CBCT (cone beam computed tomography) oral cavity die body
By designing a CBCT dental phantom and utilizing a polyvinyl chloride ring and carrier structure, images were acquired and radiation source parameters were calculated, thus solving the calibration problem of the X-ray radiation source of the CBCT device and ensuring the accurate construction of the three-dimensional model.
Patent Information
- Application Number
- CN202422815510.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2034-11-19
AI Technical Summary
Existing technologies cannot effectively determine the qualification of X-ray radiation sources in CBCT devices, which affects the accuracy of three-dimensional models, and there is a lack of effective calibration methods.
A CBCT oral cavity phantom is provided, comprising a stacked first carrier, a polyvinyl chloride ring, and a second carrier, used to fix the polyvinyl chloride ring and place it at the center of the radiation field of an X-ray radiation source, to acquire images and calculate spatial resolution, contrast-to-noise ratio, and image uniformity index, thereby achieving the calibration of the radiation source.
By calculating parameters to determine the qualification of radiation sources, the accurate construction of three-dimensional models is ensured, enabling the initial verification, subsequent verification, and in-use inspection of CBCT devices, thereby improving the accuracy of the models.
Smart Images
Figure CN223585952U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the field of CT calibration, in particular to a CBCT oral cavity phantom. BACKGROUND
[0002] Cone Beam Computed Tomography (CBCT) replaces panoramic machines and traditional CT, and is a general trend. With the rapid development of core businesses of orthodontics and implantation, accurate three-dimensional modeling of the oral cavity, clear depiction of the position of blood vessels in the oral cavity and the thickness of the dental and maxillofacial bone are required. Therefore, with the increasing penetration rate of orthodontics and implantation, CBCT application equipment is indispensable in the future of dental clinics. In actual application, attention is often only paid to the final modeling result, and the CBCT device X-ray radiation source directly affects whether the constructed three-dimensional model is accurate and cannot be known. Whether the three-dimensional model is accurate or not is related to the spatial resolution, contrast noise ratio coefficient and image uniformity index of the CBCT device X-ray radiation source. Therefore, it is crucial to judge whether the CBCT device X-ray radiation source is qualified and to calibrate it. SUMMARY
[0003] The purpose of the application is to provide a CBCT oral cavity phantom to solve the problem that whether the CBCT device X-ray radiation source is qualified cannot be judged, and the radiation source cannot be calibrated.
[0004] To achieve the above-mentioned purpose, the application provides the following solutions.
[0005] In a first aspect, the application provides a CBCT oral cavity phantom, comprising: a first carrier, a polyvinyl chloride ring and a second carrier stacked together.
[0006] The first carrier and the second carrier are used for fixing the polyvinyl chloride ring.
[0007] The polyvinyl chloride ring is used for calibrating a to-be-tested medical oral and maxillofacial CBCT device X-ray radiation source.
[0008] The CBCT oral cavity phantom is placed in the center of the X-ray irradiation field of the to-be-tested medical oral and maxillofacial CBCT device X-ray radiation source, an irradiation image is collected, and the spatial resolution, contrast noise ratio coefficient and image uniformity index of the to-be-tested medical oral and maxillofacial CBCT device X-ray radiation source are calculated according to the irradiation image. The irradiation image contains the polyvinyl chloride ring.
[0009] According to the specific embodiments provided in the application, the application discloses the following technical effects: the application provides a CBCT oral cavity phantom, which comprises a first carrier, a polyvinyl chloride ring and a second carrier which are stacked; the CBCT oral cavity phantom is irradiated by an X-ray radiation source of a medical oral and maxillofacial CBCT device to be tested, an irradiation image is collected, and spatial resolution, contrast noise ratio coefficient and image uniformity index of the X-ray radiation source of the medical oral and maxillofacial CBCT device to be tested are calculated; whether the X-ray radiation source of the CBCT device is qualified is judged based on the calculated parameters, and the X-ray radiation source of the CBCT device is calibrated based on the judgment result, the CBCT oral cavity phantom is used for first verification, subsequent verification and use of the X-ray radiation source of the medical oral and maxillofacial CBCT device, so that the three-dimensional model constructed is more accurate. BRIEF DESCRIPTION OF DRAWINGS
[0010] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor.
