Contrast markers for use in medical procedures

Abstract

A contrast marker for use in medical imaging comprising: an elongated body comprising a first end and a second end, the second end opposite the first end, wherein a longitudinal axis is defined between the first end and the second end. A first portion of the elongated body is formed of a radiopaque material and a second portion of the elongated body is formed of a polymeric material, the first portion extending in a direction parallel with the longitudinal axis. The marker may be configured to receive a fluidic contrast medium so as to be imageable under CT and MR imaging. Also provided herein are methods of making the contrast marker. Further provided herein is an applicator plug for sealing a tubular brachytherapy applicator.

Description

CONTRAST MARKERS FOR USE IN MEDICAL PROCEDURESRELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 639,844, filed April 29, 2024, entitled “CONTRAST MARKERS FOR USE IN MEDICAL PROCEDURES,” which claims the benefit of U.S. Provisional Application No. 63 / 601 ,437, filed November 21 , 2023, entitled “CONTRAST MARKERS FOR USE IN MEDICAL PROCEDURES,” the contents of which are incorporated herein by reference in their entirety.FIELD

[0002] The present application is directed to a contrast marker for use in medical imaging applications, such as for the guidance of brachytherapy applicators.BACKGROUND

[0003] Radiation is commonly used to treat various types of cancer, such as prostate cancer, breast cancer, and soft tissue sarcomas. Brachytherapy, for example, is one type of radiation therapy that provides for targeted delivery of radioactive sources into a patient’ s body at or near a tumor or lesion with high precision, thereby minimizing exposure of healthy surrounding tissues to radiation. In interstitial brachytherapy, applicators can be used to facilitate precise delivery of radioactive sources to the treatment site. Interstitial applicators typically include thin, flexible tubes (e.g., needles, catheters, tubular brachytherapy applicators), one end of which is inserted through the skin or other natural openings to reach an intracorporeal treatment site, such as a tumor site. The other ends extend extracorporeally outside the patient. These catheters include channels (i.e., lumens) through which the radioactive sources (e.g., an Iridium- 192 seed fixed to the distal end of a cable) can be introduced.

[0004] Imaging techniques such as ultrasound, computed tomography (CT), or magnetic resonance (MR or MRI) may be used to guide placement of the brachytherapy applicators themselves so that they may be accurately positioned relative to the treatment site. Because brachytherapy treatment planning is complex, the precise location of each applicator must be accurately defined to determine the dwell positions of subsequently delivered radiation sources and calculate expected dose distributions accordingly. Furthermore, accurate placement of the brachytherapy applicators ensures that radiation sources subsequently delivered through the brachytherapy applicators are appropriately positioned relative to the targeted tissue.

[0005] Furthermore, because ends of the brachytherapy applicators extend outside the patient, it is possible for moisture to enter lumens of the applicators. Such moisture can damage or interfere with the proper function of radioactive sources inserted therein. Accordingly, devices and methods are needed to prevent the ingress of moisture into the lumens.SUMMARY

[0006] In some aspects, the techniques described herein relate to a contrast marker for medical imaging. In various implementations, the contrast marker includes an elongated body having a first end and a second end, where the second end is opposite the first end. A longitudinal axis is defined between the first end and the second end. A first portion of the elongated body is formed of a radiopaque material and a second portion of the elongated body is formed of a polymeric material. The first portion extends in a direction parallel with the longitudinal axis.

[0007] In some implementations, the first portion has a total thickness of 0.2 mm. In some implementations, the first portion extends along a side of the elongated body. In some implementations, the first portion extends along only a single side of the elongated body.

[0008] In some implementations, the first portion is disposed at the first end. In some implementations, the first portion includes a continuous strip of radiopaque material. In some implementations, the first portion includes two or more first portions spaced apart from one another in a direction parallel with the longitudinal axis. In some implementations, the first portion is disposed radially outward of the second portion.

[0009] In some implementations, a strip of the radiopaque material extends between each of the two or more first portions. In some implementations, the strip of the radiopaque material has a thickness narrower than the thickness of the two or more first portions. In some implementations, the radiopaque material includes copper, brass, or bronze.

[0010] In some implementations, the second portion includes one or more negative spaces sized and configured to receive the first portion such that the elongated body has a substantially smooth outer surface.

[0011] In some implementations, the second portion includes vacancies configured to receive a fluid. In some implementations, the vacancies are a porous microstructure. In some aspects, the techniques described herein relate to a contrast marker, wherein the contrast marker further includes a sealant layer disposed radially outside the second portion so as to prevent loss of thefluid received therein. In some implementations, the fluid is an imaging contrast medium that is visible under magnetic resonance imaging.

[0012] In some implementations, the elongated body has a solid cross-section between the first end and the second end. In some implementations, the elongated body further defines a central lumen extending at least partially therethrough. In some implementations, the central lumen extends through an entire length of the elongated body. In some implementations, the central lumen has an inner diameter of 0.8 mm. In some implementations, the contrast marker further includes at least one end cap configured to retain a fluid in the central lumen. In some implementations, the fluid is an imaging contrast medium that is visible under magnetic resonance imaging.

[0013] In some implementations, the polymeric material includes PLA, PGA, and / or PLGA.

[0014] In some implementations, the elongated body has an outer diameter sized and configured to be inserted into a lumen of a tubular brachytherapy applicator. In some implementations, the outer diameter is 1 .3 mm. In some implementations, the elongated body has a length sized and configured to be retrievably inserted into a lumen of a tubular brachytherapy applicator.

[0015] In some implementations, the first portion is fabricated using a three-dimensional (3D) printer. In some implementations, the first portion is fabricated using a mold. In some implementations, the second portion is fabricated using a three-dimensional (3D) printer. In some implementations, the second portion is fabricated using a mold.

[0016] In some aspects, the techniques described herein relate to a method of fabricating a contrast marker for medical imaging. In various implementations, the method includes: (i) forming an absorbent portion of an elongated body of the contrast marker of an absorbent material; (ii) loading fluid into the absorbent portion; (iii) sealing the fluid within the absorbent portion; and (iv) forming a radiopaque portion of the elongated body over the absorbent portion of a radiopaque material. The radiopaque portion extends in a direction parallel with a longitudinal axis defined between first and second ends of the elongated body.

[0017] In some implementations, forming the absorbent portion further includes forming an elongated polymeric member including a network component and a dissolvable component, and dissolving the dissolvable component from the elongated polymeric member so that the network component remains, thereby forming the absorbent portion.

[0018] In some implementations, forming the elongated polymeric member further includes providing a three-dimensional (3D) printer configured to dispense a polymeric material including the network component and the dissolvable component onto a print bed, and operating the 3D printer to form the elongated polymeric member. The elongated polymeric member is formed in a direction parallel with the print bed.

[0019] In some implementations, forming the elongated polymeric member further includes adding a polymeric material including the network component and the dissolvable component into a mold.

[0020] In some implementations, loading fluid into the absorbent portion includes loading the fluid into the network component of the polymeric member.

[0021] In some implementations, sealing the fluid within the absorbent portion includes forming a sealant layer radially outside of the absorbent portion.

[0022] In some implementations, forming the radiopaque portion of the elongated body over the absorbent portion includes providing a three-dimensional (3D) printer configured to dispense a radiopaque material onto a print bed, and operating the 3D printer to form the radiopaque portion along a side of the absorbent portion of the elongated body. In some implementations, forming the radiopaque portion of the elongated body over the absorbent portion includes adding the radiopaque material to a mold including the absorbent portion. In some implementations, forming the radiopaque portion of the elongated body over the absorbent portion includes forming two or more radiopaque portions spaced apart from one another in a direction parallel with the longitudinal axis.

[0023] In some implementations, the elongated body is formed without a sacrificial support structure.

[0024] In some aspects, the techniques described herein relate to an applicator plug for sealing a lumen of a tubular brachytherapy applicator. The applicator plug includes an extension region configured to extend proximally into the lumen of the tubular brachytherapy applicator, a pull region configured to extend distally from the lumen of the tubular brachytherapy applicator, and a first raised portion that extends radially outward from the extension region. The first raised portion is sized and configured to form a friction fit with an inner diameter of the brachytherapy applicator.

[0025] In some implementations, the applicator plug tapers from the first raised portion toward the extension region.

[0026] In some implementations, wherein the applicator plug further includes a second raised portion disposed distally relative to the first raised portion, wherein the second raised portion extends radially outward from the extension region to a diameter that is greater than the inner diameter of the brachytherapy applicator.

[0027] In some implementations, the applicator plug is formed of thermoplastic polyurethane (TPU). In some implementations, the applicator plug is fabricated using a three-dimensional (3D) printer.

[0028] In some aspects, the techniques described herein relate to a method of fabricating a contrast marker for medical imaging. In various implementations, the method includes: (i) providing a three-dimensional (3D) printer configured to dispense a radiopaque material and a polymeric material onto a print bed; (ii) operating the 3D printer to form at least one first layer of an elongated body of the contrast marker, the at least one first layer forming a first portion of the elongated body including the radiopaque material; and (iii) operating the 3D printer to form one or more second layers of the elongated body on top of the at least one first layer, where the one or more second layers form a second portion of the elongated body including the polymeric material. The elongated body includes a first end and a second end, the second end opposite the first end and defines a longitudinal axis therebetween. The longitudinal axis defined parallel with the print bed.

[0029] In some implementations, the elongated body is formed without a sacrificial support structure.

[0030] In some aspects, the techniques described herein relate to a kit including a contrast marker and an applicator plug. The contrast marker includes an elongated body having a first end and a second end, where the second end is opposite the first end. A longitudinal axis is defined between the first end and the second end. A first portion of the elongated body is formed of a radiopaque material and a second portion of the elongated body is formed of a polymeric material. The first portion extends in a direction parallel with the longitudinal axis. The elongated body has an outer diameter sized and configured to be inserted into a lumen of a tubular brachytherapy applicator. The applicator plug includes an extension region configured to extend proximally into the lumen of the tubular brachytherapy applicator, a pull region configured to extend distally from the lumen of the tubular brachytherapy applicator, and a firstraised portion that extends radially outward from the extension region. The first raised portion is sized and configured to form a friction fit with an inner diameter of the brachytherapy applicator.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a side view of an exemplary contrast marker inserted into a brachytherapy applicator, according to some implementations.

