Patent Publication Number: US-2021169586-A1

Title: System and method for guided placement of medical instrument

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 62/945,100, filed Dec. 6, 2019, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present disclosure relates to a medical instrument placement, and more particularly to a system and method for a trajectory guidance placement of the medical instrument. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Medical procedures involving precision insertion and placement of a therapy device into a patient through a body portal are used to treat a variety of medical condition. For example, External Ventricular Drains (EVDs) are frequently placed by hand, which leads to a significant rate of complications such as a surface vein violation because missing the ventricles can lead to improper drain function or necessitate reinsertion, reinserting catheter or other medical instrument multiple times can needlessly damage healthy brain tissue, and inserting of catheter or other medical instruments may violate surface veins, which can lead to intracranial bleeding and/or other complications. 
     To accurately place the medical instrument, surgeons typically use conventional surgical navigation systems and methods such as frame or frameless stereotactic apparatus procedures. The stereotactic apparatus of varying configurations are well known device. For example, a “center-of-arc” stereotactic apparatus includes an arc-shaped frame and a pivot about which the frame is movable, and aligns with the target location. As a result, multiple device trajectory and entry points are available to reach the target location. Other stereotactic systems may utilize what is referred to as “frameless” or “microframe” technology. These systems typically utilize a pre-aligned, stereotactic platform custom-made for a particular patient&#39;s cranial physiology. Such systems may allow pre-operative alignment and configuration (potentially reducing the patient&#39;s time in the operating room) and may further result in less discomfort to the patient. 
     However, we have discovered that while providing accurate device placement with the microframe systems, the custom-made platform presents a recurring fee for each patient as compared to re-useable platform. Moreover, it may take days to receive the custom platform after an order is placed, reducing opportunity to offer same-day planning and surgery. Still further, such custom-made systems may have little or no ability to accommodate subsequent targeting adjustments when needed (for example, when a large blood vessel is later found within the planned insert trajectory). Accordingly, the conventional stereotactic procedures are time-consuming and require costly capital equipment. 
     SUMMARY 
     The present disclosure relates to a system and method for a guided placement of a medical instrument in a patient using a computed tomography (CT) scanner providing scanned images of the patient including a target site for the medical instrument. The guided placement system of the present disclosure improves accuracy over the hand placement of the medical instrument, and have benefits for ease of use, simplified procedure, and reduced operating time. In addition, the guidance placement system may have a disposable instrument placement kit option for using a single time to guide the placement of the medical instrument. 
     According to an aspect of the present disclosure, the guidance placement system includes an instrument placement kit (device) having an alignment frame configured to be attached to a body of the patient and one or more guidance devices each configured for selective engagement with the alignment frame. The alignment frame has one or more identifiers to define a reference plane that can be determined from scanned images from the CT scanner. Each guidance device has a set of pre-defined parameters and also the multiple guidance devices each has different sets of the pre-defined parameters for guiding the placement of the medical instrument. The guidance placement system further includes a user interface unit operable to determine the pre-defined parameters of the multiple guidance devices from the scanned images including the reference plane of the alignment frame. In addition, the user interface unit is operable to compute a planned trajectory of the medical instrument based on the target site and the reference plane of the alignment frame, the user interface unit is further operable to determine prescribed parameters among the different sets of pre-defined parameters and select a guidance device from the multiple guidance devices, and the user interface unit is operable to indicate the selected guidance and prescribed parameters such that the selected guidance device can be selectively mounted to the alignment frame according to the prescribed parameters to guide the medical instrument along the planned trajectory. 
     According to a further aspect of the present disclosure, the alignment frame is formed as a ring shape with markings around a perimeter of the alignment frame for indicating a rotational position of the selected guidance device when the guidance device is engaged with the alignment frame. 
     According to a further aspect of the present disclosure, each of the guidance devices is formed as a circular shape having an upper flange and a bottom disc extending from a plane of the upper flange such that each of the guidance devices is formed with the upper flange and the bottom disc, which are parallel and connected with a circular side wall. The upper flange of the guidance device has a marker to align with one of markings formed around a perimeter of the alignment frame to indicate an insertion direction of the medical instrument as one of the pre-defined parameters. The bottom disc of the guidance device is formed with multiple holes arranged as a honeycomb pattern for indicating an insertion location of the medical instrument as one of the pre-defined parameters, and all of the holes formed through the bottom disc of the guidance device are parallel to each other and are at a same angle, which is inclined relative to a top surface of the bottom disc for indicating an insertion angle of the medical instrument as one of the pre-defined parameters. 
