STERILIZABLE FIDUCIAL BEACON STRAND FOR RF TARGET TRACKING CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Provisional Application No. 62/453,050, filed February 1, 2017, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] Throughout this application various publications, patents, patent application publications and books are referred to. Full citations for the publications may be found at the end of the specification. The disclosures of the publications, patents, patent application publications and books are hereby incorporated by reference in their entirety into the subject application to more fully describe the art to which the subject invention pertains.

[0003] The present invention addresses the need of providing improved techniques for active transponders use in courses of therapy using MRI assessment between multiple radiofrequency energy treatments.

SUMMARY OF THE INVENTION

[0004] A device is provided comprising (i) at least three electromagnetic transponders separated from one another by a flexible spacer material, all of which are (ii) enclosed within radiofrequency -transparent sterilizable tubing.

[0005] A method of treating a prostate cancer in a subject comprising:

inserting the device as described herein into a prostate of the subject;

monitoring by cone beam CT imaging the location of the prostate within the subject;

administering an amount of external beam radiation therapy (EBRT) to the prostate of the subject;

monitoring movement of the prostate during administration of EBRT by monitoring the location of the at least three electromagnetic beacon transponders by exciting them with radiofrequency energy and collecting the signal therefrom.

[0006] A method of treating a prostate cancer in a subject comprising:

inserting the device as described into a prostate of the subject;

monitoring by CT imaging the location of the prostate within the subject; administering an amount of external beam radiation therapy (EBRT) to the prostate of the subject;

monitoring movement of the prostate during administration of EBRT by monitoring the location of the at least three electromagnetic beacon transponders by exciting them with radiofrequency energy and collecting the signal therefrom;

removing the device from the subject;

subjecting the prostate of the subject to a magnetic resonance imaging (MRI) scan to analyze the effect of the EBRT;

sterilizing the device and re-inserting it into the prostate of the subject,

monitoring by CT imaging the location of the prostate within the subject;

administering an amount of external beam radiation therapy (EBRT) to the prostate of the subject;

monitoring movement of the prostate during administration of EBRT by monitoring the location of the at least three electromagnetic beacon transponders by exciting them with radiofrequency energy and collecting the signal therefrom.

[0007] Also provided is a method of manufacturing a device comprising:

(i) assembling at least three electromagnetic transponders in a line and separating a middle electromagnetic transponder from the remaining electromagnetic transponders by an amount of a flexible spacer material;

(ii) enclosing the product of step (i) within a first layer polyethylene terephthalate heat shrink tubing;

(iii) enclosing the product of step (ii) within a second layer polyethylene terephthalate heat shrink tubing,

[0008] Additional objects of the invention will be apparent from the description which follows.

BRIEF DESCRIPTION OF THE FIGURES

[0009] Fig. 1 : Schematic of a device.

[0010] Fig. 2: Photo of exemplary product showing sterling silver C-clamps on left hand portion and three transporters within the strand.

DETAILED DESCRIPTION OF THE INVENTION

[0011] A device is provided comprising (i) at least three electromagnetic transponders separated from one another by a flexible spacer material, all of which are (ii) enclosed within radiofrequency-transparent sterilizable tubing.

[0012] In an embodiment, the device further comprises one or more silver metal clamps clamped around a portion of the device. In an embodiment, the one or more silver metal c- type clamps are crimped around a portion of the strand to provide a stop having increased diameter relative to the remainder of the strand.

[0013] In an embodiment, the device is in the form of a strand.

[0014] In an embodiment, the device is in inserted into a Foley catheter, wherein the one or more clamps are wider in diameter than the internal diameter of the Foley catheter. In an embodiment, the clamps are silver metal c-type clamps.

[0015] In an embodiment, the one or more clamps prevent insertion of an undamped portion of the device into a Foley catheter when a remaining portion of the device is inserted into the Foley catheter. In an embodiment, the clamps are silver metal c-type clamps.

[0016] In an embodiment, the diameter of the Foley catheter is 10 F to 28 F.

