WO2025175296A1 - Steerable tandem applicator for gynecological brachytherapy procedures - Google Patents

Abstract

Embodiments provide a novel intracavitary brachytherapy instrument for treatment of gynecological cancers which provides conformality to individual patient anatomy and variable angle settings to allow for customized radiation delivery. This novel applicator improves radiation delivery for cervical and uterine cancers while being a more cost-effective alternative to current devices on the market. Exemplary devices not only allow for steerability during implantation but also resolve the problem of limited angle options.

Description

STEERABLE TANDEM APPLICATOR FOR GYNECOLOGICAL BRACHYTHERAPY PROCEDURES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 63/554, 310, filed February 16, 2024, the complete contents of which are herein incorporated by reference.

FIELD OF THE INVENTION

Embodiments related to brachytherapy devices and procedures and, more particularly, tandem applicators and methods of using the same.

BACKGROUND

High dose rate brachytherapy for gynecological cancers currently serves as one of the most important aspects of cervical and uterine cancer treatment. At most Radiation Oncology centers including at Massey Cancer Center of Virginia Commonwealth University, hundreds of such procedures can be performed every year.

Female anatomy is highly variable, and normal uterine anatomy can lie in one of many different positions including anteverted, retroverted, anteflexed, retroflexed, and midline. Such variable anatomy creates challenges for radiation oncologists during high dose rate tandem and ovoid brachytherapy procedures, where a tandem device must be navigated and positioned within the uterine cavity to allow for uniform radiation delivery for cervical and uterine cancers.

Current high dose rate tandem brachytherapy devices do not allow for any form of flexibility or alteration of the angle to optimize implantation. Currently available tandem devices which are used at most institutions are rigid tandems which are set at pre-determined fixed angles and have no capability for alterations or customization for patient anatomy. Current tandem and ovoid sets typically come with multiple tandems each with a fixed angle, and it is the physician’s job to determine the optimal tandem angle for placement during the brachytherapy procedure. These angle options are very limited. Most current tandem models come with only select angle options (such as 15°, 30°, and 45°) thus significantly limiting the customizability of the radiation treatment to individual patients.

SUMMARY

Some exemplary embodiments provide a novel high dose rate intracavitary brachytherapy tandem applicator for use in cervical and uterine cancer treatments. This device has the capability to conform to individual patient anatomies through a component allowing for flexibility of the tip and variable angle settings. A component at the proximal end of the tandem gives the physician control over the flexible region of the device. Tandem angle is adjustable at any point of related procedures, e.g., before insertion, after insertion, at the time of imaging (e.g., CT), and after initial imaging evaluation.

A steering mechanism at the proximal end of the tandem allows the physician to steer the tip in a multidirectional fashion during implantation of the applicator. By having a single tandem with the capability to adjust to multiple different angles, exemplary embodiments give the physician the freedom to alter the tandem to fit individual patients’ needs. Additionally, by a steerable component of the device, the physician has the ability to guide the tandem through complex female cervical and uterine anatomy with greater ease.

According to some embodiments, a locking mechanism at the proximal end of the tandem allows for the desired tandem angle to be locked at multiple different levels, allowing for extreme customizability for each patient’s anatomy. By having a single tandem with the capability to lock at multiple different angles, exemplary embodiments give the physician the freedom to alter the tandem to fit individual patients’ needs. Additionally, by a steerable component of the device, the physician has the ability to guide the tandem through complex female cervical and uterine anatomy with greater ease prior to locking the angle of the device at a desired level for the radiation treatment.

Some exemplary steerable tandems include features and size dimensions configured for the tandem to have the capability to be integrated seamlessly with existing brachytherapy instruments. Specifically, an exemplary tandem may be paired with “ovoids” which are attached to the sides of the tandem. Not only do exemplary embodiments offer devices and methods which allow physicians to deliver more accurate radiation therapy and thus provide better cancer care to their patients, exemplary embodiments provide a more cost-effective alternative to current tandem devices on the market, since a single device is able to replace the current need for multiple different rigid tandems set at permanently fixed different angles.

This disclosure adds a much-needed improvement to currently available brachytherapy devices, giving radiation oncologists the ability to treat their cancer patients with more accuracy and precision. Not only may this improve radiation dose delivery to the target tumors, but it may also help reduce unwanted radiation to surrounding normal tissues thus limiting toxicity from treatments.

