A method of treatment, clinical treatment assembly, robotic manipulator
and controlling arrangements for the treatment of cancers are described.
The invention has particular application in the treatment of breast
cancer. A robotic manipulator (18) carries a jig assembly (30).
The jig assembly (30) includes an array of treatment probes (52,
54, 56) and a single identification/diagnostic probe (58). The probes
can be moved by the robotic manipulator (18) in three directions
(x, y, .theta.). A subject breast tissue is received in a tank (16)
through an operating window (14), and the robotic manipulator (18)
is to firstly determine the site of a tumour in the breast tissue.
Once the tumour has been located by use of the identification/diagnostic
probe (58), the treatment probes (52, 54, 56) are used to ablate
the tumour by the superposition of ultrasonic waves at a focal region.
A series of such lesions may be performed in sequence to traverse
the full extent of the tumour.
1. A method for use during ultrasonic treatment of a cancer in
subject tissue, comprising: robotically manipulating an array of
two or more ultrasonic treatment probes, that are mechanically focused
onto a con-focal region, to sight said con-focal region on at least
a portion of a target tumour whose site is determined by ultrasound.
2. A method as claimed in claim 1, further comprising manipulating
said array to sight on one or more other focal regions of said target
3. A method claimed in claim 2, wherein said manipulations are
performed as a series of step-wise motions in one plane.
4. A method as claimed in claim 1, further comprising determining
the site of said target tumour by ultrasound, prior to said robotically
manipulating said array.
5. A method in claim 4, wherein said determining said site of said
target tumour includes: ultrasonically scanning at least a portion
of subject tissue in a series of step-wise slices to derive a pseudo
three-dimensional representation thereof.
6. A method as claimed in claim 1, further comprising preceding
said robotically manipulating said array, by mechanically configuring
said array of probes to give a desired convergent con-focal region.
7. A method as claimed in claim 1, further comprising, following
said robotically manipulating said array, activating said probes
to ablate said portion of said target tumour.
9. A method as claimed in claim 7, wherein at least one of frequency,
power and on-time of said probe are adjusted.
10. A method as claimed in claim 7 further comprising, defining
a safe working envelope for said robotic manipulation.
11. A method as claimed in claim 10, wherein said robotic manipulation
is interlocked with said activation such that said robotic manipulation
and said activation cannot occur simultaneously.
12. A method as claimed in claim 1, further comprising locating
and orientating said array and a patient relative to each other,
such that said target tumour site is within the range of motion
of said array.
14. Apparatus for the ultrasonic treatment of cancer in subject
tissue, comprising: an array of (i) two or more ultrasonic treatment
probes, that are mechanically configurable to be focused onto a
desired con-focal region, and (ii) an ultrasonic identification
probe; a robotic manipulator, carrying said array, and operable
to move said array and thus sight said con-focal region; and a programmed
controller which operates to activate said probes and cause motion
of said robotic manipulator in a manner such that said ultrasonic
identification probe is scanned over at least a portion of said
tissue to determine a site of a target tumour, and said treatment
probes are sighted such that said con-focal region coincides with
at least a portion of said target tumour and are activated to ablate
said portion of said target tumour.
15. The apparatus of claim 14, wherein said controller activates
said robotic manipulator to sight and operate said treatment probes
at other focal regions coinciding with said target tumour.
16. Apparatus as claimed in claim 15, wherein said controller activates
said robotic manipulator as a series of step-wise motions in one
plane to sight and operate said treatment probes in aggregation
to coincide with said target tumour in that plane.
17. Apparatus as claimed in any one of claims 14, wherein said
robotic manipulator operates to cause said identification probe
to scan at least a portion of subject tissue as a series of step-wise
slices to derive a pseudo three-dimensional representation thereof.
18. Apparatus as claimed in claim 14, wherein said array of probes
is mechanically configured to give a desired focal region matching
to said site of said target tumour.
19. Apparatus as claimed in claim 18, wherein said ultrasonic treatment
probes have predetermined parameters to be applied to said target
20. Apparatus as claimed in claim 14, further comprising a procedure
table upon which a subject can lie, having an acoustic window therein
at which said subject tissue is sited.
21. Apparatus as claimed in claim 20, wherein said acoustic window
is arranged to be aligned with the breast of said subject.
