CN212972948U - CBCT geometric parameter calibration die body - Google Patents
CBCT geometric parameter calibration die body Download PDFInfo
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- CN212972948U CN212972948U CN202020514522.4U CN202020514522U CN212972948U CN 212972948 U CN212972948 U CN 212972948U CN 202020514522 U CN202020514522 U CN 202020514522U CN 212972948 U CN212972948 U CN 212972948U
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Abstract
The utility model belongs to the technical field of radiotherapy test mould bodies, and relates to a CBCT geometric parameter calibration mould body, which comprises a hollow cylindrical main body, wherein one end of the hollow cylindrical main body is provided with a first end cover, and the outer wall of the first end cover is fixed with a hook; a plurality of positioning balls are fixed on the outer wall of the hollow cylindrical main body and are arranged in a spiral line shape. The utility model discloses can be better to geometric model parameter calibration.
Description
Technical Field
The utility model relates to a CBCT geometric parameters calibration die body belongs to radiotherapy test die body technical field.
Background
Unlike conventional spiral CT, CBCT uses a multi-slice reconstruction technique, which allows for the observation of stereoscopic images under the operation of 3D software. The image quality of the CBCT is related to KV value, mAs size, filtering mode and reconstruction mode adopted by scanning; and also to the physiological movement of organs during scanning. At present, CBCT systems are applied to image guidance in the oral cavity field, medical electronic linear accelerators and other equipment. At present, the calibration of the geometric parameters of the CBCT is only determined by the size and the adjustment of the isocenter during mechanical design, and then, through fine adjustment and multiple attempts, the offset (i.e. the transverse offset, the longitudinal offset and the distance from the focal point of the bulb to the detector) and the inclination angle reconstruction parameters of the flat panel detector relative to the three directions of the beam center of the bulb cannot be accurately obtained, so that the reconstruction geometric distortion is caused.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model is: the CBCT geometric parameter calibration die body can easily obtain accurate offset (namely transverse offset, longitudinal offset and the distance from a bulb tube focus to a detector) and inclination angle reconstruction parameters of a flat panel detector relative to the three directions of the center of a bulb tube beam, can ensure that the reconstruction geometry is not distorted, and can better calibrate geometric model parameters.
The utility model discloses a CBCT geometric parameter calibration die body, which comprises a hollow cylindrical main body, wherein one end of the hollow cylindrical main body is provided with a first end cover, and the outer wall of the first end cover is fixed with a hook; a plurality of positioning balls are fixed on the outer wall of the hollow cylindrical main body and are arranged in a spiral line shape.
The CBCT geometric parameter calibration phantom obtains original image projection through scanning, then metal bead coordinates in each image are analyzed, offset (namely transverse offset, longitudinal offset and the distance from a bulb focus to a detector) and an inclination angle of a flat panel detector relative to the three directions of the center of a bulb beam are obtained, and then three-dimensional reconstruction is carried out according to the parameters, so that the accuracy is high. When the geometric parameters are calibrated, the die body is hung on a die body hanging box, then the position and the angle of the die body are adjusted by adjusting the hanging box, then the position of an external positioning laser line is adjusted, a spiral line formed by positioning balls of the die body is positioned to a CBCT geometric parameter calibration position, CBCT image acquisition software is used for acquiring images, and four groups of images including a full beam clockwise, a full beam anticlockwise, a half beam clockwise and a half beam anticlockwise are required to be acquired. Then, the image is analyzed and calculated, and finally parameters needed by reconstruction are obtained. The hollow cylindrical main body is made of transparent nonmetal materials, and the positioning ball is a metal positioning ball. The positioning ball and the hollow cylindrical main body are fixed in a bonding mode and the like.
Preferably, the other end of the hollow cylindrical main body is provided with a second end cover, and the second end cover is provided with a plurality of hollow holes. The end cover supports the hollow cylindrical main body, the hollow cylindrical main body can be kept cylindrical better, hollow holes are formed in the end cover II, the whole weight can be reduced, the hanging is facilitated to be safe and reliable when the die body is hung on the box, the hook and the end cover are fixed through the bolts, and the end cover II is hollow, so that the hook and the end cover I can be maintained and adjusted conveniently when the hook and the end cover I are fixed to break down.