Exemplary devices make possible improved high dose rate brachytherapy procedures that improve gynecological cancer care outcomes. Even beyond this exemplary context, exemplary steerable brachytherapy applicators are adaptable for application in other areas of the body for other cancers, such as for brachytherapy treatments of prostate cancers and gastrointestinal cancers. Exemplary steerable tandems according to this disclosure integrate a steerable tip with the proper dimensions, rigidity, and radiation delivery capability required for performing brachytherapy procedures.

According to an aspect of some embodiments, an exemplary steerable tandem is easily visualized on ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) for radiation planning purposes. The size and materials of an exemplary steerable tandem are configured to allow for clear visualization on all three of these systems.

Some exemplary devices of this disclosure are especially suited to the treatment of cervical cancer and uterine cancer. An exemplary steerable tandem is specifically designed to conform to anatomy of the cervix and uterus (as opposed to other anatomy such as vasculature). An exemplary steerable tandem is configured with adequate rigidity to allow it to overcome the cervical barrier to entry which is made more difficult by tumor burden. The length and curvature of the steerable tandem may be furthermore configured in a way to most optimally sit in the center of the uterine cavity and to reach the distal end of the uterus. The exemplary steerable tandem is built in such a way that after it has been placed within the uterus, the angle of the flexible tip can still be adjusted and locked and unlocked and relocked as needed by the physician to optimize the positioning within the uterine cavity. The device has enough rigidity to overcome the difficult insertion through the cervix, which is often made worse by tumor burden. The device has the capability of attaching (c.g., via catheter) to an aftcrloadcr system which holds the radiation source (e.g., radioactive wire), and which will deliver that source via a wire through the catheter into the device. The device can be easily visualized on ultrasound, CT scan, and MRI for positioning and radiation planning purposes.

The outer and inner diameters of an exemplary steerable tandem may be specific to allow for entry through the cervix, allow for adequate radiation delivery to surrounding tissues, and allow for the radiation source and wire to easily pass through its center. A rigid proximal stem may be configured to allow ancillary devices such as ovoids to be attached. The length of the flexible segment, and angle of curvature, may be selected to allow for placement into the center of the uterine cavity. An exemplary device provides the physician with the capability to adjust and lock the angle of the device at various positions after it has been placed within the uterus.

In some exemplary tandems, a continuous inner tube may run through the handle of the device (where the steering mechanism may exist) all the way to the flexible tip.

According to some exemplary tandems, a tensioned wire system supplies the means for steering the tandem.

According to some other exemplary tandems, a tube-in-a-tube system supplies the means for steering the tandem. Coaxially arranged inner and outer tubes are translatable relative to one another. One tube is rigid whereas the other tube has a flexible segment which is biased to bend intrinsically when not constrained. The amount of the flexible segment which is not constrained by the rigid tube determines the bend angle of the flexible segment. The locking mechanism, when locked, prevents the translation of the tubes relative to one another.

According to some exemplary embodiments, a brachytherapy devices entails a single stem or rod consisting of a series of segments. According to some other exemplary embodiments, a brachytherapy device may have two or more stems/rods or lobes. The respective stems or lobes may together form a Y-shape, for example, with a single handle at the base for guiding the multiple stems. One, multiple, or all of the stems may be steerable while a remainder, if applicable, may have fixed shape or configuration. Other shaped devices are also possible according to this disclosure such as but not limited to triangular shaped tandems. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A is a diagram of an exemplary brachytherapy device for treatment of cervical and uterine cancers;

Figure IB is a brachytherapy device with exemplary ancillary devices;

Figure 2 is a flowchart of an exemplary method of brachytherapy for cancer treatments;

Figure 3A is an exemplary brachytherapy device in a first configuration;

Figure 3B is the exemplary brachytherapy device in a second configuration;

Figure 3C is the exemplary brachytherapy device in a third configuration;

Figure 4A is a view of the proximal end of the exemplary brachytherapy device;

Figure 4B is another view of the proximal end of the exemplary brachytherapy device with part of the housing removed for visibility of internal components;

Figure 4C is a cross-sectional view of the distal end of the exemplary brachytherapy device;

Figure 5A is a view of an exemplary flexible portion of an exemplary brachytherapy device;

Figure 5B is a single joint of the exemplary flexible portion;

Figure 5C is a cross-sectional view of the exemplary flexible portion;

Figure 6A is the proximal end of the exemplary brachytherapy device with part of the housing removed for visibility of internal components;

Figure 6B is the internal assembly of the brachytherapy device with steering wires depicted;

Figures 7A, 7B, and 7C are a further exemplary tandem set at different angles using a tube-in-a-tube steering mechanism;

Figures 8 A, 8B, and 8C are a still further exemplary tandem set a different angles using another tube-in-a-tube steering mechanism.