[0011] Figure 1 It is an embodiment of the application to provide a CBCT oral cavity phantom structure diagram;
[0012] Figure 2 It is an embodiment of the application to provide a radiation source irradiating CBCT oral cavity phantom diagram;
[0013] Figure 3 It is an embodiment of the application to provide a positioning and boundary diagram of a region of interest;
[0014] Figure 4 It is an embodiment of the application to provide a positioning and boundary diagram of a region of interest; Figure 3 It is an embodiment of the application to provide a positioning and boundary diagram of a region of interest. DETAILED DESCRIPTION
[0015] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.
[0016] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and specific embodiments.
[0017] As Figures 1-3As shown, a CBCT oral phantom 2-1 comprises: a first carrier 1, a polyvinyl chloride ring 2, and a second carrier 3; the first carrier 1 and the second carrier 3 are used to fix the polyvinyl chloride ring 2; the polyvinyl chloride ring 2 is used to calibrate a medical oral and maxillofacial CBCT device X-ray radiation source (referred to as a radiation source) 2-2; the CBCT oral phantom 2-1 is placed in the center of the radiation field of the medical oral and maxillofacial CBCT device X-ray radiation source 2-2, an irradiation image is collected, and the spatial resolution, the contrast noise ratio coefficient, and the image uniformity index of the medical oral and maxillofacial CBCT device X-ray radiation source 2-2 are calculated according to the irradiation image; the irradiation image contains the polyvinyl chloride ring 2.
[0018] In an exemplary embodiment, a third carrier 4 is arranged between the first carrier 1 and the polyvinyl chloride ring 2; and a fourth carrier 5 is arranged between the second carrier 3 and the polyvinyl chloride ring 2.
[0019] The first carrier 1, the second carrier 3, the third carrier 4, and the fourth carrier 5 together constitute a phantom with a volume comparable to that of a human head, so as to better simulate the imaging conditions during patient scanning.
[0020] In actual operation, in addition to being used to fix the polyvinyl chloride ring, the third carrier 4 and the fourth carrier 5 form an integral whole with the polyvinyl chloride ring, so that the first carrier and the second carrier can be disassembled and only the middle module is used for detection in some cases where the entire phantom is not easy to place.
[0021] In an exemplary embodiment, the first carrier 1, the third carrier 4, the fourth carrier 5, and the second carrier 3 are fixedly connected through positioning pins 6. In the connection of the positioning pins 6 with the lower end of the first carrier 1, the upper end of the second carrier 3, and the upper end of the fourth carrier 5, interference fit is adopted, and the end faces of the remaining carriers adopt clearance fit.
[0022] In an exemplary embodiment, it further comprises a level bubble 7; the level bubble 7 is arranged at the bottom of the second carrier 3 and is used to detect whether the CBCT oral phantom 2-1 is in a horizontal state.
[0023] In an exemplary embodiment, it further comprises a base 8; the base 8 is arranged at the bottom of the second carrier 3 and is used to support the CBCT oral phantom 2-1.
[0024] In an exemplary embodiment, it further comprises an adjustable leg; the adjustable leg 9 is arranged at the bottom of the base 8 and is used to adjust the base 8 so that the base 8 is in a horizontal state.
[0025] Place the CBCT oral phantom 2-1 in the center of the X-ray radiation field of the medical oral and maxillofacial CBCT device to be tested 2-2, scan the CBCT oral phantom 2-1 under the conventional recognized conditions, and there should be no material around the CBCT oral phantom 2-1 that can affect the X-ray beam, select a rectangular region of interest (ROI) 3-1 in the reconstructed axial slice obtained by the detector 2-3, the four sides of the ROI 3-1 should be parallel to the pixel rows (columns), and only contain the polyvinyl chloride (PVC) and air regions 3-2 in the CBCT oral phantom 2-1, the transition edge between the PVC and the air should be parallel to the upper and lower edges, and the parallelism of the edge is optimized by repositioning the CBCT oral phantom 2-1 and repeatedly acquiring images. The width of the upper and lower edges of the further ROI 3-1 corresponds to the width in the CBCT oral phantom 2-1, which can be 5 mm, and each vertical edge in the PVC and air regions is at least 3 mm.
