WO2006027549A1

WO2006027549A1 - Needle assembly

Info

Publication number: WO2006027549A1
Application number: PCT/GB2005/003305
Authority: WO
Inventors: Jeremy Paul Watson; Stephen Edward Connor
Original assignee: Psimedica Limited
Priority date: 2004-09-04
Filing date: 2005-08-25
Publication date: 2006-03-16
Also published as: GB0419653D0

Abstract

The present invention relates to a needle assembly (10) comprising a first hollow needle (11), and a second hollow needle (12) that is at least partly located within the first hollow needle (11), the first and second needles being shaped and arranged such that at least part of the second needle (12) is movable, relative to the first hollow needle (11), in a direction substantially parallel to the axis of at least part of the first needle (11), the first needle being substantially un-curved along its axis when no external force is applied to the first needle, the first needle (11) comprising a first inflexible material, the second needle (12) comprising a curved second needle that is curved along its axis when no external force is applied to the curved second needle, the cured second needle comprising a second resiliently flexible material. The needle assembly (10) is of value in the treatment of large tumours since it facilitates the effective delivery of an anticancer agent to the tumour.

Description

Needle Assembly

The present invention relates to a needle assembly comprising a curved resiliency flexible hollow needle. More specifically the present invention relates to a needle assembly comprising a radioactively shielded syringe and a curved resiliency flexible hollow needle.

There are several ways in which cancer can be treated. For example, an operation may be performed on a patient to remove the cancer, the patient may be treated by radiotherapy, or by chemotherapy.

One type of treatment that may be particularly effective is brachytherapy. This involves the introduction of a chemo- or radio- therapeutic agent to the region of tumour to be treated. In this way it may be possible to localise the anti-cancer agent, to the immediate area surrounding the tumour, allowing the cancer cells to be killed, with relatively minor damage to healthy cells in other parts of the patient's body.

One way in which this localisation of the radioisotope or chemotherapeutic agent may be achieved is described in WO 02067998. This involves the combination of the anticancer agent with bioactive silicon. The bioactive silicon is capable of bonding to tissue when implanted, reducing diffusion beyond the region of the tumour, and helping to avoid damage to healthy tissue.

The optimum distribution of the anticancer agent will depend upon the size, shape, and type of tumour. It may be desirable to introduce the anticancer agent at a number of locations within the tumour. For a large tumour the distance between these locations may be several centimetres.

The following patents provide background information that is relevant to the present invention: US 6,730,061; US 5,219,358; US 5,026,350; US 4,511 ,356; and US 6,425,887. US 6,730,061 describes a hypodermic needle that can potentially be used to deliver substances to a large volume of tissue. US 6,425,887 describes a needle assembly comprising a plurality of needle cannulae made of a superelastic material. US 5,219,358 describes a curved needle made from a shape memory alloy. US 4,511 ,356 relates to a cannula, obturator, stylet and needle hub connector for use in operations such as lumbar disc puncture for chemonucleolysis. US 5,026,350 describes a set of double needles for injecting liquid medicine into a patient through a single injection point.

It is an objective of the present invention to provide a needle assembly that facilitates the delivery of a beneficial substance to a number of locations within a patient. It is a further objective of the present invention to provide a needle assembly that facilitates the introduction of an anticancer agent to a number of locations within a tumour.

According to a first aspect the invention provides a needle assembly comprising a first hollow needle and a second needle, the needle assembly having a retracted configuration and an extended configuration.

The needle assembly may have a construction and be arranged such that, when in the retracted configuration, the second needle is at least partly located within the bore of first hollow needle.

The first and second needles may be shaped and arranged such that at least part of the second needle is movable, relative to the first hollow needle, in a direction substantially parallel to at least part of the axis of the first needle.

The first and second needle may be shaped and arranged such that at least part of the second needle is movable, relative to the first hollow needle, through the bore of at least part of the first needle.

