1、Implants for surgery Orthopaedic joint prosthesisPart 1: Procedure for producing parametric 3D bone models from CT data of the kneeBS ISO 19233-1:2017BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National forewordThis British Standard is the UK implementation of IS
2、O 19233-1:2017.The UK participation in its preparation was entrusted to Technical Committee CH/150/4, Surgical Implants - Bone and Joint Replacements.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the
3、 necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 86417 9ICS 11.040.40Compliance with a British Standard cannot confer immunity from legal obligations. This British Stan
4、dard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2017.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS ISO 19233-1:2017 ISO 2017Implants for surgery Orthopaedic joint prosthesis Part : Procedure for producing parametri
5、c 3D bone models from CT data of the kneeImplants chirugicaux Prothses articulaires orthopdiques Partie : Mode opratoire de production de modles paramtriques dos en 3D partir de donnes de CT du genouINTERNATIONAL STANDARDISO19233-1First edition2017-05-15Reference numberISO 19233-1:2017(E)BS ISO 1923
6、3-1:2017ISO 19233-1:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, includi
7、ng photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +4
8、1 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 19233-1:2017ISO 19233-1:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms, definitions and abbreviated terms 14 Principles . 25 Requirements 25.1 Imaging conditions 25.1.1 Medical imaging apparatus . 25.1.2
9、Region of interest 25.1.3 Body position 35.1.4 Field of view (FOV) 35.1.5 Slice thickness and slice spacing 35.1.6 Reconstruction kernel . 45.1.7 X-ray tube current . 45.1.8 X-ray tube voltage . 45.1.9 Precautions . 45.1.10 Leg alignment . 45.2 Software regulatory requirements 55.3 Generation of bon
10、e models 55.3.1 Segmentation methods for bone and cartilage region 55.3.2 3D reconstruction . 65.3.3 Data format . 6Annex A (informative) Method of the software validation 7Annex B (informative) CT scanning conditions . 8Bibliography 9 ISO 2017 All rights reserved iiiContents PageBS ISO 19233-1:2017
11、ISO 19233-1:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a sub
12、ject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (I
13、EC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be
14、noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifyi
15、ng any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience
16、of users and does not constitute an endorsement.For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical B
17、arriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.This document was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee SC 4, Bone and joint replacements.A list of all parts in the ISO 19233 series can be found on the ISO website.iv ISO 2017 All r
18、ights reservedBS ISO 19233-1:2017ISO 19233-1:2017(E)IntroductionIn accordance with its widespread use of medical X-ray computed tomography apparatus, three-dimensional (3D) bone models reconstructed from digital tomographic images have been widely used for various applications such as preoperative p
19、lanning, surgical navigation, robotic surgeries, patient matched instruments and personalized total knee joint prosthesis. However, the conditions of taking tomographic images are different among hospitals and not internationally unified. To measure bones accurately, precise 3D bone models reconstru
20、cted from tomographic images should be used. On the other hand, since conditions of this reconstruction process are left up to operators and/or medical institutions discretion, this document provides a standard way of reconstructing 3D bone models. ISO 2017 All rights reserved vBS ISO 19233-1:2017Th
21、is page deliberately left blankImplants for surgery Orthopaedic joint prosthesis Part : Procedure for producing parametric 3D bone models from CT data of the knee1 ScopeThis document provides requirements for capturing necessary bone geometries, when using a medical X-ray computed tomography apparat
22、us, to provide the information for applications such as preoperative planning, surgical navigation, robotic surgeries, patient matched instruments and personalized total knee joint prosthesis. The conditions to scan images of bones and the conditions to reconstruct three-dimensional bone models are
23、provided.NOTE Requirements for the competence of testing laboratories appropriate to help to ensure the reliability and accuracy of the computational measurements can be found in ISO/IEC 17025.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of
24、 their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 7207-1, Implants for surgery Components for partial and total knee joint prosth
25、eses Part 1: Classification, definitions and designation of dimensionsISO 14971, Medical devices Application of risk management to medical devicesISO 21536, Non-active surgical implants Joint replacement implants Specific requirements for knee-joint replacement implantsIEC 61223-2-6, Evaluation and
26、routine testing in medical imaging departments Part 26: Constancy tests Imaging performance of computed tomography X-ray equipmentIEC/TR 60788, Medical electrical equipment Glossary of defined terms3 Terms, definitions and abbreviated terms3.1 Terms and definitions For the purposes of this document,
27、 the terms and definitions given in IEC/TR 60788, IEC 61223-2-6, ISO 21536, ISO 7207-1 and the following apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform:
28、 available at http:/www.iso.org/obp 3.1.13D bone modelbone model that is reconstructed based on CT images and made from 3D shape data in the computerINTERNATIONAL STANDARD ISO 19233-1:2017(E) ISO 2017 All rights reserved 1BS ISO 19233-1:2017ISO 19233-1:2017(E)3.1.2personalized artificial knee jointk
29、nee joint prosthesis specifically designed for each patient3.1.3field of viewscanning field of view which includes the intended side of the lower limb3.1.4CT apparatusX-ray computed tomographytechnology that uses computer-processed x-rays to produce tomographic images (virtual “slices”) of specific
