Patent Publication Number: US-2021161549-A1

Title: Tethered laparoscopic probe grip

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to and is a continuation of International Patent Application No. PCT/GB2019/052055, filed Jul. 23, 2019, which claims priority from GB Patent Application No. 1812131.9, filed Jul. 25, 2018, the entire contents of which are hereby incorporated by reference in their entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to laparoscopic probes. In particular, the present disclosure relates to a tethered laparoscopic probe to be inserted into a cavity via a trocar. The present disclosure further concerns grips for tethered laparoscopic probes. 
     BACKGROUND OF THE INVENTION 
     Laparoscopic surgery, also called minimally-invasive surgery or keyhole surgery, is a surgical technique in which operations are performed using a small incision (usually 0.5-1.5 cm) in the body of a subject. Laparoscopic surgery provides a host of clinical benefits over open surgery, for example pain and hemorrhaging are reduced due to smaller incisions, and recovery times for the patient are reduced. 
     In order to perform laparoscopic surgery on a subject, a small incision is made in the body of the subject and a trocar is placed into the incision. A trocar is a medical device that acts as a portal for the subsequent placement of other instruments into a cavity of the subject for use in the surgery. The size of the trocar, for example the diameter of the trocar, provides a limit on the size of the instrument(s) that can be used in the laparoscopic surgery, as the instruments need to be able to pass through the trocar into the subject. For some types of laparoscopic surgeries, multiple instruments may be required—if these instruments are required at the same time and each take up a port, then multiple incisions may be required, leading to patient discomfort and slower patient recovery times. 
     Many laparoscopic probes typically comprise a detector supported by a rigid rod, which may be inserted through a trocar into a cavity of a subject. However, such probes have limited maneuverability within the cavity due to the restriction of movement of the rigid rod within the trocar. Furthermore, such laparoscopic probes would use up an entire trocar, and so further incisions in the subject would be required if further surgical tools are required for the surgery. 
     The present application provides solutions to overcome problems such as those described above. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present disclosure, a tethered laparoscopic probe is provided. The tethered laparoscopic probe is suitable for deployment through a trocar into a cavity of a subject. The tethered laparoscopic probe is manipulatable by fenestrated laparoscopic graspers comprising opposing fenestrated jaws. The tethered laparoscopic probe comprises a probe head shaped for insertion through the trocar. The probe head comprises an elongated casing. The probe head further comprises a sensor arranged within the casing, the sensor defining a sensing direction of the probe head. The probe head further comprises a grip for secure grasping by the fenestrated laparoscopic graspers, the grip comprising protrusions for mating with the fenestrated jaws. The tethered laparoscopic probe further comprises a tether coupled to the probe head and for, in use, tethering the probe head through the trocar. The protrusions are positioned and shaped to enable the grip to be grasped securely by the fenestrated laparoscopic graspers at a first angle relative to the sensing direction of the probe head. The protrusions are positioned and shaped to enable the grip to be grasped securely by the fenestrated laparoscopic graspers at a second angle relative to the sensing direction of the probe head, the second angle different to the first angle. 
     By providing such a tethered laparoscopic probe, the laparoscopic probe may be deployed through a port of a trocar and, in use, not take up the entire capacity of the port. Accordingly, further instrument(s) may be used with the same trocar port while the laparoscopic probe is deployed. Further advantageously, in comparison to traditional laparoscopic probes which comprise a rigid rod-like structure limiting control of a detector head to four degrees of freedom, a tethered laparoscopic probe as described herein may, in use, have six degrees of freedom. 
     Laparoscopic graspers, also known as tissue graspers or forceps, are a form of grasping instrument usually used to manipulate delicate tissue during laparoscopic procedures. One of their many functions is to facilitate adequate access to the surgical site by holding tissue clear of the operating field. Modern laparoscopic graspers are typically manufactured from surgical grade stainless steel, and may also incorporate other materials including titanium, tungsten carbide and various plastics. Laparoscopic graspers are one of a range of laparoscopic tools that differ from their conventional surgical counterparts in that they have an extended shaft or stylus in order that they can be maneuvered through small incisions during minimally invasive procedures. Such laparoscopic graspers can be reusable or disposable. 
