Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/12—Arrangements for detecting or locating foreign bodies
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
  • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K49/00—Preparations for testing in vivo
  • A61K49/06—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
  • A61K49/08—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by the carrier
  • A61K49/10—Organic compounds
  • A61K49/12—Macromolecular compounds
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K49/00—Preparations for testing in vivo
  • A61K49/06—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
  • A61K49/18—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
  • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
  • A61B2090/3954—Markers, e.g. radio-opaque or breast lesions markers magnetic, e.g. NMR or MRI
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
  • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
  • A61B2090/3966—Radiopaque markers visible in an X-ray image
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K2123/00—Preparations for testing in vivo

Definitions

• This invention relates to fiducial markers.
• CT computer tomographic
• MRI magnetic resonance imaging
• CT computer tomographic
• MRI magnetic resonance imaging
• the body may be subjected to focused treatment to remove or destroy the abnormality, for example using chemotherapy, radiation therapy and/or surgery.
• images of the abnormality are used by a radiologist to adjust the irradiating device and to direct radiation solely at the abnormality while minimizing or eliminating adverse effects to surrounding healthy tissue.
• visualization techniques are used to follow the progress of the treatment.
• the images of the lesion in the patient can guide the surgeon during the operation. By reviewing the images prior to surgery, the surgeon can decide the best strategy for reaching and biopsying, excising, or otherwise manipulating the abnormality. After surgery has been performed, further scanning is utilized to evaluate the success of the surgery and the subsequent progress of the patient.
• markers in the form of wire or beads made of highly radiopaque materials such as gold or tantalum.
• the gold or tantalum marker may lead to production of artefacts in the image produced, for example information may be missing and/or "starbursts" may be present, leading to difficulties in accurately interpreting the images.
• MRI techniques eddy currents may be produced in the gold or tantalum which again may result in the production of artefacts which render image interpretation more difficult. It is desirable that any fiducial marker is visible under MRI, CT and X-ray imaging so that, in any situation, one or more of the techniques may be used to visualize any marker .
• fiducial markers which are as small as possible, to minimise patients' discomfort.
• clinicians require markers to provide a strong signal which implies such markers should be as large as possible.
• a fiducial marker which comprises a radiopaque material encapsulated in a bio-compatible polymeric material.
• Said marker suitably has a maximum dimension measured in a first direction of less than 50mm.
• a marker may be elongate, for example in the form of a string or the like.
• said marker has a maximum dimension measured in a first direction of less than 10mm, preferably less than 8mm, more preferably less than ⁇ mm, especially less than 4mm.
• the maximum dimension may be at least lmm or at least 2mm.
• the maximum dimension in said first direction may be in the range 1.5 to 4mm.
• Said marker preferably has a dimension in a second direction perpendicular to the first direction which is less than said maximum dimension in said first direction.
• the ratio of the maximum dimension in said first direction to said dimension in said second direction may be greater than 1, preferably greater than 1.1, more preferably greater than 1.3, especially greater than 1.5.
• the ratio may be less than 5, preferably less than 4, more preferably less than 3, especially less than 2.
• the volume of the marker may be less than 20mm 3 , suitably less than 15mm 3 , preferably less than 10mm 3 , more preferably less than 8mm 3 , especially less than ⁇ mm 3 .
• the volume may be at least 0.75mm 3 , preferably at least lmm 3 .
• the density of the marker may be at least 1.1 g/cm 3 , suitably at least 1.2 g/cm 3 , preferably at least 1.3 g/cm 3 , more preferably at least 1.5 g/cm 3 , especially at lest 1.6 g/cm 3 .
• the density may be less than 3.5 g/cm 3 , suitably less than 3.2 g/cm 3 .
• the density may be in the range 1.5 to 3 g/cm 3 .
• Said marker preferably has a substantially constant cross- section along at least 50%, suitably at least 70%, preferably at least 90%, more preferably at least 95%, especially about 100%, of its extent in one direction, for example said first direction referred to.
• Said cross- section is preferably substantially symmetrical about a first plane which bisects the cross-section in one direction; preferably also it is symmetrical about two mutually orthogonal planes which bisect the cross-section.
