Slit needle for radiotherapy

Abstract

A needle for delivery of radioactive sources. The needle is an elongate needle and has a distal end and a proximal end, and also has a circumferential tube defining an internal lumen. A sharp tip is defined at the distal end of the needle. The needle has a partially open section along a portion of a length of the elongate needle, adjacent the proximal end of the needle.

Description

[0001] SLIT NEEDLE FOR RADIOTHERAPY

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application claims the benefit of U.S. Provisional Patent Application 63 / 520,654, filed August 21, 2023, which is incorporated herein by reference.

[0004] FIELD OF THE INVENTION

[0005] This invention relates generally to radiotherapy, and specifically to delivery of radioactive sources to a patient .

[0006] BACKGROUND OF THE INVENTION

[0007] Placing sealed radioactive sources, also termed seeds, in or close to a tumor is an effective treatment for many types of tumor, for example prostate or breast tumors. When the sources are correctly positioned in a patient, the irradiation from the sources only affects a localized region around the sources, so that the exposure of healthy tissue farther away from the sources is reduced .

[0008] The sources are very small (of the order of 1 mm in diameter) , and a specialized applicator, which has the sources installed in the applicator, is typically used to position the sources. However, the applicator itself is small, since it has to be inserted into the patient, and so is delicate. The delicacy means that it is typically difficult and time-consuming to work with the applicator.

[0009] SUMMARY OF THE INVENTION

[0010] An embodiment of the present invention provides a needle for delivery of radioactive sources, consisting of : an elongate needle having a di stal end and a proximal end, and having a circumferential tube defining an internal lumen; a sharp tip defined at the distal end of the needle; and a partially open section along a portion of a length of the elongate needle , adjacent the proximal end of the needle .

[0011] In a disclosed embodiment the partially open section includes a semicylinder .

[0012] In a further disclosed embodiment a cros s-section of the partially open section includes a shape of a step . The step may have a runner parallel to an axis of symmetry of the circumferential tube , and at least one ri ser orthogonal to the axis of symmetry . The runner may be coincident with the axi s of symmetry . The at least one ri ser may consi st of a first riser and a second riser having equal lengths .

[0013] In a yet further di sclosed embodiment the partially open section subtends an angle of at least 90 ° at an axis of symmetry of the circumferential tube . Alternatively or additionally the partially open section subtends an angle of at least 120 ° at an axis of symmetry of the circumferential tube . Further alternatively or additionally the partially open section subtends an angle less than 270 ° at an axis of symmetry of the circumferential tube . In some embodiments the partially open section subtends an angle between 160 ° and 200 ° at an axis of symmetry of the circumferential tube .

[0014] In an alternative embodiment the partially open section has a length of at least 3 millimeters . Alternatively or additionally the partially open section has a length of not greater than 10 millimeters .

[0015] The partially open section may have a length of at least 1% of the length of the needle . Alternatively or additionally the partially open section may have a length of less than 5% of the length of the needle .

[0016] There is further provided, according to an alternative embodiment of the present invention, a method of delivering one or more radioactive sources to a tumor, consisting of : providing an elongate needle , having a di stal end and a proximal end and a circumferential tube defining an internal lumen and having a partially open section along a portion of a length of the elongate needle , adjacent the proximal end; inserting the di stal end of the elongate needle proximate to the tumor; placing an applicator, carrying therein the one or more radioactive sources , on the partially open section of the needle; and pushing the applicator via the partially open section distally into the needle so that the one or more radioactive sources are in a predetermined location with respect to the tumor .

[0017] The present disclosure will be more fully understood from the following detailed description of the embodiments thereof , taken together with the drawings , in which : BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figs . 1A and IB illustrate a hollow needle, according to an embodiment of the present invention;

[0019] Figs . 2A - 2G schematically illustrate dif ferent aspects of the hollow needle , according to an embodiment of the present invention;

[0020] Figs . 3A and 3B are schematic diagrams illustrating a partially open section of the needle , according to an embodiment of the present invention; Fig . 4 is a schematic diagram illustrating an applicator, according to an embodiment of the present invention; and

[0021] Fig . 5 i s a flowchart of steps of a source-placement procedure using a needle for a procedure on a tumor, according to an embodiment of the present invention

[0022] DETAILED DESCRIPTION OF EMBODIMENTS

[0023] Overview

[0024] Brachytherapy is an effective procedure for treatment of a tumor, and comprises insertion of one of more radioactive sources , al so herein termed seeds , into the tumor . The sources may be formed into an applicator which comprises a hollow flexible tube having an internal lumen which i s used to retain the sources . Before the procedure , a predetermined number of sources are positioned, and separated spatially, within the lumen of the tube .

