Biopsy system and method

Abstract

A system for and method of examining a volume of tissue and taking a sample therefrom are described. The system comprises: at least first and second radiation detection modules disposed apart from one another to define a receiving zone therebetween for receiving a volume of tissue to be examined; each detection module comprising a detector system in communication with an data module configured in use to receive radiation from the volume of tissue to be examined, determine spatially registered information about the radiation so received, and construct spatially registered data about the structure and / or function of the volume of tissue from the spatially registered information; wherein one of the detection modules further comprises a biopsy tool, and the detector system of that said one of the detection modules comprises a detection area defining and at least partially surrounding an open portion, and the biopsy tool is configured to be moveable through the open portion and thereby into and out of the receiving zone. A method based on the operation of such a system is also disclosed.

Description

[0001] BIOPSY SYSTEM AND METHOD

[0002] Field of Invention

[0003] The invention relates to a biopsy system for taking a sample of tissue from a subject, while examining and for example imaging the volume from which the sample of tissue is being taken to improve sampling accuracy. The invention in particular relates to a biopsy system combining a biopsy tool and a nuclear medicine imaging system whereby the tool may take a sample of tissue from a subject under guidance from an image of the volume from which the sample of tissue is being taken generated by the nuclear medicine imaging system. Suitable nuclear medicine imaging systems include single-photon emission computed tomography (SPECT). Methods for taking a sample of tissue from a subject, while imaging the volume from which the sample of tissue is being taken are also described.

[0004] Applications include scenarios where the target sample is a biopsy sample human or other animal tissue, and in particular where the target sample is human breast tissue, and where the nuclear medicine imaging system or method is molecular breast imaging.

[0005] Background to the Invention

[0006] Various systems and methods are known to obtain image data from a part of the volume of the body of a subject for medical and related purposes, and in particular for the imaging of human breast tissue.

[0007] Examples include nuclear medicine imaging systems and methods, where radiation from a radioisotope source is caused to pass to a part of the body comprising a region of interest of a subject under investigation, and where spatially registered information about the radiation received at a remote detector is used to obtain information regarding the structure and / or the real time physiological function of that part of the patient’s anatomy, and for example to build up an image of that structure and / or physiological function. An example of an established nuclear medicine imaging technique is single-photon emission computed tomography (SPECT) which is a nuclear medicine tomographic imaging technique using gamma rays. The technique requires the delivery into the patient, for example via the bloodstream, of a gamma-emitting radioisotope. In a typical application, the radioisotope is bound to a specific ligand, allowing it to be carried to and bound within a region of interest in the body of the subject under investigation.

[0008] The radioisotope emits gamma rays which passes through the tissue of the subject under investigation and can be detected at a suitable detector, and for example by a gamma camera. SPECT imaging by the gamma camera acquires multiple two- dimensional images which are then built up into a three-dimensional dataset using a suitable tomographic reconstruction technique.

[0009] Similar principles are employed in positron-emission tomography (PET). In this case a positron-emitting radioisotope, again typically as part of a radioligand, is introduced into the body. In this case, the emitted positron is locally annihilated, and the system detects the pairs of gamma rays emitted indirectly by this annihilation event.

[0010] Both techniques are particularly powerful, allowing not merely imaging of the relevant part of the body but active functional imaging of biological processes.

[0011] A further known technique for imaging of breast tissue, for example to detect abnormalities that might lead to the early detection of breast cancer, is mammography. Standard mammography uses X-rays to create images. These images are then analysed for abnormal findings and in particular for characteristic dense masses that might indicate potential tumours for example. These patients are then referred for further, usually more invasive, testing. Standard mammography is thus a widely adopted first stage screening technique.

[0012] However, the response of normal but relatively dense breast tissue to the low-energy x-rays can be similar to that of the sort of masses that might be indicative of potential development of many commonplace tumours, and the ability of the technique to distinguish in those patients which have a high proportion of high density breast tissue is consequently reduced. Therefore, molecular breast imaging (MBI) is a developed nuclear medicine imaging technique that utilises many of the above principles of SPECT-type techniques. A radioisotope source, again typically bound to a suitable ligand to cause it locate within breast tissue, is introduced into the subject under investigation. A suitable system of small semiconductor-based gamma cameras in a configuration generally corresponding to that for a more conventional mammogram is used to detect radiation from the source after it has passed through the breast tissue. The technique can be particularly effective at detecting incipient tumours, as it can differentiate structures and physiological activity.

[0013] It is generally necessary if suspicious regions of body tissue and for example breast tissue are to be investigated for particular pathologies that a tissue sample is taken for testing, and for example for histological examination. A controllable biopsy tool might be used to take such a sample. The accurate guidance of that tool is of significant importance to the effective use of a biopsy tool and the mitigation of harm or discomfort in the subject.

[0014] For example in seeking to take a biopsy of a suspicious breast lesion, there may be value in guidance of the biopsy tool using a nuclear medicine image of the breast, and for example a MBI image, or using other indications of the location of the lesion. Typically, the lesion is detected using three-dimensional imaging techniques. As such, a location and depth of the lesion can be determined from the image. The depth of the lesion aids, for example, in guiding a biopsy needle during extraction of a lesion sample for pathological examination.

[0015] A typical generic MBI apparatus might be as described in US5519221. In described embodiments therein, the breast immobilised and lightly compressed between two compression plates usually above and below, and two associated camera heads comprising gamma detectors record multiple image views to be reconstructed into a tomosynthetic image.

[0016] However, taking a biopsy in such a system requires to access the breast. In an example system, this may be done by moving the top camera head unit away or by slanting one or both camera heads to gain access to the breast through the top compression plate. The plate is responsible for compressing breast and keeping it in place. Some arrangement is then required to align the biopsy needle with the camera moved away. For example the system could have a grid structure to allow needle insertion. Using the reconstructed MBI image, the cell of the grid above the biopsy location is determined. An additional plastic insert with smaller holes may be dropped into the cell and one of those smaller holes used to insert the biopsy needle and perform the procedure.

[0017] In an example operation of the prior art systems, the depth of the lesion is determined using the ratio between the count rates detected by top and bottom camera heads. After the needle with the sample is taken out, the biopsy jig is removed, the top camera is moved back in its place and a post-procedure MBI scan is performed. A successful biopsy procedure requires observing a visible drop in the count rate coming from the lesion. If that is not observed, the biopsy will be repeated.

