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BACKGROUND AND SUMMARY OF THE INVENTION
In the treatment of intracranial lesions with radiation, a number of
practical difficulties exist in conventional procedures. In such
treatments, it is necessary for the treatment beams to be accurately aimed
in all treatment sessions in order to treat effectively with minimum
adverse peripheral consequences. In order to insure accurate
repeatability, it is necessary to positively fix the patient's head with
respect to the radiotherapy machine and/or a CT scanner, and the
mechanisms for accomplishing this have been unwieldy and require removal
and reattachment from treatment session to treatment session. Because of
limitations inherent in conventional procedures, it is difficult to
effectively treat by radiotherapy extremely small intracranial lesions
(i.e. smaller than 4.times.4 centimeters), although treatment of such
lesions would be extremely advantageous in effecting total patient care.
According to the present invention a halo assembly is provided, for use
with a stereotaxic device, which eliminates or minimizes most of the
drawbacks associated with current devices and procedures. Utilizing the
halo assembly, with stereotaxic device, according to the invention, a
method of practicing radiotherapy on a patient having an intracranial
lesion or the like is provided which is substantially more simplified
and/or more accurate than conventional methods.
The preferred stereotaxic device with which the invention is utilized
includes a frame having four radiolucent substantially planar walls
arranged in a quadrate in plan view. Radiopaque indicia means are formed
on each of the walls. The halo assembly comprises a conventional halo for
treatment of cervical fractures, with means for operatively fixing the
position of the halo assembly to the frame walls to positively position
the halo assembly in a predetermined position with respect to the walls.
Also, means are provided for fixing the frames with respect to a
radiotherapy machine. Preferably the frame also includes a substantially
planar base plate substantially perpendicular to the walls, and means
defining a through passage in the base plate, interior of a volume defined
by the walls, for receipt of the halo assembly. Fixation of the halo
assembly to the frame is preferably accomplished utilizing a plurality of
brackets, each bracket having a first portion affixed to the ring
component of the halo assembly, and a second substantially planar portion
extending radially outwardly from the ring component of the halo assembly,
the second portions being substantially coplanar.
The invention also comprises a method of practicing radiotherapy
(rotational or a fixed source) on a patient having an intracranial lesion
or the like. The method comprises the following sequential steps: (a)
Determining the approximate position of the intracranial lesion or the
like in the patient's head. (b) Surgically affixing a halo assembly to the
patient's head to be maintained in place until all radiotherapy sessions
for the patient are completed, taking care to position the ring component
of the halo assembly with respect to the patient's skull so that effective
treatment with radiation will be practiced. (c) Positioning the halo
assembly in, and fixing it to, a stereotaxic guide having radiopaque
indicia associated therewith. (d) Fixing the stereotaxic guide in a CT
scanner. (e) Operating the CT scanner to determine the exact position of
the intracranial lesion or the like with respect to the indicia provided
by the stereotaxic guide. (f) Transferring the patient to a radiotherapy
machine. (g) Fixing the stereotaxic guide with respect to the radiotherapy
machine. (h) Inputting the coordinates of the intracranial lesion or the
like, determined from the CT scan, to the radiotherapy machine. (i)
Operating the radiotherapy machine to provide one treatment session for
the patient, positioned in the stereotaxic guide in the radiotherapy
machine. (j) Removing the halo assembly from the stereotaxic guide. (k)
Replacing the stereotaxic guide on the halo assembly when the patient
returns for the next treatment session, the halo assembly remaining in
place on the patient between treatment sessions. (l) Repeating steps (g)
through (k) until all desired radiotherapy sessions for the patient are
completed; and (m) removing the halo assembly from the patient's head.
Step (a) is preferably practiced utilizing a CT scanner. Also, as a further
step (n) between steps (f) and (g), the patient is removed from the
stereotaxic guide, and as further steps between steps (g) and (i), (o)
proper position of the radiotherapy machine with respect to the
intracranial lesion is tested utilizing a target device in the stereotaxic
guide, and the relative position of the radiotherapy machine is adjusted
if necessary; and (p) the halo assembly is fixed in the stereotaxic guide,
and step (l) further comprises repeating steps (n) through (p) for each
session.
It is the primary object of the present invention to provide for the simple
and effective radiotherapy of patients having an intracranial lesion or
the like. This and other objects of the invention will become clear from
an inspection of the detailed description of the invention, and from the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an exemplary stereotaxic device for use in
practicing the present invention, shown in place on a patient's head;
FIG. 2 is a top view of the device of FIG. 1 with one indicia-containing
wall in plan and the other wall in top perspective, and shown in schematic
association with a CT scanner or a radiotherapy machine;
FIG. 3 is a perspective view of a special halo assembly according to the
present invention, utilized in the stereotaxic device of FIGS. 1 and 2;
FIG. 4 is a top plan view of a stationary target member in association with
the stereotaxic guide of FIGS. 1 and 2; and
FIG. 5 is a perspective view of an exemplary movable target member
utilizable with the structure of FIG. 4.