Preferably, the hollow cylindrical main body has an outer diameter of 50mm-200mm, a length of 200 mm-400 mm and a wall thickness of 0.02 mm-5 mm.
Preferably, the positioning balls are arranged in a spiral line. When the positioning balls are arranged on the die body in a spiral line, the die body is also called a full beam die body.
Preferably, the plurality of positioning balls are respectively arranged in two spiral lines. When the positioning balls are arranged on the die body in two spiral lines, the die body is also called a half-bundle die body.
Preferably, the pitch of the spiral line is 100-200 mm.
Preferably, the periphery of the hollow cylindrical main body is provided with 3 transparent circular ring lines, the 3 transparent circular ring lines are arranged in parallel, and the central lines of the 3 transparent circular ring lines are superposed with the central line of the hollow cylindrical main body; the distance between the first transparent circular line and the third transparent circular line is more than or equal to one thread pitch of the spiral line formed by the positioning balls, and the first transparent circular line and the third transparent circular line are symmetrically arranged relative to the second transparent circular line. The positioning balls are basically uniformly distributed between the first transparent circular ring line and the third transparent circular ring line, and when the positioning balls are calibrated, the positioning laser lines are superposed with the 3 transparent circular ring lines.
Preferably, 2-4 transparent scribed lines are uniformly arranged on the periphery of the hollow cylindrical main body, and the transparent scribed lines are parallel to the central line of the hollow cylindrical main body. During calibration, the positioning laser line is superposed with the transparent scribed line, and the length of the positioning laser line is 100-200 mm.
The 3 transparent circular ring lines and the transparent scribed lines are used as reference lines during positioning.
Preferably, a plurality of location balls that are two helix type and arrange all be located different anchor rings, the location ball on two helices can not appear the condition of sheltering from each other, guarantees that every location ball is effective reference point.
Preferably, the distance between the adjacent 2 transparent circular ring lines is 50-100 mm.
Compared with the prior art, the utility model beneficial effect who has is:
the utility model has the advantages of reasonable design, can easily obtain accurate flat panel detector for the offset (be transverse offset, longitudinal offset and bulb focus to the distance of detector) and the inclination reconstruction parameter of the three direction at bulb beam center, can guarantee to rebuild the geometry undistorted, better to geometric model parameter calibration.
Drawings
FIG. 1 is a schematic structural diagram (front view) of a CBCT geometric parameter calibration phantom;
FIG. 2 is a schematic structural diagram (right view) of a CBCT geometric parameter calibration phantom;
FIG. 3 is a schematic structural diagram (top view) of a CBCT geometric parameter calibration phantom;
FIG. 4 is an expanded view taken along line A-A of FIG. 1;
FIG. 5 is a schematic structural view (front view) of a mold body with positioning balls arranged in two spiral lines;
FIG. 6 is an expanded view taken along line B-B of FIG. 5;
fig. 7 is a schematic structural view (perspective view) of the mold body with the positioning balls arranged in two spiral lines.
In the figure: 1. a hollow cylindrical body; 2. a second end cover; 3. a first transparent circular line; 4. transparent scribing; 5. a positioning ball; 6. hooking; 7. a first end cover; 8. hollowing out holes; 9. initially marking a positioning ball; 10. a bolt; 11. a second transparent circular line; 12. and a third transparent circular ring line.
Detailed Description
The invention will be further described with reference to the accompanying drawings:
the first embodiment is as follows:
referring to fig. 1-4, the CBCT geometric parameter calibration mold of the present invention includes a hollow cylindrical main body 1, wherein a first end cover 7 is disposed at one end of the hollow cylindrical main body 1, a hook 6 is fixed on an outer wall of the first end cover 7, a second end cover 2 is disposed at the other end of the hollow cylindrical main body, and a plurality of hollow holes 8 are disposed on the second end cover 2; a plurality of positioning balls 5 are fixed on the outer wall of the hollow cylindrical main body 1, and the positioning balls 5 are arranged in a spiral line shape.
The periphery of the hollow cylindrical main body 1 is provided with 3 transparent circular ring lines, the 3 transparent circular ring lines are arranged in parallel, and the central lines of the 3 transparent circular ring lines are superposed with the central line of the hollow cylindrical main body 1; the distance between the first transparent circular line 3 and the third transparent circular line 12 is greater than or equal to one thread pitch of the spiral line formed by the positioning balls 5, and the first transparent circular line 3 and the third transparent circular line 12 are symmetrically arranged relative to the second transparent circular line 11.