The first needle may be substantially un-curved along its axis when no external force is applied to the first needle. The first hollow needle may comprise a first metal tube. The first needle may comprise a first cylindrical needle portion and a first tapered portion. The first cylindrical needle portion may comprise a first cylindrical needle wall. The first hollow needle may comprise a first tip. The first tapered portion may comprise the first tip. The first tapered portion may comprise a conical first tip. The first tip may be rotationally symmetric about the axis of the first needle. The first needle may comprise a first orifice. The first orifice may be located at the first tip. The first orifice may be located at the cylindrical needle portion of the first hollow needle. The first orifice may be formed in the first cylindrical needle wall.

The second needle may comprise a second hollow needle. The second needle may comprise a curved second needle. The curved second needle may comprise a second metal tube. The second needle may comprise a curved second needle that is curved along its axis when no external force is applied to the curved second needle. The curved second needle may comprise a second resiliently flexible material. The second needle may have a second tip in which a second orifice is formed.

In the retracted configuration, the first and second needle may be shaped and arranged such that the second tip is located within the bore of the first needle. In the extended configuration, the first and second needle may be shaped and arranged such that the second tip is located outside the bore of the fist needle. In the retracted configuration the first and second needles may be shaped and arranged such that the two needles are substantially coaxial. In the extended configuration the first and second needles may be shaped and arranged such that a portion of the second needle is located outside the bore of the first needle, and such that the portion of the second needle that is outside the bore of the first needle is curved along its axis. In the retracted configuration the distance between the first and second tips may be less than in the extended configuration. In the retracted configuration less than 10% of the length of the second needle may extend beyond the bore of the first needle. In the retracted configuration between 0.01% and 10% ^• of the length of the second needle may extend beyond the bore of the first needle.

The first needle may have a length between 50 mm and 300 mm. The first needle may have an outside diameter between 0.5 mm and 5 mm. The first needle may have an inner diameter between 0.49 and 4.5 mm.

The first needle may comprise a first inflexible material. The first needle may comprise one or more of: stainless steel, titanium, a nickel titanium alloy, a medically compatible metal, a medically compatible alloy, a cobalt chromium alloy, a titanium alloy, a cobalt-chromium- molybdenum alloy, a cobalt-chromium-tungsten alloy, a copper alloy, a copper-aluminium- nickel alloy, a copper-aluminium-zinc alloy, and a copper-zinc alloy. Preferably the first needle comprises stainless steel or titanium.

The curved second needle may have a structure and composition such that, when two or more forces are applied, to cause the second needle to be substantially un-curved, and then removed, the curved second needle substantially returns to its original shape, which it had assumed prior to the application of the forces. The second resiliently flexible material may comprise one or more of the following: Nitinol, stainless steel, titanium, a nickel titanium alloy, a medically compatible metal, a medically compatible alloy, a cobalt chromium alloy, a titanium alloy, a cobalt-chromium-molybdenum alloy, a cobalt-chromium-tungsten alloy, a copper alloy, a copper-aluminium-nickel alloy, a copper-aluminium-zinc alloy, and a copper-zinc alloy, and a super elastic alloy. Preferably the second resiliently flexible material comprises Nitinol.

The second curved needle may have an inner diameter of between 0.2 and 4.3 mm. The second curved needle may have an outer diameter of between 0.4 and 4.5 mm.

An arrangement in which the first needle is un-curved and the second needle is curved, when unconstrained by the first needle, is advantageous because it facilitates the delivery of a beneficial substance through the second needle to a particular location in a patient. As the second needle passes out from the first orifice, from a retracted to an extended configuration, then it will curve, and the position of the second tip can therefore be moved in three dimensions. The tip of the second needle can be moved in a direction parallel to the axis of the un-curved first needle by moving the first needle in or out of the patient, when the needle assembly is in the retracted configuration. The tip of the second needle can be rotated to an appropriate angle before it is moved out of the tip of the first needle. The tip of the second needle can be moved in a direction having a component perpendicular to the axis of the first needle by moving the second needle out from the first tip orifice.

This allows a beneficial substance to be introduced into a patient at a number of different ^• locations. For example a chemotherapeutic or radiotherapeutic substance may be introduced into a tumour at a number of locations in the tumour, allowing the effective treatment of the cancer.

