Preoperative positioning method for ileum bladder replacement ostomy based on CT body surface projection

Abstract

The invention discloses an ileum bladder replacement stoma preoperative positioning method based on CT body surface projection. The ileum bladder replacement stoma preoperative positioning method comprises the following steps that S1, region division is conducted on the abdomen; s2, externally adhering developing grid paper to the lower right abdomen of the patient, wherein the developing grid paper is consistent with the human body coordinate system of the lower right abdomen; s3, performing CT scanning on the right lower abdomen of the patient, and establishing a horizontal and vertical coordinate system in an image generated by CT scanning; s4, a plurality of rectus abdominis outer edge positioning points are marked in the foot side direction; s5, inputting the horizontal coordinate values of the plurality of rectus abdominis outer edge positioning points into a laser positioning system on the CT machine tool, finding corresponding longitudinal grid lines on the developing grid paper according to the longitudinal coordinate values corresponding to the horizontal coordinate values and the path information, and dotting and marking on the abdominal skin; s6, the rectus abdominis outer edge positioning points are connected into a line, projection marking is completed, and therefore a final stoma positioning area is determined.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a CT body surface projection-based preoperative positioning method for ileal bladder replacement. BACKGROUND

[0002] Bladder cancer is one of the common male malignant tumors, ranking in the top ten of male cancers in China. Radical cystectomy + urinary diversion (ileal bladder and ureteral skin stoma) is one of the means to treat such diseases. Patients will carry a stoma and wear a stoma bag for life. Foreign literature reports that the incidence of stoma complications is 11.0% to 60.0%, and about 20.8% seriously affect the quality of life of patients. Studies have shown that preoperative stoma positioning refers to designing the best abdominal stoma position for patients before surgery. The stoma position should be located in the rectus abdominis. Preoperative stoma positioning can reduce parastomal hernia, stoma prolapse, and skin-related complications around the stoma, which is beneficial to the postoperative recovery of patients and reduces the difficulty of stoma care.

[0003] The existing stoma positioning method is a body surface bony landmark palpation positioning, and the specific position is the upper 1 / 3 of the rectus abdominis on the line connecting the navel and the right anterior superior iliac spine. The positioning process is as follows: ① The positioner stands on the left side of the patient, the patient lies flat, raises the head and neck, holds the head with both hands, looks straight at the feet, and slightly presses the abdomen. The palm is placed on the navel, and a longitudinal contractile muscle is touched on both sides of the abdomen, which is the rectus abdominis. The edge of the rectus abdominis is palpated; ② The positioning point is preliminarily selected. The ileal stoma is in the right lower abdomen, and the intersection of the three midlines formed by the navel, the anterior superior iliac spine, and the pubic symphysis. ③ Adjust the best positioning point to avoid surgical incision, skin depression, wrinkles, scars, belt position, etc., and also facilitate the patient's own observation and replacement of the stoma bag. ④ After selecting the best position, mark the best positioning point with a non-fading marker pen, and cover the mark point with a transparent film dressing.

[0004] The disadvantages of the technical solution are: the core requirement of stoma positioning is that the stoma should be positioned on the rectus abdominis. The existing rectus abdominis positioning method relies on manual palpation of bony landmarks for positioning. For medical personnel with thick abdominal fat layer, separated rectus abdominis, abdominal surgery history, and lack of stoma positioning experience, it is difficult to accurately palpate the bony landmarks. The positioning method lacks precision, resulting in a large error between the final stoma position and the positioning position. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide a CT body surface projection-based ileal neobladder preoperative positioning method, which obtains the coordinate information of the in-vivo anatomical structure through CT computer tomography, and then maps the anatomical information to the patient's body surface with the aid of an auxiliary tool, namely a development grid and a laser positioning system, to realize accurate correspondence between the in-vivo structure and the body surface position, and overcome the inaccuracy of positioning relying solely on anatomical landmarks or experience palpation, thus having higher accuracy for special groups such as emergency surgery, obesity and abdominal rectus muscle rupture.