22. Apparatus as claimed in claim 14, wherein said controller is
programmed to define a safe working envelope for manipulation.
23. Apparatus as claimed in claim 22, wherein said controller further
interlocks said treatment probes and said robotic manipulator so
that both cannot be operated simultaneously.
24. A jig array assembly for ultrasonic treatment probes comprising:
a central shaft; two or more segmented collars, in a stacked manner
rotatably of said shaft, and adapted to be fixed in a chosen orientation
by a fastener; a respective mounting member extending from each
said collar, and providing mounting point, said mounting point lying
in a common plane orthogonal to said shaft; a respective arm attached
at the end to a respective mounting point; and a respective probe
holder attached to the other end of each said arm.
25. An assembly as claimed in claim 24, wherein each of said respective
arms are of chosen lengths.
26. An assembly as claimed in claim 24, further comprising an identification
ultrasonic probe located at an end of the shaft.
FIELD OF THE INVENTION
 This invention relates to the treatment of cancers. It relates
particularly to the use of focused ultrasonic energy to treat cancers/tumours
in the breast, and in the organs through the clear acoustic window
of the abdominal and supra-pubic routes.
BACKGROUND OF THE INVENTION
 Cancer is a life-threatening medical condition that is deserving
of serious scientific and medical investigation with a view to finding
improved curative treatments. Breast cancer is the most frequent
form that occurs in women. Other common susceptible sites in the
abdomen--affecting both men and women--are the kidney, liver, colon
 Two broad categories of cancer treatment are: direct surgical
manipulation on the affected tissue and non-invasive treatment.
Non-invasive techniques utilise modalities such as X-rays, lasers,
microwave, hyperthermia, cryoablation etc., the selection of which
depends upon the stage, size, shape and position of the target area.
Ultrasound is known to be useful as one form of hyperthermia. Single
focused transducers, however, are not very flexible in creating
a desired spatial distribution of ultrasound energy within the treatment
field. This is because they have a fixed focal depth and frequency
of operation. Also, the size of the focal region may not match the
size of the tumour. To treat the whole abnormal region, an ultrasonic
beam needs to be mechanically scanned over the target area Besides
this, the residual amount of energy residing in dispersion zone
and its overlap during scanning over the target region may result
in undesirable hot-spots in the overlying normal tissue.
 High Intensity Focused Ultrasound is a non-invasive technique
capable of selective destruction of tissue volumes within the body.
The aim is to produce damage in the focal region of an acoustic
beam in a predictable and reproducible manner, while sparing overlying
and surrounding tissue. A specific multi-probe technique, such that
the individual probes are excited in unison, at comparatively low
power levels, is known.
 One example of this known approach--for use in the treatment
of brain cancers--is described in the publication: Chauhan, S, Davies,
B. L., Lowe, M. J., `A Multiple Focused Probe System for HIFU-based
Neurosurgery`, Ultrasonics, vol 39, 33-44, 2001. This approach,
as outlined in the publication, is not directly applicable to the
treatment of abdominal and breast cancers. There are important anatomical
differences between the human torso and head, most notably the bone
enveloping the brain. As such, no immediate acoustic window to the
brain is available without removing a section of the skull. This
limits the ability to manipulate the orientation of the ultrasonic
transducers. In the abdomen, it is the ribs that pose obstacles
to an acoustic window, however there are interstices between the
ribs that make orientation of the ultrasonic probes easier.
 It is an object of the present invention to provide a form
of focused ultrasonic treatment of cancers that seeks to improve
the efficacy of such a modality, and reduce the unwanted damage
to normal tissue.
SUMMARY OF THE INVENTION
 The invention discloses a method for the ultrasonic treatment
of a cancer in subject tissue, comprising the step of:
 robotically manipulating an array of two or more ultrasonic
treatment probes, that are mechanically focused onto a con-focal
region, to sight said focal region on at least a portion of a target
tumour whose site is determined by ultrasound.