The use of the second curved resiliently flexible needle in the absence of the first inflexible needle would be impractical for the purposes of the accurate delivery of a beneficial substance to a particular location. This is because passage of the second curved needle through the tissue of the patient may cause the second needle to deflect away from that location. An arrangement in which the first orifice is located away from the tip of the first needle, may be advantageous if the needle is to be used to inject a beneficial substance into the body of a subject. The location of the first orifice away from the tip of the first needle may reduce interaction of the orifice with tissue through which it passes when inserted into the animal or human patient. The reduced interaction may facilitate insertion of the first needle to the location required for delivery of the beneficial substance. It may also reduce blockage of the first orifice.

A further advantage of the arrangement is that it allows a number of locations, within a patient, to be treated, without the need for multiple injections. This is of particular value in the treatment of cancer, since an increase in the number punctures made in a tumour is likely to cause an increase in the escape of tumour cells.

The needle assembly may have a construction such that when the first needle is rotated about its axis, the second needle rotates by substantially the same angle as the first.

The rotational motion of the first and second needles may be coupled such that when the first needle is rotated through an angle about its axis, the second needle rotates about its axis by the same angle.

The presence of the first inflexible un-curved needle allows the second needle to be rotated, when in the retracted configuration, without causing damage, or with minimal damage, to the tissue of the patient. The second needle may be rotated while it is not protruding from the tip of the first needle, and then it may be moved out of the tip in the appropriate direction. If rotation were carried out while the second needle protruded from the tip of the first needle, then it may cause damage to the tissue of the patient.

The syringe may comprise a piston and syringe cylinder having a syringe cylinder wall. The syringe cylinder wall may have a thickness and composition such that beta particles are substantially unable to pass through the syringe cylinder wall. The syringe cylinder wall may have a thickness and composition such that alpha particles are substantially unable to pass through the cylinder wall.

The syringe cylinder wall may comprise Perspex. The syringe cylinder wall may have a thickness between 1 mm and 30 mm. The needle assembly may have a construction such that the cylinder of the syringe is in fluid communication with the hollow bore of the second needle so that liquid can pass from the syringe cylinder into and through the second needle.

Preferably the needle assembly further comprises a first actuator means for altering the position of the first needle. Advantageously the medical device comprises a second actuator means for positioning the second needle. Preferably the first and second actuator means each have a shape and construction such that rotation of the first needle through an angle causes rotation of the second needle by substantially the same angle.

The plane of the first tip orifice may be parallel to the axis of the first needle. The plane of the first tip orifice may non-perpendicular to the axis of the first needle. The first tip may comprise a Touhy tip.

The axis of at least part of the second needle may, when no external force is applied to the second needle, be substantially coincident with the arc of a circle. The axis of at least part of the second needle may, when no external force is applied to the second needle, be substantially coincident with the arc of a circle having radius between 5 and 100mm. The axis of at least part of the second needle may, when no external force is applied to the second needle, be substantially coincident with the arc of a circle having radius between 10 and 30mm. The axis of at least part of the second needle may, when no external force is applied to the second needle, be substantially coincident with the arc of an ellipse.

In use, the second hollow needle may be moved relative to the first by moving the first hollow needle relative to a patient.

The needle assembly may comprise a third hollow needle.

The needle assembly may have a construction and be arranged such that, when in the retracted configuration, the third hollow needle is at least partly located within the bore of first hollow needle.

The needle assembly may have a construction and be arranged such that at least part of the third needle is movable, relative to the first hollow needle, in a direction substantially parallel to at least part of the axis of the first needle.

The needle assembly may have a construction and be arranged such that at least part of the third needle is movable, relative to the first hollow needle, through the bore of at least part of the first needle.

The curved third needle may comprise a third metal tube. The third needle may comprise a curved third needle that is curved along its axis when no external force is applied to the curved third needle. The curved third needle may comprise a third resiliently flexible material.

According to a further aspect the invention provides a medical kit comprising a needle assembly as defined in any of the above aspects, the kit comprising a beneficial substance.