• Said cross-section preferably includes a substantially circular outer wall.
• Said cross-section described may be substantially annular or circular. It preferably includes substantially no void areas.
• Said cross-section preferably has an area of less than 5mm 2 , preferably less than 4mm 2 , more preferably less than 3mm 2 , especially less than 2mm 2 .
• the area may be less than 1.5mm 2 .
• the area is preferably greater than 0.5mm 2 .
• Said cross-section is preferably of substantially constant shape on moving from one side of the marker to an opposite side thereof.
• said marker may be substantially spherical .
• Said fiducial marker may be in the form of an extruded tube, coil or solid member.
• Said marker preferably includes substantially no void areas; it is preferably substantially solid throughout.
• Said radiopaque material is preferably an integral part of said marker. Said radiopaque material is preferably not flowable within the marker. Said radiopaque material is preferably substantially immovably fixed in position in said marker so that its position relative to that of the polymeric material is substantially immovably fixed.
• Said radiopaque material is preferably covered, at least in part, by said bio-compatible polymeric material. Said radiopaque material is preferably substantially fully enclosed by said bio-compatible polymeric material.
• Radiopaque material and polymeric material are preferably contiguous. Preferably substantially all of the radiopaque material is contiguous with bio-compatible polymeric material.
• Said fiducial marker preferably includes no part which is arranged to be moved, for example pivoted, between predetermined first and second positions.
• Said marker preferably includes no moving parts. It should be appreciated however that this does not exclude the possibility of the marker being manipulated, for example bent, into any particular shape.
• Said fiducial marker preferably comprises radiopaque material and polymeric material which have been extruded.
• Said fiducial marker may have a weight of at least 3 mg, preferably at least 5 mg.
• the weight may be less than 100 mg, suitably less than 75 mg, preferably less than 50 mg, more preferably less than 25 especially less than 10 mg.
• Said marker may include at least lwt%, suitably at least 3wt%, preferably at least 10wt%, more preferably at least 20wt%, especially at least 30wt% of radiopaque material. In some embodiments said marker may include at least 35wt% or at least 40wt% of said radiopaque material.
• the amount of radiopaque material may be less than 80wt%, suitably less than 70wt%, preferably less than 60 wt%, more preferably 55wt% or less, especially 50wt% or less.
• Said marker may include at least 30wt%, preferably at least 40wt%, more preferably at least 45wt%, especially at least 50wt% of said bio-compatible material.
• the amount of bio-compatible polymeric material may be 97wt% or less, suitably 90wt% or less/ preferably 80wt% or less, more preferably 70wt% or less, especially 65wt% or less.
• the sum of the wt% of said bio-compatible polymeric material and said radiopaque material in said fiducial marker may be at least 60wt%, suitably at least 70wt%, preferably at least 80wt%, more preferably at least 90wt%, especially at least 99wt%.
• Said bio-compatible polymeric material may be any polymeric material which is non-toxic and not otherwise harmful when introduced into the human or animal body as a fiducial marker.
• Said bio-compatible polymeric material may have a Notched Izod Impact Strength (specimen 80mm x 10mm x 4mm with a cut 0.25mm notch (Type A), tested at 23°C, in accordance with ISO180) of at least 4KJm "2 , preferably at least
• Impact Strength measured as aforesaid, may be less than 10KJm "2 , suitably less than 8KJm "2 .
• the Notched Izod Impact Strength, measured as aforesaid, of the composite material of said fiducial marker may be at least 3KJm "2 , suitably at least 4KJm "2 , preferably at least 5KJm "2 .
• Said impact strength may be less than 50 KJm "2 , suitably less than 30KJm "2 .
• Said bio-compatible polymeric material suitably has a melt viscosity (MV) of at least 0.06 kNs ⁇ f 2 , preferably has a MV of at least 0.09 kNsirf 2 , more preferably at least 0.12 kNs ⁇ f 2 , especially at least 0.15 kNs ⁇ f 2 .
• MV is suitably measured using capillary rheometry operating at 400 0 C at a shear rate of 1000s "1 using a tungsten carbide die, 0.5x3.175mm.