[0026] Based on the region of interest, the spatial resolution, the contrast noise ratio coefficient and the image uniformity index of the X-ray radiation source 2-2 of the medical oral and maxillofacial CBCT device to be tested are calculated, so as to accurately calibrate whether the X-ray radiation source 2-2 of the medical oral and maxillofacial CBCT device to be tested is qualified.
[0027] Further, based on the region of interest, the spatial frequency value at 10% on the measured modulation transfer function (MTF) curve is calculated, and the spatial frequency value is characterized as the spatial resolution.
[0028] The contrast noise ratio coefficient CNI is: is the average value of the pixels in the m max th row of the region of interest; is the average value of the pixels in the m min th row of the region of interest; is the standard deviation of the pixel values in the m max th row of the region of interest; is the standard deviation of the pixel values in the m min th row of the region of interest.
[0029] wherein, and are calculated by the following method:
[0030] The average value (P1, P2, P3,..., P n ) and the standard deviation (s1, s2, s3,..., s n ) of each row of pixels are read from the selected ROI 3-1, a first-order difference is obtained by using a sliding average value to obtain P’5, P’6, P’7,..., P’ n-4 , and the calculation formula is:
[0031]
[0032] For the obtained P' m According to formula P” m =P' m+1 -P' m Calculate the second-order difference to obtain P”6, P”7, ..., P” n-6 .
[0033] From P”6, P”7, ..., P” n-6 The extreme point is obtained in and The pixel row m max and m min .
[0034] The image uniformity index H is: Among them, H z H represents the average pixel value of the central region within the region of interest. o H represents the average pixel value of the upper region within the region of interest. l H represents the average pixel value of the left region within the region of interest. r H represents the average pixel value of the right region within the region of interest. u H represents the average pixel value of the lower region within the region of interest. M For H z H o H l H r and H u The average value, such as Figure 4 As shown.
[0035] The CBCT oral cavity phantom 2-1 provided in this application can be used to determine whether the X-ray radiation source 2-2 of the CBCT device is qualified, and to calibrate the radiation source 2-2 based on the judgment result. The CBCT oral cavity phantom 2-1 can be used for the initial verification, subsequent verification and in-use inspection of the X-ray radiation source 2-2 of the medical oral and maxillofacial CBCT device, so as to make the constructed three-dimensional model more accurate.
[0036] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0037] The principles and implementation manners of the present application are described herein by using specific examples, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will have changes. In conclusion, the content of the specification should not be understood as a limitation of the present application.
Claims
1. A CBCT oral phantom, characterized in that, The CBCT oral phantom comprises a first carrier, a polyvinyl chloride ring and a second carrier which are stacked; The first carrier and the second carrier are used for fixing the polyvinyl chloride ring; The polyvinyl chloride ring is used for calibrating an X-ray radiation source of a medical oral and maxillofacial CBCT device to be tested; The CBCT oral phantom is placed in the center of a radiation field of the X-ray radiation source of the medical oral and maxillofacial CBCT device to be tested, an irradiation image is collected, and spatial resolution, contrast noise ratio coefficient and image uniformity index of the X-ray radiation source of the medical oral and maxillofacial CBCT device to be tested are calculated according to the irradiation image; the irradiation image contains the polyvinyl chloride ring.
2. The CBCT mouth phantom of claim 1, wherein, A third carrier is arranged between the first carrier and the polyvinyl chloride ring; and a fourth carrier is arranged between the second carrier and the polyvinyl chloride ring.
3. The CBCT mouth phantom of claim 2, wherein, The first carrier, the third carrier, the fourth carrier and the second carrier are fixedly connected through positioning pins.
4. The CBCT mouth phantom of claim 1, wherein, Further comprising: A level bubble; The level bubble is arranged at the bottom of the second carrier and is used for detecting whether the CBCT oral phantom is in a horizontal state.
5. The CBCT mouth phantom of claim 1, wherein, Further comprising: A base; The base is arranged at the bottom of the second carrier and is used for supporting the CBCT oral phantom.
6. The CBCT mouth phantom of claim 5, wherein, Further comprising: An adjusting leg; the adjusting leg is arranged at the bottom of the base and is used for adjusting the base so that the base is in a horizontal state.