[0018] Because in such systems the top camera head is moved out of position to take the biopsy, the technique relies on a prior image to guide the biopsy needle. A simultaneous image from the single camera is in consequence likely to have less clinical value. Guiding the biopsy needle is more difficult and the chance of missing the lesion with the needle is increased.

[0019] In addition, there is a need to verify that the biopsy procedure removed the tissue sample from the intended location. A post-biopsy image of the breast and the needle inside the field of view is taken, which must show a decrease in the size and total activity in the lesion area and detect activity emitted from the removed tissue sample in the needle. If the biopsy is not successfully targeted, it will need to be repeated. As a result, a large number of samples may have to be taken, thereby causing pain and discomfort to the patient.

[0020] As a result, there is a general desire for a biopsy system and method for taking a sample of tissue from a subject that allows for the more accurate simultaneous imaging of the volume from which the sample of tissue is being taken to improve sampling target accuracy and / or reduce the number of samples that may have to be taken. It is also desirable to provide a system which enables a post-biopsy verification image to be more easily obtained. There is a particular desire for a biopsy system and method for taking a sample of human breast tissue that allow for the more accurate simultaneous generation of a MBI image of the breast volume from which the sample of tissue is being taken to improve sampling target accuracy and / or reduce the number of samples that may have to be taken.

[0021] Summary of Invention

[0022] In accordance with the invention in a first aspect, a system for examining a volume of tissue and taking a sample therefrom comprises: at least first and second radiation detection modules disposed apart from one another to define a receiving zone therebetween for receiving a volume of tissue to be examined; each detection module comprising a detector system in communication with a data module configured in use to receive radiation from the volume of tissue to be examined, determine spatially registered information about the radiation so received, and construct spatially registered data about the structure and / or function of the volume of tissue and for example imaging data from the spatially registered information; wherein one of the detection modules further comprises a biopsy tool, and the detector system of that said one of the detection modules comprises a detection area defining and at least partially surrounding an open portion, and the biopsy tool is configured to be moveable through the open portion and thereby into and out of the receiving zone.

[0023] The system requires at least two radiation detection modules disposed apart from one another to define a receiving zone therebetween for receiving a volume of tissue to be examined. In embodiments the system may comprise paired generally opposed detection modules disposed apart from one another, for example in a top and bottom or side to side configuration. A larger plurality of detection modules may be provided for example in an alternative suitable geometry. Each radiation detection module may comprise separately operable submodules. Discussion herein considers in particular by way of example a detector geometry in which paired detection modules are conformed as opposed imaging heads in a top and bottom configuration, but the principles of the invention are not necessarily limited by any particular geometry. The basic structure of the system, comprising at least two spaced and for example generally opposed detection modules disposed apart from one another to define a receiving zone therebetween for receiving a volume of tissue to be examined and for example imaged will be familiar. In use, a volume of tissue, and typically a portion of a human or animal body, and for example of a living human or animal body, is located in the receiving zone. It may be held therein under applied pressure from the respective detection modules, for example conformed as opposed imaging heads in a top and bottom or side to side configuration with pressure plates for this purpose.

[0024] Information about the structure, for example comprising at least an image of the tissue is then obtained for example using a suitable imaging method, which is for example a nuclear medicine imaging method, in particular one where radiation from a radioisotope source is caused to pass to a part of the human or animal body comprising a region of interest of a subject under investigation, whereby spatially registered information about the radiation received at the detectors or is used to obtain information regarding the structure and / or the real time physiological function of that part, and to build up an image of its structure and / or its real time physiological function, as will be familiar.

[0025] The system is not merely an examination / imaging apparatus but is also an apparatus that is able to take a biopsy of a targeted sample from the volume of tissue from a target region identified as a target by the examination. A tool for this purpose is provided in co-operable association with one of the detection modules. In contrast to the prior art, it is arranged such that the particular detection module that is arranged to function co-operably with the biopsy tool is adapted to be so co-operable in two ways. First, the detector system of that said one of the detection modules comprises a detection area defining and at least partially surrounding an open portion, and the biopsy tool is configured to be moveable through the open portion. Second, to facilitate this, the detection module preferably comprises a through aperture aligned with the open portion, and the biopsy tool is configured to be moveable through the aperture and thereby into and out of the receiving zone. In this way, it is not necessary to move the detector module out of position in order to access a volume of tissue in the receiving zone and remove a sample of tissue from a target region. A number of potential advantages accrue, discussed in detail below, including the potential for more accurate targeting of the target region, the ability where useful to continue to image in real time from a paired detector system the target region while sampling, and the ability to maintain a more accurate registration between the biopsy tool and the target region as the biopsy tool is moved into and out of the volume of tissue as the tissue is held between the two detection modules throughout.

[0026] In accordance with the invention, the detector system of the detection module that includes the biopsy tool comprises a detection area defining and at least partially surrounding an open portion. It is not necessary for the detection area fully to surround or to enclose the open portion. At least some functionality may be achieved so long as a detection capability is provided on at least two portions of a detection area spaced apart and with the open portion between them. In preferred embodiments, the detection area may substantially surround the open portion, for example extending around the apertured portion for an extent greater than 180 degrees of a notionally entire surround, although useful effects may be obtained in other embodiments where the detector area extends for less than 180 degrees. In preferred embodiments, the detection area may essentially entirely surround the open portion, for example extending around the apertured portion for an extent approaching a full 360 degrees of a notionally entire surround. In preferred embodiments the detection area may enclose the open portion to define a closed aperture therein.

[0027] This adaptation may be applied to any suitable detection system and in particular any suitable imaging system where the principle is that a target region for biopsy is identified using a nuclear medicine imaging method and deploying a pair of stationary detector heads to produce spatially registered data, such as spatially registered image data, and to build up therefrom a three-dimensional (3D construction) of the structure and / or function of the volume of tissue under examination containing the target region.

[0028] Each detector system must be adapted to detect and allow resolution of spatially registered information about the radiation received at the detector system. The invention may be applied to a detector system comprising multiple discrete detector formations and / or to a single detector formation defining multiple discrete detection areas and / or to a single detector formation defining a single continuous detection area which is virtually subdivided into separately addressed sub-areas. The plurality of responses necessary to obtain spatially registered information about the radiation received at the detector system may be received from multiple detector formations and / or from a single detector formation defining multiple discrete detection areas and / or from a single detector formation defining a single continuous detection area which is virtually subdivided into separately addressed sub-areas.

[0029] Preferably, at least the detector system of the detection module that includes the biopsy tool and optionally both detector systems comprise multiple discrete detector formations.