• Said bio-compatible polymeric material may have a MV of less than 1.00 kNs ⁇ f 2 , preferably less than 0.5 kNs ⁇ f 2 .
• Said bio-compatible polymeric material may have a MV in the range 0.09 to 0.5 kNs ⁇ f 2 , preferably in the range 0.14 to 0.5 kNs ⁇ f 2 .
• Said bio-compatible polymeric material may have a tensile strength, measured in accordance with ISO527 (specimen type Ib) tested at 23 0 C at a rate of 50mm/minute of at least 20 MPa, preferably at least 60 MPa, more preferably at least 80 MPa.
• the tensile strength is preferably in the range 80-110 MPa, more preferably in the range 80-100 MPa.
• Said bio-compatible polymeric material may have a flexural strength, measured in accordance with ISO178 (80mm x 10mm x 4mm specimen, tested in three-point-bend at 23 0 C at a rate of 2mm/minute) of at least 50 MPa, preferably at least 100 MPa, more preferably at least 145 MPa.
• the flexural strength is preferably in the range 145-180MPa, more preferably in the range 145-164 MPa.
• Said bio-compatible polymeric material may have a flexural modulus, measured in accordance with ISO178 (80mm x 10mm x 4mm specimen, tested in three-point-bend at 23 0 C at a rate of 2mm/minute) of at least 1 GPa, suitably at least 2 GPa, preferably at least 3 GPa, more preferably at least 3.5 GPa.
• the flexural modulus is preferably in the range 3.5- 4.5 GPa, more preferably in the range 3.5-4.1 GPa.
• Said bio-compatible polymeric material may be amorphous or semi-crystalline. It is preferably semi-crystalline.
• the level and extent of crystallinity in a polymer is preferably measured by wide angle X-ray diffraction (also referred to as Wide Angle X-ray Scattering or WAXS) , for example as described by Blundell and Osborn (Polymer 24, 953, 1983) .
• WAXS Wide Angle X-ray Scattering
• crystallinity may be assessed by Differential Scanning Calerimetry (DSC).
• the level of crystallinity of said bio-compatible polymeric material may be at least 1%, suitably at least 3%, preferably at least 5% and more preferably at least 10%. In especially preferred embodiments, the crystallinity may be greater than 25%.
• the main peak of the melting endotherm (Tm) of said bio- compatible polymeric material (if crystalline) may be at least 300 0 C.
• Said bio-compatible polymeric material may include a polymeric moiety which is: an acrylate (e.g. it comprises or consists of methylmethacrylate moieties) ; a urethane; a vinyl chloride; a silicone; a siloxane (eg comprising dimethylsiloxane moieties) ; a sulphone; a carbonate; a fluoroalkylene (e.g. a flu ⁇ roethylene) ; an acid (e.g. a glycolic acid or lactic acid); an amide (e.g. comprising nylon moieties); an alkylene (e.g. ethylene or propylene); an oxyalkylene (e.g.
• a polymeric moiety which is: an acrylate (e.g. it comprises or consists of methylmethacrylate moieties) ; a urethane; a vinyl chloride; a silicone; a siloxane (eg comprising dimethylsiloxane
• polyoxymethylene polyoxymethylene
• ester e.g. polyethylene terephthalate
• ether e.g. an aryletherketone, an arylethersulphone (e.g. polyethersulphone or polyphenylenesulphone) or an ether imide
• aryletherketone e.g. an aryletherketone
• arylethersulphone e.g. polyethersulphone or polyphenylenesulphone
• ether imide e.g. an aryletherketone, an arylethersulphone (e.g. polyethersulphone or polyphenylenesulphone) or an ether imide
• Said bio-compatible polymeric material may be a resorbable polymer.
• Said bio-compatible polymeric material may be selected from a polyalkylacrylate (e.g. polymethylmethacrylate), a polyfluoroalkylene (e.g. PTFE), a polyurethane, a polyalkylene (e.g. polyethylene or polypropylene), a polyoxyakylene (e.g. polyoxymethylene), a polyester (e.g. polyethylene terephthalate or polybutylene terephthalate) , a polysulphone, a polycarbonate, a polyacid (e.g. polyglycolic acid or polylactic acid) , a polyalkylene oxide ester (e.g.