The kit may comprise a syringe, and the beneficial substance may, when the kit is in use, be located in the syringe. In this way the beneficial substance may be delivered from the , syringe, through the second needle, and into the patient.

For the purposes of this specification, a beneficial substance is a substance that, when administered to a patient, results in the patient experiencing a beneficial effect.

The medical kit may further comprise a silicon component.

The silicon component may comprise a silicon particulate product, the particulate- product comprising a multiplicity of silicon microparticles. The mean particle size of the silicon particulate product may be between 500 microns and 0.1 microns. The mean particle size of the silicon particulate product may be between 100 microns and 1 micron.

The silicon component may comprise one or more of: bulk crystalline silicon, porous silicon, polycrystalline silicon, amorphous silicon, resorbable silicon, and bioactive silicon.

Certain forms of porous silicon, and other forms of silicon, are bioactive and/or resorbable. This was first described in WO 9706101 , which is herein incorporated by reference in its entirety. For the purposes of this specification bioactive silicon is silicon that, when implanted, is capable of forming a bond with tissue. For the purposes of this specification resorbable silicon is silicon that is capable of eroding when implanted in a patient.

The kit may further comprise a medical dressing, having angles of rotation marked on it.

The medical kit may comprise a silicon suspension, the silicon suspension comprising the silicon particulate product and a liquid.

The beneficial substance may form part of an implant. The beneficial substance may form part of a silicon implant. The beneficial substance may form part of a silicon implant comprising porous and/or polycrystalline silicon.

The implant may be deliverable through the bore of the second needle.

According to a further aspect the invention provides a medical kit comprising a needle assembly as defined in any of the above aspects, the kit comprising an anti cancer agent.

The anticancer agent may comprise a radionucleotide and/or a chemotherapeutic agent. The anticancer agent may comprise a silicon component. The silicon component may comprise a silicon particulate product, the particulate product comprising a multiplicity of silicon microparticles. The mean particle size of the silicon particulate product may be between 5OQ microns and 0.1 microns. The mean particle size of the silicon particulate product may be between 100 microns and 1 micron. The silicon component may comprise one or more of: bulk crystalline silicon, porous silicon, polycrystalline silicon, amorphous silicon, resorbable silicon, and bioactive silicon.

The anti-cancer agent may comprise a liquid suspension of the silicon particulate product.

The radionucleotide may be selected from one or more of:⁹⁰Y, ³²P, ¹²⁴Sb, ¹¹⁴In, ⁵⁹Fe, ⁷⁶As, 140 , _ 47,-_* 103_D . 89_O>. 131 , 125, 60^_Λ 192. 12_D 71^ -, 64^₁ , 203_D. . 198_Λ , , La, Ca, Pd, br, I, I, Co, Ir, b, ue, Cu, Pb and Au.

Preferably the radionucleotide is ³²P.

The chemotherapeutic agent may be selected from one or more of: an alkylating agent such as cyclophosphamide, a cytotoxic antibody such as doxorubicin, an antimetabolite such as fluorouracil, a vinca alkaloid such as vinblastine, a hormonal regulator such as GNRH, and a platinum compound such as cis platin.

The anticancer agent may comprise bioactive porous silicon and a chemotherapeutic agent, at least part of the chemotherapeutic agent being located in at least some of the pores of the porous silicon. The anticancer agent may comprise bioactive silicon and a radionucleotide, at least part of the radionucleotide being distributed throughout at least part of the volume of the silicon.

The use of bioactive silicon, which has been associated with the chemotherapeutic agent or radionucleotide, is advantageous since bioactive silicon bonds to tissue. The chemotherapeutic agent or radionucleotide may be at least partly trapped by the silicon from which the anticancer agent is formed. The bond between the silicon and the tissue may help to prevent escape of the chemotherapeutic agent or radionucleotide from the tumour, thereby reducing side effects of the treatment.