The periphery of the hollow cylindrical main body 1 is uniformly provided with 4 transparent scribed lines 4, the transparent scribed lines 4 are parallel to the central line of the hollow cylindrical main body 1, and the 4 transparent scribed lines 4 are equally divided into 360 degrees at the circumference.
The hollow cylindrical main body 1 has an outer diameter of 50mm-200mm, a length of 200 mm-400 mm and a wall thickness of 0.02 mm-5 mm. The pitch of the spiral line is 100-200 mm. The distance between every two adjacent transparent circular ring lines is 50-100 mm.
The specific operation process comprises the following steps: when the geometric parameters are calibrated, the whole beam of die body is hung on a die body hanging box, then the position and the angle of the die body are adjusted by adjusting the hanging box, so that the plane where the second transparent circular line 11 of the die body is located penetrates through the center of the beam, and when the die body is horizontally hung, 2 horizontal lines in 4 transparent scribed lines 4 of the die body are adjusted to be respectively superposed with 2 horizontal positioning laser lines of the medical equipment. When the die body is horizontally hung, the 1 transparent scribed line 4 above the die body is adjusted to be superposed with the vertical positioning laser line in the medical equipment head when the die body is viewed from top to bottom. After the die body position is set, the flat panel detector is placed at the full beam position, exposure of an x-ray device is controlled, generated x-rays penetrate through the die body and are received by the flat panel detector, image data are generated by the flat panel detector, then CBCT image acquisition software is used for acquiring images, the images are analyzed and calculated through acquisition of two groups of clockwise and anticlockwise images of the full beam die body, and finally parameters required by full beam reconstruction are obtained.
Example two:
referring to fig. 5-7, the CBCT geometric parameter calibration mold of the present invention includes a hollow cylindrical main body 1, wherein a first end cover 7 is disposed at one end of the hollow cylindrical main body 1, a hook 6 is fixed on an outer wall of the first end cover 7, a second end cover 2 is disposed at the other end of the hollow cylindrical main body, and a plurality of hollow holes 8 are disposed on the second end cover 2; be fixed with a plurality of location balls 5 on the 1 outer wall of hollow cylindrical main part, a plurality of location balls 5 are two helix type respectively and arrange to the contained angle is 180 between the initial mark location ball 9 that two helix type correspond respectively, and a plurality of location balls 5 that are two helix type and arrange all are located different ring surfaces, make the condition that shelters from each other can not appear in location ball 5 on two helices, guarantee that every location ball 5 is effective reference point.
The periphery of the hollow cylindrical main body 1 is provided with 3 transparent circular ring lines, the 3 transparent circular ring lines are arranged in parallel, and the central lines of the 3 transparent circular ring lines are superposed with the central line of the hollow cylindrical main body 1; the distance between the first transparent circular line 3 and the third transparent circular line 12 is greater than or equal to one thread pitch of the spiral line formed by the positioning balls 5, and the first transparent circular line 3 and the third transparent circular line 12 are symmetrically arranged relative to the second transparent circular line 11.
The periphery of the hollow cylindrical main body 1 is uniformly provided with 4 transparent scribed lines 4, the transparent scribed lines 4 are parallel to the central line of the hollow cylindrical main body 1, and the 4 transparent scribed lines 4 are equally divided into 360 degrees at the circumference.
The hollow cylindrical main body 1 has an outer diameter of 50mm-200mm, a length of 200 mm-400 mm and a wall thickness of 0.02 mm-5 mm. The pitch of the spiral line is 100-200 mm. The distance between every two adjacent transparent circular ring lines is 50-100 mm.
The specific operation process comprises the following steps: when the geometric parameters are calibrated, the half beam of the die body is hung on the die body hanging box, then the position and the angle of the die body are adjusted by adjusting the hanging box, so that the plane where the second transparent circular line 11 of the die body is located penetrates through the center of the beam, and when the die body is horizontally hung, 2 horizontal lines in 4 transparent scribed lines 4 of the die body are adjusted to be respectively superposed with 2 horizontal positioning laser lines of the medical equipment. When the die body is horizontally hung, the 1 transparent scribed line above the die body is adjusted to be superposed with the vertical positioning laser line in the medical equipment handpiece when viewed from top to bottom. After the die body position is set, the flat panel detector is placed at the half-beam position, exposure of an x-ray device is controlled, generated x-rays penetrate through the die body and are received by the flat panel detector, image data are generated by the flat panel detector, then CBCT image acquisition software is used for acquiring images, the images are analyzed and calculated through acquisition of two groups of clockwise and anticlockwise images of the half-beam die body, and finally parameters needed by half-beam reconstruction are obtained.