[0032] FIG. 2A is another side view of an exemplary contrast marker, according to some implementations .

[0033] FIG. 2B is a front view of an exemplary contrast marker, according to some implementations.

[0034] FIG. 3 is another side view of an exemplary contrast marker, according to some implementations .

[0035] FIGS. 4A,4B, and 4C are additional side views of exemplary contrast markers, according to some implementations.

[0036] FIG. 5 is a diagram illustrating the fabrication of a contrast marker, according to some implementations.

[0037] FIG. 6 is a view of the fabrication of a contrast marker, according to some implementations.

[0038] FIG. 7 is a detailed view of the fabrication of a contrast marker, according to some implementations .

[0039] FIG. 8 is an alternate view of the fabrication of a contrast marker, according to some implementations.

[0040] FIG. 9 is a flow chart of a method of fabricating a contrast marker, according to some implementations.

[0041] FIG. 10 is a flow chart of a method of using a contrast marker for application of brachytherapy, according to some implementations.

[0042] FIG. 11 shows cross-sectional and side views of computed tomography (CT) images comparing CT imaging artifacts generated by contrast markers according to some implementations described herein and commercially available markers.

[0043] FIG. 12 shows side views of magnetic resonance (MR) images of contrast markers according to some implementations described herein.

[0044] FIG. 13 is a chart of contrast-to-noise ratios (CNR) and metal artifact (HU) for contrast markers of various materials under magnetic resonance (MR) and computed tomography (CT) imaging.

[0045] FIG. 14 is a side view of an exemplary contrast marker, according to some implementations .

[0046] FIG. 15 is a flow chart of a method of using a contrast marker for application of brachytherapy, according to some implementations.

[0047] FIG. 16 is a side view of an exemplary contrast marker, according to some implementations .

[0048] FIG. 17 is a detailed side view of an exemplary contrast marker taken along 17-17, according to some implementations.

[0049] FIG. 18 is a side view of an exemplary contrast marker, according to some implementations.

[0050] FIG. 19 is a flow chart of a method of using a contrast marker for application of brachytherapy, according to some implementations.

[0051] FIG. 20 is a magnetic resonance (MR) image taken along a coronal plane of a contrast marker according to some implementations described herein.

[0052] FIG. 21 is a magnetic resonance (MR) image taken along an axial plane of contrast markers according to some implementations described herein.

[0053] FIG. 22 is a perspective view of an exemplary applicator plug, according to some implementations .

[0054] FIG. 23 is a detailed side view of an exemplary applicator plug, according to some implementations .

[0055] FIG. 24A is a perspective view of an exemplary applicator plug, according to some implementations.

[0056] FIG. 24B is a side view of an exemplary applicator plug inserted into a brachytherapy applicator, according to some implementations.

[0057] Various objects, aspects, features, and advantages of the disclosure will become more apparent and better understood by referring to the detailed description taken in conjunction with the accompanying drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements.DETAILED DESCRIPTION

[0058] Referring generally to the figures, contrast markers and related fabrication methods are shown, according to various implementation. Contrast markers, as will be appreciated by those in the art, are used in conjunction with medical imaging techniques (e.g., CT, MRI, etc.) to guide placement of, e.g., brachytherapy applicators, for positioning relative to a treatment site. Thus, in some implementations, the contrast marker(s) described herein may be particularly well-suited for brachytherapy. In this regard, it should be appreciated that the disclosed contrast marker(s) and their related fabrication techniques are generally described herein with respect to brachytherapy; however, the present disclosure is not intended to be limiting in this regard. Notably, the disclosed fabrication methods for contrast markers integrate radiopaque sections into a polymeric body in a way that is customizable and lower cost than producing the wires that are currently used for guidance, e.g., of brachytherapy applicators. Additional features and details of the disclosed contrast markers and related fabrication methods are provided below.

[0059] Overview

[0060] As mentioned above, brachytherapy applicators utilize hollow catheters that are difficult to visualize using day-of-treatment CT or MR imaging. Current interstitial brachytherapy applicators utilize radiopaque markers that are expensive, largely incompatible with MR technologies, and / or create significant artifact on CT and / or MR imaging. For example, in an effort to introduce a radiopaque material to the catheters, practitioners may perform CT imaging using commercially available stainless-steel wires installed in each hollow catheter and then attempt to cross-reference these images with MR images. While such commercially available wires allow for improved delineation of catheter channels, they introduce significant CT artifact that can interfere with mapping of catheter channels and contouring anatomic structures. Additionally, transferring the patient between multiple scanners and manipulating the applicator or catheter wires between scans may contribute to prolonged procedure time, additionalanesthesia risks, and the potential for applicator displacement, impacting applicator catheter location and accuracy of CT-MR image fusions.

[0061] Unlike commercially available wires, the contrast markers described herein are low-cost, easy to fabricate, and demonstrate improved CT and MR compatibility. For example, in some implementations, the contrast markers may be fabricated using 3D printing by forming a first portion that includes a radiopaque-polymer composite material, such as a copper-polylactic acid (Cu-PLA) composite material. This composite material is available in the form of inexpensive filaments. Then, a subsequent portion including a polymeric material can be formed on top of the first portion. This 3D printing technique can be easily adapted to provide customizable contrast marker geometries and tailor the distribution of materials therein. In some implementations, for example, the contrast marker further includes a central lumen into which a fluidic imaging contrast medium is added. The use of these materials and configurations provide improved CT and MR compatibility by reducing imaging artifact while maintaining contrast-to- noise ratio. Furthermore, in implementations that utilize 3D printing for fabricating the first portion, forming the first portion parallel with a 3D printer print bed allows the contrast marker to be fully fabricated without the use of additional sacrificial materials, thereby reducing fabrication costs and post-fabrication processing.

[0062] As further described herein, in further implementations, the contrast markers include a first portion that includes a radiopaque-polymer composite material that is added to a second portion that includes an absorbent polymeric material. In such implementations, the absorbent polymeric material is loaded with a fluidic imaging contrast medium and sealed to prevent egress of the fluid during use.

[0063] For the purposes of brevity, this disclosure describes various implementations in which the contrast markers are fabricated using 3D printing. However, the contrast markers provided herein may be fabricated using various other methods, such as other additive manufacturing techniques or molding.

[0064] Contrast Markers

[0065] Referring to FIGS. 1-2B, a contrast marker 100 for medical imaging is shown, according to some implementations. The contrast marker 100 generally includes an elongated body 102 defined between a first end 112 and a second end 114, where the second end 114 is opposite the first end 112. A longitudinal axis 116 is defined between the first end 112 and the second end 114, and extends parallel with the elongated body 102, as shown. The elongated body 102 isfurther shown to include a first portion 106 formed of a radiopaque material and a second portion 110 formed of a polymeric material, as described in greater detail below.

[0066] Generally, the elongated body 102 has an outer diameter (OD) sized and configured to be inserted into a lumen of a tubular brachytherapy applicator. In some implementations, the contrast marker 100 may have an outer diameter (OD) of up to 1.5 mm. In some implementations, the outer diameter (OD) of the elongated body 102 can range from 0.5 mm to 1.5 mm. For example, the outer diameter (OD) can be 1.3 mm. In some examples, the outer diameter (OD) is 1.26 mm. The particular implementation of the contrast marker 100 shown in FIG. 1 and FIGS. 2A-2B has an elongated body 102 having an outer diameter of 1.00 mm.

[0067] Furthermore, in some implementations, the elongated body 102 has a length sized and configured to be retrievably inserted into a lumen of a tubular brachytherapy applicator. For example, the contrast marker 100 shown in FIG. 1 and FIG. 2A-2B has an elongated body 102 having a length of 240 mm; however, the length of the elongated body 102 can be shorter (e.g., 200 mm) or longer in various implementations. In some implementations, the length of the elongated body 102 is 250 mm + 50 mm.

[0068] As described herein, the polymeric material used for the second portion 110 is any suitable polymeric-based material that allows for the elongated body 102 of the contrast marker 100 to flex without mechanical failure. In some implementations, such as those illustrated in FIGS. 1-4C, 6-8, 11-12, and 14, the polymeric material comprises polylactic acid (PLA). In other implementations, the polymeric material comprises poly (glycolic) acid (PGA). In some implementations, the second portion 110 is formed of a combination of two or more polymeric materials, such as the copolymer poly(lactic-co-glycolic) acid (PLGA). As provided further herein, in other implementations, such as those illustrated in FIGS. 16-18, the polymeric material comprises an absorbent material.

[0069] Notably, the first portion 106 of the elongated body 102 is formed of a radiopaque material. Generally, radiopaque materials are substances that appear relatively opaque when imaged using ionizing radiation. Thus, inclusion of radiopaque material in the contrast marker enhances visibility of the contrast marker under medical imaging. In other words, a practitioner is able to determine the placement of a contrast marker by visualizing the location of the radiopaque portion using medical imaging. In some implementations, the radiopaque material - and therefore, the first portion 106 - is a metallic material that is configured to be visible under and compatible with both computed tomography imaging and magnetic resonance imaging.Example metallic materials that are suitable for use as a radiopaque material include, but are not limited to, copper, brass, and bronze. For example, the first portion 106 may include copper in the form of copper (II) sulfate (CuSO4).

[0070] As illustrated in FIG. 1, the first portion 106 extends in a direction parallel to the longitudinal axis 116. Specifically, in the illustrated implementation, the first portion 106 is disposed in a band or strip configuration. In some such implementations, (e.g., illustrated by FIG. 2B) the first portion 106 is configured as a band or strip having a total thickness (Tl) and a width extending to an outer surface of the elongated body 102. In other words, the total thickness (Tl) is the sum thickness of one or more layers of a radiopaque material. For example, as shown in FIG. 2B, the total thickness (Tl) is the thickness from an outer surface of the elongated body 102 to a central lumen 118. In some examples, the total thickness of the band or strip of the first portion 106 can have a range of 0.25 mm to 0.5 mm. Specifically, the example band or strip of the first portion 106 illustrated in FIG. 2B has a total thickness (Tl) of 0.25 mm. In further examples, the band or strip of the first portion 106 can have a total thickness (Tl) of 0.225 mm.