The bioactivity of the silicon may also reduce diffusion of the anticancer agent through the tumour. It may further be noted that beta and alpha particles emitted by certain radionucleotides have a relatively short path length. These factors may mean that the use of a needle assembly, as defined in one of the above mentioned aspects, with an anticancer agent that comprises bioactive silicon, is particularly advantageous for the treatment of relatively large tumours. The needle assembly allows delivery to a number of locations within the tumour, thereby allowing the whole tumour to be killed, while the presence of the bioactive silicon prevents spread of the chemotherapeutic agent or radionucleotide to the surrounding healthy tissue.

According to a further aspect the invention provides a needle assembly as defined in any of the above aspects for use in the treatment of cancer. According to a further aspect the invention provides a needle assembly as defined in any of the above aspects for use in the treatment of one or more of: brain cancer, liver cancer, pancreatic cancer, breast cancer, prostate cancer, testicular cancer, lung cancer.

According to a further aspect the invention provides a medical kit as defined in any of the above aspects for use in the treatment of cancer. According to a further aspect the invention provides a medical kit as defined in any of the above aspects for use in the treatment of one or more of: brain cancer, liver cancer, pancreatic cancer, breast cancer, prostate cancer, testicular cancer, lung cancer.

According to a further aspect the invention provides a method of delivering an anticancer agent to a tumour comprising the steps of:

(a) using a needle assembly comprising a first hollow needle, and a second hollow needle that is at least partly located within the first hollow needle, the first and second needles being shaped and arranged such that at least part of the second needle is movable, relative to the first hollow needle, in a direction substantially parallel to the axis of at least part of the first needle, the first needle being substantially un-curved along its axis when no external force is applied to the first needle, the first needle comprising a first inflexible material, the second needle comprising a curved second needle that is curved along its axis when no external force is applied to the curved second needle, the curved second needle comprising a second resiliently flexible material; and (b) passing an anti-cancer agent through the curved second needle and into the tumour.

The first needle may have a first tip, and the second needle may have a second tip. The method may comprise the step of introducing the first needle into a patient until the first tip is located in the region of a tumour or tumours to be treated.

The method may comprise the step of altering the configuration of the needle assembly from a retracted configuration to an extended configuration.

The method may comprise the steps of: introducing the first tip to the region of a tumour, and then moving the second needle though the first needle until the second tip extends beyond the first tip, so that at part of the second needle is located outside the bore of the first needle.

The step (b) may be performed when the needle assembly is in the extended configuration, so that the tip of the second needle extends beyond the tip of the first needle.

The anticancer agent may comprise a radionucleotide and/or a chemotherapeutic agent. The anticancer agent may comprise a silicon component. The silicon component may comprise a silicon particulate product, the particulate product comprising a multiplicity of silicon microparticles. The mean particle size of the silicon particulate product may be between 500 microns and 0.1 microns. The mean particle size of the silicon particulate product may be between 100 microns and 1 micron. The silicon component may comprise one or more of: bulk crystalline silicon, porous silicon, polycrystalline silicon, amorphous silicon, resorbable silicon, and bioactive silicon.

The anticancer agent may comprise a radioactive seed. The anti-cancer agent may comprise a radioactive seed comprising a titanium casing.

The radionucleotide may be selected from one or more of:⁹⁰Y, ³²P, ¹²⁴Sb, ¹¹⁴In, ⁵⁹Fe, ⁷⁶As,

140 , La, 47^ C_^a, 103_D Pd., 89 S~r, 131 , I, 125, I, 60 C,-vo, 192. Ir, 12_D B, 71, G-*e, 64 C ~,u ,, 203_D P.b a __nd . 198 A_Λ ,u .. Preferably the radionucleotide is P.

According to a further aspect the invention provides a catheter assembly comprising a first inflexible catheter and an inner catheter flexible tube that is located in the catheter.

Preferably the catheter and inner catheter tube are shaped and arranged such that at least part of the inner catheter tube is movable, relative to the catheter, in a direction substantially parallel to the axis of at least part of the catheter.

The catheter may be substantially un-curved along its axis when no external force is applied to the catheter. The inner catheter tube may comprise a metal and/or polymer tube.