[0006] The above technical problems are solved by the following technical solutions: The application discloses a CT body surface projection-based ileal bladder replacement pre-positioning method, which comprises the following steps: S1, a human body coordinate system is established by drawing a cross line according to an abdominal four-partition method to divide the abdomen into regions, and a right lower abdomen is selected as a stoma precise positioning region; S2, a developing grid paper is externally attached to the right lower abdomen of a patient, a horizontal edge and a vertical edge of the developing grid paper are respectively parallel to a horizontal line and a vertical line of the human body coordinate system in the step S1, and a grid direction on the developing grid paper is consistent with the human body coordinate system of the right lower abdomen; S3, CT computer tomography is performed on the right lower abdomen of the patient in the step S2, an image set is established according to a cross-sectional image generated by scanning, a computer system generates a horizontal coordinate value corresponding to each cross-sectional image, and thus a right lower abdomen horizontal coordinate system is formed; after the CT computer tomography, the developing grid paper generates a vertical grid line, each vertical grid line is sequentially marked with a value from small to large in a left-to-right direction, and a vertical coordinate system is formed in the vertical grid line region, so that a horizontal and vertical coordinate system is established in the image generated by the CT computer tomography on the right lower abdomen of the patient; S4, a frame of picture when the developing grid paper in the step S3 is developed for the first time is taken as a starting point, an umbilicus and an upper edge of a pubic symphysis are taken as an end point, a plurality of rectus abdominis outer edge positioning points are marked along a foot side direction, and horizontal and vertical coordinate information and positioning path information of the rectus abdominis outer edge positioning points are recorded; S5, the horizontal coordinate values of the rectus abdominis outer edge positioning points in the step S4 are respectively input into a laser positioning system on a CT computer tomography machine bed, a horizontal laser line is projected to the right lower abdomen of the patient, and intersects with the vertical grid line on the developing grid paper externally attached to the right lower abdomen, and then, according to the vertical coordinate value corresponding to each horizontal coordinate value and the path information, each vertical grid line on the developing grid paper on the right lower abdomen of the patient is found, and a dot is marked on the skin of the abdomen at the intersection point of each vertical grid line and the laser line; and S6, after each rectus abdominis outer edge positioning point in the step S5 is marked on the skin of the abdomen, the developing grid paper is removed, all the rectus abdominis outer edge positioning points are connected into a line, a rectus abdominis outer edge body surface projection mark is completed, and thus a final stoma positioning region is determined. Through CT development and coordinate establishment, the stoma positioning range is expanded to a "selectable region", doctors can flexibly adjust the final stoma position in combination with individual anatomic differences of patients in an operation, and postoperative nursing problems caused by unreasonable preset points can be effectively reduced.

[0007] Preferably, in the step S1, the abdominal four-partition method draws a cross line by taking the umbilicus as a horizontal line and a vertical line, taking the umbilicus as a center, drawing a horizontal line through the abdomen, taking the umbilicus as a center, and drawing a vertical line perpendicular to the horizontal line, so that the abdomen is divided into four regions. Through the abdominal four-partition method, the precise position of the stoma can be quickly positioned.

[0008] Preferably, in step S2, the developing grid paper is a lead-containing developing grid paper. When the lead-containing developing grid paper is used in CT computer tomography, it can closely fit the curved profile of different parts of the human body, avoiding grid deformation and positioning deviation caused by rigid material.

[0009] Preferably, in step S3, the developing grid paper generates longitudinal grid lines after CT computer tomography, and the spacing between each longitudinal grid line is 1 cm. The spacing between the longitudinal grid lines facilitates the establishment of longitudinal line coordinates.

[0010] Preferably, in step S3, an image set is established for the cross-sectional images generated by scanning, and the spacing between each frame of cross-sectional images is 0.5 cm. By fixing the spacing between each frame of cross-sectional images, the accuracy of the cross-sectional values can be ensured.