• a polyalkylacrylate e.g. polymethylmethacrylate
• a polyfluoroalkylene e.g. PTFE
• a polyurethane e.g. polyethylene or polypropylene
• a polyoxyakylene e.g. polyoxymethylene
• polyester e
• polyethylene oxide terephalate a polyvinylchloride, a silicone, a polysiloxane, a nylon, , a polyaryletherketone, a polarylethersulphone, a polyether imide and any copolymer which includes any of the aforementioned .
• said bio-compatible polymeric material is selected from resorbable polymers, polyethylene, polypropylene, silicone and polyetheretherketone. More preferably, said polymeric material is selected from polyethylene, polypropylene, silicone and polyetheretheketone .
• Said bio-compatible polymeric material may be a homopolymer having a repeat unit of general formula
• A, B, C and D independently represent 0 or 1
• E and E 1 independently represent an oxygen or a sulphur atom or a direct link
• G represents an oxygen or sulphur atom, a direct link or a -O-Ph-0- moiety
• Ph represents a phenyl group
• m, r, s, t, v, w, and z represent zero or 1
• Ar is selected from one of the following moieties (i) to (v) which is bonded via one or more of its phenyl moieties to adjacent moieties
• a phenyl moiety has 1,4-, linkages to moieties to which it is bonded.
• biocompatible polymeric material may be a homopolymer having a repeat unit of general formula or a homopolymer having a repeat unit of general formula
• A, B, C, and D independently represent 0 or 1 and E, E 1 , G, Ar, m, r, s, t, v, w and z are as described in any statement herein.
• said bio-compatible polymeric material is a homopolymer having a repeat unit of general formula IV.
• Ar is selected from the following moieties (vi) to (X)
• the middle phenyl may be 1,4- or 1, 3-substituted. It is preferably 1, 4-substituted.
• Suitable moieties Ar are moieties (ii) , (iii) , (iv) and (v) and, of these, moieties, (ii), (iii) and (v) are preferred.
• Other preferred moieties Ar are moieties (vii), (viii), (ix) and (x) and, of these, moieties (vii) , (viii) and (x) are especially preferred.
• An especially preferred class of bio-compatible polymeric materials are polymers (or copolymers) which consist essentially of phenyl moieties in conjunction with ketone and/or ether moieties. That is, in the preferred class, the first polymer material does not include repeat units which include -S-, -SO2- or aromatic groups other than phenyl.
• Preferred bio-compatible polymeric materials of the type described include:
• B represents 0 (i.e. polyetherketone) ;
• Said bio-compatible polymeric material may consist essentially of one of units (a) to (f) defined above.
• said polymeric material may comprise a copolymer comprising at least two units selected from (a) to (f) defined above.
• Preferred copolymers include units
• a copolymer may comprise units (a) and
• Said bio-compatible polymeric material preferably comprises, more preferably consists essentially of, a repeat unit of formula (XX)
• said bio-compatible polymeric material is selected from polyetheretherketone, polyetherketone, polyetherketoneetherketoneketone and polyetherketoneketone .
• said polymeric material is selected from polyetherketone and polyetheretherketone.
• said polymeric material is polyetheretherketone.
• Said radiopaque material may be any material which when added to the bio-compatible polymeric material increases the radiopacity of the combination. Said radiopaque material preferably improves the imageability of the biocompatible polymeric material when imaged using both CT and MRI techniques .
• Said radiopaque material may comprise a metal, an inorganic material or an iodine-containing organic material .
• Said radiopaque material may comprise a metal selected from barium, bismuth, tungsten, gold, titanium, iridium, plantinum, rhenium or tantalum; a compound, for example a salt incorporating one of the aforesaid metals; a radiodense salt; or an iodine-containing organic material.
• Said radiopaque material preferably has a decomposition temperature which is greater than 300°C, suitably greater than 325°C, preferably greater than 350°C, more preferably greater than 500 0 C, especially greater than 700 0 C, suitably so it can be melt-processed with the preferred bio-compatible polymeric materials.