DETAILED DESCRIPTION

Figure 1A is a diagram of am exemplary brachytherapy device 100 for, e.g., treatment of cervical and uterine cancers. For a number of embodiments of this disclosure, a “brachytherapy device” may be interchangeably referred to in the following description as “brachytherapy tandem applicator”, “tandem applicator”, “applicator”, and “tandem”. In some instances, however, a “brachytherapy device” includes elements distinguishable from (though complimentary to) a “tandem”, as the context will make clear.

The tandem 100 comprises a rigid distal segment 101 at its distal end 104, a flexible segment 102 which allows for flexibility, and a rigid proximal segment 103 at its proximal end 106. The segments 101, 102, and 103 may each and/or collectively have the form of tubes, rods, and/or stems. The distal tandem tip 104 is configured to enter the uterus. Flexible portion 102 of tandem 100 allows for multidirectional movement of segments 102 and 101 relative to segment 103. The lengths of the segments 101, 102, and 103 may each vary depending on the embodiment. As a non-limiting example, the flexible segment may be in the distal half of the device. In some embodiments an entirety of the flexible segment is closer to the distal end of the device than to the proximal end of the device. As further non-limiting examples, segment 101 may be 1-2 cm in length, segment 102 may be 7-10 cm in length, and segment 103 may be 20-25 cm in length.

The tandem 100 further includes a steering mechanism 107 which controls the steering of segments 101 and 102. The tandem 100 further includes a locking mechanism 108 that allows for locking of tandem angle. The locking mechanism 108 may be separate from or integral with the steering mechanism 107.

The tandem 100 is multidirectional in that it is configured to permit movement of the distal end 104 in at least two different directions. In Figure 1A the tandem 100 is shown bent in a first direction 112a relative to position 111. In position 111, all three segments 101, 102, and 103 are substantially aligned such that the tandem is characterized as having a 0° angle. The tandem 100 is steerable via steering mechanism 107 to cause distal end 104 to move in first direction 112a or second direction 112b. As illustrated, direction 112a is “up/upward” relative to neutral position 111, and direction 112b is “down/downward” relative to the neutral position. Directions 112a and 112b may both be considered “vertical” directions. The tandem 100 may be configured to be steerable in still further directions. For example, the tandem 100 may be steerable via steering mechanism 107 to cause distal end 104 to move in third direction 113a or fourth direction 113b. As illustrated, direction 113a may be characterized as a “right/rightward" direction, and direction 113b may be characterized as a “left/leftward” direction. Directions 113a and 113b may both be considered “horizontal” directions. Accordingly, the exemplary tandem 100 may be steered to achieve variable angles in vertical and/or horizontal directions.

The proximal end 106 has a hollow to allow for insertion of radiation source. The hollow extends through segments 103, 102, and 101 of the tandem 100 to allow for the radiation source to pass through the applicator to its tip 104 during radiation delivery. A hollow may also be referred to as a hole or lumen or cavity, for example.

Figure 1A depicts several elements in broken lines which may not technically be part of tandem 100 but which may be combined with tandem 100 for an exemplary brachytherapy system. An afterloader 121 is configured to hold the radiation source 124. The steerable tandem 100 is configured to attach (e.g., via catheter(s) 123) to the afterloader 121 which holds the radiation source 124. The radiation source 124 is delivered via a wire 122 through the catheter(s) 123 into the tandem 100. The internal hollow of the tandem 100 provides a path for the radiation source 124 to pass from the proximal end 106 to the distal end 104 of the tandem 100. The radiation source 124 is positionable anywhere in the tandem.

Figure IB is a brachytherapy device 150 which corresponds with tandem 100 of Figure 1A but with additional features one or more of which may be included in some embodiments depending on the needs and desire of medical professionals and their particular patients. The device 150 includes, in addition to the features of tandem 100 already discussed above, attachments 114 which allow ancillary devices such as any ovoid rods to be connected to the tandem and thus allow for the tandem to be utilized with any current ovoid products. The attachments 114 may be positioned on the rigid proximal stem of segment 103.