     Laparoscopic graspers, as described herein, typically comprise a pair of opposing jaws at the end of the shaft or stylus that is to be inserted into the cavity. The jaws can be opened or closed in order to release or grasp tissue or other objects. The inner surfaces of such teeth may be profiled with waves, teeth, protruding hemispheres or cross-serrated ribbing. The inner surfaces may be smooth. Several types of jaw are available, including straight or flared, traumatic or atraumatic, single or dual-action, and fenestrated or solid. Fenestrated designs incorporate an open area or window into one or both jaws, making them lighter, and may offer a safer grip than friction alone by enclosing a portion of tissue within the window. The term “fenestrated laparoscopic graspers” or “fenestrated grasping forceps” as used herein refers to laparoscopic graspers having a pair of fenestrated laparoscopic jaws i.e. two jaws, each of which has located in it a gap, window, open area or slot. The slots may be of any suitable shape. For example, the slots may be rectangular or oblong. Such fenestrated laparoscopic jaws may be manually operable, for example Johan graspers. Such fenestrated laparoscopic graspers may be operable by a processor or robotics system. 
     The term “sensing direction” is used herein to denote a direction of reference only, as would be understood by the person skilled in the art. In some embodiments, the sensor may be a directional sensor, in which case the sensing direction may be defined as the direction in which the sensor is directed; however, the sensing direction may be any other direction defined with reference to the sensor. Similarly, in some embodiments the sensor may comprise a multi- or omni-directional sensor, and the “sensing direction” may be any direction defined with reference to the sensor—the sensing direction is for reference purposes. 
     Advantageously, the tethered laparoscopic probe provides protrusions positioned and shaped to enable the grip to be grasped securely by the fenestrated laparoscopic graspers at a first angle relative to the sensing direction of the probe head, and at a second angle relative to the sensing direction of the probe head, the second angle different to the first angle. In this way, a user (whether human or processor) of the fenestrated laparoscopic graspers is able to grasp the probe securely with at least two angles of engagement—that is, angles relative to the sensing direction. In the confined spaces in which laparoscopic surgery is performed, such an ability to securely hold the probe at a variety of angles is invaluable as it allows for better manipulation of the probe within the cavity. 
     In the context of the present disclosure, the fenestrated laparoscopic graspers may grasp “securely” the probe head of the laparoscopic probe when the jaws of the graspers engage with the probe head such that unintentional rotational movement away from the angle of engagement is greatly inhibited. 
     As the tethered laparoscopic probe is for deployment into a cavity, it is necessary that the probe head is small enough to pass through a port of a trocar, which may be, for example, 12 mm in diameter. Typically, a trocar will have a diameter of around 12 mm, although in recent years trocars are often used which have diameters of 10 mm of smaller. The diameter of the probe head, and therefore the components therein, must be small enough to pass through the trocar. 
     The grip may be beveled. The grip may be magnetic. 
     The elongated casing may comprise one or more of tungsten (with a biocompatible coating applied), stainless steel, tantalum and plastic. 
     The protrusions may comprise a pair of protrusions positioned such that the first protrusion of the pair of protrusions is graspable by a first jaw of the fenestrated laparoscopic graspers while a second protrusion of the pair of protrusions is graspable by a second jaw of the fenestrated laparoscopic graspers. The pair of protrusions may be positioned and shaped to be graspable securely by the fenestrated laparoscopic graspers at the first angle. The pair of protrusions may be positioned and shaped to be graspable securely by the fenestrated laparoscopic graspers at the second angle. 
     In one or more embodiments, the first angle and the second angle may be substantially perpendicular to one another. For example the first angle may be substantially 0 degrees and the second angle may be substantially 90 degrees to the sensing direction. 
     The protrusions may comprise a first pair of protrusions and a second pair of protrusions. A first protrusion of the first pair of protrusions may be positioned and shaped to be graspable by a first jaw of the fenestrated laparoscopic graspers at the first angle, and a second protrusion of the first pair of protrusions may be positioned and shaped to be graspable by a second jaw of the fenestrated laparoscopic graspers at the first angle. A first protrusion of the second pair of protrusions may be positioned and shaped to be graspable by the first jaw of the fenestrated laparoscopic graspers at the second angle, and a second protrusion of the second pair of protrusions may be positioned and shaped to be graspable by the second jaw of the fenestrated laparoscopic graspers at the second angle. The first angle and the second angle may or may not be perpendicular to each other. The first angle may be substantially 105 degrees relative to the sensing direction. The second angle may be substantially 60 degrees relative to the sensing direction. 
     The protrusions may be positioned and shaped to enable the grip to be graspable by the fenestrated laparoscopic graspers at a third angle relative to the sensing direction of the probe head, the third angle different to the first angle and the second angle. Advantageously, this would enable a user to manipulate the probe still further within the cavity. 
     The grip may further comprise a rib. The rib may be grippable by jaws of a surgical instrument. The rib may separate adjacent recesses of the grip. The surgical instrument may comprise a needle driver or needle holder. 