According to the description of the first embodiment and the second embodiment, when calibrating the geometric parameters, the full-beam phantom and the half-beam phantom are hung on the phantom hanging box in two times. The hollow cylindrical main body 1 is made of transparent nonmetal materials, and the positioning ball 5 is a metal positioning ball 5. The first end cover 7 and the second end cover 2 support the hollow cylindrical main body 1, so that the hollow cylindrical main body 1 can be kept cylindrical better; the hollow holes 8 are formed in the second end cover 2, so that the whole weight can be reduced, the hanging on the die body hanging box is facilitated to be safer and more reliable, the hook 6 and the first end cover 7 are fixed through the bolts 10, and the second end cover 2 is hollow, so that the hook 6 and the first end cover 7 can be conveniently maintained and adjusted when a fault occurs when the hook is fixed.
Claims (10)
1. A CBCT geometric parameter calibration die body is characterized in that: the device comprises a hollow cylindrical main body (1), wherein one end of the hollow cylindrical main body (1) is provided with a first end cover (7), and the outer wall of the first end cover (7) is fixed with a hook (6); a plurality of positioning balls (5) are fixed on the outer wall of the hollow cylindrical main body (1), and the positioning balls (5) are arranged in a spiral line shape.
2. The CBCT geometric parameter calibration phantom of claim 1, wherein: the other end of the hollow cylindrical main body (1) is provided with a second end cover (2), and the second end cover (2) is provided with a plurality of hollow holes (8).
3. The CBCT geometric parameter calibration phantom of claim 1, wherein: the hollow cylindrical main body (1) has an outer diameter of 50mm-200mm, a length of 200 mm-400 mm and a wall thickness of 0.02 mm-5 mm.
4. The CBCT geometric parameter calibration phantom of claim 1, wherein: the positioning balls (5) are arranged in a spiral line.
5. The CBCT geometric parameter calibration phantom of claim 1, wherein: the positioning balls (5) are respectively arranged in two spiral lines.
6. A CBCT geometric parameter calibration phantom according to claim 4 or 5, wherein: the pitch of the spiral line is 100-200 mm.
7. A CBCT geometric parameter calibration phantom according to claim 4 or 5, wherein: the periphery of the hollow cylindrical main body (1) is provided with 3 transparent circular ring lines, the 3 transparent circular ring lines are arranged in parallel, and the central lines of the 3 transparent circular ring lines are superposed with the central line of the hollow cylindrical main body (1); the distance between the first transparent circular ring line (3) and the third transparent circular ring line (12) is larger than or equal to one thread pitch of a spiral line formed by the positioning balls (5), and the first transparent circular ring line (3) and the third transparent circular ring line (12) are symmetrically arranged relative to the second transparent circular ring line (11).
8. A CBCT geometric parameter calibration phantom according to claim 4 or 5, wherein: 2-4 transparent scribed lines (4) are uniformly arranged on the periphery of the hollow cylindrical main body (1), and the transparent scribed lines (4) are parallel to the central line of the hollow cylindrical main body (1).
9. The CBCT geometric parameter calibration phantom according to claim 5, wherein: the positioning balls (5) which are arranged in two spiral lines are all positioned on different circular ring surfaces.
10. The CBCT geometric parameter calibration phantom of claim 7, wherein: the distance between every two adjacent transparent circular ring lines is 50-100 mm.
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| CN202020514522.4U CN212972948U (en) | 2020-04-09 | 2020-04-09 | CBCT geometric parameter calibration die body |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113749681A (en) * | 2021-11-10 | 2021-12-07 | 极限人工智能(北京)有限公司 | Tool for evaluating CBCT machine image precision |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113749681A (en) * | 2021-11-10 | 2021-12-07 | 极限人工智能(北京)有限公司 | Tool for evaluating CBCT machine image precision |
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