     According to a further aspect of the present disclosure, the instrument kit further includes oen or more sleeves each having different pre-defined lengths for guiding the placement of the medical instrument such that the user interface unit is operable to determine a prescribed length among the different pre-defined lengths based on the planned trajectory. The user interface unit is further operable to select a sleeve from the multiple sleeves based on the prescribed length such that the selected sleeve can be selectively engaged with the selected guidance device mounted to the alignment frame. In addition, the selected sleeve is inserted into one of multiple holes formed through a bottom disc of the selected guidance device determined as an entry location of the medical instrument, and each of the sleeves has a chamfered end for engaging with an entry hole drilled on the body of the patient for stability when the medical instrument is placed in the body of the patient along the planned trajectory. 
     According to another aspect of the present disclosure, each of the guidance devices is formed as a circular shape having an outer ring and a middle rail formed along a center line of the outer ring such that each of the guidance devices is formed with the outer ring and the middle rail in a single plane. The outer ring of the guidance device is formed with a marker to align with one of markings formed around a perimeter of the alignment frame and the middle rail of the guidance device is formed with multiple holes arranged in a line such that the marker and holes of the guidance device mounted to the alignment frame indicate an insertion location of the medical instrument as one of the pre-defined parameters. 
     According to a further aspect of the present disclosure, the instrument placement kit further includes multiple guide carriages each having different sets of pre-defined parameters such as an insertion angle and an insertion direction of the medical instrument for guiding the placement of the medical instrument such that the user interface unit is operable to select one among the multiple guide carriages determined from the prescribed parameters based on the planned trajectory. 
     According to another aspect of the present disclosure, a method for a guided placement of a medical instrument in a patient includes the steps of providing an instrument placement kit, placing an alignment frame onto a body of the patient adjacent a determined entry point, acquiring images including the alignment frame scanned by a computed tomography (CT) scanner, determining a planned trajectory relative to an anatomy of the patient and the alignment frame, determining prescribed parameters from a set of pre-defined parameters and indicating to an operator the prescribed parameters, mounting one of multiple guidance devices selectively to the alignment frame according to the prescribed parameters, and positioning the medical instrument along the guidance devices mounted to the alignment frame such that the medical instrument is placed along the planned trajectory. 
     According to a further aspect of the present disclosure, the step of determining the planned trajectory includes the step of indicating a target site in the acquired scanned images having the anatomy of the patient and a reference plane identified as the alignment frame. 
     According to a further aspect of the present disclosure, the step of mounting one of the multiple guidance devices selectively to the alignment frame includes the steps of selecting one of the guidance devices each having one inclined angle of multiple holes formed in each of the guidance devices according to a prescribed hole angle, and rotatably positioning the selected guidance device in the alignment frame according to a prescribed ring angle. 
     According to a further aspect of the present disclosure, the step of positioning the medical instrument along the guidance devices mounted to the alignment frame includes the steps of selecting one of multiple holes formed in each of the guidance devices as an insertion location of the medical instrument according to a prescribed hole number, and making an entry hole on the body of the patient at the insertion location of the medical instrument through the selected hole of the selected guidance device engaged with the alignment frame. 
     According to a further aspect of the present disclosure, the method further includes the step of providing multiple sleeves each having different pre-defined lengths for guiding an insertion length of the medical instrument through the entry hole on the body of the patient. The step of providing the multiple sleeves includes the steps of selecting one sleeve among the multiple sleeves having the different pre-defined lengths according to a prescribed length determined from the planned trajectory, inserting the selected sleeve into the selected hole of the selected guidance device, and engaging a chamfered end formed in each of the sleeves with the entry hole on the body of the patient. 
     Further details and benefits will become apparent from the following detailed description of the appended drawings. The drawings are provided herewith purely for illustrative purposes and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a diagram of a guidance placement system in accordance with an exemplary form of the present disclosure; 
         FIG. 2  is a detailed perspective view of an instrument placement kit placed onto a body of a patient according to the guidance placement system of  FIG. 1 ,  FIG. 2A  is a detailed perspective view of the assembly of the instrument placement kit of  FIG. 2 , and  FIG. 2B  is a side view of the assembly of the instrument placement kit of  FIG. 2 ; 
         FIG. 3A  is a top view of an alignment frame in the instrument placement kit of  FIG. 2 ,  FIG. 3B  is a side view of the alignment frame in the instrument placement kit of  FIG. 2 , and  FIG. 3C  is a top view of the alignment frame having a locking feature in the instrument placement kit of  FIG. 2 ; 
         FIGS. 4(A), 4(B) , and  4 (C) are top views of multiple guidance devices in the instrument placement kit of  FIG. 2 ; 
         FIG. 5  is a side view of one of the multiple guidance devices in the instrument placement kit of  FIG. 2 ; 
         FIGS. 6(A), 6(B) , and  6 (C) are isometric views of multiple sleeves in the instrument placement kit of  FIG. 2 ; 
         FIG. 7  is a detailed top view of an assembly of an instrument placement kit in accordance with another exemplary form of the present disclosure, and  FIGS. 7(A), 7(B) , and  7 (C) are side views of multiple guide carriages in the instrument placement kit of  FIG. 7 ; 
         FIG. 8  shows a display screen showing scanned images and prescribed parameters as an output in a user interface unit of the guidance placement system of  FIG. 1 ; and 
         FIG. 9  shows a flow diagram of a method for a guidance placement of a medical instrument in accordance with an exemplary form of the present disclosure. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     The present disclosure is directed toward a system and method for the guided placement of the medical instrument. In particular, the present disclosure relates to the system and method for image-guided placement of a surgical or cranial instrument in a body of the patient. The system and method of the present disclosure could also be used for a biopsy needle or other intracranial procedure, and the system can be used with various patients and in various regions of a patient&#39;s body, The system and method can use of an instrument placement kit  100  to guide the placement of the medical instrument. The instrument placement kit  100  including a computed tomography (CT) scanner  12  and a user interface unit  20  such as a computer system having a processor and a memory can be used in an operating room as illustrated in  FIG. 1 . 