[0071] Furthermore, as shown in FIG. 2B, the width of the band or strip may taper in accordance with the profile of the elongated body 102. As shown, the band or strip extends the entire length of the elongated body 102. However, it should be appreciated that the specific dimensions of the first portion 106 may be customizable, e.g., using the fabrication process described below. For example, the first portion 106 may be wider or narrower than 0.2 mm and / or may extend only a portion of the length of the elongated body 102.

[0072] With additional reference to FIG. 3, rather than having one continuous strip of radiopaque material, the first portion 106 of the elongated body 102 may be formed in a plurality of separate sections. In other words, the first portion 106 may include a plurality of sub-first portions, shown as first portions 106, 106’, and 106”. Each of first portions 106, 106’, and 106” may be formed of the same radiopaque material; however, it should also be appreciated that one of more of first portions 106, 106’, and 106” may be formed of a different radiopaque material than the rest. Such an arrangement may reduce the percent weight of radiopaque material required for fabrication. As illustrated, at least one of the first portions 106, 106’, and 106” are disposed at the first end 112 of elongated body 102. Such a distribution of radiopaque material ensures that the first end 112 of the contrast marker 100 is localizable with respect to the treatment site.

[0073] In conjunction with implementations that include more than one radiopaque portion (e.g., first portions 106, 106’, and 106”), the second portion 110 of elongated body 102 (e.g., the polymeric material) may separate each of the first portions 106, 106’, and 106”, as illustrated in FIG. 3. In this regard, the first portions 106, 106’, and 106” may be disposed in discrete, discontinuous pockets or clusters spaced apart from each other along the length of the elongated body 102. As shown, the first portions 106, 106’, and 106” are spaced apart from each other and arranged along the elongated body 102 in a direction parallel to the longitudinal axis 116; however, it should be appreciated that the first portions 106, 106’, and 106” may be arranged in any manner along the elongated body 102. Additionally, it should be appreciated that the first portions 106, 106’, and 106” may represent any number of sections of radiopaque material (e.g., three sections, as shown, or more / less).

[0074] Referring back to FIG. 2B, in some implementations, the elongated body 102 further includes a central lumen 118 extending at least partially therethrough. In some implementations, the central lumen 118 may extend through an entirety of the elongated body 102. As shown in FIG. 2B, the central lumen 118 defines an inner diameter (ID) of the elongated body 102. In some examples, the inner diameter (ID) of the central lumen 118 can have a range of about 0.5 mm to about 1.5 mm. In the example illustrated in FIG. 2B, the inner diameter (ID) of the central lumen 118 is 0.80 mm. However, in other implementations, the inner diameter (ID) may be wider or narrower than 0.8 mm or may extend through only a portion of the length of the elongated body 102.

[0075] With additional reference to FIG. 4 A, one implementation of the contrast marker 100 is shown in which a fluid 122 is added to the central lumen 118. In some implementations, the fluid 122 is added after the elongated body 102 is formed. Specifically, in some such implementations, the fluid 122 may be added to the central lumen 118 by a practitioner during use of the contrast marker 100. The fluid 122 is generally any suitable fluid that is visible under magnetic resonance imaging, thereby serving as a contrast medium. In some implementations, the fluid 122 may be a viscous contrast media, such as glycerin gel. Notably, the combination of a radiopaque material (e.g., the first portion 106) visible under CT imaging, and the fluid 122, serving as a MR contrast medium, allows the contrast marker 100 to be used for localizing interstitial brachytherapy applicator catheters using either imaging modality. In such examples, the first portion 106 extends along only a single side of the elongated body 102 so that, when imaging, signal emitted from the fluid 122 within the central lumen 118 is not blocked by the radiopaque material.

[0076] In such implementations, the contrast marker 100 further includes at least one end cap 120 configured to contain the fluid 122 in the central lumen 118. For example, the contrast marker 100 may include two end caps, shown as 120 and 120’ such that the fluid 122 is entirely retained within the central lumen 118. In another example, the contrast marker 100 includes only one of end caps 120, 120’ such that the fluid 122 can be easily removed from the central lumen 118. To this point, one of the end caps 120, 120’ may be left uninstalled from the elongated body 102 until the fluid 122 is added, after which time the uninstalled one of end caps 120, 120’ is attached to the elongated body 102, e.g., to encapsulate the fluid 122.

[0077] In some implementations, the end cap 120 is a discrete component formed separate from the elongated body 102 and subsequently coupled to the elongated body 102. For example, the end cap 120 may be frictionally engaged with the first end 112 of the elongated body 102. In some implementations, the end cap 120 is permanently bonded to the elongated body 102, e.g., using an adhesive or molding technique. In some such implementations, the end cap 120 can be integrally formed with the elongated body 102. In implementations wherein the central lumen 118 extends through only a partial extent of the elongated body 102, the portion of the elongated body 102 through which the central lumen 118 does not extend may be considered an end cap 120.

[0078] With additional reference to FIG. 4B, another implementation of the contrast marker 100 is shown. Specifically, FIG. 4B shows the contrast marker 100a, which is similar to the contrast marker 100 described in reference to FIG. 4A. Accordingly, like reference numbers are used to refer to like features. However, rather than including the central lumen 118a, the elongated body 102a has a solid cross-section between the first end 112a and the second end 114a. In other words, the elongated body 102a does not have a central lumen or other cavity formed therein. As illustrated, the first portion 106a extends in a direction parallel to the longitudinal axis 116a of the elongated body 102a along one side of the elongated body 102a and the second portion 110a extends along the longitudinal axis 116a itself.

[0079] FIG. 4C shows the contrast marker 100b, which is similar to the contrast marker 100a described in reference to FIG. 4B. Accordingly, like reference numbers are used to refer to like features. However, in FIG. 4C, the first portion 106b extends along the longitudinal axis 116b itself. For example, as shown in FIG. 4C, where the contrast marker 100b does not have a central lumen, the first portion 106b is formed internally to the elongated body 102b, e.g., as opposed to be formed on an outside portion of the elongated body 102b as in contrast marker100a. In such examples, the longitudinal axis 116b can be considered a central axis of the elongated body 102b. Furthermore, in such examples, the second portion 110b extends circumferentially around the elongated body 102b of the contrast marker 100b.

[0080] Another implementation of the contrast marker is shown in FIG. 14. Specifically, FIG. 14 shows the contrast marker 100c, which is similar to the contrast marker 100 described in reference to FIG. 4A. Accordingly, like reference numbers are used to refer to like features. However, the first portion 106c is disposed over a tubular body fully formed by the second portion 110c. In the illustrated example, the contrast marker 100c is formed from the combination of a radiopaque first portion 106c coupled to a tubular polymeric second portion 110c. Coupled together, the first portion 106c and second portion 110c form an elongated body 102c. For example, as shown in FIG. 14, the second portion 110c is formed as a fully closed tubular body that defines a lumen extending therethrough and a longitudinal axis 116c. In the implementation illustrated in FIG. 14, radiopaque first portion 106c is disposed radially outward relative to the tubular body of the second portion 110c. In other implementations, the radiopaque first portion 106c may be disposed radially inward relative to the second portion 110c such that the radiopaque first portion 106c is positioned within the lumen. Furthermore, in the implementation shown, the radiopaque first portion 106c is a continuous strip extending along an outer surface of the tubular polymeric second portion 110c. However, in other implementations, the radiopaque first portion 106c may be divided into more than one discrete segments spaced apart from one another, which may be regarded as more than one first portion 106c. As further described below, various fabrication techniques may be used to fabricate the contrast marker 100c, including but not limited to additive manufacturing or molding techniques.

[0081] Another implementation of the contrast marker is shown in FIGS. 16-17. Specifically, FIGS. 16-17 show the contrast marker lOOd, which is similar to the contrast marker 100a described in relation to FIG. 4B. Accordingly, like reference numbers are used to refer to like features. However, the second portion 1 lOd is formed of a polymeric material that is absorbent. In some implementations, the absorbent polymeric material is one that includes vacancies that can receive a fluid as a fluidic imaging contrast medium. In some implementations, the vacancies may also retain the fluid. For example, the vacancies may be a porous microstructure in the absorbent polymeric material. In the illustrated implementation, the second portion 1 lOd has a porous microstructure network. Specifically, the second portion 1 lOd shown is formed of PORO-LAY GEL-LAY filament. In some implementations, the second portion may have a thickness of 0.8 mm. However, the thickness of the second portion may be varied relative to thethickness of the first portion 106d such that, when coupled, the first portion 106d and second portion 1 lOd are sized to be inserted into a tubular brachytherapy applicator.

[0082] Furthermore, in the implementation shown, the absorbent polymeric material of the second portion 1 lOd is loaded with a fluid. Specifically, in the illustrated implementation, water is received and retained within the vacancies of the absorbent polymeric material. However, as described herein, the fluid may generally be any suitable fluid that is visible under magnetic resonance imaging. For example, the fluid may be vitamin E or vegetable oil.

[0083] In the illustrated implementation, a sealant is applied radially outward of the second portion 1 lOd to the outer surface of the second portion 1 lOd as a sealant layer 108d. The sealant prevents loss of the fluid retained within the absorbent polymeric material of the second portion 1 lOd. In the illustrated implementation, the sealant is epoxy resin. However, any sealant may be used that prevents egress of the fluid from the absorbent material of the second portion 1 lOd.