[0011] Preferably, in step S4, the outer edge of the rectus abdominis positioning point is five. By setting 5 positioning points, the length of the stoma abdominal incision can be accurately predicted.

[0012] Preferably, in step S4, when marking multiple rectus abdominis outer edge positioning points in the lateral direction of the foot and recording the transverse and longitudinal coordinate information and positioning path information of each rectus abdominis outer edge positioning point, the thickness of the rectus abdominis on the frame of cross-sectional images at each positioning point is measured by using the ruler function on the CT computer tomography machine bed. By CT computer tomography, the positioning difficulties in scenes such as thick abdominal fat, rectus abdominis separation, and emergency surgery can be effectively avoided, and the risk of patients with weak rectus abdominis can be identified in advance.

[0013] Preferably, in step S5, when the transverse laser line is projected onto the lower right abdomen of the patient, the CT computer tomography machine bed moves according to the input transverse coordinate value of the rectus abdominis outer edge positioning point until the transverse section of the laser projection overlaps the rectus abdominis outer edge positioning point. By overlapping the transverse section of the laser projection with the rectus abdominis outer edge positioning point, the accuracy of projecting the rectus abdominis outer edge surface positioning point onto the abdominal skin is ensured.

[0014] Preferably, in step S5, the marker pen is a skin marker pen. The skin marker pen is not easy to fade and is convenient to clean.

[0015] The abdominal four-part method divides the abdomen into four regions, namely the right upper abdomen, the right lower abdomen, the left upper abdomen, and the left lower abdomen.

[0016] Compared with the prior art, the present application has the following beneficial effects: 1. Through CT computer tomography, imaging and coordinate establishment is generated, the stoma positioning range is expanded to a "selectable area", the surgeon can flexibly adjust the final stoma position combined with the individual anatomic differences of the patient during the operation, such as the position of the surgical incision, the skin condition, etc., and effectively reduce the postoperative nursing problems caused by unreasonable preset points; at the same time, relying on the clear visible laser line and the precise controllable CT bed transverse movement equipment, the abdominal rectus muscle positioning area contour can be intuitively presented, the manual operation error is reduced, the consistency of the "image-surface" projection data is ensured, and the equipment and technical double protection are provided for the stoma positioning accuracy.

[0017] 2. Through the synergistic effect of CT computer tomography and laser positioning, the image of the abdominal rectus muscle area is accurately captured and projected to the surface, which can effectively avoid the positioning problems in the scenes of thick abdominal fat, abdominal rectus muscle separation and emergency surgery, and can identify the risk of patients with weak abdominal rectus muscle in advance, and is suitable for special groups and conventional scenes. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a step flowchart of the present application; Figure 2 It is a schematic diagram of the abdominal four-partition method of the present application; Figure 3 It is a schematic diagram of the external application of the imaging grid paper to the right lower abdomen of the present application; Figure 4 It is a schematic diagram of the patient lying on the CT computer tomography machine bed surface of the present application; Figure 5 It is a schematic diagram of establishing longitudinal and latitudinal coordinates according to CT images of the present application; Figure 6 It is a schematic diagram of establishing longitudinal coordinates according to CT images of the present application; Figure 7 It is a schematic diagram of determining the body surface projection positioning point of the outer edge of the abdominal rectus muscle according to CT images of the present application; Figure 8-1 It is a schematic diagram of starting the laser positioning system when the patient's body surface projection positioning of the present application; Figure 8-2 It is a schematic diagram of setting the latitudinal laser coordinate value of the positioning point when the patient's body surface projection positioning of the present application; Figure 8-3 It is a schematic diagram of the intersection point of the laser line and the imaging grid paper when the patient's body surface projection positioning of the present application; Figure 8-4 It is a schematic diagram of using a marking pen to mark points when the patient's body surface projection positioning of the present application; Figure 9-1 It is a schematic diagram of the body surface projection of the outer edge of the abdominal rectus muscle and the patient's abdominal skin of the present application; Figure 9-2 It is a schematic diagram of the final stoma position of the patient of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0020] As shown in the drawings, Figure 1 a CT body surface projection-based ileal neovesical stoma preoperative positioning method has the following steps: S1, a cross line is drawn according to the abdominal four-partition method to establish a human body coordinate system for regional division of the abdomen, and the right lower abdomen is selected as the precise positioning area of the stoma.