[0030] In particular, in some embodiments at least the detector system of the detection module that includes the biopsy tool may comprise multiple discrete detector formations disposed to at least partly surround and define an open portion, and the biopsy tool is configured to be moveable through the open portion. In preferred embodiments, the multiple discrete detector formations may be configured to substantially or entirely surround the open portion. In preferred embodiments, the multiple discrete detector formations may be configured to enclose the open portion to define a closed aperture therein.

[0031] Each detector system may be subdivided into discrete regions such as pixels or voxels. In some embodiments, each detector system may comprise a plurality of discrete detector formations. Additionally or alternatively each detector system may comprise a plurality of discrete detector layers. Additionally or alternatively each detector system may be subdivided into discrete regions such as pixels or voxels by suitable signal processing electronics. Additionally or alternatively each detector system may comprise a material inherently exhibiting the ability to localise a radiation interaction and thereby provide spatially registered information. Combinations of such systems will be familiar.

[0032] In some embodiments, each detection module may comprise a substantially or entirely planar detector system. That is to say, the detection surface(s) of the detector system or elements thereof may largely or entirely sit in the same plane, which may be considered a detection plane of the detection system. The respective planar detector systems of the respective detection modules may be configured to be deployed in use face to face in parallel. Such arrangements are often preferred. However, it will be understood that the principles the invention does not require or even necessarily render desirable a strictly planar detector system. A detector system may be generally planar but deviate from strict planarity. For example, where a detector system comprises multiple discrete detector formations, some of these formations may be angled away from a general plane of the detector. Additionally or alternatively, nonplanar surfaces may be provided. Even in such arrangements, it is likely that the surfaces of the detector system or elements thereof lie predominantly in a single plane comprising a general plane of the detector.

[0033] In some embodiments, each planar detector system may comprise an array of detector elements. In such a case, preferably the detector system of the said one of the detection modules that is associated with the biopsy tool comprises an array of planar detector elements disposed around the open portion and for example defining a central aperture, and the biopsy tool is configured to be moveable through the open portion and for example the central aperture and thereby into and out of the receiving zone to take a tissue sample Preferably, the system is a planar detector system with each element of the array of elements having a planar detection surface and the said surfaces positioned in a single detection plane.

[0034] In typical embodiments each detection module is adapted to detect radiation emergent from a volume of tissue located in the receiving zone, and for example high energy photons such as x-rays or gamma-rays. Each detector system preferably comprises detectors for high energy photons such as x-rays or gamma-rays.

[0035] Each detection module is for example an imaging camera. Each detection module is for example a gamma camera.

[0036] In a typical mode of use, the radiation will be generated in the tissue by use of a suitable radioactive tracer source, for example using one of the techniques described above in relation to the prior art. For example the technique is a SPECT, PET or MBI technique. Each detection module is adapted in a typical mode of use for stationary operation, whereby spatially registered information about the radiation is received, spatially registered data about the structure and / or function of the volume of tissue and for example imaging data is constructed, while the volume of tissue is retained between the detection modules.

[0037] Each detection module may be adapted to hold the volume of tissue statically in the receiving zone, and for example to apply a holding pressure thereto. For example, each detection module may comprise a holding face to hold the volume of tissue statically in the receiving zone.

[0038] Typically, the volume of tissue so held may be a part of the body, and for example a human breast.

[0039] Suitable detectors may be familiar to the skilled person, and may include scintillator detectors and semiconductor detectors. In preferred embodiments, the detector systems or detector formations thereof comprise semiconductor detectors.

[0040] In example embodiments, the detector systems or detector formations thereof comprise bulk crystal cadmium telluride type solid state semiconductor detector. The materials making up the semiconductor detector are for example selected from cadmium telluride, cadmium zinc telluride (CZT), cadmium manganese telluride (CMT) and alloys thereof, and for example comprise crystalline Cdi-(a+b)MnaZnbTe where a+b <1 and a and / or b may be zero. Bulk single crystal detectors may be particularly preferred.

[0041] A possible advantage of cadmium telluride type solid state semiconductor detectors in that such materials inherently allow depth of interaction information to be extracted. A possible exploitation of this is discussed in more detail below.

[0042] Preferably, the biopsy tool includes a registration system to fix a registration of the tool before use relative to its associated detection module such as to be operable to a predetermined direction and / or depth into the receiving zone to take a tissue sample from the volume of tissue, the registration system being operable to determine such a predetermined direction and / or depth from the constructed spatially registered data about the structure and / or function of the volume of tissue.

[0043] For example, the biopsy tool comprises positioning means to position the tool in an x, y direction relative to the detection module, defined for example relative to a detection plane of the detection system thereof, and drive means to move the tool through the open portion in a z direction, and the registration system determines these before use from the constructed spatially registered data about the structure and / or function of the volume of tissue.

[0044] Additionally or alternatively, biopsy tool guide means may be provided configured to be selectable from the constructed spatially registered data about the structure and / or function of the volume of tissue to guide the direction of the biopsy tool through the open portion in the detector system. For example, the guide means may comprise a guide plate with a two-dimensional array of holes, locatable in juxtaposition with the open portion such that a selected one of the said holes in use guides the direction of the biopsy tool. Such a guide plate has the additional advantage of maintaining a locating compression on a volume of tissue in the receiving zone. Such a guide plate may be removable. Interchangeable guide plates may be provided.

[0045] The system may be adapted at least in a possible mode of operation for simultaneous examining a volume of tissue and taking a sample therefrom. That is, the system is adapted such that each detection module is configured in use to receive radiation from the volume of tissue to be examined, determine spatially registered information about the radiation so received, and construct spatially registered data about the structure and / or function of the volume of tissue and for example imaging data from the spatially registered information; while simultaneously the biopsy tool is moved into and out of the receiving zone. Notably, in contrast to prior art systems, the detection module associated with the biopsy tool need not be, and in this case is not, moved away from the zone being examined and so an image may be generated using both detector systems to guide the tool.

[0046] In particular, control means are provided operable to move the biopsy tool into and out of the receiving zone in a direction and to a depth determined from the simultaneously generated spatially registered information. In some embodiments, the detector system comprises a means to localise an interaction within the detector to each of an x and a y direction in a plane generally perpendicular to a direction of incident radiation, and a z direction comprising a depth within the detector in a direction generally orthogonal to the x, y plane.