[0084] Furthermore, as shown in FIG. 16, for example, the contrast marker lOOd includes two or more first portions 106d, shown as 106d, 106d’, 106d”, 106d” ’, and 106d””. As shown, each of the first portions 106d is spaced apart from the adjacent first portion (e.g., 106d’ ) in a direction parallel with the longitudinal axis 116d. Furthermore, as shown in FIG. 17, for example, a strip of radiopaque material 107d extends between each of the two or more first portions 106d. The strip of radiopaque material 107d provides rigidity to the elongated body 102d. Accordingly, the stiffness of the elongated body 102d can be controlled by varying the parameters of the strip of radiopaque material 107d. For example, in the illustrated implementation, the strip of radiopaque material 107d has a width narrower than the width of the two or more first portions. Thus, the strip of radiopaque material 107d contributes moderate stiffness while still allowing flexibility on account of the elastomeric absorbent polymeric material of the second portion 1 lOd. For example, the strip of radiopaque material 107d may have a thickness of 0.2 mm while the first portions 106d may have thicknesses of 0.4mm. In other implementations, the strip of radiopaque material 107d may have a width that is narrower than the width of the first portions 106d. Furthermore, as noted above, the thickness of the first portions 106d may be varied relative to the thickness of the second portion 110c such that, when coupled, the first portion 106d and second portion 1 lOd are sized to be inserted into a tubular brachytherapy applicator.

[0085] Another implementation of the contrast marker is shown in FIG. 18. Specifically,FIG. 18 shows the contrast marker lOOe, which is similar to the contrast marker lOOd describedin reference to FIGS. 16-17. Accordingly, like reference numbers are used to refer to like features. However, the two or more first portions 106e, shown as 106e, 106e’, 106e”, 106e” ’, and 106e” ” are discretely spaced apart along the elongated body 102e in a direction parallel with the longitudinal axis 116e. In other words, no strip of radiopaque material connects the two or more first portions 106e. Rather, the each of the two or more first portions 106e is discontinuous from the adjacent first portion 106e (e.g., 106e’). Such implementations may permit greater flexibility of the elongated body 102e compared to implementations having a strip of radiopaque material such as the strip of radiopaque material 107d described in reference to the contrast marker lOOd of FIGS. 16-17.Fabrication of a Contrast Marker

[0086] Referring now to FIG. 5, a method 500 of fabricating the contrast marker 100 for medical imaging is shown, according to some implementations. As mentioned above, when compared to existing techniques for fabricating wires to act as contrast markers, method 500 is more customizable, cheaper to implement, and can be used to produce contrast markers more quickly (e.g., on-site). As described herein, because the fabrication process is dynamic, placement of the radiopaque and polymeric materials is customizable. Various implementations of a contrast marker may be fabricated according to the requirements of a given clinical scenario. It will be appreciated that certain steps of method 500 may be optional and, in some implementations, method 500 may be implemented using less than all of the steps. It will also be appreciated that the order of steps shown in FIG. 5 is not intended to be limiting.

[0087] At step 502, a 3D printer configured to dispense polymeric and radiopaque material onto a print bed is provided. Additional discussion of the 3D printer is provided below with respect to FIGS. 6-9. At step 504, at least one layer of a first material is formed, e.g., by depositing the first material onto a print bed of the 3D printer. As described herein, the first material is a radiopaque material; thus, with respect to the contrast marker 100 described above, step 504 generally describes the formation of the first portion 106. At step 506, one or more second layers of a second material are formed on top of the at least one first layer. These one or more second layers are formed of polymeric material; thus, with respect to the contrast marker 100 described above, step 506 generally describes the formation of the second portion 110.

[0088] For a more complete understanding of method 500, additional reference is now made to FIGS. 6-8, which generally illustrates an implementation of method 500 using an example 3D printing system 900. As shown, the 3D printing system 900 is used to produce, by method 500, a contrast marker 600 having an elongated body 602. The elongated body 602 includes a firstend 612 and a second end 614, where the second end 614 is opposite the first end 612. A longitudinal axis 616 is defined between the first end 612 and the second end 614. Thus, in this regard, it should be appreciated that the contrast marker 600 - and thereby, the components thereof - is the same as or substantially similar to the contrast marker 100 described above.

[0089] In FIGS. 6-8, the at least one first layer formed at step 504 of method 500 is shown as a first layer 604. The one or more second layers formed at step 506 of method 500 are shown as second layers 608. As discussed above, the first layer 604 is initially deposited upon a print bed 902 of the 3D printing system 900, after which the second layers 608 are deposited on top of the first layer 604, such that the longitudinal axis 616 of the elongated body 602 is parallel with the print bed 902. In some implementations, printing the first layer 604 and the second layers 608 in this configuration allows for fabrication of the elongated body 602 of the contrast marker 600 without the use of a sacrificial support structure. This is particularly advantageous because removing sacrificial support features can prove tedious and time-consuming, if not altogether infeasible. These challenges are especially prevalent for structures, such as the contrast marker 600, that include precisely formed features.

[0090] With additional reference to FIG. 7, an enlargement of a section (indicated as A-A) of FIG. 6 is shown. As illustrated, method 500 results in an arrangement of the second layers 608 so as to define a central lumen 618 extending through the elongated body 602. In some implementations, the first layer 204 is disposed along the radially outward facing surface of the elongated body 602. In some implementations, the first layer 604 extends from the central lumen 618 to an outside surface of the elongated body 602, as illustrated. Thus, the first layer may form a portion of an interior surface of surface of the elongated body 602 that defines the central lumen 618. In some implementations (e.g., illustrated by FIG. 4A), the first layer 604 is deposited in a continuous portion resembling a band or strip that extends along the elongated body 602 parallel to the longitudinal axis 616. In other implementations (e.g., illustrated by FIG. 3), the first layer 604 is deposited discontinuously so as to form a plurality of space-apart portions of radiopaque material.

[0091] As mentioned above, in some implementations (e.g., illustrated by FIGS. 4B and 4C), a contrast marker can be formed without a central lumen (e.g., with a solid-cross-section). In this regard, it should be appreciated that method 500 is suitable to produce contrast markers of various configurations. In such solid-core configurations, the second layers 608 may be deposited directly on top of and covering first layer 604, such that the central lumen 618 is notformed, as shown in FIG. 4B. Alternatively, the second layers 608 may be deposited directly onto the print bed 902 and the first layer 604 may be deposited onto the second layers 608, e.g., centrally to the elongated body 602, as shown in FIG. 4C described above. In some such implementations, the first layer 604 may be deposited along the longitudinal axis 616 between the first end 612 and the second end 614.

[0092] Referring now to FIG. 15, a method 1100 of fabricating the contrast marker 100c for medical imaging is shown, according to some implementations. The tubular portion formed at step 1102 corresponds to the second portion 110c and the radiopaque portion formed at step 1104 corresponds to the first portion 106c. As discussed above with respect to FIG. 14 and shown in FIG. 15 at step 1106, a contrast marker 100c can be formed by coupling together a radiopaque portion (i.e., first portion 106c), which includes a radiopaque material (e.g., copper), and a tubular portion (i.e., second portion 110c), which includes a polymeric material (e.g., PLA). In such implementations, the second portion 110c may be formed as a fully closed tubular body that defines a lumen extending therethrough, and the radiopaque first portion 106c may be deposited directly on the tubular body of the second portion 110c. In some implementations, the tubular second portion 110c may be formed by additive manufacturing techniques, such as 3D printing. In other implementations, the tubular second portion 110c may be formed from other fabrication methods, such as extrusion or molding techniques. Further still, the radiopaque first portion 106c may also be formed by any of the above fabrication techniques, including techniques that differ from the one used to fabricate the tubular second portion 110c. For example, the tubular second portion 110c may be formed by extrusion and the radiopaque first portion 106c may be deposited onto an outer surface of tubular second portion 110c using 3D printing or molding. In such implementations, the step 1106 of coupling the radiopaque first portion of the elongated body to the tubular second portion of the elongated body occurs as the radiopaque portion is dispensed onto the outer surface of the tubular second portion. As compared to the method 500 provided above, method 1 100 allows for the tubular second portion 110c to be formed separately from the radiopaque first portion 106c and then for the tubular second portion 110c and first portion 106c to be coupled thereafter.

[0093] Referring now to FIG. 19, a method 1200 of fabricating the contrast marker lOOd (e.g., as shown in FIGS. 16-17) for medical imaging is shown, according to some implementations. As mentioned above, when compared to existing techniques for fabricating wires to act as contrast markers, method 1200 is more customizable, cheaper to implement, and can be used to produce contrast markers more quickly (e.g., on-site). As described herein, because the fabricationprocess is dynamic, placement of the radiopaque and polymeric materials is customizable. As compared to the method 500 provided above, method 1200 allows for the polymeric second portion 1 lOd to be formed separately from the radiopaque first portion 106d and then for the second portion 1 lOd and first portion 106d to be coupled thereafter. Furthermore, the method 1200 permits containment of a fluidic contrast medium within a porous structure of the second portion 1 lOd itself rather than within a lumen formed within the contrast marker lOOd. Thus, the method 1200 provides a method of fabricating the contrast marker lOOd that does not require precise formation of a lumen structure, thereby making fabrication less technically demanding.

[0094] Various implementations of a contrast marker may be fabricated according to the requirements of a given clinical scenario. It will be appreciated that certain steps of method 1200 may be optional and, in some implementations, method 1200 may be implemented using less than all of the steps. It will also be appreciated that the order of steps shown in FIG. 19 is not intended to be limiting.

[0095] At step 1202, an absorbent portion of the elongated body 102d of contrast marker lOOd is formed of an absorbent material. As described herein, the absorbent corresponds to the second portion 1 lOd described above. Thus, step 1202 generally describes formation of the second portion HOd.

[0096] In the implementations illustrated in FIGS. 16-18, the absorbent portion is formed of a copolymer (e.g., PORO-LAY GEL-LAY) containing an elastomeric network component and a dissolvable component (e.g., poly vinyl alcohol (PVA)). In various implementations, forming the absorbent material includes forming the copolymer into an elongated polymeric member. The dissolvable component is then dissolved from the elongated polymeric member. For example, in some implementations, the elongated polymeric member may be at least partially submerged in water to dissolve the dissolvable component. The portion of the elongated polymeric member that remains is the elastomeric network component. In the illustrated implementations, the elastomeric network component includes vacancies formed by the negative spaces left behind by the dissolved dissolvable component. For example, dissolving PVA from a copolymer elongated polymeric member yields an absorbent portion with a porous microstructure defined where the PVA has been dissolved away.