Figure IB depicts exemplary ovoids 160 which are a non-limiting example of ancillary devices which exemplary tandems according to this disclosure may be configured to receive for attachment. The rigid stem of segment 103 in combination with receiving parts 114 of the exemplary steerable tandem 100 allow for devices such as the ovoids 160 to be attached. Ancillary device attachment means 114 may be permanent elements of an exemplary tandem 150. Alternatively, attachments means 114 for attaching ancillary devices may themselves be removably attachable to segment 103 of the tandem 150. The latter configuration may be desirable in embodiments in which it is advantageous to have differently shaped and/or sized attachments 114 which respectively are configured (in shape and size, for instance) to receive different respective commercially available ovoids. The tandem 150 may be configured to have one or more “tube in a tube” configurations. One such configuration is inclusion of a sleeve 151 which covers and seals from an external environment those parts of the tandem which would otherwise be exposed to bodily fluids during use. The sleeve 151 covers the distal segment 101, flexible segment 102, and at least part of the proximal segment 103. The sleeve 151 is flexible to allow deformation of the sleeve 151 in the region of the flexible segment 102. The sleeve 151 may be sized and of such material choice (e.g., plastic, silicone, etc.) as to grip the underlying tandem surfaces with adequate surface friction that the sleeve 151 resists removal from the tandem in a state of use. The sleeve is nevertheless removable and replaceable with another sleeve between uses of the tandem. In addition or in the alternative to sleeve 151, the tandem 150 may be configured for use with tubing 152 which extends through internal cavity 115 of the tandem. The tubing 152 may extend substantially the entire length of the tandem. The tubing 152 seals the radiation source delivered therethrough against the environment outside the tubing 152. The tubing 152 may be a closed ended plastic catheter (e.g., single use) in which the radioactive source wire moves during a procedure. The tubing 152 has at least two roles: to insulate the wire from being contaminated by any bodily fluid, and to provide a smooth surface for the wire to move along (as opposed to for example coming in contact with links and the possibly uneven surface within the steerable tandem).

Exemplary devices such as but not limited to devices 100 and 150 may be made from MRI compatible materials such as MRI compatible metals (e.g., stainless steel) and/or plastics. An exemplary tandem and its mechanical components may be out of a lightweight material (such as plastics) which are MRI compatible and will not result in significant additional weight at the end of the tandem.

Figure 2 is an exemplary method 200. Method 200 is a method of brachytherapy treatment. In particular, method 200 is suitable for intracavitary /intracavity high dose rate brachytherapy. Method 200 is also a method of using an exemplary brachytherapy device such as those described by this disclosure. Method 200 allows for customizability of treatment and device usage for individual patient anatomy. Method 200 is especially suited for but not limited to treatment of cervical cancer and/or uterine cancer.

Method 200 comprises guiding a tandem through intracavity anatomy (block 201). For example, the tandem is guided through a cervix and into a uterus. As the whole tandem is being guided, a distal segment of the tandem is steered in a multidirectional fashion (block 202). In practice, guiding and steering may occur concurrently and/or sequentially. For purposes of this discussion, “guiding” may be regarded as movement of the tandem or parts thereof in relation to patient anatomy. “Steering” also involves movement of part of the tandem relative to patient anatomy. However, unlike “guiding”, “steering” entails movement of at least one part of the tandem relative to some other part of the tandem. In exemplary embodiments discussed above, a distal segment I tip is moved relative to a proximal segment of the tandem. Through a combination of guiding and steering, the tandem is positioned within an anatomical cavity in a position which best conforms to individual patient anatomy. Once in this position, it is advantageous for accidental adjustments to be avoided. At block 203, the angle of the tandem is locked at one of multiple different angles available, the locked angle being selected based on the individual patient anatomy. In a locked state, further steering of the distal tip is not possible.

Locking may entail, for example, disabling the steering mechanism. External forces acting on the distal segment or flexible segment (such as from contact with anatomical surfaces) cannot change the angle. However, the locking action is reversible. The tandem may be unlocked, the position of the distal tip adjusted by further steering, then relocked, as needed until the medical professional is satisfied that the distal tip of the tandem is optimally placed for treatment of the patient in question. After the placement of the tandem, and the distal tip in particular, is completed, a radiation source is passed through the tandem to the distal segment (tip) of the tandem (block 204). The radiation source is left in place in the distal segment of the tandem until the predetermined dose of radiation has been delivered (block 205). After treatment is completed, the radiation source and the tandem are removed from the patient. The tandem may be unlocked after treatment to facilitate ease of removal of the tandem from the patient.