[0047] For example, the detector system comprises a detection surface divided into a plurality of separately addressable detection portions defined positionally across the detection surface in each of two orthogonal directions, hereinafter an x-direction and a y- direction, whereby an interaction at the detection module of a particle of a radiation incident from the source may be localised positionally to a detection portion; and a depth in a third orthogonal direction, hereinafter a z-direction, the radiation detector being configured such that an interaction at the detection module of a particle of a radiation incident from the source may be further localised positionally to a depth in the z direction.

[0048] Thus, the detector system is configured to enable a determination of a depth of interaction (that is, a dimension in a z-direction) at which each photon interaction occurs. This may be achieved in any suitable way by combination of materials, structural features and processing electronics.

[0049] For example, a detector system may be fabricated from a material that inherently allows depth of interaction information to be extracted, such as a bulk crystal cadmium telluride type solid state semiconductor detector as above described. Additionally or alternatively, the detector may comprise multiple discrete layers in a z-direction of suitable detector materials. For example, multi-layer scintillator detectors may be suitable.

[0050] The use of such detectors allows depth of interaction effects such as embodied by the system described in WO2021 / 176232A1 and W02022 / 090722A1 , the disclosure and contents of which are incorporated by reference, in which a combination of a detector with a non-trivial depth by means of which successive responses to successive interactions with incident radiation occurring within the detector may be located in three dimensions comprising two area dimensions and a depth dimension, with a multi-apertured collimator having a non-trivial spread angle for emergent radiation such as a pinhole collimator that introduces complexity through divergence and overlap into the emergent radiation pattern, is exploited to draw additional inferences regarding the pattern of radiation from the target object.

[0051] For example, in embodiments of the system of the invention at least one of and optionally each detection module comprises a collimator associated with each detector, wherein the collimator has a plurality of apertures having a spread angle for emergent radiation, configured such that radiation emergent from the target object is caused to pass through the respective collimators to be incident upon the respective detectors.

[0052] In some embodiments, the collimator comprises a one-dimensional array or a two- dimensional array of at least partly diverging apertures. The apertures may for example have a spread angle of at least 15 degrees.

[0053] In some embodiments, the collimator comprises one or more pinholes. In some embodiments, the collimator comprises a one-dimensional array or a two-dimensional array of pinholes. In some embodiments, the collimator comprises diverging pinholes and for example a one-dimensional array or a two-dimensional array of diverging pinholes.

[0054] A collimator based on an array of pinholes or similar structures acts as a multiplexing filter which will differentially pass only some of the incident radiation on a directionally registered basis to create a pattern which is at least in part a function of position in x, y co-ordinates, to create some registration between x, y in the radiation emitted from the source and x, y at the detector, but not produce a substantially one to one registration in x, y.

[0055] By the use of a multiplexing transformer which intentionally adds some complexity in three dimensions to the radiation pattern, and the purposeful detection and reconstruction of this complexity in three dimensions at the detector, it is possible to reconstruct information regarding the object under test / body from this more complex data with a much lower inherent source level of radioactivity, and for example in the case of medical imaging a consequent lower radiation dose into the patient’s tissue. Such arrangements, particularly with the use of an array of divergent pinholes or similar structures create additional functionality in respect of imaging outside the standard field of view (FOV) of a conventional detector such as a conventional imaging camera. In a parallel hole collimation system, the FOV of is limited to the area which is directly above a single detector array, or directly between paired detector arrays. Therefore, no part of the object outside that area could be imaged. In a non-parallel aperture collimation system used by the invention, the data in the detectors is collected within a certain angular acceptance. The part of angular acceptance going beyond the FOV defined by the detector area would provide addition area which could be imaged without extending the detector coverage to be directly above it. The arrangement additionally offers the ability to exploit minification which may further improve the flexibility / usefulness of the imaging information that can be obtained from the region of interest.

[0056] This may be used to extend the field of view of a planar detector beyond the direct field of view defined perpendicular to the detection plane, and thus mitigate the loss of data that might otherwise be associated with the aperture in the detection system associated with the biopsy tool, making the apertured arrangement more practical.

[0057] In accordance with the invention in a second aspect, a method for examining a volume of tissue in preparation for taking a sample therefrom comprises: disposing at least first and second radiation detection modules each comprising a detector system in communication with a data module apart from one another to define a receiving zone therebetween; receiving a volume of tissue to be examined in the receiving zone; causing radiation to be emitted from the volume of tissue; receiving radiation from the volume of tissue at each detector system and, via the detector module, determining spatially registered information about the radiation so received, and constructing spatially registered data about the structure and / or function of the volume of tissue and for example imaging data from the spatially registered information; wherein one of the detection modules further comprises a biopsy tool, the detector system of that said one of the detection modules comprises a detection area defining and at least partially surrounding an open portion, the biopsy tool is configured to be moveable through the open portion and thereby into and out of the receiving zone, and the method further comprises: using the spatially registered data about the structure and / or function of the volume of tissue to determine a target zone of tissue within the volume of tissue; setting the biopsy tool to be moved through the open portion and thereby into the target zone.

[0058] In a more complete aspect, a method for examining a volume of tissue and taking a sample therefrom comprises the method of the second aspect and the further step of operating the biopsy tool to move through the open portion and thereby into the target zone to take a sample of tissue therefrom.

[0059] In accordance with the method, a volume of tissue, and typically a portion of a human or animal body, and for example of a living human or animal body, is located in the receiving zone. It may be held therein under applied pressure from the respective detection modules, for example conformed as opposed imaging heads with pressure plates for this purpose.

[0060] Information about the structure, for example comprising at least an image of the tissue is then obtained for example using a suitable imaging method, which is for example a nuclear medicine imaging method, in particular one where radiation from a radioisotope source is caused to pass to a part of the human or animal body comprising a region of interest of a subject under investigation, whereby spatially registered information about the radiation received at the detectors or is used to obtain information regarding the structure and / or the real time physiological function of that part, and to build up an image of its structure and / or its real time physiological function, as will be familiar.

[0061] The method identifies and preconfigures a biopsy tool to take, and in the more complete aspect operates the tool to take a biopsy of a targeted sample from the volume of tissue from a target region identified as a target by the examination stage.

[0062] In contrast to the prior art, the biopsy tool and its associated detection module function co-operably in that the biopsy tool moves through an open portion in its detector system and a co-operably located aperture as necessary in the detector module structure, thereby into and out of the receiving zone. In this way, it is not necessary to move the detector module out of position in order to access a volume of tissue in the receiving zone and remove a sample of tissue from a target region.