[0097] At step 1204, a fluid, such as a fluidic imaging contrast medium, is loaded into the absorbent portion of the elongated body 102d. In various implementations, the fluid is received within vacancies within the absorbent portion, such as a porous microstructure. As describedherein, the fluidic imaging contrast medium allows the contrast marker lOOd to be imageable using MR imaging.

[0098] At step 1206, the fluid is sealed within the absorbent portion of the elongated body 102d. This prevents moisture from egressing out of the absorbent portion into the lumen of a tubular brachytherapy applicator into which the contrast marker lOOd is inserted. In some implementations, the step of sealing the fluid within the absorbent portion includes forming a sealant layer over the absorbent portion such that the sealant layer is radially outside of the absorbent portion. As described below, application of the sealant layer may occur before or after the radiopaque portion of the elongated body 102d is formed over the absorbent portion.

[0099] At step 1208, a radiopaque portion formed of radiopaque material is formed over the absorbent portion. As described herein, the radiopaque portion corresponds to the first portion 106d described above. Thus, step 1208 generally describes formation of the first portion 106d. As shown in the illustrated implementations, radiopaque portion (e.g., first portion 106d) is formed along the absorbent portion such that it extends in a direction parallel with the longitudinal axis 116d of the elongated body 102d.

[0100] As described above, the sealant may be applied in a sealant layer covering only the absorbent portion if applied before coupling of the absorbent portion and radiopaque portion or in a sealant layer covering both the absorbent portion and the radiopaque portion if applied after coupling of the absorbent portion and radiopaque portion.

[0101] As provided herein, one or both of the elongated polymeric member or the radiopaque material may be fabricated using an additive manufacturing process such as 3D printing. For example, the elongated polymeric member may be formed of a network component-dissolvable component copolymer filament (e.g., containing PVA) dispensed from a 3D printer, where the elongated member is printed so that it extends longitudinally in a direction parallel with the print bed of the 3D printer. In some implementations, forming the radiopaque portion over the absorbent portion includes providing a 3D printer configured to dispense a radiopaque material onto a print bed and operating the 3D printer to form the radiopaque portion along a side of the absorbent portion either after the dissolvable component has been dissolved out or the elongated polymeric member either before the dissolvable component has been dissolved out.

[0102] As provided herein, one or both of the elongated polymeric member or the radiopaque material may be fabricated another fabrication method, such as molding. For example, in some implementations, the elongated polymeric member is formed using a mold. In suchimplementations, the network component and dissolvable component (e.g., containing PVA) are first added to a mold. Then the elongated member formed by the combined network component and dissolvable component is released from the mold and the dissolvable component is dissolved out. In some implementations, forming the radiopaque portion over the absorbent portion includes adding radiopaque material to a mold containing the absorbent portion or elongated polymeric member. That is, the radiopaque material may be added after the dissolvable component has been dissolved out or the elongated polymeric member before the dissolvable component has been dissolved out.

[0103] As described herein, one or both of the absorbent portion and radiopaque portion may be fabricated using additive manufacturing such as 3D printing, and one or both of the absorbent portion and radiopaque portion may be fabricated using molding processes. Further still, each of the absorbent portion and radiopaque portion may be formed separately and then coupled.

[0104] In some implementations, the second portion (or absorbent portion) is formed to define negative spaces configured to receive the first portion (or radiopaque portion). In such implementations, the first portion is substantially flush with the second portion so as to form a substantially smooth outer surface of the elongated body. In other implementations, the first portion is disposed radially outside the second portion.3D Printing System

[0105] Referring to FIG. 9, a block diagram of the 3D printing system 900 is shown, according to some implementations. As mentioned above, the 3D printing system 900 generally includes a 3D printer 920 and a controller 910 for operating the 3D printer. As discussed below, the 3D printer 920 generally includes print bed 902 and a nozzle 926 for depositing a radiopaque material 922 and a polymeric material 924 onto the print bed 902. The 3D printer 920 also includes motors 928 which are coupled to each of the print bed 902 and the nozzle 926 to move the print bed 902 and the nozzle 926 to print a contrast marker. As illustrated, controller 910 generally provides control signals to the nozzle 926 and the motors 928 to control operations of the 3D printer 920, as described below.

[0106] Controller 910 generally includes a processor 904 and memory 906. The processor 904 can be a general-purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a group of processing components, or other suitable electronic processing structures. In some embodiments, the processor 904 is configured to execute program code stored on the memory 906 to cause the 3D printing system 900 toperform one or more operations, as described herein. In particular, the program code stored on the memory 906 can include instructions for 3D printing an object, e.g., in the form of an .STL file or other suitable file type. It will be appreciated that, in embodiments where the controller 910 is part of another computing device (e.g., a laptop computer), the components of the controller 910 may be shared with, or the same as, the host device.

[0107] The memory 906 of the controller 910 can include one or more devices (e.g., memory units, memory devices, storage devices, etc.) for storing data and / or computer code for completing and / or facilitating the various processes described in the present disclosure. In some embodiments, memory 906 includes tangible (e.g., non- transitory), computer-readable media that stores code or instructions executable by the processor 904. Tangible, computer-readable media refers to any physical media that is capable of providing data that causes the controller 910 to operate in a particular fashion. Example tangible, computer-readable media may include, but is not limited to, volatile media, non-volatile media, removable media and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Accordingly, memory 906 can include RAM, ROM, hard drive storage, temporary storage, non-volatile memory, flash memory, optical memory, or any other suitable memory for storing software objects and / or computer instructions. Memory 906 can include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. Memory 906 can be communicably connected to the processor 904, such as via a processing circuit, and can include computer code for executing (e.g., by the processor 904) one or more processes described herein.

[0108] While described above as individual components, it will be appreciated that the processor 904 and / or memory 906 of the controller 910 can be implemented using a variety of different types and quantities of processors 904 and memory 906. For example, the processor 904 may be a single processing device or multiple processing devices. Similarly, memory 906 may be a single memory device or multiple memory devices. Additionally, in some / embodiments, the controller 910 may be implemented within a single computing device (e.g., one server, one housing, etc.). In other embodiments, the controller 910 may be distributed across multiple devices.

[0109] As discussed above with respect to FIGS. 5-8, the 3D printing system 900 may be configured to implement method 500 to fabricate a contrast marker (e.g., contrast marker100 / 600). Specifically, a model of a contrast marker may first be generated using a computer- aided design (CAD) program. In some implementations, the CAD program may be executed via controller 910; however, in other implementation, the CAD program is executed on a remote computing device. In either case, the CAD model of the contrast marker may be saved as a suitable 3D printing file (e.g., an STL or 3MF file) and either stored on, or uploaded to, the memory 906. For example, the CAD model of the contrast marker may be saved onto portable memory (e.g., a flash drive) and then uploaded to controller 910 or the CAD model of the contrast marker may be transmitted from a remote device to controller 910. In some implementations, controller 910 is configured to operate a slicing software to prepare the 3D printing file for printing by dividing it into a continuous series of cross-sectional slices. Alternatively, the CAD model of the contrast marker may be sliced or otherwise prepared by a remote computing device.

[0110] In some implementations, radiopaque material 922 and polymeric material 924 are operatively connected to, or included in, an attached automatic material system (AMS) unit. In other words, 3D printer 920 may include an ASM unit to provide radiopaque material 922 and polymeric material 924 to nozzle 926. As described herein, radiopaque material 922 and polymeric material 924 are commonly stored as rolls of filament, which is fed to nozzle 926. The nozzle 926 may include a hardened steel nozzle (e.g., a 0.2 mm hardened steel nozzle) configured to selectively dispense the filament according to commands transmitted by controller 910 according to the slicing software. Dispensed filament is disposed on a high temperature polyetherimide (PEI) print bed, e.g., print bed 902, on which the contrast marker is formed.Using a Contrast Marker

[0111] Referring now to FIG. 10, a method 1000 of implanting a brachytherapy applicator using the contrast marker 100 is shown, according to some implementations. It should be appreciated that method 1000 may generally be performed by a human actor, such as a physician; however, implementations are contemplated herein where the method 1000 is at least partially performed by a robotic surgery system. It will be appreciated that certain steps of the method 1000 may be optional and, in some implementations, the method 1000 may be implemented using less than all of the steps. It will also be appreciated that the order of steps shown in FIG. 10 is not intended to be limiting.

[0112] At step 1002, a tubular brachytherapy applicator (e.g., a catheter or needle) is inserted into the body of a patient. At step 1004, the contrast marker 100 (e.g., according to anyimplementation described herein) is then inserted into a lumen of the tubular brachytherapy applicator. At step 1006, the brachytherapy applicator and the contrast marker 100 are advanced toward a target region, such as a tumor or lesion to be treated with radiation therapy. At step 1008, the brachytherapy applicator and the contrast marker 100 are intermittently imaged using any suitable medical imaging modality, such as CT and / or MR, to aid in and subsequently confirm proper placement of the tubular brachytherapy applicator relative to the target region. At step 1010, once proper placement of the brachytherapy applicator is confirmed via imaging, the contrast marker 100 is removed and is replaced by a radiation source (e.g., Iridium-192) for the duration of a treatment session.Applicator Plug

[0113] Also provided herein is an applicator plug for sealing the lumen of a tubular brachytherapy applicator. As described herein, it is clinically important to reduce the likelihood that moisture inadvertently enter the lumens of the tubular brachytherapy applicators. For example, preventing moisture ingress into the lumens prevents damage to or interference with the radioactive sources inserted therein. Because the brachytherapy applicators remain in place between treatment sessions, the openings of the lumens must be reversibly sealed following treatment sessions.

[0114] Referring generally to FIG. 22-24B, an applicator plug 1300 for sealing a lumen of a comprising tubular brachytherapy applicator is shown. As shown in FIG. 22, the applicator plug 1300 has an extension region 1302 that is configured to extend proximally into the lumen of the tubular brachytherapy applicator. The applicator plug 1300 also includes a pull region 1306 that is configured to extend distally from the lumen of the tubular brachytherapy applicator. As shown in FIG. 22, for example, the applicator plug 1300 further includes a first raised portion 1310 that extends radially outward from the extension region 1302. The first raised portion 1310 has a diameter sized to form a friction fit with an inner diameter of the brachytherapy applicator. As shown in FIG. 22, the first raised portion 1310 forms an annular ring extending around a circumference of the extension region 1302. FIG. 23 shows an enlarged view of the pull region 1306 and first raised portion 1310. In other implementations, the applicator tapers from the first raised portion 1310 toward the extension region 1302.