Figures 3A, 3B, and 3C show an exemplary tandem 300, each figure showing the tandem 300 set at a different respective angle. Tandem 300 is consistent with tandem 100 of Figure 1. In brief, tandem 300 comprises a rigid distal segment 301, flexible segment 302, and rigid proximal segment 303. The tandem includes a user interface 331, in this example an articulation knob, which is part of the steering mechanism that enables the user to steer the distal segment 301 to and between a variety of angles including but not limited to the angles portrayed by Figures 3A, 3B, and 3C. Further components of the exemplar)' steering mechanism are disposed within housing 332. The steering mechanism advantageously includes at least one indicium which remains outside the patient when the tandem is in use. The exemplary indicium in Figures 3A, 3B, and 3C is a marking, in particular an arrow in this case, arranged on the user interface (the articulation knob) 331. The indicium is configured to change when the angle of the flexible segment 302 changes. Accordingly, the indicum is configured to indicate from outside the patient the angle of the tandem while the tandem is inside the patient. In Figures 3A, 3B, and 3C, the indicium rotates so that it points in different directions based on the angle of the flexible segment 302.

Figure 4A is a close up of the housing 332 and user interface 331 of the steering mechanism. The housing 332 doubles as a handle for the user (the medical practitioner). The proximal end of the tandem has an opening 333 which is the proximal end of a hollow which runs from the proximal end all the way to the distal end of the tandem. The opening 333 is configured as an insertion point for a radiation source.

Figure 4B shows part of the housing 332 removed to show internal components which are sealed against the external environment by the housing 332 when housing 332 is fully assembled. A dotted line traces the wire travel path 334 a radiation source follows from the proximal end of the tandem through the housing 332 and out through the proximal segment 303. Part of the travel path 334 is through a hollow defined by a conduit 335 which prevents the radiation source from becoming entangled or snagged on other components within housing 332. Other exemplary components visible in Figure 4B are discussed below in connection with Figures 6A and 6B. The travel path 334 runs through housing 332 to continue into a hollow of rigid proximal segment 303.

Figure 4C shows via cross-sectional view the continuation of the hollow 442 that allows for a radiation source to pass through the rigid proximal segment 303 and flexible segment 302 to the rigid distal segment 301 during radiation delivery. The steerable tandem is built in such a way to allow for a radiation source to be threaded on a wire through the center hole 442, from the proximal end all the way to the distal tip 304. The outer and inner diameters of the steerable tandem may be selected specifically to allow for entry through the cervix, allow for adequate radiation delivery of uniform distribution to surrounding tissues, and allow for the radiation source and wire to easily pass through its center. Exemplary outer diameters for all segments 301, 302, and 303 is at least 4 mm, e.g., 4-7 mm. Exemplary inner diameters for the hollows through these segments is at least 1 mm, e.g., 1-3 mm. In some embodiments, a continuous inner tube may run through the handle of the device (where the steering mechanism exists) all the way to the distal tip. The distal end of the steerable tandem is close ended so that the radiation source cannot exit the device.

As depicted in Figure 4C, an exemplary flexible segment 302 is jointed. The flexible segment 302 comprises a plurality of linkages 441 which link together end to end to achieve a desired length of flexible segment 302. An exemplary flexible segment 302 may be at least 7 cm, e.g., 7-10 cm, in length, for example. The rigid proximal segment 303 between the flexible segment 302 and housing/handle 332 may be at least 20 cm, e.g., 20-25 cm, in length, for example. The distal segment 301 may be at least 1 cm, e.g., 1-2 cm, in length, for example.

Figure 5A is a closeup of an exemplary flexible segment 302 comprising a plurality of linked linkages 441. Figure 5B is a perspective view of a single exemplary linkage 441, and Figure 5C is a cross-sectional view of the same. The linkage 441 comprises male end 551 and female end 552. A male end 551 of one linkage 441 is configured to slide laterally into a corresponding opening of a female end 552 of a neighboring linkage. So assembled, the neighboring linkages are configured to prevent disassembly/separation by longitudinal displacement of either linkage relative to the other. The linkage 441 includes holes 553 for accommodating pull wires. Holes 553 are separate from center hole 442. Holes 553 run parallel to hole 442. The two holes 553 are positioned at different circumferential positions about hole 553. A single linkage 441 may comprise two or more than two holes 553 for pull wires. The holes 553 are through holes that are parallel with the longitudinal axis of the linkage. Holes 553 of one linkage align with holes 553 of neighboring linkages so that pull wires may run continuously through the length of the flexible segment 302 to region 444 of the distal segment 301 (see Figure 4C). The pull wires are anchored in region 444 of the distal segment 301.