[0021] As shown in the drawings, Figure 2 a cross line is drawn according to the abdominal four-partition method, a horizontal line is drawn through the umbilical region, and a vertical line is drawn vertically to the horizontal line with the umbilical region as the center. The abdomen is divided into four regions, i.e., the right upper abdomen, the right lower abdomen, the left upper abdomen, and the left lower abdomen. According to the surgical method, the stoma is determined to be located in the abdominal quadrant region, and the right lower abdomen is selected as the precise positioning area of the ileal neovesical stoma.

[0022] S2, the developed grid net paper is externally attached to the right lower abdomen of the patient, and the horizontal edge and the vertical edge of the developed grid net paper are respectively parallel to the horizontal line and the vertical line of the human body coordinate system in step S1, so that the grid direction on the developed grid net paper is consistent with the human body coordinate system of the right lower abdomen.

[0023] As shown in the drawings, Figure 3 the prepared developed grid net paper is externally attached to the right lower abdomen of the patient, so that the horizontal edge of the developed grid net paper is parallel to the trans-umbilical horizontal line of the human body coordinate system, and the vertical edge of the developed grid net paper is parallel to the vertical line perpendicular to the horizontal line of the human body coordinate system, so as to facilitate the consistency of the grid direction on the developed grid net paper with the human body coordinate system of the right lower abdomen. The developed grid net paper is a lead-containing developed grid net paper. When CT computer tomography is performed, the lead-containing developed grid net paper can closely fit the curved surface profile of different parts of the human body, thereby avoiding grid deformation and positioning deviation caused by rigid material.

[0024] S3, CT computer tomography is performed on the right lower abdomen of the patient in step S2, an image set is established for the cross-sectional images generated by scanning, and a horizontal coordinate value corresponding to each cross-sectional image is generated by the computer system, thereby forming a right lower abdomen horizontal coordinate system; after CT computer tomography, the developed grid net paper generates longitudinal grid lines, each longitudinal grid line is sequentially labeled with a value from small to large in the left-to-right direction, and a vertical coordinate system is formed in the longitudinal grid line region, thereby establishing a horizontal and vertical coordinate system in the image generated by CT computer tomography of the right lower abdomen of the patient.

[0025] As shown in the drawings, Figure 4 to Figure 6As shown, the patient lies supine on the CT scanner bed for a CT scan of the right lower abdomen. After the CT scan, a set of cross-sectional images is created with each frame measuring 0.5 cm. Based on each frame, the computer system generates a corresponding horizontal coordinate value, thus forming an abdominal horizontal coordinate system. Using the function of highlighting grid paper on the CT image, it can be observed that the highlighting grid paper generates vertical grid lines after the CT scan. The spacing between each vertical grid line is 1 cm. Each vertical grid line is labeled with a number from 1 to 15 from left to right, thus obtaining a series of vertical coordinate values ​​in the image generated by the CT scan. A vertical coordinate system is formed in the area of ​​the vertical grid lines in the image. At this point, the patient's right lower abdomen image generated by the CT scan has reconstructed the horizontal and vertical coordinate systems on the computer. The patient still needs to remain supine on the CT scanner bed.

[0026] S4. Starting from the frame of the first development of the developing grid paper in step S3, and ending at the upper edge of the umbilicus and pubic symphysis, mark multiple positioning points at the outer edge of the rectus abdominis muscle along the foot side and record the horizontal and vertical coordinates and positioning path information of each positioning point at the outer edge of the rectus abdominis muscle.