[0025] To position the applicator correctly into the tumor of a patient , a hollow needle may be first introduced into the patient ' s tumor . The hollow needle is configured to have a lumen that accommodates the tube of the applicator, and the applicator may then be introduced to the tumor by threading the applicator into the needle ' s lumen .

[0026] However, the diameters of the applicator tube and of the hollow needle are small , typically of the order of 1 mm . In addition, the tolerances between the internal diameter of the hollow needle ' s lumen and the external diameter of the applicator tube are al so small , so that it is difficult and time-consuming to insert the applicator tube into the lumen of the hollow needle .

[0027] Embodiments of the present invention overcome the di fficulty referred to above by increasing the size of the opening at the proximal end of the hollow needle . The increase i s ef fected by removing a portion of the proximal end so that the remaining needle compri ses a partially open proximal section . The partially open proximal section acts as a guide for the applicator tube when it is inserted into the proximal end, as well as providing a larger opening than that of an unchanged hollow needle. Both properties reduce the time taken, and lessen the difficulty involved, for insertion of the applicator tube.

[0028] Detailed Description

[0029] In the following description, like elements in the drawings are identified by like numerals. In addition, all directional references (e.g., upper, lower, upward, downward, left, right, top, bottom, above, below, vertical, and horizontal) are only used for identification purposes to aid the reader' s understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of embodiments of the invention.

[0030] Reference is now made to Figs. 1A and IB, which illustrate a hollow needle 20, according to an embodiment of the present invention. The figures illustrate hollow needle 20, herein also termed slit-needle 20, connected to a detachable handle 24 used for holding the needle. Fig. 1A shows the external surface of hollow needle 20 and handle 24, and Fig. IB is a cross-section of the handle and the needle.

[0031] While hollow needle 20 may be curved or straight, in the following description, except where otherwise stated, the needle is assumed to be straight, and those having ordinary skill in the art will be able to modify the description, mutatis mutandis, for non-straight needles.

[0032] Hollow needle 20 is tubular, having a circumferential tube 26 defining a central lumen 28. Needle 20 is biocompatible, and in one embodiment is formed from stainless steel. While needle 20 is typically formed from a single tubular element, it comprises three regions: a proximal termination 32, a central region 36, and a distal termination 40. The single tubular element from which needle 20 is formed is herein, by way of example, assumed to be cylindrical, so that central region 36 and lumen 28 both have a cylindrical form. Proximal termination 32 and distal termination 40 both comprise modifications of the cylindrical form and are described further below, with reference to Figs. 2A - 2G.

[0033] For simplicity and clarity hollow needle 20 and handle 24 have been drawn on an xyz set of Cartesian axes, wherein the z-axis is parallel to an axis of symmetry 44 of lumen 28, the y-axis lies in the plane of the paper, and the yz plane is a plane of symmetry of the needle. The plane of symmetry is described below.

[0034] Needle 20 acts as a guide for an applicator (described in more detail below) that is used to deposit one or more radioactive seeds, also herein termed sources, in a patient undergoing a procedure on a tumor within the patient. A surgeon using the needle may attach handle 24 to proximal termination 32 of the needle, manipulate the needle as desired, and then detach the handle from the proximal termination.

[0035] When manipulating needle 20, the surgeon typically uses the handle to insert a sharp distal end 48 of distal termination 40 into the patient, and to guide the distal end to a desired location, usually proximate to or within the tumor being operated on. Once the distal end is at its desired location, the surgeon may detach the handle, leaving needle 20 temporarily in place. Figs. 2A - 2G schematically illustrate different aspects of needle 20, according to an embodiment of the present invention. Fig. 2A illustrates the complete needle, and Figs. 2B and 2C are different two-dimensional (2D) views of proximal termination 32 and of a partially open section 52 comprised in the termination. Figs. 2E and 2F are different 2D views of distal termination 40. Figs. 2B, 2C, 2E, and 2F are sectional drawings drawn on the Cartesian axes. Fig. 2D is a three-dimensional (3D) perspective view of proximal termination 32 and of partially open section 52. Fig. 2G is a 3D perspective view of distal termination 40.

[0036] As is apparent from inspection of Figs. 2B, 2C, and 2D, partially open section 52 generates a mirror plane of symmetry 66, containing axis 44, and the yz axes of the Cartesian coordinates have been drawn in the mirror plane. Mirror plane 66 is illustrated in Fig. 2C.

[0037] As is illustrated in Fig. 2D, proximal termination 32 comprises a partially open section 52. Fig. 2B is a cross-section of proximal termination 32, taken in a yz plane, and Fig. 2C is a cross-section of the proximal termination, taken in an xy plane, and presenting the view of the needle as viewed along axis 44 into the needle. As seen in Fig. 2B, partially open section 52 has a cross-section that is in the form of a step 56, having a "runner" 60 of the step that is parallel to the z-axis, and thus to axis of symmetry 44, and "risers" 64 and 68 of the step that are orthogonal to the axis of symmetry. The locations of runner 60 and risers 64 and 68 are also indicated in Fig. 2C.