 The above step may be preceded by the step of determining
the site of a target tumour by ultrasound. The above step may be
succeeded by the step of activating said probes to ablate said portion
of the target tumour
 The invention further discloses apparatus for the ultrasonic
treatment of cancer in subject tissue, comprising:
 an array of (i) two or more ultrasonic treatment probes,
that are mechanically configurable to be focused onto a desired
con-focal region, and (ii) an ultrasonic identification probe;
 a robotic manipulator, carrying said array, and operable
to move said array and thus sight said focal region; and
 a programmed controller which operates to activate said
probes and said cause motion of robotic manipulator in a manner
such that the identification probe is scanned over at least a portion
of the tissue to determine the site of a target tumour, and the
treatment probes are sighted such that the focal region coincides
with at least a portion of the target tumour and are activated to
ablate said portion of the target tumour.
 The invention yet further discloses a jig array assembly
for ultrasonic treatment probes comprising:
 a central shaft;
 two or more segmented collars, in a stacked manner rotatably
of said shaft, and adapted to be fixed in a chosen orientation by
 a respective mounting member extending from each said collar,
and providing mounting point, said mounting point lying in a common
plane orthogonal to said shaft;
 a respective arm attached at the end to a respective mounting
 a respective probe holder attached to the other end of each
BRIEF DESCRIPTION OF THE DRAWINGS
 The invention is further described by way of non-limitative
example, with reference to the accompanying drawings, in which:
 FIG. 1 is a perspective view of a surgical treatment assembly;
 FIGS. 2A, 2B and 3 are perspective views of a probe jig
assembly in three configurations;
 FIG. 4 is a schematic diagram showing the range of controlled
movement that may achieved by the robotic manipulator;
 FIG. 5 is a perspective view of the robotic manipulator
 FIG. 6 is a schematic block diagram showing the control
circuitry and interface to the robotic manipulator;
 FIG. 7 shows the clinical treatment assembly in use;
 FIG. 8 is a perspective view of a framed cup element of
the surgical treatment apparatus;
 FIG. 9 is a schematic block diagram of the operational modes
of the surgical treatment; and
 FIG. 10 shows a sample display representing surgical planning
using a graphical user interface.
 An embodiment will be described with reference to the treatment
of breast cancer. In particular, a method of treatment, a clinical
treatment assembly, a robotic manipulator and controlling arrangements
therefor will be described. It should be understood, however, that
the invention is not so limited. The various aspects are equally
applicable to the treatment of other forms of cancer through soft
tissue acoustic windows. Embodiments of the invention also can be
applicable in a purely diagnostic mode.
 In summary, a method of treatment, clinical treatment assembly,
robotic manipulator and controlling arrangements for the treatment
of cancers are described. The invention has particular application
in the treatment of breast cancer. A robotic manipulator carries
a jig assembly. The jig assembly includes an array of treatment
probes and a single identification/diagnostic probe. The probes
can to be moved by the robotic manipulator in three directions.
A subject breast tissue is received in a tank through an operating
window, and the robotic manipulator is firstly to determine the
site of a tumour in the breast tissue. Once the tumour has been
located by use of the identification/diagnostic probe, the treatment
probes are used to ablate the tumour by the superposition of ultrasonic
waves at a focal region. A series of such lesions may be performed
in sequence to traverse the full extent of the tumour.
Mechanical and Electrical Arrangement
 FIG. 1 shows a surgical treatment assembly 10 in broad detail.
An operating table 12 has an operating window 14 that is arranged
to receive the patient's breasts. The subject breast is received
into a half-hemispherical framed cup 15 to descend into a tank 16
containing a coupling medium (e.g. degassed water). The patient's
breasts are isolated from the couplant by an elastic membrane forming
a boundary of the operating window 14. Suitable forms of membrane
include latex or polyurethane. A robotic manipulator 18 is sited
partially underneath and partially within the tank 16, and carries
the ultrasonic probe assembly 30 used for the treatment of the subject
breast Operational controls are housed within a cabinet 20, mounted
on the base of the operating table 12. The relative location of
the frame 15 and the robotic manipulator 18 is such that the subject
breast will be within the range of motion of the robotic manipulator.
 Turning then to FIG. 2A, a first form of jig assembly 30
is shown. A central shaft 32 has three segmented collars 34, 36,
38 arranged in a stacked manner on the shaft. Each collar can rotate
about, and be fixed into position on the shaft, typically by a grub
screw or the like (not shown). Each collar has attached to it a
mounting member 35, 37, 39. The top and bottom mounting members
35, 39 in the stack provide an offset such that all three members
provide a mounting point that is co-located in the horizontal plane
through the central collar 36 (i.e. having a common origin). Extending
from the mounting point of each mounting member 35, 37, 39 is an
arm 40, 42, 44, at the free end of which is a sleeve 46, 48, 50,
into which is received respective ultrasound transducer probes.