     Advantageously, the rib enables a user to hold the tethered laparoscopic probe in place within the cavity with the e.g. needle driver, while releasing the grip of the fenestrated laparoscopic graspers to adjust the angle of engagement from the first angle to the second angle (or vice versa). As the probe head is for insertion through a trocar, it is beneficial to provide the recesses around the rib in order to provide a grippable area without substantially increasing the diameter of the probe head. 
     The tethered laparoscopic probe may further comprise a collar grip fitted to the tether. The collar grip may be grippable by jaws of a surgical instrument. The surgical instrument may comprise a needle driver. Once again, the collar grip enables the user to hold the tethered laparoscopic probe in place within the cavity while releasing the grip of the fenestrated laparoscopic graspers to adjust the angle of engagement from the first angle to the second angle (or vice versa). The collar grip further allows manipulation of the tether itself without running the risk of requiring the user to directly contact the tether with the surgical instrument, which may result in damage to the tether. 
     The sensor may comprise a gamma radiation detector configured to detect gamma radiation through an aperture of the casing. The gamma radiation detector may comprise a scintillator configured to scintillate, in use, in response to received gamma radiation. A scintillator is a material that exhibits scintillation (luminescence) in response to ionizing radiation; when struck by a charged particle, the scintillator absorbs the energy of the charged particle and re-emits energy in the form of light. The gamma radiation detector may further comprise a photodetector to detect the scintillated light from the scintillator. The photodetector may comprise a silicon photomultiplier (“SiPM”). The photodetector may comprise an avalanche photodiode (“APD”). The scintillator may comprise Thallium activated Cesium Iodide, CsI:TI. The scintillator may be silvered on one or more surfaces, for example on a circumferential face of the scintillator or a face of the scintillator closest to the detection end of the laparoscopic probe, to reflect scintillated light towards the photodetector. This advantageously results in better signal collection and is also useful for achieving a good energy resolution. 
     The aperture may be a hole or gap in the casing, or may comprise a window. The window may comprise plastic or polyethylene terephthalate (PET). 
     By providing a gamma radiation detector, the laparoscopic probe may be used for radioguided laparoscopic procedures. A subject may receive a radiopharmaceutical in advance of surgery, the radiopharmaceutical designed to locate abnormal tissue such as tumors in the subject and to emit radiation detectable by the probe. A radiopharmaceutical is a drug that can be used for diagnostic or therapeutic purposes and comprises a radioisotope bonded to a molecule. The radiopharmaceutical conveys the isotope to specific organs, tissues or cells, and is selected for its properties and purpose. Many radiopharmaceuticals are known in the art and are used for radioguided surgery and other procedures. The tethered laparoscopic probe may therefore be inserted through a trocar into a cavity of the subject in an attempt to locate the source of the radiation and thereby locate any abnormal tissue. 
     The probe head may further comprise radiation shielding, either as part of or within the casing for inhibiting gamma radiation from passing through the probe head. The radiation shielding may comprise tungsten. The radiation shielding may have a thickness, and the scintillator may have a radius, and the thickness of the radiation shielding and the radius of the scintillator may be selected such that, in use, the ratio of the gamma radiation permeating through the radiation shielding that is detected by the gamma detection means to the gamma radiation incident on the radiation shielding is less than or equal to 1:1000, and such that, in use, the sensitivity of the gamma detection means to gamma radiation incident through the detection aperture is maximized. By providing such radiation shielding and scintillator, the ability of the probe to locate the source of radiation is greatly improved as such a ratio is suitable to assure a user that any detected radiation came from a known direction (e.g. the sensing direction) as opposed to passing through any other part of the probe head. Accordingly, such radiation shielding enables better directional resolution of the device. The aperture may comprise a designed gap or hole in the radiation shielding. 
     The gamma radiation detector may comprise a semiconductor gamma radiation detector. The semiconductor radiation detector may comprise Cadmium Zinc Telluride, CZT. 
     The sensor may comprise a beta radiation detector configured to detect beta radiation through an aperture of the casing. The beta radiation detector may comprise a scintillator configured to scintillate, in use, in response to received beta radiation. The beta radiation detector may further comprise a photodetector to detect the scintillated light from the scintillator. The scintillator configured to scintillate in response to received beta radiation may comprise cesium iodide, CsI. The scintillator configured to scintillate in response to received beta radiation may comprise fluorophore doped vinyltoluene. 
