriptions and examples provided in U.S. Pat. No. 6,413,204,
issued Jul. 2, 2002, and entitled "Interstitial Brachytherapy
Apparatus and Method for Treatment of Proliferative Tissue
Diseases," which has been incorporated herein by reference above.
The radiation treatment may end upon removal of the brachytherapy
apparatus 80, or the brachytherapy may be supplemented by further
doses of radiation supplied externally.
[0032] Suitable radiation sources for use with the system of the
present invention include both solids and liquids. By way of
non-limiting example, the radiation source can be a radionuclide,
such as I-125, I-131, Yb-169, Ir-192 as a solid source, I-125 as a
solid source, or other radionuclides that emit photons, beta
particles, gamma radiation, or other therapeutic rays. The
radioactive material can also be a fluid made from any solution of
radionuclide(s), e.g., a solution of I-125 or I-131, or a
radioactive fluid can be produced using a slurry of a suitable
fluid containing small particles of solid radionuclides, such as
Au-198, Y-90. Moreover, the radionuclide(s) can be embodied in a
gel. One radioactive material useful in the invention is
Iotrex.TM., a sterile single use, non-pyrogenic solution containing
sodium 3-(.sup.125I)iodo-4-hydroxybenzenesulfonate (.sup.125I-HBS),
available from Proxima Therapeutics, Inc. of Alpharetta, Ga..
[0033] Solid radioactive micro spheres of the type available from
the 3M Company of St. Paul, Minn., may also be used. This
radioactive source can either be preloaded into the catheter at the
time of manufacture or loaded into the device after it has been
implanted into the space formerly occupied by the excised tumor
with one or more solid radioactive micro spheres inserted through
the catheter on a wire, for example, using an afterloader (not
shown). As with the liquid radioactive source embodiment, the solid
radioactive source embodiment may also be used to selectively apply
radiotherapy along the length of catheter 80. A plurality of seeds
can be provided in a spaced relation along a wire so that they are
located proximate to the region of selective treatment.
Alternatively, one or more seeds can be moved by the afterloader so
as to provided desired dwell times proximate to regions of
selective treatment.
[0034] The system of the present invention can also have a variety
of other configurations. For example, the device can be adapted to
control the distribution of radiation to tissue surrounding the
treatment site. One advantage to controlling the distribution of
radiation to tissue surrounding the treatment site is that a
minimum prescribed dose can be delivered to the tissue in the
target treatment region without over-exposing radiation-sensitive
tissue, which can cause healthy tissue necrosis. By way of
non-limiting example, referring to FIG. 2, each centering mechanism
64, 66 can be effective to receive a radiation source and to
position the radiation source a predetermined distance apart from
each anchoring element 52, 54, thereby providing a minimum absorbed
dose for delivering radiation to tissue adjacent the anchoring
element. This configuration is described in more detail in U.S.
Pat. No. 6,413,204, issued Jul. 2, 2002, and entitled "Interstitial
Brachytherapy Apparatus and Method for Treatment of Proliferative
Tissue Diseases," which has been incorporated herein by reference
above. In general, the centering mechanisms and the anchoring
elements have a volume that is configured to provide an absorbed
dose within a predetermined range throughout a target tissue.
[0035] In another embodiment, at least one of the anchoring element
52, 54 and/or the centering mechanisms 64, 66 can be partially
coated with a radio-opaque material effective to shield radiation
sensitive tissue from a portion of the radiation source. The
coating (not shown) can be strategically positioned to shield
radiation sensitive tissue, and/or to provide an asymmetric isodose
curve as described in U.S. Pat. No. 6,482,142, issued on Nov. 19,
2002, and entitled "Asymmetric Radiation Dosing Apparatus and
Method," which is incorporated herein by reference.
[0036] Radio-opaque materials suitable for coating onto an
expandable surface include, for example, barium, tungsten, bismuth,
tantalum, and tin. As an alternative to coating the anchoring
elements and/or the centering mechanisms with a radio-opaque
material, a radiation-blocking or absorbing shield (not shown) can
be positioned between each anchoring element and the centering
mechanisms disposed therein, or within the centering mechanisms to
produce a desired isodose curve. A person having ordinary skill in
the art will appreciate that other configurations may be employed
to achieve the desired isodose curves and/or shielding of radiation
sensitive tissue. In particular with the present invention,
longitudinal shielding could be provided between the radiation
source and the patient's spinal cord in order to treat cancerous
tissue in and around the spine while protecting the spinal cord
from radiation.
[0037] In yet another embodiment, the radiation source itself can
be configured to provide radiation to a desired region of tissue
surrounding the interstitial space. By way of non-limiting example,
the radiation source can comprise a wire having one or more solid
radioactive particles located thereon. The radioactive source can
either be preloaded into the catheter at the time of manufacture,
or loaded into the device after it has been implanted into the
space formerly occupied by the excised tumor. If loaded after
implantation, the solid radiation emitting material can be inserted
through one of the lumens 56, 57, 58, 59 (or through another lumen)
on a wire, for example, using an afterloader (not shown). In this
embodiment, the catheter 40 may need to be adapted to have a size
sufficient to receive such a radiation source. The radiation source
has an asymmetric configuration with respect to a longitudinal axis
of the instrument. That is, radiation source is shaped so as to
result in an isodose profile that varies radially about the
longitudinal axis A. The asymmetrically shaped isodose curve may be
created by providing a plurality of solid radioactive particles on
a curved wire in a spaced apart relationship. This configuration
will result in certain of the solid radioactive particles being
farther from the longitudinal axis of the instrument than others,
and will result in the illustrated asymmetric isodose profile.
[0038] One way to provide the radioactive source configuration is
to form wire from a solid or tubular shape memory alloy such as
nickel-titanium alloys known in the art to have such properties.
Wire can then be preformed to the desired shape, can be compressed
into a substantially straight configuration to pass through the
first lumen, and will resume its desired shape once inside volume
where wire will be free from steric constraints imposed inside the
first lumen. The resulting asymmetric isodose curve can be further
tailored by using solid radioactive particles having differing
specific activities to achieve the desired dosing. Such a
configuration is described in more detail in U.S. Pat. No.
6,482,142, issued on Nov. 19, 2002, and entitled "Asymmetric
Radiation Dosing Apparatus and Method."
[0039] A person having ordinary skill in the art will appreciate
that the foregoing is only illustrative of the principles of the
invention, and that various modifications can be made by those
skilled in the art without departing from the scope and spirit of
the invention. All references cited herein are expressly
incorporated by reference in their entirety.
* * * * *