DETAILED DESCRIPTION OF THE DRAWINGS
A stereotaxic device for use in the method, and with the halo assembly,
according to the present invention is shown generally by reference numeral
10 in FIGS. 1 and 2, and includes a stereotaxic guide, shown generally by
reference numeral 12, and a halo assembly 14 according to the invention.
The assembly 14, has means associated therewith for operatively fixing it
to the stereotaxic guide 12.
The stereotaxic guide main components comprise a frame, which preferably
has four radiolucent substantially planar walls 16, 17, 18, 19 arranged in
a quadrate (square) in plan view. A substantially planar base plate 20 is
disposed substantially perpendicular to the walls 16 through 19, with
means defining a through passage 21 (see FIG. 2) in the base plate 20,
interior of a volume defined by the walls 16 through 19, for receipt of
the halo assembly 14. The base plate 20 also preferably comprises
portions, such as mounting disc 23 and mounting grooves 24, for fixing the
frame with respect to a radiotherapy machine, CT scanner, or the like.
Such means 23, 24 (see FIG. 2) are disposed exteriorly of the volume
defined by the walls 16 through 19.
Each of the walls 16 through 19 include radiopaque indicia means formed
thereon. Such indicia means are provided for determining the x, y, and z,
coordinates of an intracranial lesion or the like, which ultimately will
be treated by radio-therapy. The indicia may take a variety of forms, such
as metallic layered strips or the like applied to the walls 16 through 19.
A preferred form of the indicia means is illustrated in FIGS. 1 and 2, and
comprises a plurality of parallel linear grooves 26 formed in the walls 16
through 19, extending substantially from the bottom to the top thereof,
perpendicular to the base plate 20. The grooves are spaced from each other
a predetermined distance, a spacing of 5 millimeters being effective. The
indicia means further comprises at least one diagonal linear groove formed
in each wall 16 through 19, two such diagonal grooves 27 being shown
associated with each wall 16 through 19 in the embodiment illustrated in
the drawings. In use, the grooves 26 provide x-y location, while the
diagonal grooves 27 provide depth (z) location.
The grooves 26, 27 may be formed by any suitable means, such as by
machining or etching. The diagonal grooves 27 preferably are disposed in a
general V-shape as illustrated in FIG. 1, and are of a greater depth than
the parallel grooves 26. While a wide variety of suitable materials are
utilizable for the stereotaxic guide 12, one particular useful material is
Lucite, or a like transparent hard thermoplastic material. The edges of
the grooves 26, 27 are, in practice, radiopaque although the material
forming the walls 16 through 19 itself is not. The term "radiopaque" as
used in the present specification and claims means that the indicia will
show up on a scan display, and thus may be utilized for positively
locating the intracranial lesion or the like, which also will show up on
the scan display.
The halo assembly 14 according to the invention is shown most clearly in
FIGS. 2 and 3. The basic halo assembly is a conventional device commonly
utilized for the treatment of cervical fractures. The term "halo assembly"
as used in the present specification and claims means such conventional
halo assemblies which comprise a relatively narrow width oblong ring
component 30 (which may be formed in two parts which are adjustable with
respect to each other, and bolted together, as illustrated in FIGS. 2 and
3) with a plurality (e.g. four) of skin penetrating pins 32 extending
radially through the ring component 30 and operatively engaging (e.g. by
screw-threading) the ring component 30 for positive positioning with
respect to the ring component. A special halo assembly according to the
invention, shown in FIG. 3 includes--in addition to the conventional halo
assembly components--a plurality of brackets, shown generally by reference
numerals 34. Each bracket 34 has a first portion 35 thereof affixed (e.g.
welded or riveted) to the ring component 30 (such as to the exterior
peripheral surface thereof), and a second substantially planar portion 36
extending radially outwardly from the ring component 30. The planar
portions 36 of each of the brackets 34 are substantially coplanar and
adapted to the be connected to the stereotaxic guide 12.
In the embodiment illustrated in the drawings, each of the second portions
36 of the brackets 34 has a through-extending opening 37 formed therein,
which cooperates with a corresponding opening in the base plate 20 through
which the shaft of a fastener 39 passes. Each fastener shaft 39 preferably
is screw-threaded, as is the interior of each of the openings 37 and the
corresponding openings in the base plate (see FIG. 2). The brackets 34,
fasteners 39, and base plate 20 with cooperating openings for the
fasteners 39 formed therein, collectively comprise means for operatively
fixing the position of the halo assembly 14 to the frame walls 16 through
19 to positively position the halo assembly in a predetermined rigid
position with respect to the walls 16 through 19. As illustrated in FIG.
2, the upper faces of the second portions 36 of the brackets 34 are
preferably disposed flush with the bottom of the base plate 20, with the
fasteners 39 extending through each.