• Said radiopaque material preferably comprises a metal selected from those described or a compound for example a salt incorporating one of said metals, provided said compound has a decomposition temperature of greater than 350 0 C, preferably of greater than 500 0 C.
• Said fiducial marker may include one or a plurality of bio-compatible polymeric materials .
• said marker includes a second or subsequent bio-compatible polymeric material
• the second or subsequent material may have any feature of said bio-compatible polymeric material described herein.
• said fiducial marker in said fiducial marker is preferably in the range 50 to 80wt%, more preferably 55-75wt%.
• Said fiducial marker may include one or a plurality of radiopaque materials.
• each radiopaque material may independently be as described herein.
• the sum of the wt% of all radiopaque materials in said fiducial marker may be in the range 20 to 80wt%, suitably 20 to 70wt%, preferably 20 to 55wt%, more preferably in the range 20 to 50wt%, especially 25 to 50wt%.
• the sum of the wt% of all organic polymeric materials and all radiopaque materials in same fiducial marker is suitably at least 80wt%, preferably at least 90wt%, more preferably at least 95wt%, especially at least 99wt%.
• said fiducial marker may comprise a radiopaque material in particulate form dispersed within, preferably throughout, said bio-compatible polymeric material.
• Said fiducial marker preferably has a substantially constant density throughout.
• Said marker is preferably substantially homogenous.
• said polymeric material defines a matrix in which particles of radiopaque material are substantially uniformly dispersed and embedded.
• the total wt% of all particulate radiopaque materials in said marker may be at least 14wt%, suitably at least 20wt%, preferably at least 25wt%, more preferably at least 30wt%, especially at least 35wt%.
• the total may be 70wt% or less, suitably less than 60wt%, preferably less than 55wt%. If too much radiopaque material is included the integrity and/or strength of the marker may be compromised; if there is too little, the marker may not be satisfactorily visible in for example CT or MRI imaging techniques .
• the total wt% of all bio-compatible polymeric materials in said marker may be at least 40wt%, preferably at least 50wt%.
• the total may be less than 85wt%, preferably less than 70wt%, more preferably less than 65wt%.
• the sum of the wt% of all particulate radiopaque materials and all bio-compatible polymeric materials in said marker may be at least 80wt%, preferably at least 90wt%, more preferably at least 95wt%, especially at least 99wt%.
• said fiducial marker includes 40 to 75wt% of bio-compatible polymeric material (preferably of formula [XX] above, especially polyetheretherketone) and 25 to 60wt% of radiopaque material (especially particulate material, for example a metal salt such as a barium salt) .
• a fiducial marker includes 45 to 70wt% of polyetheretherketone and 30 to 55wt% of a particulate radiopaque material, especially barium sulphate.
• said fiducial marker includes 60 to 85wt% of bio- compatible polymeric material (preferably of formula [xx] above, especially polyetheretherketone) and 15 to 40wt% of a radiopaque material (especially particulate material, for example a bismuth compound for example a bismuth salt such as bismuth trioxide or bismuth oxychloride) .
• a radiopaque material especially particulate material, for example a bismuth compound for example a bismuth salt such as bismuth trioxide or bismuth oxychloride
• said fiducial marker includes 15-30wt% of a bismuth compound as aforesaid and 70-85wt% of a polyaryletherketone, especially polyetheretherketone.
• a wire for example a metal wire may be encapsulated in said bio-compatible polymeric material.
• the wire may have a diameter in the range 10 to 200 ⁇ m, suitably 20 to lOO ⁇ m, more preferably 25 to 75 ⁇ m, especially about 50 ⁇ m.
• the wire may be metal, for example selected from tantalum or another radiopaque wire.
• the wire is selected from stainless steel, tungsten and tantalum. Because the wire is very fine and is encapsulated in an inert and strong bio- compatible polymeric material, the level of underdesirable artefacts noticeable on imaging may be significantly less than when thicker wire is used; and the bio-compatible polymeric material maintains the integrity of the marker.