Figures 6A and 6B depict an exemplary steering mechanism for controlling and changing an angle of the flexible segment of a steerable tandem. Figure 6B depicts the same steering mechanism but includes illustration of pull wires 661 which are omitted from illustration in Figure 6A. As introduced above, the pull wires 661 pass through the small holes 553 in the linkages 441 and are anchored in region 444 of distal segment 301. The pull wires extend through not only linkages 441 but through proximal segment 303 to the housing 332 and the steering mechanism elements housed within. The ends of pull wires 661 which are inside housing 332 are anchored at position 664 to wire anchor gear 662. The anchoring is such that rotation of gear 662 clockwise pulls on one wire while slackening the other. Rotation of the gear 662 counterclockwise switches which wire is pulled and which is slackened. Rotating the knob 331 rotates gear 662. Embodiments may employ different configurations of gears including the option of gears arranged between the knob 331 and gear 662 to achieve desired gear ratios. One or more pins 663 may be included for positioning the pull wires 661. The pins and wires may be positioned so that the knob action matches the articulation action of the flexible segment 302. For example, when the knob 331 rotates forward and down, the articulation goes down. When the knob 331 rotates backward and up, the articulation goes up.

The exemplary tandem illustrated by Figures 6A and 6B is configured to permit not only adjustment of the angle of the flexible segment of the tandem but also locking of the distal angle once the distal tip is in the final desired position for radiation delivery. An exemplary locking mechanism includes means for arresting rotation of the wire anchor gear 662. In the illustrated embodiment, a locking gear 665 is provided which is incapable of rotation. The knob 331 is fixedly connected with an articulation knob gear 668. Together the knob 331 and knob gear 668 are displaceable along an axis which is parallel with the center axis of locking gear 665. The knob 331 and knob gear 668 are displaceable between a locked position, whereby the teeth of knob gear 668 mesh with teeth of locking gear 665, and an unlocked position, whereby the teeth of knob gear 668 do not mesh with locking gear 665. Only when the teeth of the two respective gears are meshed is rotation of the entire gear assembly, including wire anchor gear 662, prevented.

The exemplary tandem may be biased into either an unlocked or locked state. Figure 6A presents the example of a knob spring 667 that biases the tandem into a locked state. Absent external forces to the contrary, the spring 667 urges the knob gear 668 into the locked position. A user may apply a force to knob 331 which acts against the spring 667 and pushes the knob 331 inward, thereby unlocking the gear assembly by disconnecting the locking gear 665 from the remainder of the gear assembly. While the knob 331 is pressed inward, the knob 331 is free to be rotated by the user to permit adjustment of the angle of the tandem.

Figures 6 A and 6B depict a further feature which may be included in some embodiments. A wire tensioning mechanism is provided which comprises a tensioning screw 671 and tensioning knob 672. The knob 672 has a threaded through hole and is mounted on the threaded shaft of screw 671. The knob 672 is fixed in place relative to housing 332. Rotation of knob 672 causes the screw 671 to advance left or right, depending on the direction of rotation (clockwise or counterclockwise). Movement of the screw 671 in one direction adds tension to both wires 661, whereas movement of the screw 671 in the opposite direction reduces tension to both wires 661. The screw is connected to the tandem shaft and linkages such that these elements are pushed forward when the screw is pushed forward, lengthening the system and pulling the wires taught. The wire tensioning mechanism may be concealed within the housing 332 to reduce accidental misuse, as it may only be needed in the infrequent occasion that the steerable tandem requires tuning.

Figures 7A, 7B, and 7C depict a further exemplary tandem 700. Tandem 700 comprises an inner tube 771 and an outer sheath/tube 772. Together the tubes 771 and 772 form a tube-in-a- tube system. Inner tube 771 comprises a distal segment 701, a flexible segment 702, and a proximal segment 703. Inner tube 771 is configured to inherently bend in flexible segment 702 in the absence of external forces which resist such bending. Outer tube 772 is configured as a steering mechanism for controlling the angle that flexible segment 702 of inner tube 771 is permitted to bend. Outer tube 772 is rigid. In Figure 7A, outer tube 772 surrounds an entirety of flexible segment 702 and holds flexible segment 702 straight. Outer tube 772 prevents the flexible segment 702 from bending.