[0027] like Figure 7 As shown, browsing the cross-sectional images generated by CT computed tomography (CT) scans, the computer system matches a horizontal coordinate value for each frame of the cross-sectional image. Starting from the lowest point of the navel in the first frame of the imaging grid paper (i.e., the lowest point of the navel), and ending at the upper edge of the pubic symphysis, multiple stoma positioning points at the outer edge of the rectus abdominis muscle are marked along the foot-side direction. First, the first positioning point at the outer edge of the rectus abdominis muscle is located. Using the first frame of the imaging grid paper (i.e., the lowest point of the navel) as the starting point, the horizontal coordinate value of this cross-sectional image is recorded as 0352.2. The position of the rectus abdominis muscle at the outer edge of this frame is then located. Based on the vertical coordinate value of this horizontal coordinate point in the CT-generated image, a vertical line is drawn at this horizontal coordinate point in the generated image. The vertical coordinate value is recorded as the 8th vertical grid line from right to left, based on the overlap between this drawn vertical line and the vertical grid lines on the imaging grid paper. Therefore, the coordinate information of the first positioning point is recorded as: horizontal coordinate 0352.2, vertical coordinate 8, positioning path from right to left 8th vertical grid line.

[0028] The second lateral margin of rectus abdominis positioning point is searched again, and the picture is continuously browsed in the lateral direction in the computer system to select a second frame cross-sectional image with an interval of 1 cm between cross sections, and the lateral coordinate value of the second frame cross-sectional image is recorded as 0365.3. A point at the lateral margin of rectus abdominis is searched on the frame picture, and the longitudinal coordinate number where the point is located on the image is searched. A vertical line is drawn on the point where the lateral coordinate value of the second frame cross-sectional image is located on the image. According to the vertical coordinate overlapping value formed by the vertical line drawn and the longitudinal grid lines on the developing grid net paper, the vertical coordinate overlapping value is the seventh longitudinal grid line from right to left. Therefore, the coordinate information of the second positioning point is established as follows: lateral coordinate 0365.3, longitudinal coordinate 8, and the positioning path is the seventh longitudinal grid line from right to left.

[0029] The coordinate information of the remaining third to fifth lateral margin of rectus abdominis positioning points is sequentially established according to the above method. The coordinate points are located with the umbilicus and the upper edge of the pubic symphysis as the terminal point. The coordinate points are located with three points forming a straight line. A table of lateral and longitudinal coordinate information and positioning path information of each positioning point is established and recorded to facilitate positioning. When the lateral margin of rectus abdominis positioning points are marked in the lateral direction and the lateral and longitudinal coordinate information and positioning path information of each lateral margin of rectus abdominis positioning point are recorded, the thickness of the rectus abdominis on the frame cross-sectional image of each positioning point can also be measured by using the scale function on the CT computer tomography machine bed to assist in predicting the size of the individualized stoma abdominal incision, so as to avoid stoma abdominal incision being too large or too small due to individual differences, which leads to stenosis obstruction or mucosal separation. The lateral and longitudinal coordinate information and positioning path information are shown in Table 1.

[0030] Table 1: Lateral and longitudinal coordinate information and positioning path information Horizontal coordinate information Vertical coordinate information Positioning path 1st external rectus abdominis positioning point 0352.2 8 8th grid from right to left 2nd external rectus abdominis positioning point 0365.3 7 7th grid from right to left 3rd external rectus abdominis positioning point 0377.1 6.5 6.5th grid from right to left 4th external rectus abdominis positioning point 0392.1 5 5th grid from right to left ...... ...... ...... ...... With the cooperation of CT scanning and laser positioning, the image of the rectus abdominis region is accurately captured and projected to the body surface, which can effectively avoid the positioning difficulties in scenes such as thick abdominal fat, separation of rectus abdominis, emergency surgery, etc. According to the thickness of the rectus abdominis on the frame cross-sectional image of each positioning point measured by the scale, the risk of patients with weak rectus abdominis can be identified in advance, which provides early prevention basis for complications such as parastomal hernia, and is suitable for special groups and conventional scenes.