The halo assembly 14, being of the type commonly worn by patients with
cervical fractures preferably is made of aluminum or other suitable
radiolucent material, and once surgically attached by conventional
techniques is worn by the patient inbetween treatment sessions. When the
halo assembly 14 is fixed with respect to the stereotaxic guide 12, as
illustrated in FIG. 2, and the guide 12 is in turn fixed to a CT scanner
or radiation therapy machine (shown schematically by reference numeral
42--a typical scanner is illustrated in U.S. Pat. No. 4,002,917), the
position of the patient's head with respect to the machine 42 is
positively determined.
Operation
In the method of practicing radiotherapy on a patient having an
intracranial lesion or the like according to the invention, the
approximate position of the intracranial lesion or the like in the
patient's head is first determined. This preferably is accomplished
utilizing a conventional CT scanner. With this information in mind, the
halo assembly 14 is surgically affixed to the patient's head in a position
which will ultimately allow proper positioning of the intracranial lesion
within the stereotaxic guide 12. The halo assembly 14 is worn by the
patient over the entire time period from the first radiotherapy session to
the last, the patient being able to function normally with the halo
assembly 14 in place.
The halo assembly 14 is positioned in, and fixed to, the stereotaxic guide
12 utilizing the readily releasable fasteners 39, which pass through the
openings 27 in brackets 34 and the corresponding openings in the base
plate 20 once such openings are aligned. In this position the ring
component 30 of the halo extends through opening 21 into the volume
defined by the walls 16 through 19. The guide 12 is then fixed in a CT
scanner, such as by utilizing mounting disc 23 and mounting grooves 24
associated with base plate 20, and the CT scanner is operated to determine
the exact position of the intracranial lesion or the like with respect to
the indicia 26, 27 provided by the stereotaxic guide 12.
The stereotaxic guide 12 utilized for diagnosis with the CT scanner
preferably has openings formed thereon which allow adjustment of the
position of the halo assembly 14 with respect to it. This makes proper
location of the intracranial lesion simpler. Ultimately, when the patient
goes to a rotational or fixed source radiotherapy machine, a second
stereotaxic guide may be utilized--that being of the type illustrated in
the drawings--where adjustment between it and the halo assembly 14 is not
provided.
Usually the halo assembly 14 will be removed from the stereotaxic guide 12
after the diagnostic scan, and the patient will thereafter immediately (or
at some subsequent date) go to a radiotherapy machine. A stereotaxic guide
12 is fixed with respect to the radiotherapy machine, and the coordinates
of the intracranial lesion determined from the CT scan are inputted into
the radiotherapy machine. The proper positioning of the radiotherapy
machine (i.e. the treatment source thereof) with respect to the
intracranial lesion is tested utilizing a target device mounted in the
stereotaxic guide, and the relative position of the radiotherapy machine
is adjusted if necessary.
A typical target device is illustrated in FIGS. 4 and 5, and includes a
stationary base 50 (see FIG. 4) having x and y coordinates thereon, and
radially extending brackets 51 which cooperate with the base plate 20 of
the stereotaxic guide 12 in the same manner that brackets 42 cooperate
with it. A movable target member 53, including a magnetized base 54 which
is mounted on the target plate 50, is movable to the appropriate x,y
coordinate. An actual target component 55 of the movable target member 53
is vertically positionable on the shaft 56 of the device 53 to determine
the z coordinate. The component 55 is moved to the appropriate x, y, z
coordinates for the intracranial lesion, the radiotherapy machine is
actuated, and the position is tested.
Once it is determined that the radiotherapy machine is operating properly,
the target device is removed and the patient's halo assembly 14 is mounted
in the stereotaxic guide 12 and the radiotherapy machine is operated to
provide one treatment session for the patient. Note that the patient's
head will be positioned in the stereotaxic guide and in the radiotherapy
machine so that the treatment radiation is applied to the intracranial
lesion. In this manner an extremely accurate treatment can be provided,
with treatment of intracranial lesions on the order of 4.times.4
centimeters being possible.
Once one treatment session is completed, the halo assembly 14 is removed
from the stereotaxic guide, and the patient is free to move about. When
the patient ultimately returns for the next treatment session, the halo
assembly 14 is again fixed in the stereotaxic guide 12, and the treatment
steps (including testing) practiced in the first treatment session are
repeated. Each session follows the same procedures until finally all
radiotherapy sessions for the patient are completed, at which time the
halo assembly is surgically removed from the patient's head.
It will thus be seen that according to the present invention a simple yet
effective method of practicing radiotherapy on a patient having an
intracranial lesion or the like, has been provided. While the invention
has been herein shown and described in what is presently conceived to be
the most practical and preferred embodiment thereof, it will be apparent
to those of ordinary skill in the art that many modifications may be made
thereof within the scope of the invention, which scope is to be accorded
the broadest interpretation of the appended claims so as to encompass all
equivalent structures and methods.
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