[0063] The method in both aspects is thus in a preferred case a method of operation of a system of the first aspect, and preferred features of each aspect will be understood by analogy from discussion of other aspects.

[0064] Each detector system must be adapted to detect and allow resolution of spatially registered information about the radiation received at the detector system. The plurality of responses necessary to obtain spatially registered information about the radiation received at the detector system may be received from multiple detector formations and / or from a single detector formation defining multiple discrete detection areas and / or from a single detector formation defining a single continuous detection area which is virtually subdivided into separately addressed sub-areas.

[0065] In some embodiments, each detection module may comprise a planar detector system. The respective planar detector systems of the respective detection modules may be configured to be deployed in use face to face in parallel.

[0066] In some embodiments, each planar detector system may comprise an array of detector elements. In such a case, preferably the detector system of the said one of the detection modules that is associated with the biopsy tool comprises an array of planar detector elements disposed around and defining the open portion and for example enclosing a central aperture, and the biopsy tool is configured to be moveable through the open portion and for example the central aperture and thereby into and out of the receiving zone to take a tissue sample. Preferably, the system is a planar detector system with each element of the array of elements having a planar detection surface and the said surfaces positioned in a single detection plane.

[0067] The method comprises detecting radiation emergent from a volume of tissue located in the receiving zone, and for example high energy photons such as x-rays or gammarays.

[0068] In preferred embodiment of the method, the radiation is generated in the tissue. For example the radiation is generated by use of a suitable radioactive source, and the method comprises first introducing such a source into the volume of tissue.

[0069] The method thus comprises using a nuclear medical imaging technique to generate radiation, determine spatially registered information about the radiation, and construct spatially registered data. Suitable techniques include those described above in relation to the prior art. For example the technique is a SPECT, PET or MBI technique.

[0070] Preferably, the spatially registered data is constructed and for example and image is generated in a stationary mode of operation, whereby spatially registered information about the radiation is received, spatially registered data about the structure and / or function of the volume of tissue and for example imaging data is constructed, while the volume of tissue is retained statically between the detection modules.

[0071] Each detection module may be adapted to hold the volume of tissue statically in the receiving zone, and for example to apply a holding pressure thereto. The method may comprise applying such a holding pressure to hold the volume of tissue statically in the receiving zone.

[0072] Typically, the volume of tissue so held may be a part of the body, and for example a human breast.

[0073] In preferred embodiments, the detector systems or detector formations thereof comprise semiconductor detectors as above described.

[0074] The use of such detectors allows depth of interaction effects such as embodied by the system described in WO2021 / 176232A1 and W02022 / 090722A1 , for example by making use in addition of multiplexing collimators to generate further information in three dimensions which can then be processed to generate further data for locating structures within the tissue.

[0075] Thus, the method may comprise: using the collimator to applying a multiplexing transformation to radiation from the source to create complexity in three dimensions in the pattern of radiation from the source; receiving a plurality of responses each being a response to an interaction with incident radiation occurring within the detector; determining, for each of the plurality of responses, a characteristic of the interaction, wherein the characteristic comprises at least a position in three dimensions of the interaction within the detector; processing the said plurality of responses in accordance with the determined position in three dimensions of each interaction within the detector and drawing inferences therefrom regarding the pattern of radiation from the source.

[0076] The method identifies and preconfigures a biopsy tool to take, and in the more complete aspect operates the tool to take, a biopsy of a targeted sample from the volume of tissue from a target region identified as a target by the examination stage.

[0077] Preferably the method comprises a registration step to fix a registration of the tool before use relative to its associated detection module such as to be operable to a predetermined direction and / or depth into the receiving zone to take a tissue sample from the volume of tissue.

[0078] For example, the tool may have programmable control means and the method may comprise a programming step in which a predetermined direction and / or depth of operation determined from the constructed spatially registered data about the structure and / or function of the volume of tissue is used to create a series of instructions for an operation of the biopsy tool. The method of the second aspect then comprises operating the tool according to the series of instructions.

[0079] Biopsy tool guide means may be provided configured to be selectable from the constructed spatially registered data about the structure and / or function of the volume of tissue to guide the direction of the biopsy tool through the open portion in the detector system, the method comprising selecting such guide means.

[0080] In a preferred embodiment of the more complete aspect of the method, the method comprises simultaneous examining a volume of tissue in accordance with the method of the second aspect of the invention while operating the biopsy tool to move through the open portion and thereby into the target zone to take a sample of tissue therefrom.

[0081] Thus, the method continues to obtain radiation from the volume of tissue to be examined, determine spatially registered information about the radiation so received, and construct spatially registered data about the structure and / or function of the volume of tissue and for example imaging data from the spatially registered information while simultaneously the biopsy tool is moved into and out of the receiving zone. The simultaneously obtained data may be used to guide the tool dynamically.

[0082] Thus the method comprises moving the biopsy tool into and out of the receiving zone in a direction and to a depth determined from the simultaneously generated spatially registered information.

[0083] Alternatively the steps of examining a volume of tissue to determine a target zone and operating the biopsy tool to move through the open portion and thereby into the target zone may be performed sequentially.

[0084] Preferably, the step of obtaining spatially registered information about the radiation comprises localising each radiation interaction within the detector to each of an x and a y direction in a plane generally perpendicular to a direction of incident radiation, and a z direction comprising a depth within the detector in a direction generally orthogonal to the x, y plane.

[0085] Thus, the method enables a determination of a depth of interaction (that is, a dimension in a z-direction) at which each photon interaction occurs. This may be achieved in any suitable way by combination of materials, structural features and processing electronics.

[0086] For example, a detector system may be fabricated from a material that inherently allows depth of interaction information to be extracted, such as a bulk crystal cadmium telluride type solid state semiconductor detector as above described.

[0087] This may be used as above described to extend the field of view of a planar detector beyond the direct field of view defined perpendicular to the detection plane, and thus mitigate the loss of data that might otherwise be associated with the open portion in the detection system associated with the biopsy tool, making the apertured arrangement more practical.

[0088] Thus, the method may comprise, at least in respect of the detector system with the open portion: providing a detector system having an area and a depth and configured to generate successive responses to successive interactions with incident radiation occurring within the detector in such manner as to determine a position of each interaction in three dimensions comprising two area dimensions and a depth dimension; receiving a plurality of responses each being a response to an interaction with incident radiation occurring within the detector system; determining, for each of the plurality of responses, a position of each interaction within the detector in three dimensions comprising two area dimensions and a depth dimension; processing the said plurality of responses by simultaneously processing position data in such manner as to obtain information about parts of the target object within a primary field of view and further information about parts of the target object beyond the primary field of view in the region of the open portion.