[0017] In an embodiment, the electromagnetic transponders are passive electromagnetic oscillators, ("transponders"), that emit a unique electromagnetic signal when excited using an external transmitted electromagnetic signal. In an embodiment, the transponders are low activity Ir-192 seeds.

[0018] In an embodiment, the transponders wirelessly emit an electromagnetic signal when subjected to an artificially induced electromagnetic field.

[0019] In an embodiment, the sterilizable radiofrequency-transparent tubing is polyethylene terephthalate heat shrink tubing. In an embodiment, the sterilizable radiofrequency-transparent tubing is a plastic tubing. In an embodiment, the sterilizable radiofrequency-transparent tubing is 3D-printed tubing.

[0020] A method of treating a prostate cancer in a subject comprising: inserting the device as described herein into a prostate of the subject;

monitoring by cone beam CT imaging the location of the prostate within the subject;

administering an amount of external beam radiation therapy (EBRT) to the prostate of the subject;

monitoring movement of the prostate during administration of EBRT by monitoring the location of the at least three electromagnetic beacon transponders by exciting them with radiofrequency energy and collecting the signal therefrom.

[0021] A method of treating a prostate cancer in a subject comprising:

inserting the device as described into a prostate of the subject;

monitoring by CT imaging the location of the prostate within the subject;

administering an amount of external beam radiation therapy (EBRT) to the prostate of the subject;

monitoring movement of the prostate during administration of EBRT by monitoring the location of the at least three electromagnetic beacon transponders by exciting them with radiofrequency energy and collecting the signal therefrom;

removing the device from the subject;

subjecting the prostate of the subject to a magnetic resonance imaging (MRI) scan to analyze the effect of the EBRT;

sterilizing the device and re-inserting it into the prostate of the subject,

monitoring by CT imaging the location of the prostate within the subject;

administering an amount of external beam radiation therapy (EBRT) to the prostate of the subject;

monitoring movement of the prostate during administration of EBRT by monitoring the location of the at least three electromagnetic beacon transponders by exciting them with radiofrequency energy and collecting the signal therefrom.

[0022] In an embodiment, the methods further comprise moving the subject in whom the prostate has been monitored as having moved, so as to position the subject's prostate in the line of or the therapeutic axis of the EBRT.

[0023] In an embodiment, the EBRT is stereotactic body radiation therapy.

[0024] In an embodiment, the method further comprises removing the device from the subject after administering the amount of extemal beam radiation therapy (EBRT) and sterilizing the device for re-use. [0025] In an embodiment, the electromagnetic transponders are each less than 1 cm in length and less than 2 mm in diameter.

[0026] In an embodiment, if the monitoring by CT shows a movement of 1mm or more, then the EBRT is re-positioned to ensure it is targeted at the prostate of the subject so moved.

[0027] Also provided is a method of manufacturing a device comprising:

(i) assembling at least three electromagnetic transponders in a line and separating a middle electromagnetic transponder from the remaining electromagnetic transponders by an amount of a flexible spacer material;

(ii) enclosing the product of step (i) within a first layer polyethylene terephthalate heat shrink tubing;

(iii) enclosing the product of step (ii) within a second layer polyethylene terephthalate heat shrink tubing,

so as to form the device.

[0028] In an embodiment, the method further comprises clamping one or more silver metal clamps around a portion of the device.

[0029] In an embodiment, the device is manufactured in the form of a strand.

[0030] In an embodiment, the electromagnetic transponder is configured to wirelessly transmit a location signal in response to wirelessly transmitted non-ionizing excitation energy. In an embodiment, the electromagnetic transponder is configured to wirelessly transmit a location signal in response to wirelessly transmitted radiofrequency excitation energy.

[0031] In an embodiment, each transponder emits a signal in response to non-ionizing excitation energy at a unique frequency specific to that transponder.

[0032] In an embodiment, the electromagnetic transponder contains an electrical circuit contained within a glass vial.