These probes 52, 54, 56 are best seen in FIG. 2B.
 The orientation of the probes can be adjusted to give a
desired con-focal region by the relative positioning of the arms
40, 42, 44 with respect to the shaft 32 (i.e. the inter-probe angle),
and the respective lengths of the arms 40, 42, 44. These relative
lengths determine the angles of the sleeve 46, 48, 50 (and thus
the respective probes 52, 54, 56) from the horizontal plane. The
embodiment of FIG. 2A differs from that of FIG. 2B in this regard.
 For the configuration of FIGS. 2A and 2B, a symmetrical
focal region is achieved. For the example of FIG. 3, in which only
two probes are in use, a focal region of an irregular (thin) shape
is achieved. The range of adjustments described allows a focus region
to be identified within a half-hemispherical volume of space; this
broadly representing the volume occupied by a breast.
 The resultant shape of focal region can be manipulated further
by the choice of probe, such that small clusters of cancer cells
can be sighted. It is envisaged that the minimum number of treatment
probes is two, since a degree of superimposition must be achieved
in the focus region. Equally, more than three probes may be utilised--the
decision is a clinical one based upon the location and localised
shape of the subject tumour itself. In other words, a desired spatial
focal region is designed by way of the number, type and relative
orientation of the probes.
 The treatment probes typically are extra-corporeal, spherical
bowl types, operating in unison at 2 MHz and a focal depth of 65-80
mm. The focal region of an individual probe is oblate in shape with
typical dimensions of 18 mm and 1.5 mm. In the multiple probe approach,
the desired flexibility can be achieved in the shape, size and energy
distribution within the con-focal region by orienting the probes
in a specific configuration.
 The ultrasonic radiation from the respective probes 52,
54, 56 superimposes in a con-focal manner so that there is, in combination,
a heating effect sufficient to raise the temperature in that focal
region to ablate the targeted cancer cells. The surrounding tissue,
through which the respective ultrasonic waves pass, is spared.
 Of course, once the probes are fixed into alignment it is
only movement of the shaft 32 that can `move` the focal region in
space. In other words, a cancer in the breast typically is of a
far greater size then the focal region, and thus a path needs to
be traversed by the focal region in order to ablate the entire tumour
site. This function is achieved by the robotic manipulator 18.
 The shaft 32 is adapted to receive at its free end a further
ultrasonic identification/diagnostic probe 58. The purpose of this
probe 58 is to provide an image of the target tissue as a function
of distance, that can be used to define positioning of the focus
region achieved by the treatment probes, as will be explained in
further detail below.
 Referring then to FIGS. 4 and 5, these show, respectively,
a generalised schematic diagram and a detailed mechanical arrangement
drawing of the location of the robotic manipulator 18 and the jig
assembly 30 within the tank 16. The shaft 32 supporting the three
probes 52, 54, 56 mounts from a carriage 60 that is able to be moved,
in a controllable manner, in the horizontal plane carried on a platform
62, by an electrical motor 63. The platform 62 is mounted on a further
shaft 64 that passes through a water-tight joint 66 in the base
of the tank 16, terminating on a rotary stage 68. The stage causes
the shaft 64 to be rotated by a further electrical motor 69. The
rotary stage 68 is carried by a further carriage 70 that mounts
from a vertical platform member 72. A yet further electrical motor
74 causes the carriage 70 to be controllably moveable in the vertical
plane. The x and y motion can be achieved by a screw thread or belt-driven
arrangement. Other arrangements, apparent to one skilled in the
art, also are possible. In this way a 3-axis (x, y, .theta.) robotic
manipulator is achieved.
 Plainly, the elements of the robotic manipulator within
the tank need to be appropriately protected from water ingress.