[0115] In some implementations, the applicator plug 1300 also includes a second raised portion 1314 disposed distally relative to the first raised portion 1310. As shown in FIG. 23, the second raised portion 1314 extends radially outward from the extension region 1302 to a diameter that isgreater than the inner diameter of the brachytherapy applicator. Specifically, the diameter of the second raised portion 1314 is such that it cannot readily be inserted into the lumen of the brachytherapy applicator. Accordingly, the second raised portion 1314 limits the insertion of the applicator plug 1300 into the lumen of the prevents the brachytherapy applicator.

[0116] FIG. 24A shows an example applicator plug 1300 further including a plurality of ribs 1318 disposed circumferentially about the extension region 1302. The plurality of ribs 1318 have diameters sized to form a friction fit with the inner diameter of the brachytherapy applicator. However, the diameters of the ribs 1318 are less than the diameter of the first raised portion 1310. The applicator plug 1300 in the illustrated implementation is formed of thermoplastic polyurethane (TPU) and was fabricated using a three-dimensional (3D) printer. Specifically, as shown for example in FIG. 22 and 24B, the pull region 1306 has a flattened face that is coplanar with the extension region 1302. Such implementations improve ease of fabrication by additive manufacturing.

[0117] FIG. 24B shows the applicator plug 1300 inserted into the lumen of a brachytherapy tubular applicator. As shown, the extension region 1302 is inserted into the lumen until the first raised portion 1310 frictionally engages with the inner diameter of the lumen and / or the second raised portion 1314 abuts a distal opening of the lumen, thereby forming a fluid-tight seal to prevent egress of fluids into the lumen.Experimental Results

[0118] Referring now to FIGS. 11-13, the results of fabricating and testing a contrast marker (e.g., the contrast marker 100) using the systems and methods described above are shown. As described herein, the imaging characteristics of various hollow and solid contrast markers under CT and MR imaging were evaluated and compared to commercially available markers. Specifically, various exemplary implementations of the contrast marker were imaged to evaluate MRI, CNR, and CT metal artifact characteristics against traditional commercially available markers formed of stainless steel and nitinol.

[0119] In particular, FIG. 11 shows an image comparing computed tomography (CT) imaging artifacts generated by contrast markers according to some implementations described herein and commercially available markers. FIG. 12 shows an image of sagittal slices of magnetic resonance (MR) images containing contrast markers according to some implementations described herein. FIG. 13 shows a chart of contrast-to-noise ratios (CNR) and metal artifact(HU) for contrast markers of various materials under magnetic resonance (MR) and computedtomography (CT) imaging. Further discussion of FIGS. 8-10 is provided below in context with experimental results.

[0120] Solid Cu-PLA Contrast Markers: Third, a contrast marker having a solid cross-section (e.g., such that the contrast marker was solid between a first end and a second end) was designed and fabricated using the systems and methods described above. Specifically, the elongated body of the contrast marker was formed as a solid member from 3D printed copper-infused PLA (Cu- PLA) filament.

[0121] Homogeneous Hollow Cu-PLA Contrast Markers: Second, a contrast marker having a hollow cross-section was designed and fabricated using the systems and methods described above. Specifically, the entire elongated body was formed of 3D printed Cu-PLA filament so as to have an approximately homogeneous distribution of the radiopaque material throughout the elongated body. This set of contrast markers were printed with a flattened at first layer so as to improve adherence to the print bed. Each contrast marker had an outer diameter of 1 .26 mm and an inner bore diameter of 0.8 mm. The print time per homogenous hollow contrast marker formed of 0.54 g Cu-PLA was 3 minutes and 29 seconds. The print time per homogenous hollow contrast marker formed of 0.4 g Cu-PLA was 1 minute and 17 seconds.

[0122] Heterogenous Hollow Cu-PLA Contrast Markers: First, a contrast marker having a hollow cross-section (e.g., having a central lumen defined between a first end and a second end) was designed and fabricated using the systems and methods described above. Specifically, a plurality of first layers of an elongated body were formed using a 3D printed (Cu-PLA) filament and a plurality of second layers of the elongated body were formed using a 3D printed PLA filament. In other words, the contrast marker included a heterogenous mixture of PLA filament and copper-infused PLA filament, where the copper-infused PLA filament formed a band of radiopaque material extending parallel to a longitudinal axis along an edge of the elongated body. The print time per heterogenous hollow contrast marker having a 0.2 mm band of radiopaque material (0.66 g of PLA+, 0.56 g Cu) was 11 minutes and 34 seconds, given the need to conduct filament changes. The print time for a set of 24 of such contrast was 1 hour 24 and minutes, given one filament change.

[0123] In order to evaluate MR contrast among the hollow contrast markers, the central lumens of each test contrast marker were filled with a glycerin-based gel. A small amount of green food coloring was added to the glycerin-based gel to visualize filling the hollow contrast markers. The first ends and second ends were then closed using conical-shaped PLA end caps.

[0124] Initial evaluations of the homogeneous hollow Cu-PLA contrast markers under CT revealed that metal artifact generation (HU) and contrast-to-noise ratio (CNR) in the homogenous hollow Cu-PLA contrast marker was indistinguishable from that of the solid Cu- PLA contrast markers. Unlike the homogenous Cu-PLA contrast markers, heterogeneous hollow Cu-PLA contrast markers did not generate a CT signal at the center of the central lumen (e.g., along the longitudinal axis). Additional evaluations using MR showed that the contrast markers having a homogenous distribution of Cu-PLA acted as a Faraday cage and would not allow for MRI contrast enhancement.

[0125] To best simulate an interstitial implant scenario, 240 mm interstitial needles inserted into a prostate ultrasound phantom that was fully CT and MR compatible. The interstitial needles were left in place for all scans so as to compare dissimilar materials. Once inserted into the tissue equivalent prostate phantom, images were acquired using CT and MR techniques. For comparison, commercially available stainless steel and nitinol markers were imaged using the same techniques.

[0126] CT images were acquired using CT simulators using the helical scanning modality. Standard scan settings for a clinical brachytherapy case (e.g., slice thickness of 2.5 mm, 120 kV accelerating potential and 100 mA electron current) were used. The same settings were used for each configuration of marker tested. To quantify CT metal artifact, a contour was created around each needle within the phantom that included the marker. Then, a standard deviation in the volume around each marker was evaluated. Specifically, for CT, a standard deviation was calculated in a region of 1 cm around each marker. MR images were acquired using a 3.0 T MR simulator and a 1.5 T MR scanner. All phantom and marker combinations were imaged using both T1 and T2 weighted axially reconstructed pulse sequences. Contrast-to-noise ratios (CNR) were evaluated for both CT and MR imaging modalities. Differences in artifact between each set of markers were compared. For MR imaging, a CNR was calculated using a homogeneous region of tissue equivalent material within 2 mm of the marker. Equation 1 was used to estimate the CNR for each marker.

[0127] Equation 1 is defined as:

[0128] Referring to Equation 1 , SA is the average signal of the volume encapsulating the marker of interest, SB is the signal from a homogeneous tissue region, and GO is the standard deviation of a region encompassing a volume 1 cm around each marker.

[0129] Results of CT Imaging: Referring to FIG. 11, the results of CT scans of the solid Cu- PLA contrast markers (i.e., “Solid Cu-PLA”) and the heterogenous hollow Cu-PLA contrast markers (i.e., “Hollow Cu-PLA strip”) were compared with commercially available markers wire and nitinol markers. As illustrated, reduced CT metal artifact (i.e., “starring”) was observed in each of the solid and heterogenous hollow Cu-PLA contrast markers while still preserving CT contrast. This finding was observed in all metal-infused PLA contrast markers that were tested.

[0130] To quantify the CT metal artifact improvement, a volume was defined surrounding the contoured marker volume. A standard deviation was calculated of that volume. More severe CT metal artifacts exhibited higher standard deviation of the Hounsfield Units (HU) within that defined volume. This process was repeated for all markers that were tested, including commercially available markers. A table summarizing the CT metal artifact values is provided in FIG. 13. For example, as shown in FIG. 13, the heterogenous hollow Cu-PLA (i.e., “Hollow Copper PLA”) contrast marker had a HU of 37.6, whereas wire markers had a HU of 206.1 and nitinol had a HU of 41.6

[0131] Results of MR Imaging: Contrast-to-noise ratios (CNR) were calculated using Equation 1 and the contoured volumes described above. Referring to FIG. 12, sagittal slices of MR images of a heterogenous hollow Cu-PLA contrast marker imaged using clinical MR scanners at both 1.5 T and 3.0 T are illustrated. In each instance, the contrast marker was filled with glycerin gel as a MR contrast medium. As illustrated, the heterogenous hollow Cu-PLA contrast marker was visible when imaged at both 1.5 T and 3.0 for T2- weighted pulse sequences while T1 -weighted sequences yielded favorable visibility results only at 3.0 T.

[0132] This process was repeated for all markers that were tested, including commercially available markers. A table summarizing the MR CNR values is provided in FIG. 13. For example, as shown in FIG. 10, the heterogenous hollow Cu-PLA contrast marker (i.e., “Hollow Copper PLA”) had a CNR of 196.6, whereas wire markers had a CNR of 23.4 and nitinol had a CNR of 167.2. Thus, taken together with the previously described CT imaging results, the exemplary contrast marker performed better than the commercial markers in terms of metal artifact generation (HU) while still producing high contrast-to-noise ratio (CNR).