     With reference to  FIG. 1 , the guidance placement system  10  that can be used for various procedures is illustrated. The guidance placement system  10  can be used to guide the placement of the External Ventricular Drain (EVD) catheter relative to a patient  16  to assist in the implementation or performance of a surgical procedure. It should be noted that the guidance placement system  10  may be used to guide other devices including: catheters, probes, needles, leads, implants, etc. According to various embodiments, examples include ablation catheters, deep brain simulation (DBS) or macro-electrodes or leads, micro-electrodes (ME) or leads for recording, etc. Moreover, the guided medical device may be used in any region of the body. The guidance placement system  10  and the various medical devices may be used in any appropriate procedure, such as one that is generally minimally invasive, arthroscopic, percutaneous, or an open procedure. Although an exemplary guidance placement system  10  including an imaging device  12  are discussed herein, one skilled in the art will understand that the disclosure is merely for clarity of the present discussion and any appropriate imaging system, guidance system, patient specific data, and non-patient specific data can be used. For example, the interoperative imaging system can include a computed tomography (CT) scanner such as a XCAT™IQ sold by Xoran Technologies, LLC., and also disclosed in U.S. Patent Publication No. U.S. Pat. No. 9,055,874 B2, filed on Jan. 28, 2008, etitled “Motion tracker to detect and correct for movement of a patient in a CT scanner”, incorporated herein by reference. In addition, another image system disclosed in U.S. Patent Publication No. U.S. Pat. No. 8,303,181 B2, filed on Aug. 9, 2004, etitled “Intraoperative collapsable CT imaging system”, incorporated herein by reference, can be used. It will be understood that the guidance placement system  10  can incorporate or be used with any appropriate preoperatively or intraoperatively acquired image data. 
     The guidance placement system  10  includes an imaging device  12  that is used to acquire pre-, intra-, or post-operative or real-time image data of the patient  16 . Alternatively, various imageless system can be used. It will be understood, however, that patient image data are generally acquired using the imaging device  12  such as a point-of-care CT scanner discussed above and herein. As illustrated in  FIG. 1 , according to an exemplary form of the present disclosure, a patient  16  is scanned with the CT scanner  12  which include an x-ray source  11  and x-ray detector  13  revolving around a body of the patient  16  such as a head  18 . In addition, the CT scanner  12  further includes a control unit  14  generating and storing a 3D image which is forwarded to the user interface unit  20 . It will also be understood that the image data may be directly transmitted to the user interface unit  20 , and also the control unit  14  of the CT scanner  12  can generate a 2D or 4D image if needed. 
     As illustrated in  FIG. 1 , the user interface unit  20  includes a display  22  showing images scanned and transmitted from the CT scanner  12 , an input device  24  enabling a user to interface with the user interface unit  20 , such as a touchpad, touch pen, touch screen, keyboard, mouse, or a combination thereof, and a control module  26  computing a planned trajectory for the guidance placement system  10 . In addition, a planning tool software is installed in the control module  26  of the user interface unit  20  for processing the scanned images and generating an implementation plan or a surgical plan having prescribed parameters for guiding the placement of the medical instrument  28  such as the EVD catheter, exemplary discussed herein, in the head  18  of the patient  16 . 
     Also, as illustrated in  FIG. 1 , the guidance placement system  10  further includes an instrument placement kit  100  having an alignment frame  102 , multiple guidance devices  104 , and multiple sleeves  106  for guiding the placement of the medical instrument  28  in a body of the patient  16 . In the guidance placement system  10 , the instrument placement kit  100  is utilized for guiding the placement of the medical instrument  28  in the patient  16  according to the implementation plan generated from the control module  14  of the user interface unit  20 . As illustrated in  FIGS. 1 and 2 , for example, the alignment frame  102  is present on the head  18  of the patient  16  during scanning the head  18  of the patient  16  using the CT scanner. The guidance devices  104  and the sleeves  106  are each configured and engaged with the alignment frame  102  (see  FIGS. 2-2B ) based on the prescribed data generated from the control module  26  having the planning software to support achieving the surgical plan. Accordingly, the guidance placement system  10  achieves a planned trajectory using surgical instrument such as an EVD catheter, biopsy needle, or other surgical instrumentation. 