[0089] In an embodiment, in a practical implementation, the method comprises: positioning the radiation detector system and the collimator relatively to the region of interest of the target object such that the distance between the radiation detector system and the collimator is smaller than the distance between the collimator and a region of interest of the volume of tissue.

[0090] Particular advantages of the invention may arise in relation to nuclear medicine imaging embodying techniques such as SPECT, PET or MBI. In a preferred embodiment, the method comprises a method for generating a nuclear medicine image, for example using such SPECT, PET or MBI, which is practised on a target object comprising biological tissue. The biological tissue may comprise a sample, or may comprise a part of the body of a living organism. In particular, the method may allow for examination of processes within the organism. Suitable organisms include human and non-human organisms, and the invention may be practised on the human body or tissues, the non-human animal body or tissues, or non-animal bodies or tissues. The method may provide images for a subsequent review stage, for example to determine whether further tests or interventions might be required or to make or contribute to a subsequent diagnostic step. The method may provide images as part of a diagnostic method to determine a condition state therefrom.

[0091] A suitable radioactive source may be introduced into and caused to spread through parts of the tissue, at least in the vicinity of a region of interest.

[0092] The method may comprise in a first step introducing such a radioactive source, for example via the bloodstream of a subject. The source is for example a gamma-emitting radioisotope. The source is for example a positron-emitting radioisotope.

[0093] In a typical application, the radioisotope is bound to a specific ligand, allowing it to be carried to and bound within a region of interest in the body of the organism under investigation.

[0094] In some embodiments, the method further comprises generating an image and optionally further displaying the image. The system may further comprise an image generation module for generating an image and an image display. The method may further comprise generating successive images as a tomographic reconstruction. The system may further comprise a tomographic reconstruction module to effect the same.

[0095] In some embodiments, the image is a tomographic image and the image generation module comprises a tomographic image reconstruction module for generating successive images as a tomographic reconstruction, for example utilising the 3D location of detected events to account for uncertainties in the origin of radioactivity. Optionally, this may be done directly within the reconstruction or as a prior processing step. Optionally, hybrid approaches such as the hybrid method explored below may be employed.

[0096] Other preferred features of the method of the second aspect will be understood by analogy from the discussion of the system of the first aspect and vice versa.

[0097] Brief Description of Drawings The invention will now be described by way of example only with reference to figures 1 to 4 of the accompanying drawings, in which:

[0098] Figure 1 is a view of a system with dual molecular breast imaging and biopsy capability;

[0099] Figure 2 is a further view of the system with dual molecular breast imaging and biopsy capability that may embody the principles of the invention;

[0100] Figure 3A shows a possible modified detector array that embodies the principles of the invention suitable for inclusion in a dual molecular breast imaging and biopsy apparatus as part of the imaging head that combines with the biopsy tool;

[0101] Figure 3B shows some possible alternative geometries of modified detector array that embody the principles of the invention;

[0102] Figure 4 illustrates the extended field of view principles that can be exploited in a possible embodiment of the invention.

[0103] Detailed Description

[0104] An MBI biopsy system shown in Figure 1A in perspective view, and with side and front elevation views respectively in Figures 1 B and 1C. These views do not show the adaptation of the present invention and so could be representative generally both of a prior art system and of an embodiment of the invention.

[0105] This system includes a stand 1 and a camera system 3. The camera system 3 includes a top camera head 5 and a bottom camera head 7. During imaging, the breast is held between the two camera heads 5, 7, typically at least lightly in compression. If the breast is to be accessed for biopsy, a typical operational mode relies the top camera head 5 back thus exposing the breast from the top side. This is shown in that moved back position in the figure 2 close up perspective view.

[0106] There is a plastic plate below the top camera which is responsible for compressing breast and keeping in place. On top of that plate, there is an alignment plastic grid 9 as shown in the alternative view of Figure 2. The grid has ~1 cm cells. Using the reconstructed MBI image, the grid cell above the biopsy location is determined. Lastly, a plastic insert with a 3x3 array of smaller holes is dropped into the cell (see Fig.2). One of those nine holes in the 3x3 array will be used to insert the biopsy needle and perform the procedure. The top camera head 5 could be moved back to expose the breast for performing biopsy.

[0107] The depth of the supposed tumour is determined using the ratio between the tumour area count rates detected by top and bottom camera heads. The tissue sample taken is approximately 20 mm long, therefore the depth coordinate of the tumour location doesn’t require precision beyond a few mm. After the needle with the sample is taken out, the biopsy jig is removed, the top camera is moved back in its place and a postprocedure MBI scan is performed. A successful biopsy procedure requires observing a visible drop in the count rate coming from the supposed tumour area. If that is not observed, the biopsy will be repeated.

[0108] An embodiment of the invention is discussed as a modification of the apparatus of Figures 1 and 2 by way of example only.

[0109] The principles of the invention encompass a biopsy tool provided in co-operable association with one of the camera heads. In contrast to the prior art, it is arranged such that the particular head that is arranged to function co-operably with the biopsy tool has a detector array that comprises an open portion, allowing the head to define a through aperture, and the biopsy tool is configured to be moveable through the aperture and thereby into and out of the breast or other tissue volume to effect the biopsy. It is not necessary to move the camera head out of position in order to access a volume of tissue in the receiving zone and remove a sample of tissue from a target region.

[0110] Examples of such a detector array, and its possible use to modify the prior art system into one comprising an illustrative embodiment of the invention by providing a modified detector system for the imaging head that combines with the biopsy tool are shown in Figure 3 and discussed by way of example. Various possible arrangements are shown, each comprising multiple detector elements. Typically, the array is a planar detector system with each element of the array of elements having a planar detection surface and the said surfaces positioned in a single detection plane.

[0111] The skilled person will of course appreciate that the invention is not limited to this system, or to SPECT MBI systems more generally, and is not limited to modifications of existing designs, whether after market or as original manufacture. Rather the invention potentially encompasses all scenarios within the scope of the claims where a system and method is desired that requires a combined capability to construct spatially registered data about the structure and / or function of the volume of tissue and for example imaging data from the spatially registered information and to use the same to inform a biopsy process using an integrated biopsy tool, and in particular where it is desired to image simultaneously with the biopsy process and to use the image to control and more accurately locate the tool.