[0031] S5, the lateral coordinate values of the plurality of lateral margin of rectus abdominis positioning points in step S4 are input into the laser positioning system on the CT computer tomography machine bed, the lateral laser line is projected to the right lower abdomen of the patient, and intersects with the longitudinal grid lines on the developing grid net paper attached to the right lower abdomen. According to the longitudinal coordinate values corresponding to each lateral coordinate value and the path information, each longitudinal grid line corresponding to each positioning point is found on the developing grid net paper on the right lower abdomen of the patient, and a mark is made on the skin of the abdomen at the intersection of each longitudinal grid line and the laser line using a marking pen. The marking pen is a skin marking pen, which is not easy to fade and is convenient to clean.

[0032] As Figure 8-1 to Figure 8-4 shown, the laser positioning system is started, the patient's abdomen appears a transverse laser line, the transverse coordinate value corresponding to the first lateral margin of rectus abdominis positioning point is input into the laser positioning system, the input number is -0352.2, the CT machine bed moves according to the input transverse coordinate information, at this time the position of the laser line projected to the abdomen is the transverse coordinate of the first lateral margin of rectus abdominis positioning point, it can be seen that the longitudinal grid lines on the developed grid net paper intersect with the laser line, then according to the longitudinal coordinate value of the first lateral margin of rectus abdominis positioning point and the path, the longitudinal coordinate value of the first positioning point is 8, the positioning path is the 8th longitudinal grid line of the developed grid net paper from right to left, find the longitudinal grid line, and mark the point at the intersection of the longitudinal grid line and the laser line using a skin marker pen, and the mark must be printed on the abdominal skin, and other lateral margin of rectus abdominis positioning points are also marked on the abdominal skin in turn.

[0033] S6, after each lateral margin of rectus abdominis positioning point in step S5 is marked on the abdominal skin, the developed grid net paper is removed, and all lateral margin of rectus abdominis positioning points are connected into a line to complete the surface projection marking of the lateral margin of rectus abdominis, so as to determine the final stoma positioning area.

[0034] As Figure 9-1 to 9-2 shown, after the lateral margin of rectus abdominis positioning point marking is completed on the abdominal skin, the developed grid net paper is removed, the lateral margin of rectus abdominis positioning points on the abdominal skin are connected into a line in turn to complete the surface projection marking of the lateral margin of rectus abdominis, and the final stoma positioning area confirmation is implemented. The articles used in this method include developed grid net paper, electronic computed tomography machine, skin marker pen and the like. Through CT development and coordinate establishment, the stoma positioning range is expanded to a "selectable area", so that the surgeon can flexibly adjust the final stoma position in combination with the individual anatomic differences of the patient during the operation, such as the position of the surgical incision, the skin condition and the like, effectively reducing the postoperative nursing problems caused by unreasonable preset points; at the same time, relying on the clear and visible laser line and the precisely controllable CT bed transverse movement equipment, the contour of the rectus abdominis positioning area can be intuitively presented, the manual operation error is reduced, the consistency of the "image-surface" projection data is ensured, and the equipment and technical double protection for the accuracy of stoma positioning is provided.

[0035] At the same time, relying on the CT computed tomography image data, this technology can simultaneously measure key anatomic parameters such as ileum diameter, thereby accurately predicting the length of the stoma abdominal incision, avoiding postoperative complications such as stoma stenosis obstruction, mucosal separation caused by individual intestinal size difference, and realizing the "tailor-made" surgical planning.

[0036] The technical solution of the present application is not limited to a single stoma type, and can cover all intestinal stomas and urinary stomas, such as ileostomies, colostomies, and the like, and urinary stomas such as ileal bladder replacement stomas and the like. The preoperative positioning requirements do not need to adjust the core technical process for different stoma scenarios, and adapt to the clinical diversification of surgical requirements.

[0037] The above examples only illustrate the technical idea of the present application and cannot limit the protection scope of the present application. Any modification made on the basis of the technical solution according to the technical idea of the present application falls within the protection scope of the present application.