     Advantageously, by providing such a beta radiation detector in the tethered laparoscopic probe, the laparoscopic probe is enabled to pick up further signatures of a radioisotope. Furthermore, charged particles from radiopharmaceuticals do not travel far through tissue and so, using a beta radiation detector, one may determine that the radiation source is close (and therefore a tumor is close) when charged particles are detected. Some beta decaying radioisotopes, including Fluorine-18 (18F), Carbon-11 (11C), Nitrogen-13 (13N), Copper-64 (64Cu), Iodine-124 (1241) and Gallium-68 (68Ga), emit positrons during radioactive decay and are known to be used in positron emission tomography imaging. Some beta decaying radioisotopes, including tritium (3H), Carbon-14 (14C), and Silicon-35 (35S), emit electrons during radioactive decay. Some radiopharmaceuticals are primarily gamma radiation emitters but may also emit charged particles. For example, Technetium-99m (99mTc) is a gamma radiation emitter, but through a process of internal conversion emits K, L or M shell electrons for approximately 10% of decays. 
     The sensor may comprise an ultrasound sensor. Advantageously, this would enable the tethered laparoscopic probe to be used to take ultrasound readings. 
     The probe head may further comprise a second sensor arranged within the casing, the second sensor for sensing through an aperture of the casing. By providing multiple sensors, the probe may be used to detect multiple signals. 
     The second sensor may be different to the first sensor. For example, the probe may comprise a gamma radiation detector and a beta radiation detector. 
     The second sensor may be of the same type as the first sensor. For example, the tethered laparoscopic probe may comprise two gamma radiation detectors. Advantageously, by providing two such gamma radiation detectors, the laparoscopic probe is capable of “active collimation”. The signals from both detectors may be used to extract directional information on detected gamma radiation, and accordingly the signal to noise ratio of the laparoscopic probe is greatly increased. 
     The laparoscopic probe may be arranged to communicate a composite signal, the composite signal representative of detections of both sensors. The laparoscopic probe may be switchable between a first mode, in which the probe head configured to communicate a first signal representative of a detection using the first sensor, and a second mode, in which the probe head is configured to communicate a second signal representative of a detection using the second sensor. 
     The grip may be structurally integral/intrinsic to the casing. That is, the grip may be a feature of the casing. The grip may alternatively be a modular addition to the casing. 
     According to an aspect of the present disclosure, a tethered laparoscopic probe for deployment through a trocar into a cavity of a subject is provided. The tethered laparoscopic probe comprises a probe head shaped for insertion through the trocar. The probe head comprises an elongated casing. The probe head further comprises a sensor arranged within the casing, the sensor defining a sensing direction of the probe head. The tethered laparoscopic probe further comprises a tether coupled to the probe head and for, in use, tethering the probe head through the trocar. The tethered laparoscopic probe further comprises a collar grip fitted to the tether, the collar grip grippable by jaws of a surgical instrument. 
     Advantageously, such a tethered laparoscopic probe is highly versatile and manipulatable. 
     According to an aspect of the present disclosure, a kit is provided. The kit comprises a tethered laparoscopic probe as described herein. The kit further comprises fenestrated laparoscopic graspers comprising opposing fenestrated jaws, the fenestrated jaws shaped to mate with protrusions of the grip of the tethered laparoscopic probe to securely grasp the tethered laparoscopic probe. 
     The fenestrated laparoscopic graspers may be any suitable graspers for grasping the probe. The fenestrated laparoscopic graspers may be robotically controllable. The fenestrated laparoscopic graspers may be manually controllable. For example, the fenestrated laparoscopic graspers may comprise Johan graspers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described by way of example only, with reference to the accompanying figures, in which: 
         FIG. 1  illustrates a first example of a tethered laparoscopic probe from a first perspective; 
         FIG. 2  shows the tethered laparoscopic probe of  FIG. 1  from a second perspective; 
         FIG. 3  shows the probe head of the tethered laparoscopic probe of  FIG. 1  being held with fenestrated laparoscopic graspers at a first angle; 
         FIG. 4  shows the probe head of the tethered laparoscopic probe of  FIG. 1  being held with fenestrated laparoscopic graspers at a second angle; 
         FIG. 5  shows the probe head of the tethered laparoscopic probe of  FIG. 1  being held with fenestrated laparoscopic graspers at the first angle; 
         FIG. 6  illustrates a second example of a tethered laparoscopic probe from a first perspective; 
         FIGS. 7A, 7B and 7C  illustrate a collar grip for use with any tethered laparoscopic probe; 
         FIGS. 8A, 8B and 8C  illustrate a grip of the tethered laparoscopic probe of  FIG. 6 ; 
         FIG. 9  shows the probe head of the tethered laparoscopic probe of  FIG. 6  being held with fenestrated laparoscopic graspers at a first angle; and 
         FIG. 10  shows the probe head of the tethered laparoscopic probe of  FIG. 6  being held with fenestrated laparoscopic graspers at a second angle. 