• a metal wire having a diameter in the range 0.1mm to 0.4mm (preferably in the range 0.1mm to 0.3mm) and preferably being selected from stainless steel, tungsten and tantalum defines a core which is encapsulated in a bio-compatible polymeric material as described herein (preferably one of formula [xx] and especially poletheretherketone) , wherein the bio-compatible polymeric material is filled with a radiopaque material, especially a metal salt, with barium and bismuth salts (e.g. barium sulphate, bismuth trioxide and bismuth oxychloride) being especially preferred.
• a bio-compatible polymeric material as described herein (preferably one of formula [xx] and especially poletheretherketone)
• the layer which encapsulates the wire may include 40 to 85wt% of said bio-compatible polymeric material and 15 to 60wt% of filler (e.g. one or more radiopaque fillers as described) .
• filler e.g. one or more radiopaque fillers as described
• the layer may include 40 to 70wt% (preferably 45 to 60wt%) of said salt with the balance being said bio-compatible polymer.
• the layer may include 15 to 40wt% (preferably 15 to 30wt%, more preferably 18 to 28wt%) of said bismuth salt.
• said fiducial marker may comprise bio-compatible polymeric material and fibrous radiopaque material .
• Such a marker may be made using a pultrusion technique .
• a fiducial marker may comprise first and second fillers encapsulated in said biocompatible polymeric material, which may be of formula [xx] and is preferably polyetheretherketone .
• a first filler may be a metal, suitably in powderous form, which may be selected from stainless steel, tantalum and titanium.
• a second filler may be a radio dense salt, suitably as described herein, with barium salts and bismuth salts being preferred examples.
• Said fiducial marker may include 5-20wt% of said first filler 15-60wt% of said second filler and 20-80wt% of said bio-compatible polymeric material.
• said marker when said marker includes a bismuth salt, it may include 5-20wt% of said first filler 15 to 40wt% (preferably 15 to 30wt%, more preferably 18 to 28wt%) of said bismuth salt and the balance being said bio-compatible polymeric material.
• said marker when said marker includes a barium salt, it may include 5-20wt% of said first filler, 40-70wt% (preferably 45-60wt%) of said salt, with the balance being said bio-compatible polymeric material .
• a member which comprises a radiopaque material encapsulated in a bio-compatible polymeric material as a fiducial marker.
• the member may be a fiducial marker as described in said first aspect.
• a third aspect of the invention there is provided the use of a radiopaque material encapsulated in a bio-compatible polymeric material in the manufacture of a fiducial marker for use in marking a position on a human or animal body.
• the fiducial marker may be as described according to said first aspect.
• a method of marking a position in the human or animal body comprising positioning, preferably securing, within the body a fiducial marker as described according to the first aspect.
• the method may include positioning a plurality, preferably at least four, markers in the body.
• a method of obtaining images of predetermined positions of a human or animal body comprising imaging a human or animal body in which has been positioned one or a plurality (preferably a plurality) of fiducial markers according to said first aspect.
• the method may include imaging the body by CT or MRI scanning techniques.
• the method involves imaging by both CT and MRI scanning techniques.
• the method may involve X-ray imaging.
• the fiducial markers are visible to X-ray imaging and compatible with CT and MRI methods.
• the method may include the step of positioning one or a plurality of said fiducial markers in position within the body prior to said imaging.
• a method of making a fiducial marker comprising encapsulating a radiopaque material in a biocompatible material .
• the method preferably includes the step of extrusion to encapsulate said radiopaque material.
• a mixture comprising radiopaque and polymeric materials may be extruded suitably to define a filament.
• a wire may be coated with extruded polymeric material.
• the method may include chopping extruded material to define fiducial markers of appropriate dimensions.
• the invention extends to a pack comprising a fiducial marker according to said first aspect contained in a packaging material .
• the packaging material could be sterile .
• fiducial markers described herein are for use and/or use in relation to human bodies.
• Figures 1 (a) to (c) are CT images of different fiducial markers.
• Figures 2 (a) and (b) are MRI images of different fiducial markers .
• PEEK OPTIMA LT3 polymer refers to polyetheretherketone obtained from Invibio Limited, UK.
• Example 1 hereinafter the preparation of fiducial markers comprising polyetheretherketone and barium sulphate is described. Such markers are compared to known metal markers in CT-imaging, MRI-imaging and X-ray imaging in the following examples.