[0133] Referring to FIGS. 20 and 21, the result of further MR scans of contrast markers lOOd, which include a first portion formed of radiopaque material (Cu-PLA) disposed on a second portion formed of an absorbent polymeric material (PORO-LAY GEL-LAY with the PLA dissolved out) are shown. Specifically, the porous microstructures of the absorbent polymeric materials of three contrast markers lOOd were loaded with fluidic contrast medium and sealed with epoxy. Conversely, one additional contrast marker lOOd was not loaded with fluidic contrast medium. Then, the four contrast markers lOOd were inserted into tubular brachytherapy applicators immobilized between bags containing saline. As shown in both FIGS. 20 and 21, the three contrast markers lOOd loaded with fluidic contrast medium are readily imageable using MR imaging. Conversely, the contrast marker lOOd that was not loaded with fluidic contrast medium is not visible.

[0134] Configuration of Certain Implementations

[0135] The construction and arrangement of the systems and methods as shown in the various implementations are illustrative only. Although only a few implementations have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes, and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative implementations. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the implementations without departing from the scope of the present disclosure.

[0136] The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing various operations. The implementations of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Implementations within the scope of the present disclosure include program products including machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM,EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures, and which can be accessed by a general purpose or special purpose computer or other machine with a processor.

[0137] When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0138] Although the figures show a specific order of method steps, the order of the steps may differ from what is depicted. Also, two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.

[0139] It is to be understood that the methods and systems are not limited to specific synthetic methods, specific components, or to particular compositions. It is also to be understood that the terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting.

[0140] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another implementation includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another implementation. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0141] “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0142] Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other additives, components, integers or steps. “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal implementation. “Such as” is not used in a restrictive sense, but for explanatory purposes.

[0143] Disclosed are components that can be used to perform the disclosed methods and systems. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutation of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all methods and systems. This applies to all aspects of this application including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific implementation or combination of implementations of the disclosed methods.Exemplary Aspects

[0144] In view of the described processes and compositions, hereinbelow are described certain more particularly described aspects of the disclosures. These particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

[0145] Example 1: A contrast marker for medical imaging, the contrast marker comprising: an elongated body comprising a first end and a second end, the second end opposite the first end, wherein a longitudinal axis is defined between the first end and the second end, wherein a first portion of the elongated body is formed of a radiopaque material and a second portion of the elongated body is formed of a polymeric material, the first portion extending in a direction parallel with the longitudinal axis.

[0146] Example 2: A contrast marker according to any example herein, particularly example 1, wherein the first portion has a total thickness of 0.2 mm.

[0147] Example 3: A contrast marker according to any example herein, particularly examples 1- 2, wherein the first portion extends along a side of the elongated body.

[0148] Example 4: A contrast marker according to any example herein, particularly example 3, wherein the first portion extends along only a single side of the elongated body.

[0149] Example 5: A contrast marker according to any example herein, particularly examples 1-4, wherein the first portion is disposed at the first end.

[0150] Example 6: A contrast marker according to any example herein, particularly examples 1-5, wherein the first portion comprises a continuous strip of radiopaque material.

[0151] Example 7 : A contrast marker according to any example herein, particularly examples 1- 4, wherein the first portion comprises two or more first portions spaced apart from one another in a direction parallel with the longitudinal axis.

[0152] Example 8: A contrast marker according to any example herein, particularly example 7, wherein a strip of the radiopaque material extends between each of the two or more first portions.

[0153] Example 9: A contrast marker according to any example herein, particularly example 8, wherein the strip of the radiopaque material has a thickness narrower than the thickness of the two or more first portions.

[0154] Example 10: A contrast marker according to any example herein, particularly examples 1-9, wherein the radiopaque material comprises copper, brass, or bronze.

[0155] Example 11 : A contrast marker according to any example herein, particularly examples 1-10, wherein the first portion is disposed radially outward of the second portion.

[0156] Example 12: A contrast marker according to any example herein, particularly examples 1-10 wherein the second portion comprises one or more negative spaces sized and configured to receive the first portion such that the elongated body has a substantially smooth outer surface.

[0157] Example 13: A contrast marker according to any example herein, particularly examples 1-12, wherein the second portion comprises vacancies configured to receive a fluid.

[0158] Example 14: A contrast marker according to any example herein, particularly example 13, wherein the vacancies are a porous microstructure.

[0159] Example 15: A contrast marker according to any example herein, particularly examples 13-14, wherein the contrast marker further comprises a sealant layer disposed radially outside the second portion so as to prevent loss of the fluid received therein.

[0160] Example 16: A contrast marker according to any example herein, particularly examples 13-15, wherein the fluid is an imaging contrast medium that is visible under magnetic resonance imaging.

[0161] Example 17: A contrast marker according to any example herein, particularly examples 1-16, wherein the elongated body has a solid cross-section between the first end and the second end.

[0162] Example 18: A contrast marker according to any example herein, particularly examples 1-16, wherein the elongated body further defines a central lumen extending at least partially therethrough.

[0163] Example 19: A contrast marker according to any example herein, particularly example 18, wherein the central lumen extends through an entire length of the elongated body.

[0164] Example 20: A contrast marker according to any example herein, particularly examples 18-19, wherein the contrast marker further comprises at least one end cap configured to retain a fluid in the central lumen.

[0165] Example 21 : A contrast marker according to any example herein, particularly example 20, wherein the fluid is an imaging contrast medium that is visible under magnetic resonance imaging.

[0166] Example 22: A contrast marker according to any example herein, particularly examples 18-21, wherein the central lumen has an inner diameter of 0.8 mm.

[0167] Example 23: A contrast marker according to any example herein, particularly examples 18-22, wherein the polymeric material comprises PLA, PGA, and / or PLGA.

[0168] Example 24: A contrast marker according to any example herein, particularly examples 1-23, wherein the elongated body has an outer diameter sized and configured to be inserted into a lumen of a tubular brachytherapy applicator.

[0169] Example 25: A contrast marker according to any example herein, particularly example 24, wherein the outer diameter is 1.3 mm.

[0170] Example 26: A contrast marker according to any example herein, particularly examples 1-25, wherein the elongated body has a length sized and configured to be retrievably inserted into a lumen of a tubular brachytherapy applicator.

[0171] Example 27: A contrast marker according to any example herein, particularly examples 1-26, wherein the first portion is fabricated using a three-dimensional (3D) printer.

[0172] Example 28: A contrast marker according to any example herein, particularly examples 1-26, wherein the first portion is fabricated using a mold.

[0173] Example 29: A contrast marker according to any example herein, particularly examples 1-28, wherein the second portion is fabricated using a three-dimensional (3D) printer.

[0174] Example 30: A contrast marker according to any example herein, particularly examples 1-28, wherein the second portion is fabricated using a mold.

[0175] Example 31 : A method of fabricating a contrast marker for medical imaging, the method comprising: forming an absorbent portion of an elongated body of the contrast marker of an absorbent material; loading fluid into the absorbent portion; sealing the fluid within the absorbent portion; and forming a radiopaque portion of the elongated body over the absorbent portion of a radiopaque material, wherein the radiopaque portion extends in a direction parallel with a longitudinal axis defined between first and second ends of the elongated body.

[0176] Example 32: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly example 31 , wherein forming the absorbent portion further comprises: forming an elongated polymeric member comprising a network component and a dissolvable component; and dissolving the dissolvable component from the elongated polymeric member so that the network component remains, thereby forming the absorbent portion.

[0177] Example 33: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly example 32, wherein forming the elongated polymeric member further comprises: providing a three-dimensional (3D) printer configured to dispense a polymeric material comprising the network component and the dissolvable component onto a print bed; and operating the 3D printer to form the elongated polymeric member; wherein the elongated polymeric member is formed in a direction parallel with the print bed.

[0178] Example 34: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly example 32, wherein forming the elongated polymeric member further comprises adding a polymeric material comprising the network component and the dissolvable component into a mold.

[0179] Example 35: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly examples 32-34, wherein loading fluid into the absorbent portion comprises loading the fluid into the network component of the polymeric member.

[0180] Example 36: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly examples 32-35, wherein sealing the fluid within the absorbent portion comprises forming a sealant layer radially outside of the absorbent portion.

[0181] Example 37 : A method of fabricating a contrast marker for medical imaging according to any example herein, particularly examples 32-36, wherein forming the radiopaque portion of the elongated body over the absorbent portion comprises: providing a three-dimensional (3D) printer configured to dispense a radiopaque material onto a print bed; and operating the 3D printer to form the radiopaque portion along a side of the absorbent portion of the elongated body.

[0182] Example 38: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly examples 32-37, wherein forming the radiopaque portion of the elongated body over the absorbent portion comprises adding the radiopaque material to a mold comprising the absorbent portion.

[0183] Example 39: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly examples 32-38, wherein forming the radiopaque portion of the elongated body over the absorbent portion comprises forming two or more radiopaque portions spaced apart from one another in a direction parallel with the longitudinal axis.

[0184] Example 40: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly examples 32-39, wherein the elongated body is formed without a sacrificial support structure.

[0185] Example 41 : An applicator plug for sealing a lumen of a tubular brachytherapy applicator, the applicator plug comprising: an extension region configured to extend proximally into the lumen of the tubular brachytherapy applicator; a pull region configured to extend distally from the lumen of the tubular brachytherapy applicator; and a first raised portion that extendsradially outward from the extension region, wherein the first raised portion is sized and configured to form a friction fit with an inner diameter of the brachytherapy applicator.

[0186] Example 42: An applicator plug according to any example herein, particularly example 41, wherein the applicator plug tapers from the first raised portion toward the extension region.

[0187] Example 43: An applicator plug according to any example herein, particularly examples 41-42, wherein the applicator plug further comprises a second raised portion disposed distally relative to the first raised portion, wherein the second raised portion extends radially outward from the extension region to a diameter that is greater than the inner diameter of the brachytherapy applicator.

[0188] Example 44: An applicator plug according to any example herein, particularly example 41, wherein the applicator plug is formed of thermoplastic polyurethane (TPU).

[0189] Example 45: An applicator plug according to any example herein, particularly examples 41-44, wherein the applicator plug is fabricated using a three-dimensional (3D) printer.