[0112] The prior art system is a SPECT system to produce a reconstructed 3D image with two stationary camera heads. Shifting aside one of the camera heads will make the image reconstruction hardly possible. The resulting image will have a very poor quality.

[0113] Applicant’s proposed solution, based on the modified detector arrays of Figure 3 and other consequent modifications as discussed below, provides a solution which would allow to reconstruct a 3D image in the volume around the supposed tumour.

[0114] In a possible embodiment, at least four detectors could be arranged in an array as shown in Figure 3A leaving a square hole in the middle for letting through the biopsy needle. This additional detector array (“biopsy insert”) will be made as a tethered head which could be positioned either manually or mechanically using a motorised jig.

[0115] In this Figure 3A embodiment, the four detectors create a detection area that surrounds, encloses and defines a closed aperture within itself, through which the biopsy tool may pass. In accordance with the invention, the detector system merely needs to provide an open portion, with the detector array being required to create a detection area defining and at least partially surrounding the open portion. It is not necessary for the detection area fully to surround or to enclose the open area. At least some functionality may be achieved so long as a detection capability is provided on at least two portions of a detection area spaced apart and with the open portion between them. Alternative geometries are suggested in Figure 3B.

[0116] In a further possible modification to the prior art system to encompass principles of the invention, the plastic grid of Figure 2 may be replaced, for example, by a flat plastic plate keeping the breast compressed and immobilised with a mechanical fixture for positioning the biopsy insert on top of it.

[0117] A potential design implementation could be as following:

[0118] Manual positioning - the plastic grid shown in Figure 2 will be replaced by another design with a matching structure at the bottom of the biopsy insert. This would allow positioning the insert with a precision comparable to what is possible with the current design. The radiographer will obtain the coordinates of the tumour from the reconstructed 3D image, very similar to how it’s being done now.

[0119] Mechanical positioning - the plastic grid in Figure 2 will be replaced by a jig comprised of a set of motorised stages which would move the biopsy insert into the required place by, for example, pointing at the desired location on the reconstructed image on the computer screen. The biopsy insert could be either integrated into the positioning jig or be a separate unit which will go into a dedicated place in the jig. The motorised version will provide a more precise positioning since the insert location will not be limited by fixed positions of the alignment jig cells as in the case of manual option.

[0120] The imaging data from the biopsy insert with a detector array as in Figure 3 will allow better reconstructing of a 3D image in the volume containing the tumour. The imaging process could be going on during the biopsy procedure providing essentially a real time visualisation of the process along with a possibility to monitor the removal of a part of the tumour as required for a successful biopsy. That would provide a significant improvement to the procedure, making it quicker and removing a potential need for inserting the needle second time.

[0121] A preferred detector material is a semiconductor detector of the cadmium telluride type. Such detectors have an inherent ability to resolve a depth of interaction with incoming photons. If such detectors are used, or others that have in any way an ability to resolve spatially registered information in a z-direction are used with a suitable depth and suitable processing electronics and with a divergent pinhole collimator, this depth information may be used to extend the effective field of view of the aperture detector and mitigate the effect of the aperture in accordance with principles embodied in UK application No 2304760.8 and W02024 / 201081A1.

[0122] The principle is illustrated in Figure 4. A thick bulk semiconductor detector array of cadmium zinc telluride (CZT) is used. Such a detector array intrinsically allows for a depth of a photon interaction in a z direction as well as a location in a particular pixel in x, y to be determined. The invention is not limited to such detectors however. Such a semiconductor detector could be replaced by any “depth sensing” or “3D position sensing” detector structure, including for example scintillator detector modules made of a few layers to provide some depth sensing.

[0123] Figure 4 shows a pinhole collimator being used to project an image from the source to a detection plane. This principle is described generally for example in WO2021 / 176232A1. The source is in the case of the invention a part of a biological system under investigation, into which a radioactive species has been introduced and caused to spread. This reference describes use of a multi-apertured collimator having a non-trivial spread angle for emergent radiation such as a pinhole collimator that introduces complexity through divergence and overlap into the emergent radiation pattern. The same principle is exploited with such a collimator in figure 4.

[0124] In a parallel hole collimation MBI system, the FOV of is limited to the area which is directly above the detector array. Therefore, none of the tissue which is outside that area could be imaged.

[0125] In a collimation system with divergent pinholes such as described and envisage for figure 4, the data in the detectors is collected within a certain angular acceptance around the detector array. The part of angular acceptance going beyond the primary FOV defined conventionally by the detector area would provide additional area which could be imaged without extending the detector coverage to be directly above it.

[0126] In the illustrated embodiment it can be seen that the distance between each detector array and its respective collimator will be smaller than the distance between the collimator and the extended FOV region of interest (ROI) of the imaged object. Therefore, the method would usually involve minification and not magnification as in known methods. Thus, two principles are exploited to give additional functionality: The part of angular acceptance going beyond the primary FOV may be imaged without extending the detector coverage to be directly above it, and the generation of a minified image may be used co-operably with this to collect and present in a tomographic or other image more information from a target object for any given process and level of irradiation. Particular advantages may accrue from this in the embodiment as an MBI system to provide for improved physiologically relevant images from the breast of a patient. Figure 4 illustrates, and UK application No 2304760.8 discusses, extension of the effective field of view outside the detection plane, but the principle may equally be applied additionally to a Figure 3 array to extent the effective field of view into the aperture area.

Claims

CLAIMS1. A system for examining a volume of tissue and taking a sample therefrom comprising: at least first and second radiation detection modules disposed apart from one another to define a receiving zone therebetween for receiving a volume of tissue to be examined; each detection module comprising a detector system in communication with an data module configured in use to receive radiation from the volume of tissue to be examined, determine spatially registered information about the radiation so received, and construct spatially registered data about the structure and / or function of the volume of tissue from the spatially registered information; wherein one of the detection modules further comprises a biopsy tool, and the detector system of that said one of the detection modules comprises a detection area defining and at least partially surrounding an open portion, and the biopsy tool is configured to be moveable through the open portion and thereby into and out of the receiving zone.

2. A system in accordance with claim 1 wherein at least the detector system of the detection module that includes the biopsy tool and optionally both detector systems comprise multiple discrete detector formations.

3. A system in accordance with claim 2 wherein the detector system of the detection module that includes the biopsy tool comprises an array of detector elements disposed around and defining the open portion.