     FIGS,  3 A and  3 B illustrate an exemplary embodiment of the alignment frame  102  formed as a ring shape such as, for example, a mini stereotactic frame. The alignment frame  102  is configured as a ring to be attached to a head  18  of the patient  16  adjacent an entry point of the head  18  for guiding the placement of the medical instrument  28  (see  FIGS. 1 and 2 ). The attached alignment frame  102  serves as a base of the guidance devices  104  and also facilitates co-registered image-guided minimally-invasive intracranial procedures such as ventricular shunt placement or needle biopsy. As shown in  FIG. 3B , the alignment frame  102  is formed with legs  108  to support the annular or ring shaped frame  102  in a stable manner and is securely attached to the body of the patient  16 . As shown in an example of  FIG. 3B , due to three legs  108  forming a tripod design, the alignment frame  102  avoids any rocking or instability associated with other configurations of legs. In addition, an end of each leg  108  is formed with a hole  110  for affixing to the body of the patient  16  via an adhesive, small bone screws, sutures, staples, or wires. In accordance with other forms of the present disclosure, however, the alignment frame may be formed with other design shapes with other attachment features to securely serve as the base, and also more legs or less legs for stability may be formed as needed. 
     As shown in  FIGS. 3A and 3B , the alignment frame  102  has a bore or interior space defining an inner diameter ID, which has enough clearance for engaging with the guidance devices  104 . For example, the inner diameter ID and the outer diameter OD of the alignment frame  102  are each generally between 50 mm˜150 mm. Preferably, the outer diameter OD of the alignment frame  102  is around 120 mm, and the inner diameter ID of the alignment frame  102  is around 110 mm, which may be enough to create skin incision (around 20˜30 mm) and a burr hole (around 15 mm) with tolerance to accommodate 10˜20 mm of potential alternative entry positions if needed. In addition, the alignment frame  102  is sufficiently rigid to retain its shape during at least single use and initial sterilization. For example, the alignment frame  102  may be formed by the 3D print with medical grade Nylon/Polyamide materials using SLS (selective laser sintering) additive manufacturing process. In accordance with other forms of the present disclosure, however, the alignment frame may be formed by other manufacturing processes or methods with other medical grade materials. 
     Furthermore, the alignment frame  102  includes a top surface  112  having markings  114  around the perimeter of the frame  102  to indicate positioning of the guidance devices  104  when one of the guidance devices  104  is engaged with the alignment frame  102 . The frame  102  and device  104  may have corresponding flanges or shoulders sized and configured to allow the device to rest within the interior space of the frame  102 . The alignment frame  102  further includes a locking feature  116  such as a thumbscrew or wingnut bolt for removably attaching one of the guidance devices  104  and/or other instrument guides for making incision, location of burr hole, or other procedural steps. As shown in  FIG. 3C , at least one thumbscrew  116  would come in through the side of the alignment frame  102  and bind on the guidance device  104  such that more thumbscrews  116  may be used for securing the guidance device  104 . The thumbscrew  116  is also made of nylon in order not to interfere with the scanned images taken by the CT scanner and is easily tightened by the user to secure the guidance device  104  when the selected guidance device is in engagement with the alignment frame  102 . Furthermore, the locking feature  116  supports the stable engagement between the alignment frame  102  and the guidance devices  104  during drilling for making an entry hole of a burr hole on the body of the patient  16 . The skilled artisan will recognize that various mechanical or electromechanical locking devices may be used, including slots receiving projections, tabs and detects, frictional engagements, and actuated locks like a deadbolt. 
     In addition, as shown in  FIG. 3A , the alignment frame  102  includes one or more identifiers such as radio-opaque fiducial markers  118  which are highly visible on the CT scanner including a low-dose CT scanner, which can be used to accurately locate the frame structure relative to the patent bony anatomical landmarks including a target site inside the body of the patient  16 . In the scanned images from the CT scanner, the fiducial markers  118  of the alignment frame  102  is used as a reference plane for determining the planned trajectory of the surgical procedure. In  FIG. 3A , for example, ten (10) radio-opaqued fiducial markers  118  with a circular or dot shape are embedded in or printed on the top surface  112  around the perimeter of the alignment frame  102 . The markers  118  may take any shape, but preferably are spheres or discs embedded into the frame  102 . One of the pluralities of fiducial markers  118  has a bigger size than other fiducial markers  118  to indicate the north direction which means 0 degree of the ring angle as a pre-defined parameter. Accordingly, when one of the guidance devices  104  is engaged with the alignment frame  102 , the rotational position of the guidance device  104  is measured from the north direction fiducial marker indicated by one of the fiducial markers  118  having the bigger size of the dot. In addition, when each of the guidance devices  104  is engaged with the alignment frame  102 , the guidance devices  104  are rotated or spined in a discrete manner or a continuous manner. 