The inner catheter tube may consist of a curved inner tube that is curved along its axis when no external force is applied to the curved inner tube. The curved inner tube may comprise an inner catheter tube resiliently flexible material. The curved inner tube may have a structure and composition such that, when two or more forces are applied, to cause the curved inner tube to be substantially un-curved, and then removed, the curved second needle returns to its original shape before the forces were applied.

The catheter assembly may have a construction such that when the catheter is rotated about its axis, the inner catheter tube rotates by the same angle as the first.

According to a further aspect the invention provides a method of delivering an anticancer agent to a tumour having a tumour surface comprising the steps: (a) passing at least part of the anticancer agent through a location, A, in the tumour surface, and (b) depositing part of the anticancer agent at a first location, B, in the volume of the tumour, and (c) depositing part of the anticancer agent at a second location, C, in the volume of the tumour; characterised in that the locations A, B, and C do not lie on the same straight line.

For the absence of doubt the tumour surface is the interface between the tumour and the healthy tissue.

The method may comprise one or more further anticancer deposition steps. The or at least one of the anticancer deposition steps may occur at locations other than B and C.

The locations B and C may be the two points at which concentration of the anticancer agent is highest. The location A may be the centre of the tumour surface area through which the anticancer agent is passed. The location A may be a point within the tumour surface area through which the anticancer agent is passed. The location B may be a point wjthin the volume occupied by the anticancer agent delivered by the step (b). The location C may be a point within the volume occupied by the anticancer agent delivered by the step

(C).

The step (a) may comprise the step of passing the anticancer agent though a single area, x, in the tumour surface. The step (a) may comprise the step of passing the anticancer agent though a single area, x, in the tumour surface and at no other locations in the tumour surface. The method involves the introduction of the anticancer agent through a single location in the tumour surface, and deposition at two further locations within the tumour, such that each of the three locations lies at the apex of a triangle. Introduction of the anticancer agent in this way allows the anticancer agent to be distributed through the tumour, and reduces its leakage into healthy tissue. Leakage is reduced by only having to puncture the tumour surface at a single location. The method is particularly advantageous for the treatment of large tumours, for which the introduction of an anticancer agent at a single location would be insufficient.

The area x may be between 0.01 mm² and 1 cm². The area x may be between 1 mm² and 50 mm². The area x may be between 0.1 mm² and 25 mm². The area x may be between 0.001 mm² and 10 mm². The area x may be between 1 x 10^'6 mm² and 1 mm².

The distance between A and B, measured along a straight line between the two points may be between 0.1 mm and 15 cm. The distance between A and C, measured along a straight line between the two points may be between 0.1 mm and 15 cm. The distance between C and B, measured along a straight line between the two points may be between 0.1 mm and 15 cm. The distance between A and B, measured along a straight line between the two points may be between 5 mm and 10 cm. The distance between A and C, measured along a straight line between the two points may be between 5 mm and 10 cm. The distance between C and B, measured along a straight line between the two points may be between 5 mm and 10 cm.

The method may comprise the step of using a needle assembly as defined in any of the above mentioned aspects to deliver the anticancer agent. The. step (a) may comprise the step of using a needle assembly as defined in any of the above mentioned aspects to deliver at least part of the anticancer agent through the location A. The step (b) may comprise the step of using a needle assembly as defined in any of the above mentioned aspects to deliver part of the anticancer agent to the location B. The step (c) may comprise the step of using a needle assembly as defined in any of the above mentioned aspects to deliver part of the anticancer agent through the location C.

The anticancer agent may comprise a radionucleotide and/or a chemotherapeutic agent. The anticancer agent may comprise a silicon component.

The radionucleotide may be selected from one or more of:⁹⁰Y, ³²P, ¹²⁴Sb, ¹¹⁴In, ⁵⁹Fe, ⁷⁶As, ¹⁴⁰ La, ⁴⁷Ca, ¹⁰³Pd, ⁸⁹Sr, ¹³¹I₁ ¹²⁵1, ⁶⁰Co, ¹⁹²Ir, ¹²B, ⁷¹Ge, ⁶⁴Cu, ²⁰³Pb and ¹⁹⁸Au. Preferably the radionucleotide is ³²P.