[0038] In some embodiments partially open section 52 may be formed by laser cutting of a cylindrical hollow needle, but in other embodiments section 52 may be formed by any other convenient production method. As is illustrated in Fig. 2D, partially open section 52 is formed as a partial cylindrical section that is connected a fully cylindrical remainder of needle 20, and it will be understood that the runner and risers of step 56, described above, refer to the appearance of the cross-section of partially open section 52.

[0039] As is illustrated in Fig. 2D, partially open section 52 is formed in hollow needle 20, so that runner 60 corresponds to two straight surfaces 60S1 and 60S2, and risers 64 and 68 correspond respectively to semicircular surfaces 64S and 68S.

[0040] As is illustrated in Figs. 2C and 2D, partially open section 52 is a semicylinder, i.e., a half cylinder formed by cutting a cylinder longitudinally along its axis of symmetry. By virtue of being a semicylinder, the angle subtended at the axis of symmetry by surfaces 60S1 and 60S2 is 180° .

[0041] As stated above, partially open section 52 is a semicylinder. However, it will be understood that this is but one example of a partially open section.

[0042] Figs. 3A, 3B are schematic diagrams illustrating an alternative partially open section 152, according to an embodiment of the present invention. Apart from the differences described below, the operation and structure of partially open section 152 are generally similar to that of partially open section 52 (Figs. 1A - 2G) , and elements indicated by the same reference numerals in both partially open sections 52 and 152 are generally similar in construction and in operation. Figs. 3A and 3B have been drawn on the Cartesian axes, as described above. Fig. 3A is a cross-section of proximal termination 32, taken in a yz plane. Fig. 3B is a cross-section of the proximal termination, taken in an xy plane, and presenting the view of needle 20 as viewed along axis 44 into the needle.

[0043] As is illustrated in Fig. 3B, in contrast to partially open section 52 which is a semicylinder subtending 180° at axis of symmetry 44, partially open section 152 subtends an angle 0, different from 180°, at the axis of symmetry. In disclosed embodiments,

[0044] 90° < e < 180° (1)

[0045] From expression (1) , disclosed embodiments may have angles 0 that are at least 90°, 120°, 150° or even 170°, as well as other values given by expression (1) .

[0046] In further disclosed embodiments, angle 0 of partially open section 152 is given by expression (2) :

[0047] 180°< e < 270° (2)

[0048] From expression (2) , further disclosed embodiments may have angles 0 that are less than 270°, 240°, 210° or even 190°, as well as other values given by expression (2) .

[0049] In some embodiments partially open sections 52 and 152 typically have lengths given by expression (3) : where L is the length of the partially open section in millimeters.

[0050] However, some embodiments may have a length of the partially open section different from that given by expression (3) .

[0051] From expression (3) the length of the partially open section may be at least 1 mm, at least 2 mm, at least 3 mm or even at least 4 mm. Optionally, also from expression (3) , the length of the partially open section may be not greater than 10 mm, not greater than 7 mm or even not greater than 5 mm.

[0052] Needle 20 typically has a length between 2 cm and 30 cm, although in some embodiments the needle length may be outside this range. In disclosed embodiments the needle length is at least 2 cm, at least 3 cm, at least 5 cm, or even at least 10 cm. Optionally, the needle is not longer than 30 cm, not longer than 20 cm, not longer than 15 cm, or even not longer than 12 cm. In the procedure referred to above, the surgeon typically selects the length of the needle according to the location of the tumor within the patient .

[0053] In a disclosed embodiment, the length of partially open section 52 or 152 is at least 1% the length of the needle. In an alternative embodiment, the length of partially open section 52 or 152 is less than 5% the length of the needle.

[0054] Needle 20 typically has an outer diameter between 0.5 mm and 1.7 mm, although some embodiments may have a diameter outside this range. In a disclosed embodiment the outer diameter is at least 0.5 mm, at least 0.6 mm, at least 0.8 mm or even at least 1 mm. In an alternative embodiment the outer diameter is not greater than 1.7 mm, not greater than 1.5 mm or even not greater than 1.2 mm. The inner diameter of needle 20 is optionally between approximately 0.5 mm and approximately 1.5 mm, depending on the outer diameter.

[0055] The dimensions of needle 20 are typically selected according to the procedure to be performed, the location of the tumor, and the applicator to be used in the procedure. An applicator comprises a system that delivers one or more radioactive sources to a patient, and applicators are known in the art. An example of an applicator is described below.