     
    
    
     Throughout the description and the drawings, like reference numerals (sometimes with an apostrophe or prime symbol) refer to like parts. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a tethered laparoscopic probe  100  from a first perspective.  FIG. 2  shows the tethered laparoscopic probe  100  of  FIG. 1  from a second perspective. 
     The tethered laparoscopic probe  100  comprises a probe head  160  and a tether  110 .  FIGS. 3 and 5  show the probe head  160  held at a first angle relative to a sensing direction of the probe head  160 .  FIG. 4  shows the probe head  160  held at a second angle relative to the sensing direction of the probe head  160 . The tether  110  is not shown in  FIG. 3, 4 or 5  for clarity of illustration only. 
     The probe head  160  comprises an elongated casing  180  comprising a biocompatible material. The probe head  160  further comprises a sensor (not shown) arranged within the casing  180 . The sensor may comprise any suitable type of sensor. In the embodiment shown in  FIGS. 1 to 5 , the sensor is a gamma radiation detector or a beta radiation detector, although the skilled person would appreciate that any other type of sensor that can fit within the probe head  180  may be used. 
     In the embodiment shown in  FIG. 1 , an aperture  150  is positioned at a distal end of the casing  180  (that is, at an end of the probe head  160  located away from the tether  110 ). The sensor, a gamma radiation detector or a beta radiation detector, is arranged to sense through the aperture  150  of the probe head  160 . For example, if the sensor comprises a gamma radiation detector then the sensor may detect gamma radiation that passes through the aperture  150  of the casing  180 . If the sensor comprises a beta radiation detector then the sensor may detect beta radiation that passes through the aperture  150  of the casing  180 . 
     The casing  180  may comprise radiation shielding to inhibit gamma (or beta) radiation from passing through the casing  180 , so that a user of the tethered laparoscopic probe  100  can determine that radiation sensed by the sensor was detected through the aperture  150  of the casing  180 . The radiation shielding may comprise tungsten or tantalum. 
     The skilled person would appreciate that in other embodiments, the sensor may be configured to sense through a side of the elongated casing  180 . The aperture  150  may or may not be present. If present, the aperture  150  may be positioned in the side of the casing  180 . 
     The aperture  150  may comprise a hole, an opening or a vacant space in the casing  180 —that is, an area of space not covered by the opaque casing  180 . The aperture  150  may comprise a window in the casing  180 . The window may be permeable/transparent/transmissive to the radiation of interest, be it gamma radiation or beta radiation, and so may permit gamma (or beta) radiation to pass into the probe head  160  to be detected by the sensor. The thickness of the window may be selected to be suitable for the radiation being measured, for example the window may be very thin when the radiation of interest is beta radiation. The window may be formed from any suitable material, for example a plastic or polyethylene terephthalate (PET). 
     The sensor defines a sensing direction of the probe head  160 . The skilled person would appreciate that the term sensing direction here is to be interpreted broadly. For exemplary purposes only, the sensing direction of the probe head  160  of  FIGS. 1-5  is considered to be the transversal direction of the elongated casing  180 , passing through the aperture  150 . 
     The tether/connecting portion may comprise a biocompatible casing and one or more optical fibers for communicating to a computing device (not shown). 
     The outer casing  180  is biocompatible. The outer casing  180  may comprise one or more of tungsten (with a biocompatible coating applied), stainless steel, tantalum and plastic. 
     The probe head  160  further comprises a grip  170 . The grip is designed to be grasped securely by fenestrated laparoscopic graspers  200  (see also  FIGS. 3, 4 and 5  which illustrate the grip  170  of the probe head  160  being grasped by the fenestrated laparoscopic graspers  200 ). 
     The grip  170  comprises protrusions  140  that are positioned and shaped to enable the grip  170  to be graspable securely by the fenestrated laparoscopic graspers  200  at a first angle relative to the sensing direction of the probe head  160 . The protrusions  140  are also positioned and shaped to enable the grip  170  to be graspable securely at a second angle relative to the sensing direction of the probe head  160 . 
     In particular, in the tethered laparoscopic probe  100  of  FIGS. 1-5 , the protrusions  140  comprise a pair of protrusions positioned such that the first protrusion  140   a  of the pair of protrusions is graspable by a first jaw  220  of the fenestrated laparoscopic graspers  200  while a second protrusion  140   b  of the pair of protrusions is graspable by a second jaw  220  of the fenestrated laparoscopic graspers  200 . The protrusions  140  are provided by a T-shaped abutment on the grip  170 . 