     Referring to  FIGS. 4(A), 4(B), 4(C) , and  5 , the instrument placement kit  100  further includes the multiple guidance devices  104  each configured for selective engagement with the alignment frame  102  as shown in  FIG. 2A . Each guidance device  104  has a set of pre-defined parameters such as a given number of holes (each having a hole number) and a hole angle (an inclination of the bore forming the hole relative to the upper surface of the guidance device  104 ). As shown in  FIGS. 4(A)-4(C) , each hole number of the multiple holes  130  indicates an insertion location (a placement location) of the medical instrument  28  as an entry point of the medical instrument  28  and a common hole angle of each guidance device  104  indicates an insertion angle of the medical instrument for guiding its placement. In  FIGS. 4(A)-4(C) , and  5 , each of the guidance devices  104  is formed as a circular shape having an upper flange  122  and a bottom disc  124  extending from a plane of the upper flange  122 , such that the upper flange  122  and the bottom disc  124  are parallel and connected to each other by a circular side wall  126 . The upper flange  122  of the guidance device  104  has a point marker  128 , which is marked on the top surface of the upper flange  122  such that the guidance device  104  enables a user to indicate an insertion direction of the medical instrument  28  (for example, a rotational position of the guidance device). The point marker  128  of the guidance device  104  indicate desired orientation relative to the base alignment frame  102 . Accordingly, as shown in  FIG. 2A , the point marker  128  of the guidance device  104  aligns with one of the markings  114  of the alignment frame  102  according to one (the ring angle) of the prescribed parameters determined from the control module  26  of the user interface unit  20  when one of the guidance devices  104  is engaged with the alignment frame  102 . When the selected guidance device  104  is in engagement with the alignment frame  102 , furthermore, the top surface of the upper flange  122  and the top surface  112  of the alignment frame  102  stay flush such that they are in a co-planar, 
     As shown in  FIGS. 4(A)-4(C) , the guidance devices  104  are each formed with multiple holes  130  arranged as a honeycomb pattern on the bottom disc  124  to indicate an insertion location (a placement location) of the medical instrument  28  according to one (the hole number) of the prescribed parameters. However, in accordance with other forms of the present disclosure, the multiple holes may be formed with other patterns such as an in-line pattern or a rectangular pattern. Each hole  130  of the guidance device  104  is numbered according to the pre-defined pattern, and one hole&#39;s number of the guidance device  104  is displayed as one of the prescribed parameters in the user interface unit  20 . 
     In addition, all of the holes  130  formed through the bottom disc  124  of each guidance device  104  are parallel to each other and are at a same angle, which is inclined relative to the top surface of the bottom disc  124  to indicate an insertion angle (an inclined angle) of the medical instrument  28 . In other embodiments, each hole may be at a different angle, and/or they may be inclined relative to a common point such as the center of the guidance device.) For example, the specific angle of each guidance device  104  is relative to a vertical line Z, which is normal to the surface of the bottom disc  124  (see  FIGS. 4(A)-4(C) , and  5 . In the guidance device  104 , for example, “0 degree” mark on the surface of the bottom disc  124  means that all of the holes  130  formed in the bottom disc  124  are perpendicular to the surface of the bottom disc  124  such that all holes&#39; angle is 0 degree. Furthermore, the hole angulation of the guidance device  104  goes “up” on the disc  124  (towards an opposite direction from the point marker  128  formed on the upper flange  122 ) in order to correlate with the user directional intuition. 
     According to an exemplary form of the present disclosure, the instrument placement kit  100  generally includes a set of six (6) guidance devices  104  each having a specific hole angle such as 0/3/6/9/12/15 degree, which is printed on the top surface of the guidance device  104  such that the user can easily select one of the guidance devices  104  according to the prescribed hole angle from the user interface unit  20 . As an example,  FIGS. 4(A)-4(C)  show three (3) guidance devices having three different hole angles such as 3 degrees, 6 degrees, and 9 degrees. In accordance with other forms of the present disclosure, however, the specific hole angle on each of the guidance devices  104  may be indicated with the color-coded method instead of marking the hole angle on the upper surface. In addition, the kit  100  may have more guidance devices  104  with more specific hole angles such that the number of the guidance devices  104  having the specific hole angles may be varied. For example, the instrument placement kit  100  includes a set of ten ( 10 ) guidance devices  104  each having their specific hole angle as discussed above such that the user can select one of the ten different hole angles. 