30、areas of the scanned object, allowing the user to see what is inside it without cutting it openNote 1 to entry: Digital geometry processing is used to generate a three-dimensional (3D) image of an object from two-dimensional (2D) radiographic images taken by the CT apparatus in a spiral path around
31、a single axis of rotation.3.2 Abbreviated terms 2D two-dimensional3D three-dimensionalCT computed tomography4 PrinciplesIn order to perform applications which require information on the bone shape of the patient, it may be necessary to accurately obtain the 3D bone geometry in detail. A medical CT a
32、pparatus, which has high spatial resolution and does not require surgical invasion, can be used to reconstruct and measure the 3D bones geometries.One example may be the design of a personalized total knee joint prosthesis. In this example, at the time of implantation, leg alignments need to be cons
33、idered. Therefore, it is necessary to measure the dimensions of bones after establishing proper leg alignments.5 Requirements5.1 Imaging conditions5.1.1 Medical imaging apparatusA CT apparatus shall be used for measuring bone geometry from medical images with accurate information. A multi-slice CT a
34、pparatus should be used for scanning in short times and to obtain clear images.Consideration should be given to scan time and the amount of time a patient is required to not move during scanning to ensure that one obtains a quality image without distortion due to patient movement.5.1.2 Region of int
35、erestThe selected region of interest shall include the knee articulation and is intended to take geometric measuring from the physiological bone structure. The selected region of interest can comprise:a) the full length of the leg;b) the femoral head, the knee joint, and the talocrural joint;2 ISO 2
36、017 All rights reservedBS ISO 19233-1:2017ISO 19233-1:2017(E)c) the knee joint.Selected regions of interest are illustrated in Figure 1.In case of c) only joint scanning in Figure 1, plain X-ray images of a leg in a standing position shall be taken to identify leg alignment (see 5.1.10).For other ca
37、ses, appropriate measures should be taken to identify leg alignment (see 5.1.10).a) Full leg scanning b) Partial joints scanning c) Only joint scanningFigure 1 Illustrations of region of interest5.1.3 Body positionBody position for scanning shall be the supine position with knee in extension.5.1.4 F
38、ield of view (FOV)Field of view shall exceed the dimension of the target anatomy, but also be limited to ensure the resolution of the reconstructed image.Generally, the field of view is appropriate between 200 mm to 250 mm. For bilateral CT scanning cases, it shall be extended to 320 mm.5.1.5 Slice
39、thickness and slice spacingSince the reproducibility can be affected by reconstruction conditions, optimum conditions should be set for each software. Slice thickness and slice spacing should be determined appropriately for each subject and the value of these should be minimized.As slice thickness a
40、nd slice spacing increase, the information between the slice images becomes imprecise, and the accuracy of the reconstructed 3D bone models decreases. ISO 2017 All rights reserved 3BS ISO 19233-1:2017ISO 19233-1:2017(E)In case of the slice thickness and slice spacing exceeding more than 2,0 mm and 1
41、,5 mm respectively, it is strongly recommended to perform validation in a proper manner. Annex A presents a procedure for software validation.5.1.6 Reconstruction kernelChoose the most appropriate reconstruction kernel of the CT apparatus used to reconstruct 3D bone models.5.1.7 X-ray tube currentX-
42、ray tube current should be set so as not to cause signal noise which may significantly decrease the precision of 3D bone models. Also, use of the Automatic Exposure Control (AEC) system for the CT apparatus is recommended to reduce exposure dose.5.1.8 X-ray tube voltageSet the appropriate X-ray tube
43、 voltage within the range of 80 kV to 140 kV according to the conditions of the CT apparatus used and the subject.5.1.9 PrecautionsAttention shall be taken to:1) presence of metals around the scanning region of interest which can produce artefacts in the CT scan imageIt especially includes metallic
44、implants in the subject or opposite legs. And in case of implanted metallic components in the opposite leg, a proper positioning of the body can prevent or reduce metal artefacts.2) body moving while scanningThe subject cannot move while scanning. If the subject moves while scanning, another scan is
45、 required.NOTE Scan images with a thin, cylindrical rod attached and parallel to the patients leg are useful for detecting patient movement. If the scan image of the rod is not straight, it means that the patient has moved while scanning.5.1.10 Leg alignmentSince it is impossible to determine alignm
46、ents correctly only from CT images of the knee joint, plain X-ray images of a leg in a standing position should be used together.When taking plain X-ray images, attention should be paid to the rotation and to the use of the exact coronal and sagittal images, including the range from femoral head to
47、ankle joint.As distortions of plain X-ray images are caused by the distance between the focal point, object and film at the time of taking plain X-ray images, image correction could be necessary.Using appropriate landmarks for obtaining the images, construct the mechanical axis and the bone axes. Th
48、en, measure the angles between each axis, and apply them to 3D bone models reconstructed from CT images.See Figure 2.4 ISO 2017 All rights reservedBS ISO 19233-1:2017ISO 19233-1:2017(E)a) Example of plain X-ray image b) Example of 3D modelsKey1 mechanical axis2 anatomical axisFigure 2 Example of pla
49、in X-ray image and 3D models5.2 Software regulatory requirementsFor the generation of bone models, a software intended to be used as a segmentation system for the transfer of imaging information from a CT medical scanner to an output file shall be used.As this software is also used to diagnose and investigate the lower leg anatomy, the software should comply with the regulations on Medical Device Software. Functional verification testing should be conducted to verify that design outputs meet the requirements.