 FIG. 6 shows an electrical schematic diagram representing
control and signalling for the robotic manipulator, and the treatment
and identification/diagnostic probes. A PC-based computer 80 is
programmed to control the operation of the robotic manipulator and
the probes in a manner that will be described below. It has an output
control signal bus (of any inconvenient form) which provides control
signals to three servo-controllers, respective being for the 3-axis
movement of the robotic manipulator. The x-servo unit 84 drives
the x-axis motor 86. The z-servo unit 88 drives the z-axis motor
90. The .theta.-servo unit 92 drives the .theta.-axis motor 94.
 The control signals also control the respective amplifier
units 96, 98, 100 that provide power to excite the respective treatment
probes 52, 54, 56. Each of the motors 86, 90, 94 of the robotic
manipulator includes a form of optical encoder 102, 104, 106 that
provides a relative location (i.e. distance) feedback signal on
the input data bus 108.
 A diagnostic drive unit 110 provides excitation to the identification/diagnostic
probe 58. The probe 58 returns an ultrasound image of a scanned
field as a function of distance. This image signal is provided to
the input data bus 108.
Identification (Diagnostics) and Treatment
 FIG. 7 shows the surgical assembly 10 in use. A subject
lies face down (i.e. prone) on the operating table 12. The subject
breast is received in the framed cup 15 to descend through the operating
window 14 being supported by an elastic membrane 114. The framed
cup 15 is shown in detail in FIG. 8, having a rim 117, and three
arcuate arms 118 ending in a ring 119. The tank 16 is filled with
degassed water 116, providing a medium/couplant for effective transfer
of ultrasound energy into the breast. The jig assembly 30 has been
mechanically pre-configured and is under control of the robotic
manipulator 18. Diagnostics or identification and treatment is then
 Identification (Diagnostic) Mode
 The identification (diagnostic) mode is used to determine
the location of, and shape of cancerous tissue in the breast. This
is achieved by use of the identification/diagnostic probe 58 which
is arranged to propagate an ultrasonic wave to a known depth into
the breast and then progress in the z-axis to perform a slice-wise
scan of the breast. The breast is mapped to a coordinate system
operating in three dimensions (typically a Cartesian system). Such
a procedure can be useful to diagnose tumours in the breast, without
subsequent implementation of the ultrasonic treatment, since it
may be the cell cluster is a benign lump or cyst, or chosen to implement
an alternative modality of treatment.
 Planning and Treatment Mode
 Referring now to FIG. 9, a block flow diagram shows the
logic flow of pre-surgical planning and on-line surgical planning.
Central to the pre-surgical and on-line surgical planning is the
provision of a graphical user interface 120. In other words, the
pre-surgical and on-line procedures are undertaken by the physician
solely by use of the GUI 120.
 The pre-surgical planning constitutes the initialisation
of HIFU parameters that effect the thermal dose (step 122). These
parameters include the electrical power levels to individual probes
(calculated from the acoustical intensity required for ablation
in a particular tissue/organ type, taking in to account the transducer
probes' specifications), exposure time, probe orientation, and couplant
temperature. The exposure parameters depend on the shape, size and
extent of the cancer/tumour, as deduced by the radiologist/oncologist
during pre-surgical analysis/diagnosis, and define the thermal dose.
Indeed, the characteristic of the tumour can be determined from
the identification (diagnostic) mode of operation of the apparatus
(discussed above) or by other, conventional imaging modalities.
The joint power levels typically are in the ranges: 100-150 W (electrical),
which manifests itself into an acoustic intensity in the exposures
(i.e. lesions) formed that are required to ablate the target tissue.
The typical exposure levels are 2-8 sec with a subsequent cooling
of 10-15 sec at a given exposure site.
 In the on-line surgical planning, the subject, in an anaesthetised
state, is firstly accommodated, as discussed with reference to FIG.
7, then an initial robot homing operation is performed (step 124)
whereby the robotic manipulator defines its coordinates system (step
126). The identification/diagnostic probe 58 has a role here in
proximity sensing or localisation with reference to the site.
 It is now necessary to accurately relocate the tumour, i.e.
notwithstanding that this has been performed in the pre-surgical
planning stage (step 128). This is achieved through use of the identification/diagnostic
probe 58, that is robotically manipulated to image a series of two-dimensional
slice (typically saggital) through the breast. The physician is
able now to confirm the pre-surgical planning (or make adjustments
to the relevant parameters), but otherwise has confidence that the
robotic manipulator has spatial accuracy with respect to the actual
location of the subject tumour.