     As shown in  FIGS. 4(A)-4(C) , and  5 , the outer diameter OD of the upper flange  122  of the guidance device  104  is generally between 50 mm˜150 mm,and preferably around 110 mm. The diameter of the bottom disc  124  is generally between 25 mm˜125 mm, and preferably around 55 mm. The depth D of the bottom disc  124  from top surface of the upper flange  122  generally between 25 mm˜30 mm, and preferably around 22 mm, and the thickness t of the upper flange  122  is generally between 1 mm˜5 mm, and preferably around 3 mm. In addition, the diameter of each hole  130  is generally 2 mm˜10 mm, and preferably around 6 mm. The size of the holes  130  formed on the bottom disc  124  is large enough to support for a skull drill to drill an entry hole of the medical instrument  28  or a burr hole after one of the guidance devices  104  is engaged with the alignment frame  102  according to the prescribed parameters determined from the control module  26  of the user interface unit  20 . For example, when the skull drill is operated after one of the guidance devices  104  is engaged with the alignment frame  102 , if needed, a removable thin metal insert can be used to prevent debris during its drilling. Also, the skull drill would have a smooth shaft and only have the cutting blades at its end. 
     The instrument placement kit  100  further include multiple sleeves  106  each having different pre-defined lengths for guiding the placement of the medical instrument  28  such that the user interface unit  20  is also operable to determine a prescribed length among the different pre-defined lengths based on the planned trajectory. The sleeves  106  narrow the diameter of the selected hole  130  and can have presecribed inner diameters, e.g. to correspond to standard size catheters or other placement or guidance devices. As shown in  FIGS. 6(A)-6(C) , generally, the instrument placement kit  100  includes three or four (3 or 4) sleeves  106  each having different lengths, which are separated by 2 or 3 mm. In addition, each of the sleeves  106  is formed with a radial ring  134  to place on the top surface of the bottom disc  124  when each of the sleeves  106  is inserted into the selected hole  130  of the selected guidance device  104 . Accordingly, the radial ring  134  of the sleeve  106  is configured to perform as a stopper. In addition, the pre-defined length L of the sleeve  106  is measured as a distance between the bottom surface of the radial ring  134  and a chamfered end  132 . For example,  FIGS. 6(A)-6(C)  illustrate the sleeves  106  each having a specific length, which is printed on a surface of the sleeve  106  for the user to recognize the pre-defined length of each sleeve  106 . In accordance with other forms of the present disclosure, however, the length of the sleeves  106  may be recognized based on the different color-code of the length. 
     The user interface unit  20  is operable to select one of the sleeves  106  based on the prescribed length, and the selected sleeve  106  is engaged with the selected guidance device  104 , which is mounted to the alignment frame  102 . As shown in  FIG. 2A , the selected sleeve  106  is inserted into the selected hole  130  as the entry point of the medical instrument  28  in the selected guidance device  104 . As described above, the selected hole  130  of the guidance device  104  for drilling the entry hole with the skull drill as the entry point of the medical instrument  28  is also used for inserting the selected sleeve  106  for guiding the placement of the medical instrument  28 . Due to the sleeve  106  inserted into the hole  130  of the guidance device  104 , the diameter of the hole  130  is decreased by 2˜3 mm such that the hole diameter of the inserted sleeve  106  for the EVD catheter insertion becomes around 3˜4 mm. The inserted sleeve  106  is securely engaged with the selected hole  130  and allows the user to achieve the guided placement of the medical instrument  28  (for example, the EVD catheter or biopsy needle) based on the planned trajectory determined by the user interface unit  12 . In addition, each of the sleeves  106  is formed with the chamfered end  132 , which contacts and is engaged with the entry hole on the body of the patient  16  for stability when the medical instrument  28  inserted into the body of the patient  16  based on the planned trajectory. 
       FIG. 7  illustrates a modified instrument placement kit  200  as the second embodiment of the present disclosure. In the second embodiment of the present disclosure, the instrument placement kit  200  includes an alignment frame  202 , a guidance device  204 , and multiple guide carriages  206 , which are generally similar to each component of the first embodiment (see  FIG. 1B ). As shown in FIG. the alignment frame  202  is generally same as the alignment ring frame  102  in the first embodiment other than the pattern of markings  214  and identifiers  218  (fiducial markers) formed on the top surface  212  of the alignment frame  202 . The markings  214  indicate a rotational position of the guidance devices  204  when one of the guidance devices  204  is rotatably engaged with the alignment frame  202 . 