The inner and outer tubes 771 and 772 may be translated relative to one another. The extent of the translation controls the angle formed by the flexible segment 702. The translation may be retraction of the outer tube 772 from the distal end 704 or extension of the outer tube 772 toward the distal end 704. The translation may be extension of the inner tube 771 relative to the outer tube 772 or retraction of the inner tube 771 into the outer tube 772.

Figure 7B shows a configuration in which part of flexible segment 702 of inner tube 771 is no longer constrained by outer tube 772. Accordingly, the inner tube 771 naturally flexes to a predetermined angle that correlates with the proportion of flexible segment 702 which is not constrained. Figure 7C shows a configuration in which a greater proportion of flexible segment 702 of inner tube 771 is no longer constrained by outer tube 772. The flexible segment 702 naturally flexes to an even greater angle than was permitted in Figure 7B. The angle of the flexible segment 702 is reduced as desired simply by translating either tube relative to the other so that more of the flexible segment 702 is again inside of and therefore constrained by the straight, rigid body of outer tube 772.

The tandem 700 may be used consistent with exemplary method 200 described above. Steering at block 202 of method 200 is achieved by translating either of the tubes 771 and 772 relative to the other. The tubes 771 and 772 both have hollow interiors to permit the radiation source to pass through to distal end 704 for block 204. The distal end 704 is not open, however, which prevents accidental travel of the radiation source out of the tandem 700.

Figures 8A, 8B, and 8C depict a further exemplary tandem 800. Tandem 800 comprises an inner tube 881 and an outer sheath/tube 882. Together the tubes 881 and 882 form a tube-in-a- tube system. Outer tube 882 comprises a distal segment 801, a flexible segment 802, and a proximal segment 803. Outer tube 882 is configured to inherently bend in flexible segment 802 in the absence of external forces which resist such bending. Inner tube 881 is configured as a steering mechanism for controlling the angle that flexible segment 802 of outer tube 882 is permitted to bend. Inner tube 881 is rigid. In Figure 8A, inner tube 881 is situated in an entirety of flexible segment 802 and holds flexible segment 802 straight. Inner tube 881 prevents the flexible segment 802 from bending.

The inner and outer tubes 881 and 882 may be translated relative to one another. The extent of the translation controls the angle formed by the flexible segment 802. The translation may be retraction of the inner tube 881 from the distal end 804 or extension of the inner tube 881 toward the distal end 804. The translation may be extension of the outer tube 882 relative to the inner tube 881 or retraction of the outer tube 882 over the inner tube 881.

Figure 8B shows a configuration in which part of flexible segment 802 of outer tube 882 is no longer constrained by inner tube 881. Accordingly, the outer tube 882 naturally flexes to a predetermined angle that correlates with the proportion of flexible segment 802 which is not constrained. Figure 8C shows a configuration in which a greater proportion of flexible segment 802 of outer tube 882 is no longer constrained by inner tube 881. The flexible segment 802 naturally flexes to an even greater angle than was permitted in Figure 8B. The angle of the flexible segment 802 is reduced as desired simply by translating either tube relative to the other so that more of the flexible segment 802 is again around and therefore constrained by the straight, rigid body of inner tube 881. The tandem 800 may be used consistent with exemplary method 200 described above. Steering at block 202 of method 200 is achieved by translating cither of the tubes 881 and 882 relative to the other. The tubes 881 and 882 both have hollow interiors to permit the radiation source to pass through to distal end 804 for block 204. The distal end 804 is not open, however, which prevents accidental travel of the radiation source out of the tandem 800.

EXAMPLE

This Example examines how a steerable tandem can improve dosimetry in difficult cases of gynecological brachytherapy. This Example investigates improvements in target dose coverage and doses to organs at risk (OAR) in three patients using optimal tandem angles which could be achieved using a steerable tandem in accordance with this disclosure. The results show improvements in radiation coverage of the tumor areas and less radiation to surrounding organs in 3 example patients.