 The physician now has a pseudo three-dimensional image of
the breast from which the location of a tumour can be accurately
determined. The physician now demarcates the affected area of the
breast (step 130). References is made here to FIG. 10, which is
a single frame (i.e. single slice) of the graphical user interface
120 showing the process of demarcation.
 The physician has the choice of siting a single lesion,
siting as series of lesions in a single plane, or siting lesions
for the whole volume of the tumour before applying the focused ultrasonic
treatment. One of the considerations in making this choice is that
the shape of the tumour may change after treating any individual
 Once the set of lesions has been so identified, then the
surgical procedure may commence by application of treatment energy
to the configured treatment probes, 52, 54, 56 (step 132). Such
treatment can be in an automatic or manual mode. In other words,
the robotic manipulator can be controlled by the physician to `fire`
and then site the next lesion, or the robotic manipulator can execute
all lesions in a programmed manner. The treatment ends when the
last frame is reached (step 134).
 For the present apparatus, the concept of safety is grossly
different from industrial robots, that aren't designed/configured
to work in vicinity of human beings. Surgical/medical robots are
required to function near and `inside` humans, with human co-operation
and intervention, thus safety principles cannot be adopted directly
from fully autonomous and versatile industrial machines. Due to
the precarious nature of human anatomy and physiology, and thus
the suitably selected medical for a particular treatment, a surgical/medical
robot must be the subject of a stringent safety regimen.
 Mechanically, the robotic system is configured to move in
a restricted and well-defined work-envelope. The practical work-envelope
of the manipulator encompasses the human torso, and thus is capable
to reach and treat cancers/tumours through soft tissue windows in
this region (such as breast tissue, trans-abdominal, supra-pubic
and rib interstices). However, for a specific intervention in a
specific tissue (i.e. in a breast, as described above) and after
patient registration and homing stage, the robot is configured to
move the jig assembly 30 only in a subset of the available work-envelope
with suitably demarcated `go` and `no-go` areas. Safety limit switches
and mechanical interlocks may be provided to restrict the motion
in that area only. The primary control, however, is to restrict
the trajectory by software. For instance, in the case of breast
tissue, an annular cylindrical area is allowed as `go` area. The
radius of the `no-go` inner cylinder is same as the framed cup 15,
followed by a `go` outer annular ring area with extended radius
equivalent to the focal depth of selected ultrasonic probes, followed
by a `no-go` area in rest of the tank. This is done to ensure the
probes enveloping the descended breast can not hit the organ/tissue
at any stage of intervention during the lesioning process.
 Another safety feature can be incorporated in the energy
deployment to the probes. The treatment typically comprises an exposure
of 2-8 seconds, followed by cooling/dead time. The power supply
to the robot is accordingly programmed such that the energy sub-system
to the probes is dormant during any `robot move` operation. Once
the robot places the jig assembly 30 at a suitable lesioning position,
the power to the robot is `cut-off`. In this way, the robot can
not more during the application of ultrasonic energy.
 The embodiment described is with reference to treatment
of breast cancer, however, as foreshadowed, treatment of other cancers
through abdominal or trans-pubic routes are contemplated. The surgical
assembly would need to be modified to provide the appropriate acoustic
window onto the body and the jig assembly also may need to be reconfigured
to better suit the gross physical anatomy of the treatment site.
 Embodiments of the invention offers specific advantages
in that there is precise control over the ultrasonic energy to effectively
ablate the site of tumours. Precise lesions may be obtained to give
effective destruction of only the tumour cells. A reduction in the
duration of intervention, and precise control in terms of crude
and fine adjustments is made possible. The ability to treat the
entire volume of a tumour under automatic robotic control removes
the requirement of the physician/radiologist to have the extensive
experience of visualising the three-dimensional region and manually
guide a probe to the next suitable location/plane. Traditional surgery
on a 2 cm tumour may take up to 2 hours to perform. In contrast,
treatment by the present apparatus may take a greatly reduced time,
even of the order of only 20 minutes. For example, the physician
can chose to program and place any two subsequent lesions far away
from each other in the affected region and thus optimising a lower
or absent `cooling zone` after each exposure. The reduced time under
anaesthetic is beneficial to the subject.
 Numerous alterations and modifications, as would be apparent
to one skilled in the art, can be made without departing from the
broad inventive concept.