     The guidance device  204  in the second embodiment of the present disclosure is formed as a circular shape having an outer ring  222  and a middle rail  224  formed in a single plane. The middle rail  224  is connected to the outer ing  222  along a center line of the outer ring  222  and multiple holes  220  arranged in a line. The outer ring  222  is formed with a point marker  228 , which is marked on the top surface of the outer ring  222  and aligns with one of the markings  214  of the alignment frame  202 . Accordingly, the guidance device  204  with the multiple holes  220  and the point maker  228  in the second embodiment is configured to determine an insertion location of the medical instrument based on the prescribed parameter determined from the planned trajectory. 
     In the second embodiment of the present disclosure, the instrument placement kit  200  further includes multiple guide carriages  206  each having different sets of pre-defined parameters. As shown in  FIGS. 7 and 7A , one of the multiple guide carriages  206  is inserted into one of the multiple holes  220  of the guidance device  204  to guide the placement of the medical instrument according to the prescribed parameters determined from the planned trajectory, which is computed in the same way as in the first embodiment. Each of the multiple guide carriages  206  is formed with a sleeve  230  and a radial ring  232 , and removably engaged with one of the holes  220 . 
     As shown in  FIGS. 7 and 7A , the guide carriage  206  further includes a pointer  234  for indicating the rotational position of the carriage  206  when the selected carriage  206  is engaged with one of the holes  220 , which indicates an insertion direction of the medical instrument  28  as one of the prescribed parameters. Also, the radial ring  232  is formed with a keying feature  236  such as a star shape on the bottom surface of the radial ring  232  to securly lock the guide carriage  206  into the middle rail  224  with exact orientation. For engaging with the key feature  236  of the guide carriage  206 , a mating feature around each hole  220  of the middle rail  224  are formed as shown in  FIG. 7 . In addition, each of the carriages  206  is formed with an angle (a hole angle) which is inclined relative to a longitudinal axis of the sleeve  230 . The inclined angle inside the sleeve  230  indicates an insertion angle of the medical instrument  28  as one of the prescribed parameters. Accordingly, one of the multiple guide carriages  206  is selected and engaged with one of the holes  220  formed on the middle rail  224  of the guidance device  204  as shown in  FIG. 7 . The user interface unit  20  is operable to generate the prescribed parameters of the instrument placement kit  200  in the second embodiment, which is the same way as the first embodiment of the present disclosure described above. 
       FIG. 8  shows a display screen showing the scanned images and the prescribed parameters as an output in the user interface unit  20  of the guidance placement system  10 , and  FIG. 9  shows a flow diagram  300  of one method for the guided placement of a medical instrument  28  in a patient using the guided placement system  10  of the present disclosure as described above. In accordance with an exemplary form of the present disclosure, the instrument placement kit  100  having the alignment frame  102 , multiple guidance devices  104 , and multiple sleeves  106  is provided. The alignment frame  102  is placed or affixed onto the body of the patient  16  adjacent a determined entry point. For example, as shown in  FIGS. 1 and 2 , when the alignment frame  102  is attached to the head  18  of the patient  16 , the alignment ring frame  102  is placed onto the patient&#39;s head centered on Kocher&#39;s point defined by “Three Knuckle” rule of thumb. After placing the alignment ring frame  102  onto the patient&#39;s head, the images including the brain of the patient with the alignment ring frame  102  having the radio-opaqued fiducial markers  118  scanned by the CT scanner  12  are acquired and transmitted to the user interface unit  12 . which is shown in  FIGS. 1 and 8 . 
     In  FIG. 8 , the control module  26  of the user interface unit  12  has an installed planning software to calculate an ideal medical instrument or catheter insertion trajectory based on the scanned images. As shown in  FIG. 8 , the user interface unit  12  displays the acquired scanned images having the patient anatomical structures such as the skull and ventricles, and a reference plane defined by the fiducial markers  118  of the alignment frame  102 . The control module  26  may overlay a pre-procedure imaging (e.g., MRI or CT-V) to provide other ancillary information such as location of peripheral veins, neural tractography, suspected tumor tissue or lesion. Also, the control module  26  can be automated by computer algorithms such as machine learning based method or other methods for calculating optimal and safe insertion pathways for guiding the placement of the medical instrument. The set of optimal, safe paths can be discretized to conform to the discrete set of positions and angles easily achievable using the Alignment Ring Frame and Guidance devices. The surgical plan is also manually by a physician or medical technician in a multiplanar view by clicking on the entry point of the medical instrument and clicking on the target site to define a trajectory. Based on the planned trajectory, the control module  26  outputs the prescription specifying the configuration of the guidance devices  104  relative to the alignment frame  102  and the sleeves  106  such that the control module  26  determines the prescribed parameters from a set of pre-defined parameters. The system prescribes allows an operator to select the prescribed parameters such as a particular guidance device  104  among the set of guidance devices, a ring angle which indicates a rotational position of the guidance device  104  (e.g., an insertion direction of the medical instrument) relative to the alignment frame  102 , a hole angle which indicates an inclined angle of the multiple holes  130  formed on the guidance device  104  (e.g., an insertion angle of the medical instrument), a hole number which indicates a placement location of the medical instrument  28  (e.g., an insertion location of the medical instrument), and a sleeve size and/or length which indicates a distance between the entry point of the patient body and the bottom disc  124  (e.g., an insertion length of the medical instrument). As shown in  FIG. 8 , generally, the control module  26  provides multiple planned trajectory options each having its specific prescribed parameters. In addition, a vein map inside the patient&#39;s body can be optionally provided with the prescribed parameters. 