Claims

1. A preoperative localization method for ileal cystostomy based on CT surface projection, characterized in that, The steps are as follows: S1. Draw a cross line according to the four-zone method of the abdomen to establish a human coordinate system and divide the abdomen into regions. Select the lower right abdomen as the precise location area for the stoma. S2. Apply the radiopaque grid paper to the patient's lower right abdomen. The horizontal and vertical edges of the radiopaque grid paper are parallel to the horizontal and vertical lines of the human coordinate system in step S1, respectively, so that the grid direction on the radiopaque grid paper is consistent with the human coordinate system of the lower right abdomen. S3. Perform a CT computed tomography scan on the right lower abdomen of the patient in step S2, establish an image set for the cross-sectional images generated by the scan, and generate a horizontal coordinate value corresponding to each cross-sectional image based on each frame of the cross-sectional image, thereby forming a horizontal coordinate system for the right lower abdomen. After CT computed tomography, the imaging grid paper generates longitudinal grid lines. Each longitudinal grid line is marked with values ​​from left to right in ascending order, forming a vertical coordinate system in the longitudinal grid line area. Thus, a horizontal and vertical coordinate system is established in the image generated by CT computed tomography of the patient's right lower abdomen. S4. Starting from the frame of the first development of the developing grid paper in step S3, and ending at the upper edge of the umbilicus and pubic symphysis, mark multiple positioning points at the outer edge of the rectus abdominis muscle along the foot side and record the horizontal and vertical coordinates and positioning path information of each positioning point at the outer edge of the rectus abdominis muscle. S5. Input the abscissa values ​​of the multiple rectus abdominis muscle outer edge positioning points in step S4 into the laser positioning system on the CT computed tomography machine. Project the transverse laser line to the patient's right lower abdomen and intersect with the longitudinal grid lines on the imaging grid paper attached to the right lower abdomen. Then, based on the ordinate value and path information corresponding to each abscissa value, find each corresponding longitudinal grid line on the imaging grid paper on the patient's right lower abdomen. Mark the intersection of each corresponding longitudinal grid line and the laser line on the abdominal skin with a marker pen. S6. After each rectus abdominis outer edge positioning point in step S5 is marked on the abdominal skin, the radiopaque grid paper is removed, and all rectus abdominis outer edge positioning points are connected into a line to complete the surface projection marking of the rectus abdominis outer edge, thereby determining the final stoma positioning area.

2. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S1, the abdominal four-section method is used to draw cross lines. Horizontal and vertical lines are drawn through the navel. With the navel as the center, a horizontal line is drawn across the abdomen, and a vertical line is drawn perpendicular to the horizontal line with the navel as the center, dividing the abdomen into four regions.

3. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S2, the developing grid paper is lead-containing developing grid paper.

4. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S3, the longitudinal grid lines generated by the imaging grid paper after CT computed tomography scan have a spacing of 1 cm between each longitudinal grid line.

5. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S3, an image set is established for the cross-sectional images generated by scanning, with a spacing of 0.5 cm between each frame of cross-sectional images.

6. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S4, there are five location points on the outer edge of the rectus abdominis muscle.

7. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S4, when marking multiple positioning points at the outer edge of the rectus abdominis muscle along the foot side and recording the horizontal and vertical coordinates and positioning path information of each positioning point at the outer edge of the rectus abdominis muscle, the thickness of the rectus abdominis muscle on that frame of cross-sectional image at each positioning point is measured using the ruler function on the CT computed tomography machine.

8. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S5, when the transverse laser line is projected onto the patient's right lower abdomen, the CT computed tomography machine moves according to the input transverse coordinate value of the rectus abdominis muscle outer edge positioning point until the cross section of the laser projection overlaps with the rectus abdominis muscle outer edge positioning point.

9. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 1, characterized in that, In step S5, the marker is a skin marker.

10. The preoperative localization method for ileal cystostomy based on CT surface projection according to claim 2, characterized in that, The abdominal four-division method divides the abdomen into four regions: the upper right abdomen, the lower right abdomen, the upper left abdomen, and the lower left abdomen.

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