• PEEK OPTIMA LT3 polymer and a highly pure grade of barium sulphate comprising greater than 98% of particles lO ⁇ m or less were compounded in a twin screw melt extrusion compounder and a lace produced of 2-3mm diameter.
• the lace was passed to a conveyor, cooled and then chopped into granules.
• the granules were then introduced into an extruder and monofilaments produced which were then chopped to produce fiducial markers of predetermined lengths comprising polyetheretheketone polymer with barium sulphate dispersed substantially homogenousIy throughout the polymer.
• the markers of Examples 2 to 16, and Cl to C4 were assessed by CT-imaging. In each case it was found that the markers of Examples 2 to 16 produced very significantly fewer artefacts compared to the metal markers .
• Fiduciary markers described in Table 3 were assessed in various imaging systems .
• the central spot is the CT image of Example C5 from which it will be noted that there is a significant level of distortion and a significant starburst effect, in comparison to the two Example 17 markers which are nonetheless still clearly visible.
• Example C6 marker is substantially distorted and has produced a significant starburst effect compared to the two Example 18 markers.
• Figure 1 (c) illustrates changes in the images when wider diameter markers are used (compare Examples 17 and 18 and note that each of the markers is highly visible and has significantly less distortion compared to the marker of Examples C5 and C6 of Figures 1 (a) and 1 (b) .
• markers of Examples 17 and 18 are less visible under X-ray imaging than both platinum and gold markers, they can still readily be detected, especially when their image is enhanced by conventional image processing techniques.
• markers described herein can be imaged using CT, MRI and X-ray techniques.
• images include less distortion and/or starburst and/or other artefacts compared to metal, for example gold of platinum, markers.
• Markers as described may be provided in a range of dimensions as shown in the table below. Furthermore, spherical markers, having diameters in the range 1 to 5 mm may be provided.
• a 0.12mm diameter stainless steel wire was coated with a homogenous mixture comprising PEEK OPTIMA LT3 polymer (50wt%) and the barium sulphate referred to in previous examples (50wt%) .
• the coated wire was then cut to size to define a fiducial marker comprising a wire core and an outer homogenous sheath of PEEK OPTIMA LT3 polymer and barium sulphate.
• the inclusion of the wire core improves visibility of the marker under MRI conditions, whilst the barium sulphate improves the visibility of the marker in other imagining techniques .
• the stainless steel wire core may be replaced with tantalum or titanium; the amount of barium sulphate may be adjusted (e.g. in the range 30- 70wt%) or; alternate radio dense materials may be used instead of barium sulphate.
• a bismuth salt e.g. bismuth trioxide or bismuth oxychloride
• the metal wire may be replaced with metal powder, for example of stainless steel, tungsten or tantalum, at up to 20wt% of the entire marker.
• metal powder for example of stainless steel, tungsten or tantalum
• An example of such a marker may include up to 20wt% of metal powder, 45 to 70wt% of barium sulphate (or 15-45wt% of a bismuth salt if such a salt is used instead of the barium sulphate) and the balance being PEEK OPTIMA LT3.
• the materials are mixed to define a homogenous mass and extruded to define an elongate marker having a diameter of lmm.

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• 2005
  • 2005-10-22 GB GBGB0521536.3A patent/GB0521536D0/en not_active Ceased
• 2006
  • 2006-10-23 KR KR1020087012153A patent/KR20080070020A/ko not_active Application Discontinuation
  • 2006-10-23 CN CNA2006800393860A patent/CN101291636A/zh active Pending
  • 2006-10-23 GB GB0707734A patent/GB2438282B/en not_active Expired - Fee Related
  • 2006-10-23 EP EP06794883A patent/EP1940308A2/en not_active Withdrawn
  • 2006-10-23 JP JP2008536132A patent/JP2009512475A/ja active Pending
  • 2006-10-23 WO PCT/GB2006/003947 patent/WO2007045913A2/en active Application Filing
  • 2006-10-23 CA CA002626784A patent/CA2626784A1/en not_active Abandoned

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