[0033] The subject of the methods may be any subject. Preferably, the subject is a mammal. More preferably, the subject is a human.

[0034] As used herein "and/or", for example as in option A and/or option B, means the following embodiments: (i) option A, (ii) option B, and (iii) the option A plus B, and any subset of such options, including only one option. [0035] All combinations of the various elements described herein are within the scope of the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0036] Where a numerical range is provided herein, it is understood that all numerical subsets of that range, and all the numerical values to one decimal place, are provided as part of the invention. Thus, for example, an ablation catheter which is 10F-28F in diameter includes the subset of ablation catheters which are 1 IF, 12F, 13F etc. in diameter as well as the range of ablation catheters which are 15F-20F, 18F-28F and so forth.

[0037] This invention will be better understood from the Experimental Details, which follow. However, one skilled in the art will readily appreciate that the specific methods and results discussed are merely illustrative of the invention as described more fully in the claims that follow thereafter.

EXPERIMENTAL DETAILS

Examples

[0038] When delivering External Beam Radiation Therapy (EBRT) for the treatment of prostate cancer, beacon transponders (e.g. Calypso™ by Varian Medical Systems) can be implanted within the prostate to allow for target localization and tracking during the course of the treatment. Typically three transponders are implanted into the prostate before CT imaging and treatment begin. These transponders remain within the patient after treatment is completed and cannot be removed without surgery.

[0039] High dose per fraction EBRT, known as Stereotactic Body Radiation Therapy (SBRT) for the treatment of prostate cancer is becoming increasingly common as recent studies have shown similar/improved local control compared to conventional treatment regimens. SBRT reduces the number of treatments from 43 to 5 or fewer, making it much easier for the patient. Beacon transponders are required when delivering SBRT to allow for precise target localization during radiation delivery. The position of the prostate can change within the course of a single treatment due to organ motion; the calypso system allows for the motion of the prostate to be tracked during treatment delivery and can halt the treatment if large shifts are detected. Due to the higher does being delivered precise target and organ at risk delineation is essential. For this reason an MRI is an essential tool both for pre- treatment imaging and also as a follow up in case of disease recurrence.

[0040] Beacon transponders are essentially radio-frequency transponders and thus cause large artifacts in an MRI study. Each transponder creates a sphere approximately 2cm in radius where there is no measured MRI signal. This effectively prevents MRI studies of the prostate.

[0041] Previous work (Champalimaud Centre for the Unknown, Lisbon, Portugal) has placed Calypso transponders directly into the central lumen of a Foley catheter. This catheter is then inserted into the patient's urethra prior to treatment and removed after treatment. The catheter is sterilized using gamma sterilization between treatments. In some countries, however, including the U.S., Foley catheters are classed as single use devices. There is no FDA approved method of sterilization of such.

[0042] Herein an improved method and device for tracking and imaging studies using transponders in a single product is provided which is removable, sterilizable and reusable.

[0043] In an embodiment, the beacon transponder strand consists of the 3 beacon transponders (e.g. of the Calypso type) and a flexible beading spacer material (e.g. a thermoplastic elastomers comprising polyamide and polyether backbone, e.g. PebaxTM by Vention Medical). This is enclosed in a medical grade polyethylene terephthalate heat shrink tubing (e.g. Vention Medical). In an embodiment, in the manufacture of the beacon transponder strand, the strand containing the transponders, spacer material and covered in heat shrink tubing is placed in a water bath (e.g. 275 °F, 15 minutes) causing the outer tubing to shrink to the diameter of the transponders and spacer material. The strand is then placed in a second layer of tubing and heated once more for added strength. Finally, it is preferable that one or more clamps, such as sterling silver c type clamps, are crimped to the strand to prevent the device being inserted into a Foley catheter further than desired. The final device can be re-sterilized multiplied times, e.g. using a technique such as low temperature ethylene oxide (ETO) or low-temperature, hydrogen peroxide gas plasma (e.g. SterradTM, Advanced Sterilization Products).