4. A system in accordance with claim 3, wherein the multiple discrete detector formations are configured to substantially surround the open portion.

5. A system in accordance with claim 4, wherein the multiple discrete detector formations are configured to enclose the open area to define a closed aperture therein.

6. A system in accordance with any preceding claim wherein each detector system is subdivided into discrete regions of pixels or voxels.

7. A system in accordance with any preceding claim wherein each detection module comprises a planar detector system and the respective planar detector systems of the respective detection modules are configured to be deployed in use face to face in parallel.

8. A system in accordance with any preceding claim wherein each detection module is adapted to detect high energy photons such as x-rays or gammarays emergent from a volume of tissue located in the receiving zone.

9. A system in accordance with any preceding claim wherein each detection module comprises a gamma camera.

10. A system in accordance with any preceding claim wherein each detection module is adapted for stationary operation, whereby spatially registered information about the radiation is received, spatially registered data about the structure and / or function of the volume of tissue is constructed while the volume of tissue is retained between the detection modules.

11. A system in accordance with any preceding claim wherein each detection module is adapted to hold the volume of tissue statically in the receiving zone, comprising a holding face operable to apply a holding pressure to and hold the volume of tissue statically in the receiving zone.

12. A system in accordance with any preceding claim wherein the detector systems comprise solid state semiconductor detectors.

13. A system in accordance with claim 12 wherein the materials making up the semiconductor detector are selected from cadmium telluride, cadmium zinc telluride (CZT), cadmium manganese telluride (CMT) and alloys thereof, and for example comprise crystalline Cdi-(a+b)MnaZnbTe where a+b <1 and a and / or b may be zero.

14. A system in accordance with any one of claims 1 to 11 , wherein the detector is a scintillator detector comprising a scintillator material coupled to a light sensor such as a SiPM or photodiode.

15. A system in accordance with any preceding claim wherein at least one of and optionally each detection module comprises a collimator associated with each detector, wherein the collimator has a plurality of apertures having a spread angle for emergent radiation, configured such that radiation emergent from the target object is caused to pass through the respective collimators to be incident upon the respective detectors.

16. A system in accordance with claim 15 wherein the collimator comprises a onedimensional array or a two-dimensional array of at least partly diverging apertures.

17. A system in accordance with claim 15 or claim 16 wherein the apertures have a spread angle of at least 15 degrees.

18. A system in accordance with one of claims 15 to 17 wherein the collimator comprises a one-dimensional array or a two-dimensional array of pinholes.

19. A system in accordance with any preceding claim wherein the biopsy tool includes a registration system to fix a registration of the tool before use relative to its associated detection module such as to be operable to a predetermined direction and / or depth into the receiving zone to take a tissue sample from the volume of tissue, the registration system being operable to determine such a predetermined direction and / or depth from the constructed spatially registered data about the structure and / or function of the volume of tissue.

20. A system in accordance with claim 19 wherein the biopsy tool comprises positioning means to position the tool in an x, y direction relative to the detection module, defined for example relative to a detection plane of the detection system thereof, and drive means to move the tool through the open portion in a z direction, and the registration system determines these from theconstructed spatially registered data about the structure and / or function of the volume of tissue.21 . A system in accordance with any preceding claim adapted at least in a possible mode of operation for simultaneous examining a volume of tissue and taking a sample therefrom.

22. A method for examining a volume of tissue in preparation for taking a sample therefrom comprising: disposing at least first and second radiation detection modules each comprising a detector system in communication with a data module apart from one another to define a receiving zone therebetween; receiving a volume of tissue to be examined in the receiving zone; causing radiation to be emitted from the volume of tissue; receiving radiation from the volume of tissue at each detector system and, via the detector module, determining spatially registered information about the radiation so received, and constructing spatially registered data about the structure and / or function of the volume of tissue from the spatially registered information; wherein one of the detection modules further comprises a biopsy tool, the detector system of that said one of the detection modules comprises a detection area defining and at least partially surrounding an open portion, the biopsy tool is configured to be moveable through the open portion and thereby into and out of the receiving zone, and the method further comprises: using the spatially registered data about the structure and / or function of the volume of tissue to determine a target zone of tissue within the volume of tissue; setting the biopsy tool to be moved through the open portion and thereby into the target zone.

23. A method in accordance with claim 22 wherein the detector system of the detection module that includes the biopsy tool comprises an array of detector elements disposed around and defining the open portion, and the method comprises setting the biopsy tool to be moved through the open portion and thereby into the target zone.

24. A method in accordance with claim 22 or 23 wherein each detection module comprises a planar detector system and the method comprises deploying the detector systems of the respective detection modules face to face in parallel.

25. A method in accordance with one of claims 22 to 24 comprising locating a portion of a human or animal body in the receiving zone and holding the portion of the human or animal body in the receiving zone under applied pressure from the respective detection modules.

26. A method in accordance with one of claims 22 to 25 comprising detecting radiation emergent from a volume of tissue located in the receiving zone, and for example high energy photons such as x-rays or gamma-rays.

27. A method in accordance with one of claims 22 to 26 wherein the radiation is generated in the tissue by use of a suitable radioactive source, and the method comprises first introducing such a source into the volume of tissue.

28. A method in accordance with one of claims 22 to 27 wherein the spatially registered data is constructed in a stationary mode of operation, whereby spatially registered information about the radiation is received, spatially registered data about the structure and / or function of the volume of tissue is constructed, while the volume of tissue is retained statically between the detection modules.

29. A method in accordance with one of claims 22 to 28 further comprising a registration step to fix a registration of the tool before use relative to its associated detection module such as to be operable to a predetermined direction and / or depth into the receiving zone to take a tissue sample from the volume of tissue.

30. A method in accordance with claim 29 wherein the tool comprises programmable control means and the method comprises a programming step in which a predetermined direction and / or depth of operation determined from the constructed spatially registered data about the structure and / or function ofthe volume of tissue is used to create a series of instructions for an operation of the biopsy tool.

31. A method in accordance with one of claims 22 to 30 further comprising generating successive images constructed from the spatially registered data as a tomographic reconstruction.

32. A method in accordance with one of claims 22 to 31 further comprising the subsequent step of operating the biopsy tool to move through the open portion and thereby into the target zone to take a sample of tissue therefrom.

33. A method in accordance with claim 22 comprising the simultaneous examining a volume of tissue in accordance with the method of one of claims 22 to 30 while operating the biopsy tool to move through the open portion and thereby into the target zone to take a sample of tissue therefrom.

Images