The bioactivity of the silicon may reduce diffusion of the anticancer agent through the tumour. It may further be noted that beta and alpha particles emitted by certain radionucleotides have a relatively short path length. These factors may mean that the use of the method of delivering an anticancer agent, in which the anticancer agent comprises bioactive silicon, is particularly advantageous for the treatment of relatively large tumours. The method allows delivery to a number of locations within the tumour, thereby allowing the whole tumour to be killed, while the presence of the bioactive silicon prevents spread of the chemotherapeutic agent or radionucleotide to the surrounding healthy tissue.

The invention will now be described, by way of example only, with reference to the following figures:

Figure 1 is a schematic diagram of part of a needle assembly according to the invention, the diagram shows a cross-section of the assembly in the retracted position; Figure 2 is a schematic diagram of part of a needle assembly according to the invention, the diagram shows a cross section of the needle assembly in the extended position; Figure 3 is a schematic diagram of part of a needle assembly according to the invention, the diagram shows a cross-section of the assembly that is perpendicular to the cross- sections shown in figures 1 and 2.

Figure 1 is a schematic diagram of part of a needle assembly according to the invention, generally indicated by 10. The needle assembly comprises a first hollow needle 11, a second hollow needle 12, a needle hub 13, and a needle actuator 14.

The first hollow needle 11 comprises an inflexible material such as stainless steel. The first hollow needle comprises a metal tube having a length of 200 mm, a bore diameter of 0.95 mm and an outer diameter of 1.27 mm. The wall of the first hollow needle 11 is substantially parallel for most of the length of the first needle 11. At the first tip of the hollow needle 11 , the wall of the first needle is bent to form a fist tip orifice 11a, the first tip orifice 11a being substantially parallel to the axis of the first needle 11. The first tip orifice is fabricated by taking a metal tube (not shown in the diagrams), bending it and then removing part of the tube at the bend. The tip of the first needle 11 is commonly known as a Touhy tip.

The second hollow needle 12 is movably located in the bore of the first hollow needle 11. The second hollow needle 12 has an outer diameter of 0.91 mm, an internal diameter of 0.7 mm, and a length of 235 mm. The second needle comprises a resiliently flexible material such as Nitinol. When in an unconstrained condition the second needle 12 is at least partly curved. However, when the needle assembly is in a retracted position, so that the tip 12a of the second needle 12 is within the bore of the first needle 11 it is constrained ^• by the first needle so that it is substantially un-curved. The material used to form the second needle 12 is commonly known as a super elastic alloy. This is because when the constraint is removed, the second needle returns to substantially the same shape as when it was originally formed.

The end of the first needle 11 that is furthest from the Touhy tip is attached to the needle hub 13, and the end of the second needle 12 that is furthest from second needle tip 12a is attached to the needle actuator means 14. The needle actuator means 14 is hollow and has a rectangular external cross section, as shown in figure 3. The needle hub 13 has a rectangular recess in which the needle actuator means 14 is movably located. The needle actuator means may be moved in a direction parallel to the axis of the needle hub 13, which causes the second needle 12 to move relative to the first needle 11. In this way the tip of the second needle 12a may be moved out of the first tip orifice 11a.

Figure 2 shows the needle assembly 10 in the extended configuration. The second needle 12 is unconstrained and is therefore curved.

The first needle 11 may be introduced into a patient while the needle assembly 10 is in the retracted position. When the first tip orifice 11a is located in the appropriately within the patient, the second needle 12 may be moved through the first needle 11 , using the needle actuator 14, until the needle assembly 10 is in the extended position.

The hollow needle actuator 14 is in fluid communication with a syringe (not shown in the diagrams). Liquid, containing a beneficial substance, initially located in the syringe may flow from the syringe, through the hollow needle actuator 14, then through second needle 12, and carrying the beneficial substance into the patient.