[0056] Fig. 4 is a schematic diagram illustrating an applicator 200, according to an embodiment of the present invention. Applicator 200 comprises a narrow flexible tube 204, the tube having an internal lumen 208, a proximal end 210, and a distal end 214. Prior to the procedure wherein applicator 200 is to be used, one or more radioactive sources 212, also herein termed seeds 212, are positioned within lumen 208. Fig. 4 shows a cross-section 216 of applicator 200, illustrating a single seed 212. Each seed 212 comprises a cylindrical tube with an internal lumen through which a seedretaining wire 220 is passed.

[0057] Applicator 200, when assembled, thus comprises tube 204, one or more seeds 212, and seed-retaining wire 220. Typically, a proximal termination 224 and a distal termination 228 of wire 220 are arranged to be within lumen 208, so that the wire proximal and distal terminations do not project beyond proximal end 210 and distal end 214 of the applicator tube. Fig. 5 is a flowchart 300 of steps of a sourceplacement procedure using needle 20 for a procedure on a tumor, according to an embodiment of the present invention. In the following description needle 20 is assumed to have partially open section 52, and those having ordinary skill in the art will be able to adapt the description, mutatis mutandis , for needles using partially open section 152.

[0058] In an initial step 304, applicator 200 is assembled with sources 212, substantially as described above with reference to Fig. 4, wherein the number of sources used in the applicator is according to the procedure to be applied. Using handle 24 (Fig. 1A) , a surgeon performing the procedure inserts needle 20 into the patient, until distal end 48 is at a desired location with respect to the tumor. Once inserted, the surgeon may detach handle 24, leaving needle 20 in place.

[0059] In an operation step 308, the surgeon inserts distal end 214 of the applicator into the lumen of needle 20, via partially open section 52 of the needle. The increased size of the opening provided by the partially open section, as well as the guiding property of the open section, makes the applicator distal end insertion easier .

[0060] The surgeon continues inserting the applicator until the applicator, and the sources within the applicator, are correctly positioned with respect to the tumor.

[0061] In an ejection step 312, once the applicator has been correctly positioned, the surgeon ejects the sources from the applicator, typically so that the sources are within, or are proximate to, the tumor. Typically, the ejection is by pushing a stylet (not shown in the figures ) into the proximal end of lumen 208 of the applicator . The pushed stylet contacts proximal termination 224 of seed-retaining wire 220 , so that further pushing of the stylet e ject s the wire and sources 212 from distal end 214 of the applicator .

[0062] In a final step 316 , when sources 212 have been e j ected from the applicator, the applicator and needle 20 are both removed from the patient . It will be appreciated that the embodiments described above are cited by way of example , and that the present invention i s not limited to what has been particularly shown and described hereinabove . Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove , as well as variations and modi fications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art .

Claims

CLAIMS1. A needle for delivery of radioactive sources, comprising : an elongate needle having a distal end and a proximal end, and having a circumferential tube defining an internal lumen; a sharp tip defined at the distal end of the needle; and a partially open section along a portion of a length of the elongate needle, adjacent the proximal end of the needle .

2. The needle according to claim 1, wherein the partially open section comprises a semicylinder.

3. The needle according to claim 1, wherein a crosssection of the partially open section comprises a shape of a step.

4. The needle according to claim 3, wherein the step comprises a runner parallel to an axis of symmetry of the circumferential tube, and at least one riser orthogonal to the axis of symmetry.

5. The needle according to claim 4, wherein the runner is coincident with the axis of symmetry.

6. The needle according to claim 4, wherein the at least one riser comprises a first riser and a second riser having equal lengths.

7. The needle according to claim 1, wherein the partially open section subtends an angle of at least 90° at an axis of symmetry of the circumferential tube.

8. The needle according to claim 1, wherein the partially open section subtends an angle of at least 120° at an axis of symmetry of the circumferential tube.

9. The needle according to claim 1, wherein the partially open section subtends an angle less than 270° at an axis of symmetry of the circumferential tube.

10. The needle according to claim 1, wherein the partially open section subtends an angle between 160° and 200° at an axis of symmetry of the circumferential tube.

11. The needle according to claim 1, wherein the partially open section has a length of at least 3 millimeters .

12. The needle according to claim 1, wherein the partially open section has a length not greater than 10 millimeters .

13. The needle according to claim 1, wherein the partially open section has a length of at least 1% of the length of the needle.

14. The needle according to claim 1, wherein the partially open section has a length of less than 5% of the length of the needle.

15. A method of delivering one or more radioactive sources to a tumor, comprising: providing an elongate needle, having a distal end and a proximal end and a circumferential tube defining an internal lumen and having a partially open section along a portion of a length of the elongate needle, adjacent the proximal end; inserting the distal end of the elongate needle proximate to the tumor;placing an applicator, carrying therein the one or more radioactive sources , on the partially open section of the needle; and pushing the applicator via the partially open section distally into the needle so that the one or more radioactive sources are in a predetermined location with respect to the tumor .

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