Three unique cases of patients treated with tandem-based brachytherapy at Virginia Commonwealth University (VCU) Health were analyzed who had imperfect tandem placement due to variations in anatomy. Patients 1 and 2 were treated for FIGO stage I endometrioid adenocarcinoma, and Patient 3 for FIGO stage IIIC1 squamous cell carcinoma of the cervix. Target and OAR doses from these patients’ initial brachytherapy implants were compared to doses which would have been obtained if optimal tandem placement had been achieved using a steerable tandem. Target analysis included dose evaluation of high risk CTV (CTV_HR) and intermediate risk PTV (PTV_IR). OARs evaluated included rectum, sigmoid colon, and bladder. All plans including the clinically delivered one and those containing the steerable tandem were optimized using a two-step method as previously described by Sharma et al. (Sharma M, Fields EC, Todor DA. A novel two-step optimization method for tandem and ovoid high-dose-rate brachytherapy treatment for locally advanced cervical cancer. Brachytherapy. 2015; 14(5): 641- 649.)

Patients 1 and 2 were originally treated with rigid tandem and ovoids. Target coverage for both CTV_HR and PTV_IR were improved with use of optimal tandem angle placement. Additionally in Patient 1 , rectum D2cc was reduced with optimal tandem placement, and in Patient 2 both rectum and sigmoid colon D2cc were reduced with optimal tandem placement. Patient 3 was originally treated with rigid tandem, ovoids, and 5 interstitial needles. In this patient, PTV_IR D90% was improved, as well as rectum D2cc and bladder D2cc after optimal tandem placement.

This small study gives insight into the potential benefits of a variable angle, steerable tandem allowing for optimal tandem angle placement during difficult cases of gynecological brachytherapy. As seen with these patients, optimal tandem angles can result in improvements in target dose coverage and reductions in OAR doses.

The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s) In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions.

Where a range of values is provided in this disclosure, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are described.

It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of steps recited or in any other order which is logically possible. Alternative methods may combine different elements of specific detailed methods described above and in the figures.

While exemplary embodiments of the present invention have been disclosed herein, one skilled in the art will recognize that various changes and modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS What is claimed is:

1. A brachytherapy device for treatment of cervical and uterine cancers, comprising a rigid distal segment at a distal end of the brachytherapy device; a rigid proximal segment; a flexible segment between the rigid distal segment and rigid proximal segment, wherein the flexible segment permits movement of the rigid distal segment relative to the rigid proximal segment; a steering mechanism for controlling and changing an angle of the flexible segment; and a hollow allowing for a radiation source to pass through the rigid proximal segment and flexible segment to the rigid distal segment during radiation delivery.

2. The brachytherapy device of claim 1, further comprising a locking mechanism allowing the angle of the flexible segment to be locked.

3. The brachytherapy device of claim 1, wherein the flexible segment is jointed.

4. The brachytherapy device of claim 1, further comprising one or more attachment components for attaching ovoids to the rigid proximal segment.

5. The brachytherapy device of claim 1, made of MRI compatible materials.

6. The brachytherapy device of claim 1, wherein the steering mechanism comprises a rigid tube coaxial with the flexible segment, wherein the rigid tube and flexible segment are translatable relative to one another, wherein an amount of the flexible segment which is not constrained by the rigid tube determines the angle of the flexible segment.

7. A brachytherapy system, comprising a radiation source; and a tandem according to claim 1 ; wherein the hollow of the tandem is sized to accommodate passage of the radiation source from the proximal end to the distal segment.

8. The brachytherapy system of claim 7, wherein the hollow has an inner diameter of at least 1 mm.

9. The brachytherapy system of claim 7, the tandem further comprising a locking mechanism allowing the angle of the flexible segment to be locked.

10. The brachytherapy system of claim 7, wherein the flexible segment is jointed.

11. The brachytherapy system of claim 7, further comprising one or more attachment components for attaching ovoids to the rigid proximal segment.

12. The brachytherapy system of claim 7, the tandem being made of MRI compatible materials.

13. The brachytherapy system of claim 7, wherein the steering mechanism comprises a rigid tube coaxial with the flexible segment, wherein the rigid tube and flexible segment are translatable relative to one another, wherein an amount of the flexible segment which is not constrained by the rigid tube determines the angle of the flexible segment.

14. A method of brachytherapy treatment allowing for customizability for individual patient anatomy, comprising guiding a tandem through intracavity anatomy; steering a distal segment of the tandem in a multidirectional fashion as the tandem is positioned within a cavity to conform to individual patient anatomy; passing a radiation source through the tandem to the distal segment of the tandem; and delivering a dose of radiation.

15. The method of claim 14, further comprising locking the angle of the tandem at one of multiple different angles available, the locked angle being selected based on the individual patient anatomy.

16. The method of claim 14, wherein the tandem is guided through cervical and uterine anatomy and the cavity is a uterine cavity.