       FIG. 3  and  FIG. 5  show the probe head  160  of the tethered laparoscopic probe  100  being held at a first angle relative to the sensing direction of the probe head  160 . As explained above, for demonstrative purposes the sensing direction is considered to be the transversal direction of the elongated casing  180 , passing through the aperture  150 . The first angle is accordingly substantially 0 degrees. That is,  FIGS. 3 and 5  show the probe head  160  of the tethered laparoscopic probe  100  being held at an angle of substantially 0 degrees to the sensing direction of the probe head  160 . 
     The fenestrated laparoscopic graspers  200  comprise two opposable fenestrated jaws  220 . Each jaw  220  comprises an oblong slot  210 . The first protrusion  140   a  of the pair of protrusions is shaped and positioned such that, when the tethered laparoscopic probe  100  is grasped at the first angle relative to the sensing direction with the fenestrated laparoscopic graspers  200 , the first protrusion  140   a  engages with a slot  210  and fits snugly within the slot  210  of the first jaw  220  of the fenestrated laparoscopic graspers  200 . Similarly, the second protrusion  140   b  of the pair of protrusions is shaped and positioned such that, when the tethered laparoscopic probe  100  is grasped at the first angle relative to the sensing direction with the fenestrated laparoscopic graspers  200 , the second protrusion  140   b  engages with a slot  210  and fits snugly within the slot  210  of the second jaw  220  of the fenestrated laparoscopic graspers. 
     Both protrusions  140   a  and  140   b  in the example shown in  FIGS. 1 to 5  are square-shaped (when viewed from a side angle) with rounded corners, such that when gripped by the fenestrated laparoscopic graspers  200  as shown in  FIGS. 3 and 5 , parallel edges of the square-shaped protrusions  140   a  and  140   b  align with internal faces of the slots  210  of the fenestrated jaws  220 . Accordingly, the protrusions  140   a  and  140   b  are shaped such that they can be grasped securely by the fenestrated laparoscopic graspers  200 , in that, when engaged (jaws  220  are closed), the graspers  200  are substantially restricted from rotating about the protrusions to a different angle relative to the sensing direction. 
     Advantageously, when the grip  170  is grasped by the fenestrated laparoscopic graspers  200  at the first angle relative to the sensing direction of the probe head  160 , the pair of protrusions  140   a  and  140   b  restrict angular motion of the fenestrated laparoscopic graspers  200  about the protrusions  140   a  and  140   b  and thereby provide greater control to the user of the fenestrated laparoscopic graspers  200  of what direction the tethered laparoscopic probe  100  is directed towards. 
     The pair of protrusions  140   a  and  140   b  are also shaped to be held at an angle of substantially 90 degrees to the sensing direction of the probe head  160  using the fenestrated laparoscopic graspers  200 . As shown in  FIG. 4 , parallel edges of the substantially square-shaped protrusions  140   a  and  140   b  align with internal faces of the slots  210  of the fenestrated jaws  220 . Accordingly, the protrusions  140   a  and  140   b  are shaped such that they can be grasped securely by the fenestrated laparoscopic graspers  200 , in that, when engaged, the graspers  200  are substantially restricted from rotating about the protrusions to a different angle relative to the sensing direction. 
     The shape and position of the protrusions  140   a  and  140   b  enable the tethered laparoscopic probe  100  to be grasped at a first angle relative to the sensing direction of the probe head  100  and enable the tethered laparoscopic probe  100  to be grasped at a second angle relative to the sensing direction of the probe head  100 . However, to transition from the first angle ( FIGS. 3 and 5 ) to the second angle ( FIG. 4 ), a user of the fenestrated laparoscopic graspers  200  would be required to relax the pressure applied by the fenestrated jaws in order to disengage the jaws  220  from the protrusions  140   a  and  140   b,  and then to re-engage with the protrusions  140   a  and  140   b  at the second angle. 
     In order to assist in transitioning from the first angle relative to the sensing direction to the second angle relative to the sensing direction, the probe head is also fitted with a rib  120  suitable for grasping by a surgical instrument, and in particular, by a needle driver, to support the tethered laparoscopic probe  100  while adjusting the angle of attack of the fenestrated laparoscopic graspers  200 . In this way, a surgeon or other medical professional using fenestrated laparoscopic graspers  200  to grasp a tethered laparoscopic probe  100  at a first angle relative to the sensing direction is able to adjust their grip by holding the tethered laparoscopic probe  100  by the rib  120  using a needle driver (for example), releasing the pressure on the fenestrated laparoscopic graspers  200  to disengage the slots  210  from the protrusions  140   a  and  140   b  and re-engaging with the protrusions at a second angle. 