     As described in the diagram  300  of  FIG. 9 , one of the guidance devices  104  is selected and mounted to the alignment frame  102  according to the prescribed parameters generated from the control module  26 .  FIG. 8  shows the multiple outputs of the prescribed parameters based on the planned trajectory for guiding the placement of the medical instrument  28 . One of the guidance devices  104  is selected according to the prescribed hole angle (which is the inclined angle of the multiple holes  130 ) and rotatably positioned in the alignment frame  102  according to the ring angle (which is the rotational position of the guidance device  104 ). In the selected guidance device  104 , one of the multiple holes  130  is also selected according to the hole number (which is the placement location of the medical instrument  28 ). As shown in  FIGS. 2 and 2A , accordingly, one of the guidance devices  104  is selected based on the prescribed parameters and the selected guidance device  104  is engaged with the alignment frame  102 . 
     As shown in  FIG. 9 , furthermore, an entry hole on the body of the patient  16  is drilled as the entry point of the medical instrument  28  or a burr hole. For example, the entry hole on the skull of the patient  16  is drilled with a skull drill through the selected hole  130  of the guidance devices  104  mounted to the alignment frame  102 . In addition, the multiple sleeves  106  are provided with different pre-defined lengths for guiding an insertion of the medical instrument  28  through the entry hole drilled on the skull of the patient  16 . One of the multiple sleeves  106  is selected according to a prescribed length determined from the planned trajectory. The selected sleeve  106  is inserted into the selected hole  130  formed on the bottom disc  124  of the guidance device  104 , which was previously used for the skull drill to make the entry hole on the skull of the patient as described above. In addition, the chamfered end  132  of the selected sleeve  106  according to the prescribed length is engaged with the entry hole for stability when the medical instrument  28  is inserted into the target site of the patient body through the engaged sleeve  106 , Accordingly, the medical instrument  28  such as the EVD catheter or biopsy needle is effectively placed in the body of the patient along the planned trajectory generated from the scanned images as described above. 
     Each of the above described elements may be used with the method described above or other methods. Further, each of the described elements may be used together or independently. Further, each alternative for one element may be utilized in combination with each alternative for other elements. 
     The methods, elements, processing, and logic described above may be implemented in many different ways and in many different combinations of hardware and software. For example, all or parts of certain elements may be performed with circuitry that includes an instruction processor, such as a Central Processing Unit (CPU), microcontroller, or a microprocessor; an Application Specific Integrated Circuit (ASIC), Programmable Logic Device (PLD), or Field Programmable Gate Array (FPGA); or circuitry that includes discrete logic or other circuit components, including analog circuit components, digital circuit components or both; or any combination thereof. The circuitry may include discrete interconnected hardware components and/or may be combined on a single integrated circuit die, distributed among multiple integrated circuit dies, or implemented in a Multiple Chip Module (MCM) of multiple integrated circuit dies in a common package, as examples. 
     The circuitry may further include or access instructions for execution by the circuitry. The instructions may be stored in a tangible storage medium that is other than a transitory signal, such as a flash memory, a Random Access Memory (RAM), a Read Only Memory (ROM), an Erasable Programmable Read Only Memory (EPROM); or on a magnetic or optical disc, such as a Compact Disc Read Only Memory (CDROM), Hard Disk Drive (HDD), or other optical disk; or in or on another machine-readable medium. A product, such as a computer program product, may include a storage medium and instructions stored in or on the medium, and the instructions when executed by the circuitry in a device may cause the device to implement any of the processing described above or illustrated in the drawings. 
     The implementations may be distributed as circuitry among multiple system components, such as among multiple processors and memories, optionally including multiple distributed processing systems. Parameters, databases, and other data structures may be separately stored and managed, may be incorporated into a single memory or database, may be logically and physically organized in many different ways, and may be implemented in many different ways, including as data structures such as linked lists, hash tables, arrays, records, objects, or implicit storage mechanisms. Programs may be parts (e.g., subroutines) of a single program, separate programs, distributed across several memories and processors, or implemented in many different ways, such as in a library, such as a shared library (e.g., a Dynamic Link library (DLL)). The DLL, for example, may store instructions that perform any of the processing described above or illustrated in the drawings, when executed by the circuitry. 
     The foregoing description of various forms of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications or variations are possible in light of the above teachings. The forms discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various forms and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.