If the beneficial substance is to be delivered to another location, the tip 12a of the second needle 12 may be moved to within the bore of the first needle 11. With the needle assembly 10 in the retracted position, the first and second needles can be rotated together through the required angle. The tip 12a of the second needle can then be moved out of the first needle 11 , until the needle assembly 10 is in the extended position. The rectangular cross section of both the needle hub 13 and actuator means 14 allows this concerted rotation of the first and second needles 11 , 12.

The needle assembly may be fitted with a side port (not shown in the diagrams) and valve arrangement (not shown in the diagrams) to allow two different substances to be introduced into the patient. A first beneficial substance may be introduced from the syringe, and a second beneficial substance may be introduced from the side port. The valve may be adapted to substantially prevent flow of the first beneficial substance into the region of the side port, and to substantially prevent flow of the second beneficial substance into the syringe 14.

A scale may be marked on the open surface 14a of the actuator means 14, to allow the position of the second tip 12a to be determined. Before introducing the first needle into the patient, a dressing may be applied to the skin through which injection is to occur. The dressing may be marked with a number of angles to allow the rotational position of the second needle to be determined.

The first beneficial substance, located in the syringe may be a radioactive substance, for example it may comprise ³²P, which is a beta emitter. The walls of the syringe may comprise a plastic having a thickness that is sufficient to substantially prevent the passage of beta particles through the walls of the syringe. By the method described above, ³²P may therefore be introduced to a number of locations in a tumour, while only puncturing the tumour once. This is particularly advantageous since, if multiple punctures were required, this would increase the chances of tumour cells escaping to other parts of the patient's body, with the attendant risk of secondary cancer.

The second beneficial substance may be a sealant, which may be introduced though the side port, once the radioactive substance has been introduced, to block the puncture formed in the tumour and prevent or reduce the leakage of radioactive material away from the site of the tumour.

As is described in WO 02067998, which is herein incorporated by reference in its entirety, the phosphorous from which the ³²P is formed may be combined with silicon to form silicon microparticles. The silicon microparticles may be stain etched by standard techniques thereby porosifying the microparticles and imparting bioactivity. Irradiation of the microparticles with neutrons results in the formation of the radioactive phosphorus isotope. A suspension of these silicon microparticles, which comprise ³²P, may be injected into the tumour using a needle assembly of the present invention. The treatment of cancer in this way has been found to be particularly effective because the bioactive silicon helps to localise the ³²P to the region of the tumour, thereby helping to reduce any damage to healthy tissue.

Claims

1. A needle assembly comprising a first hollow needle, and a second hollow needle that is at least partly located within the first hollow needle, the first and second needles being shaped and arranged such that at least part of the second needle is movable, relative to the first hollow needle, in a direction substantially parallel to the axis of at least part of the first needle, the first needle being substantially un-curved along its axis when no external force is applied to the first needle, the first needle comprising a first inflexible material, the second needle comprising a curved second needle that is curved along its axis when no external force is applied to the curved second needle, the curved second needle comprising a second resiliently flexible material.

2. A needle assembly according to claim 1 characterised in that the elasticity of the second resiliently flexible material is greater than the elasticity of the first inflexible material.

3. A needle assembly according to claim 1 characterised in that the curved second needle has a structure and composition such that, when two or more forces are applied, to cause the second needle to be substantially un-curved, and then removed, the curved second needle substantially returns to its original shape before the forces were applied.

4. A needle assembly according to claim 1 characterised in that the assembly further comprises a syringe, the syringe comprising syringe wall, the syringe wall having a thickness and composition such that beta particles, emitted by a radionucleotide, are substantially unable to pass through the syringe wall.

5. A method of delivering an anticancer agent to a tumour having-a tumour surface comprising the steps: (a) passing at least part of the anticancer agent through a location,

A, in the tumour surface, and (b) depositing part of the anticancer agent at a first location,

B, in the volume of the tumour, and (c) depositing part of the anticancer agent at a second location, C, in the volume of the tumour; characterised in that the locations A, B, and C do not lie on a single straight line.

6. A method according to claim 5 characterised in that the anticancer agent comprises bioactive silicon that has been doped with a radionucleotide.