     The rib  120  separates two recesses  130   a  and  130   b,  which help to define the rib. The skilled person would appreciate that the recesses  130   a,    130   b  need not be present. A rib may protrude/jut out from the probe head  160 , but it is desirable for the probe head  160  to have a form factor suitable for passing through a trocar into the cavity. 
       FIG. 6  shows a tethered laparoscopic probe  100 ′ according to another example from a first perspective. The tethered laparoscopic probe  100 ′ comprises a probe head  160 ′ and tether  110 ′, which are similar to those described in relation to  FIGS. 1 to 5 . The probe head  160 ′ once again comprises an elongated casing  180 ′ and a sensor arranged within the casing  160 ′. The probe head  160 ′ further comprises a grip  170 ′, although the grip  170 ′ is different to the grip  170  of the example shown in  FIGS. 1 to 5 . 
     The grip  170 ′ comprises a first pair of protrusions  650  and a second pair of protrusions  660 . A first protrusion  650   a  of the first pair of protrusions  650  is positioned and shaped to be graspable by a first jaw  220  of the fenestrated laparoscopic graspers  200  at a first angle relative to a sensing direction of the tethered laparoscopic probe  100 ′. A second protrusion  650   b  of the first pair of protrusions  650  is positioned and shaped to be graspable by a second jaw  220  of the fenestrated laparoscopic graspers  200  at the first angle relative to the sensing direction of the tethered laparoscopic probe  100 ′. A first protrusion  660   a  of the second pair of protrusions  660  is positioned and shaped to be graspable by the first jaw  220  of the fenestrated laparoscopic graspers  200  at a second angle relative to a sensing direction of the tethered laparoscopic probe  100 ′. A second protrusion  660   b  of the second pair of protrusions  660  is positioned and shaped to be graspable by the second jaw  220  o the fenestrated laparoscopic graspers  200  at the second angle relative to the sensing direction of the tethered laparoscopic probe  100 ′. 
       FIG. 8A  shows a close-up illustration of the grip  170 ′ fitted to the casing  160 ′.  FIG. 8B  shows a close-up illustration of the grip  170 ′ with the casing  160 ′ and the tether removed.  FIG. 8C  shows the grip  170 ′ from the proximal end of the probe head’ (i.e. the distal end of the probe head  160 ′, at which the aperture  150 ′ is located, is seen as extending into the page). As can be seen from these figures, the protrusions  650 ,  660  are shaped to engage with and fit snugly into the oblong slots of the fenestrated laparoscopic graspers  200 . The protrusions  650  and  660  are, in the example of  FIGS. 5, 6, 8A, 8B, 8C, 9 and 10  shaped to have two substantially straight and parallel edges and a curved edge to fit an oblong slot  210  of a jaw  220  of the fenestrated laparoscopic graspers  200 . In order to grasp the tethered laparoscopic probe  100 ′ at the first angle relative to the sensing direction of the probe head  160 ′, the fenestrated laparoscopic graspers may be positioned such that, when pressure is applied to close the fenestrated jaws  220 , the protrusions  650   a  and  650   b  of the grip  170 ′ interlock with the oblong slots  210  of the respective first and second fenestrated jaws  220 . When the jaws  220  are engaged—i.e. closed around the first pair of protrusions  650 , the straight edges of the protrusions  650  help to resist any rotational movement of the fenestrated laparoscopic graspers  200  away from the first angle of engagement. If it is desired to grasp the tethered laparoscopic probe  100 ′ at the second angle relative to the sensing direction of the probe head  160 ′, then the pressure of the jaws  220  can be released and the jaws  220  can be repositioned so as to interlock with the second pair of protrusions  660  when pressure is reapplied as shown in  FIG. 10 . Once again, so long as pressure is applied with the laparoscopic graspers, the shape of the protrusions  660  resists any rotational movement of the fenestrated laparoscopic graspers  200  away from the angle of engagement. 
     As would be appreciated by the skilled person, the protrusions  650   a,    650   b,    660   a,    660   b  may be the same or different shaped so long as they engage with the oblong slots  210  of the fenestrated laparoscopic graspers  200  correctly, that is, so long as they are suitable shaped to secure the angle of the fenestrated laparoscopic graspers relative to the sensing direction of the probe head  160 ′. For example, the protrusions may be substantially square shaped as in the example of  FIG. 1 , or may be rectangular shaped. 
       FIG. 9  illustrates the tethered laparoscopic probe  100 ′ being grasped securely by the fenestrated laparoscopic graspers  200  at the first angle relative to the direction of the probe head  160 ′ (once again, for clarity of illustration, the tether  110 ′ is not shown in  FIG. 9 ). The first angle is substantially 105 degrees. 