[0190] Example 46: A method of fabricating a contrast marker for medical imaging, the method comprising: providing a three-dimensional (3D) printer configured to dispense a radiopaque material and a polymeric material onto a print bed; operating the 3D printer to form at least one first layer of an elongated body of the contrast marker, the at least one first layer forming a first portion of the elongated body comprising the radiopaque material; and operating the 3D printer to form one or more second layers of the elongated body on top of the at least one first layer, the one or more second layers forming a second portion of the elongated body comprising the polymeric material, wherein the elongated body comprises a first end and a second end, the second end opposite the first end, and defines a longitudinal axis therebetween, the longitudinal axis defined parallel with the print bed.

[0191] Example 47: A method of fabricating a contrast marker for medical imaging according to any example herein, particularly example 46, wherein the elongated body is formed without a sacrificial support structure.

[0192] Example 48: A kit comprising: a contrast marker comprising: an elongated body comprising a first end and a second end, the second end opposite the first end, wherein a longitudinal axis is defined between the first end and the second end, wherein a first portion of the elongated body is formed of a radiopaque material and a second portion of the elongated body is formed of a polymeric material, the first portion extending in a direction parallel with thelongitudinal axis, wherein the elongated body has an outer diameter sized and configured to be inserted into a lumen of a tubular brachytherapy applicator; and an applicator plug comprising an extension region configured to extend proximally into the lumen of the tubular brachytherapy applicator, a pull region configured to extend distally from the lumen of the tubular brachytherapy applicator, and a first raised portion that extends radially outward from the extension region, wherein the first raised portion is sized and configured to form a friction fit with an inner diameter of the brachytherapy applicator.

[0193] In view of the many possible aspects to which the principles of the disclosed disclosure can be applied, it should be recognized that the illustrated aspects are only preferred examples of the disclosure and should not be taken as limiting the scope of the disclosure. Rather, the scope of the disclosure is defined by the following claims. We, therefore, claim as our disclosure all that comes within the scope and spirit of these claims.

Claims

CLAIMSWhat is claimed is:

1. A contrast marker for medical imaging, the contrast marker comprising: an elongated body comprising a first end and a second end, the second end opposite the first end, wherein a longitudinal axis is defined between the first end and the second end, wherein a first portion of the elongated body is formed of a radiopaque material and a second portion of the elongated body is formed of a polymeric material, the first portion extending in a direction parallel with the longitudinal axis.

2. The contrast marker of claim 1, wherein the first portion has a total thickness of 0.2 mm.

3. The contrast marker of any one of claims 1-2, wherein the first portion extends along a side of the elongated body.

4. The contrast marker of claim 3, wherein the first portion extends along only a single side of the elongated body.

5. The contrast marker of any one of claims 1-4, wherein the first portion is disposed at the first end.

6. The contrast marker of any one of claims 1-5, wherein the first portion comprises a continuous strip of radiopaque material.

7. The contrast marker of any one of claims 1-4, wherein the first portion comprises two or more first portions spaced apart from one another in a direction parallel with the longitudinal axis.

8. The contrast marker of claim 7, wherein a strip of the radiopaque material extends between each of the two or more first portions.

9. The contrast marker of claim 8, wherein the strip of the radiopaque material has a thickness narrower than the thickness of the two or more first portions.

10. The contrast marker of any one of claims 1-9, wherein the radiopaque material comprises copper, brass, or bronze.

11. The contrast marker of any one of claims 1-10, wherein the first portion is disposed radially outward of the second portion.

12. The contrast marker of any one of claims 1-10 wherein the second portion comprises one or more negative spaces sized and configured to receive the first portion such that the elongated body has a substantially smooth outer surface.

13. The contrast marker of any one of claims 1-12, wherein the second portion comprises vacancies configured to receive a fluid.

14. The contrast marker of any one of claim 13, wherein the vacancies are a porous microstructure.

15. The contrast marker of any one of claims 13-14, wherein the contrast marker further comprises a sealant layer disposed radially outside the second portion so as to prevent loss of the fluid received therein.

16. The contrast marker of any one of claims 13-15, wherein the fluid is an imaging contrast medium that is visible under magnetic resonance imaging.

17. The contrast marker of any one of claims 1-16, wherein the elongated body has a solid cross-section between the first end and the second end.

18. The contrast marker of any one of claims 1-16, wherein the elongated body further defines a central lumen extending at least partially therethrough.

19. The contrast marker of claim 18, wherein the central lumen extends through an entire length of the elongated body.

20. The contrast marker of any one of claims 18-19, wherein the contrast marker further comprises at least one end cap configured to retain a fluid in the central lumen.

21. The contrast marker of claim 20, wherein the fluid is an imaging contrast medium that is visible under magnetic resonance imaging.

22. The contrast marker of any one of claims 18-21 , wherein the central lumen has an inner diameter of 0.8 mm.

23. The contrast marker of any one of claims 18-22, wherein the polymeric material comprises PLA, PGA, and / or PLGA.

24. The contrast marker of any one of claims 1-23, wherein the elongated body has an outer diameter sized and configured to be inserted into a lumen of a tubular brachytherapy applicator.

25. The contrast marker of claim 24, wherein the outer diameter is 1.3 mm.

26. The contrast marker of any one of claims 1-25, wherein the elongated body has a length sized and configured to be retrievably inserted into a lumen of a tubular brachytherapy applicator.

27. The contrast marker of any one of claims 1-26, wherein the first portion is fabricated using a three-dimensional (3D) printer.

28. The contrast marker of any one of claims 1-26, wherein the first portion is fabricated using a mold.

29. The contrast marker of any one of claims 1-28, wherein the second portion is fabricated using a three-dimensional (3D) printer.

30. The contrast marker of any one of claims 1-28, wherein the second portion is fabricated using a mold.

31. A method of fabricating a contrast marker for medical imaging, the method comprising:forming an absorbent portion of an elongated body of the contrast marker of an absorbent material; loading fluid into the absorbent portion; sealing the fluid within the absorbent portion; and forming a radiopaque portion of the elongated body over the absorbent portion of a radiopaque material, wherein the radiopaque portion extends in a direction parallel with a longitudinal axis defined between first and second ends of the elongated body.

32. The method of claim 31, wherein forming the absorbent portion further comprises: forming an elongated polymeric member comprising a network component and a dissolvable component; and dissolving the dissolvable component from the elongated polymeric member so that the network component remains, thereby forming the absorbent portion.

33. The method of claim 32, wherein forming the elongated polymeric member further comprises: providing a three-dimensional (3D) printer configured to dispense a polymeric material comprising the network component and the dissolvable component onto a print bed; and operating the 3D printer to form the elongated polymeric member; wherein the elongated polymeric member is formed in a direction parallel with the print bed.

34. The method of claim 32, wherein forming the elongated polymeric member further comprises adding a polymeric material comprising the network component and the dissolvable component into a mold.

35. The method of any one of claims 32-34, wherein loading fluid into the absorbent portion comprises loading the fluid into the network component of the polymeric member.

36. The method of any one of claims 32-35, wherein sealing the fluid within the absorbent portion comprises forming a sealant layer radially outside of the absorbent portion.

37. The method of any one of claims 32-36, wherein forming the radiopaque portion of the elongated body over the absorbent portion comprises:providing a three-dimensional (3D) printer configured to dispense a radiopaque material onto a print bed; and operating the 3D printer to form the radiopaque portion along a side of the absorbent portion of the elongated body.

38. The method of any one of claims 32-37, wherein forming the radiopaque portion of the elongated body over the absorbent portion comprises adding the radiopaque material to a mold comprising the absorbent portion.

39. The method of any one of claims 32-38, wherein forming the radiopaque portion of the elongated body over the absorbent portion comprises forming two or more radiopaque portions spaced apart from one another in a direction parallel with the longitudinal axis.

40. The method of any one of claims 32-39, wherein the elongated body is formed without a sacrificial support structure.

41. An applicator plug for sealing a lumen of a tubular brachytherapy applicator, the applicator plug comprising: an extension region configured to extend proximally into the lumen of the tubular brachytherapy applicator; a pull region configured to extend distally from the lumen of the tubular brachytherapy applicator; and a first raised portion that extends radially outward from the extension region, wherein the first raised portion is sized and configured to form a friction fit with an inner diameter of the brachytherapy applicator.

42. The applicator plug of claim 41, wherein the applicator plug tapers from the first raised portion toward the extension region.

43. The applicator plug of any one of claims 41-42, wherein the applicator plug further comprises a second raised portion disposed distally relative to the first raised portion, wherein the second raised portion extends radially outward from the extension region to a diameter that is greater than the inner diameter of the brachytherapy applicator.

44. The applicator plug of claim 41, wherein the applicator plug is formed of thermoplastic polyurethane (TPU).

45. The applicator plug of claim any one of claims 41-44, wherein the applicator plug is fabricated using a three-dimensional (3D) printer.

46. A method of fabricating a contrast marker for medical imaging, the method comprising: providing a three-dimensional (3D) printer configured to dispense a radiopaque material and a polymeric material onto a print bed; operating the 3D printer to form at least one first layer of an elongated body of the contrast marker, the at least one first layer forming a first portion of the elongated body comprising the radiopaque material; and operating the 3D printer to form one or more second layers of the elongated body on top of the at least one first layer, the one or more second layers forming a second portion of the elongated body comprising the polymeric material, wherein the elongated body comprises a first end and a second end, the second end opposite the first end, and defines a longitudinal axis therebetween, the longitudinal axis defined parallel with the print bed.

47. The method of claim 46, wherein the elongated body is formed without a sacrificial support structure.

48. A kit comprising: a contrast marker comprising: an elongated body comprising a first end and a second end, the second end opposite the first end, wherein a longitudinal axis is defined between the first end and the second end, wherein a first portion of the elongated body is formed of a radiopaque material and a second portion of the elongated body is formed of a polymeric material, the first portion extending in a direction parallel with the longitudinal axis, wherein the elongated body has an outer diameter sized and configured to be inserted into a lumen of a tubular brachytherapy applicator; and an applicator plug comprising an extension region configured to extend proximally into the lumen of the tubular brachytherapy applicator, a pull region configured to extend distallyfrom the lumen of the tubular brachytherapy applicator, and a first raised portion that extends radially outward from the extension region, wherein the first raised portion is sized and configured to form a friction fit with an inner diameter of the brachytherapy applicator.

Images