       FIG. 10  illustrates the tethered laparoscopic probe  100 ′ being grasped securely by the fenestrated laparoscopic graspers  200  at the second angle relative to the sensing direction. The second angle is substantially 60 degrees. 
     As illustrated in  FIGS. 6, 7A, 7B and 7C , the tethered laparoscopic probe  100 ′ is also fitted with a collar grip  610 . The collar grip  610  is fitted to the tether  110 ′ of the tethered laparoscopic probe  100 ′. The collar grip  610  comprises a substantially annular through-hole through which the tether  110 ′ extends. The collar grip  610  thereby surrounds a portion of the tether  110 ′. 
       FIG. 7A  shows a side view of the collar grip  610 .  FIG. 7B  shows the collar grip  610  along a transverse direction (i.e. with a view centered on the annular through-hole through which the tether  110 ′ (not shown in  FIGS. 7A and 7B ) extends.  FIG. 7C  shows the collar grip  610  fitted to the tether  110 ′. 
     As can be seen in  FIGS. 6, 7A, 7B and 7C , the collar grip  610  comprises a plurality of fins for gripping with a surgical instrument such as a needle driver. A first plurality of fins  620   a ,  620   b,    620   c  and  620   d  extend in a radial/axial direction and in a circumferential direction from the collar grip  610 . A second plurality of fins  630   a,    630   b,    630   c  and  630   d  extend in a radial/axial direction and in a transversal direction along the length of the collar grip  610 . 
     The collar grip  610  is configured to be used as a secondary grip for the tethered laparoscopic probe  100 ′ that enables improved maneuverability without requiring a user to touch the tether  110 ′ of the probe  100 ′ with a surgical tool, such as a needle driver. Accordingly, the collar grip  610  lessens the risk of damaging the tether  110 ′ while enabling for improved manipulation of the probe  100 ′. 
     The architecture of the collar grip  610  may vary. For example, the first plurality of fins may be absent. The first plurality of fins  620  may or may not extend the entire way around the collar grip. A different shaped fin entirely may be used. Similarly, the second plurality of fins  630  may be present or absent and may or may not extend along the entire collar grip  610 . Instead of fins, some other grippable feature may be provided on the collar grip  610 , for example a rib or bar or other protrusion that can be gripped using jaws of a surgical tool such as a needle driver. The fins enable the collar grip  610  to be gripped by a surgical tool but the exact shape of the fins is not important. The collar grip must when fitted to the tether be of a suitable diameter to pass through a trocar. 
     Variations of the described embodiments are envisaged, for example, the features of all the described embodiments may be combined in any way. 
     For example, the collar grip  610  described in relation to the example of the tethered laparoscopic probe  100 ′ in  FIGS. 6, 7A, 7B, and 7C  may be fitted to any suitable tether, such as tether  110  of the example tethered laparoscopic probe  100  described in relation to  FIG. 1 . Similarly, the rib  120  and/or the recesses  130   a  and  130   b  may be used in conjunction with the example described in relation to  FIG. 6 . 
     A tether as described herein may be any suitable connection that may, in use, be used to couple a laparoscopic probe head within the cavity, through the trocar, to the outside world and may be used to, for example, withdraw the probe head from the cavity and ensure that the probe head is not misplaced within the cavity. The tether may take any suitable form, for example the tether may comprise a ribbon or cable. The tether may comprise at least a biocompatible outer layer. The biocompatible outer layer may encompass at least a communication means such as an optical fiber for communicating a signal from the sensor through the trocar to a processor/computing device. 
     The sensor may be any suitable sensor used for laparoscopic procedures. The sensor may comprise one of a gamma radiation detector, a beta radiation detector, an ultrasound detector. When an ultrasound sensor is used, the windowed aperture may comprise a quarter wavelength index matching layer. The sensor may comprise an optical sensor, for example an optical sensor adapted to detect one or more of visible light, infra-red light, or ultra-violet light. When an optical sensor is used, the laparoscopic probe may further comprise one or more focusing elements, for example a lens or a mirror. The optical sensor may be used for imaging. 
     The laparoscopic probe  100 ,  100 ′ may comprise further components. For example, the probe  100 ,  100 ′ may comprise one or more collimators. The laparoscopic probe may further comprise a biocompatible stand-off for ensuring that the sensor is separated from the subject by a predetermined distance. 
     It is envisaged that the term “subject” as used herein may be any suitable subject. For example, the subject may be a human or may be an animal. A cavity of the subject may comprise, for example, an abdominal cavity of the subject. 
     Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. 
     Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings).