.. O código serve para colocar as fontes necessárias - dados do Google Fonts .. raw:: html ================================================================== Evaluation of Pre- and Post-Surgical Tomography via OrtogOnBlender ================================================================== .. figure:: images/Voxel_capa.jpg | **Cicero Moraes** | *3D Designer, Arc-Team Brazil, Sinop-MT, Brazil - Bachelor’s degree in Marketing, Dr. h. c. FATELL/FUNCAR (Brazil) and CEGECIS (Mexico) - Member of Sigma Xi, Mensa Brazil, Poetic Genius Society, and International Society for the Study of Creativity and Innovation (ISSCI) - Invited reviewer: Elsevier, Springer Nature, PLoS, Wiley, and LWW - Guinness World Records 2022: First 3D-printed tortoise shell.* | `Google Scholar `__, `ResearchGate `__, `ORCID `__, `Homepage. `__ | **Liat Segal-BenMoyal** | *Specialist in Oral and Maxillofacial Surgery in Wolfson Medical Center, Holon, Israel* | `ResearchGate `__, `PubMed `__ .. SERVE APENAS PARA DAR UM ESPAÇO ENTRE A IMAGEM DE CAPA E O NOME DO PRIMEIRO AUTOR .. only:: html \ .. ==== .. pdftk ~/prj/SPHINX2/OrtogOnLineMag_13/_build/latex/OrtogOnBlender.pdf cat 27-31 output Voxel.pdf && gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dNOPAUSE -dQUIET -dBATCH -dPDFSETTINGS=/printer -sOutputFile=Voxel_pre.pdf Voxel.pdf .. only:: latex | Publication date: May 4, 2026 | ISSN: **2764-9466** (Vol. 7, No. 2, 2026) | DOI: 10.6084/m9.figshare.32163054 .. only:: html | Publication date: May 4, 2026 | ISSN: **2764-9466** (Vol. 7, No. 2, 2026) | DOI: https://doi.org/10.6084/m9.figshare.32163054 **Abstract** *This work presents a standardized protocol for the comparative analysis of pre- and post-operative tomographies using the OrtogOnBlender (OOB) add-on, in versions 291 and XP. The methodology focuses on the integration of voxel data and 3D meshes within a single project environment, optimizing the workflow by avoiding the execution of multiple software instances. Detailed procedures include hierarchical parenting, structural alignment via automatic or manual tools, and the adjustment of object constraints for unified boolean visualization. This guide aims to enable advanced users to perform precise clinical measurements and photorealistic overlays.* **Keywords**: *OrtogOnBlender, Computed Tomography, Surgical Planning, Blender, Open Science.* ------------ Introduction ------------ Comparative analysis between pre- and postoperative states constitutes an essential clinical demand for evaluating surgical outcomes and therapeutic monitoring. Although the OrtogOnBlender (OOB) add-on provides tools for this purpose, the scarcity of didactic protocols hinders the learning curve and the practical application of the technology. The present work proposes a standardized methodology for volumetric comparison (voxel data in DICOM slices) and surface comparison (reconstructed 3D meshes), incorporating recent updates to the system's source code to meet the operational demands identified by users. OOB provides computed tomography import tools for both voxel data and 3D mesh reconstruction based on Hounsfield scale factors. In OOB 291, the most utilized approaches are voxel data reconstruction via slices arranged in the sagittal and coronal planes [Moraes_et_al_2021_d]_; regarding 3D meshes, the two most common methods are those based on Slicer [Moraes_et_al_2021b_d]_ and VTK-ITK [Moraes_et_al_2021c_d]_. OOB XP improved the exam tracking and selection experience [Moraes_et_al_2024_d]_, in addition to implementing AI-based tissue segmentation [Moraes_et_al_2024b_d]_ and a unified head import system [Moraes_et_al_2025_d]_. While the voxel data import interface has been simplified, it still largely follows the structural approach of the previous version. Since the knowledge regarding the tomography import process—whether via voxel data or 3D mesh—is significantly documented, these parts will not be detailed. The present material will focus on the steps necessary to adjust the models so they occupy the same coordinate space, allowing for the comparison of exams. .. important:: The approach described in this material is applicable to both OOB 291 and OOB XP. ----------- How it Woks ----------- Some structural modifications have been implemented in OOB, both in the 291 and XP versions, to provide support for pre- and post-surgical comparisons, or any other approach involving two or more tomographies and 3D meshes. However, despite these adjustments, it is still necessary for the user to open two instances of Blender—essentially running the program twice—to reconstruct the desired structures (specifically the voxel data and the 3D mesh) in each; subsequently, both models can be copied and pasted into the same file. A way to circumvent this without opening two instances is simply to reconstruct one structure within the open Blender file and duplicate the entire set. This will generate objects with the ".001" suffix added to the original names (e.g., Bones will become Bones.001, SoftTissue as SoftTissue.001, and so forth). Once this is done, preferably by placing the tomography into a separate Collection named "BEFORE" or "AFTER," the original objects (Bones, SoftTissue, etc.) can be deleted and the second tomography imported. In this manner, the entire process can be conducted within a single file. .. attention:: This material was developed for advanced OOB and Blender users, focusing exclusively on the technical details of new tools and solutions based on accumulated prior knowledge. Beginner users may find it difficult to follow the documentation and tests presented herein. .. _figVOX_1: .. figure:: images/Voxel_1.png New button as of version 2026-05-02 in OOB 291: Parent Voxels to Bones. There is only one specific adjustment to be made in OOB 291 regarding the parenting of voxel data to the 3D mesh. Unlike OOB XP, where this process is automated and occurs without the need for direct intervention, in OOB 291, the operation must be executed manually via the "Parent Voxels to Bones" button (:numref:`figVOX_1`, bottom), located within the VOXEL-FULL SLICER panel. Since OOB XP remains in the development phase and is currently focused entirely on orthognathic surgery, there is a greater feasibility for automating various functionalities. On the other hand, as OOB 291 is the release version widely utilized by specialists across different healthcare fields, its tools remain more comprehensive and feature a lower level of automation. .. _figVOX_2: .. figure:: images/Voxel_2.png Scene containing two datasets: BEFORE and AFTER, representing the pre- and post-surgical states. Since the voxel data is properly parented to the Bones object, maintaining the visibility of both meshes (Bones and Bones.001) is sufficient for the rest of the structural elements to follow any transformations. As the voxel data and the other 3D meshes are linked (via parent/child hierarchy) to the Bones and Bones.001 objects, all spatial transformations applied to the "parent" elements will be replicated across their respective "children." Consequently, the alignment between the pre- and post-operative states can be performed while keeping only these primary meshes visible (:numref:`figVOX_2`). While, in theory, parenting the initial state is not mandatory, doing so grants the user the flexibility to perform additional pre-adjustments, such as aligning to the natural head position or the Frankfurt plane. .. _figVOX_3: .. figure:: images/Voxel_3.png Aligned skulls and, consequently, all other parented structures properly positioned. Once the skulls (Bones and Bones.001) are aligned (:numref:`figVOX_3`), all dependent structures will be aligned as well. However, it is essential to note that even though they represent the same individual in pre- and post-operative states, minor structural bone discrepancies may occur. Such variations can arise from different tomograph parameterizations between acquisitions or from changes in non-surgical regions, such as dental movements resulting from orthodontic treatment. The user has several methods available for structural alignment, including ICP align (automatic), the OOB 291 Alignment tools (semi-automatic), manual adjustment, or a hybrid approach (automatic and manual). .. _figVOX_4: .. figure:: images/Voxel_4.png Unified boolean block via Object Constraint. Each voxel data block possesses its own "boolean cube," a structure utilized for internal visualization through displacements and boolean calculations. Since one of the datasets had to be realigned—undergoing translation and rotation to match the other—the respective visualization cube will be misaligned relative to the target. To correct this discrepancy, the displaced cube should be selected and assigned a Copy Transforms type Object Constraint. In this manner, the cube will mimic the behavior of the reference object, unifying the boolean visualization tool (:numref:`figVOX_4`). .. _figVOX_5: .. figure:: images/Voxel_5.png Raw overlap of the models. When observing the overlap of the models under a more opaque rendering, such as Skin (:numref:`figVOX_5`), it is evident that the rotation of the voxel planes and the boolean limitation within the same physical space hinder a full visualization of the details. This issue can be mitigated by toggling the visibility of the Collection to which the voxel belongs or by applying a slight displacement between the voxel groups. .. _figVOX_6: .. figure:: images/Voxel_6.png Controlled displacement of booleans. This positional adjustment can be achieved by decreasing the Influence parameter of the Copy Transforms Constraint or, alternatively, by individually manipulating the displacement of the other boolean object (:numref:`figVOX_6`). .. _figVOX_7: .. figure:: images/Voxel_7.png Overlap of images rendered from an orthographic side view. With the structures properly aligned, the user can perform a series of measurements and clinical observations. In addition to delineating structures of interest for pre- and post-operative comparative analysis—as well as positioning spheres or other primitives to mark cephalometric points—it is possible to render images at the same cross-sectional plane for both states. This approach allows for the composition of visualizations either within the native Blender environment or in external software, such as Gimp (:numref:`figVOX_7`). .. _figVOX_8: .. figure:: images/Voxel_capa.jpg Voxel data and 3D mesh overlay. There is also the possibility of customizing the voxel materials to visually distinguish between different datasets in an interactive manner. If the user desires, textured facial photogrammetry can be imported into the scene, enabling the observation of surface alterations with realistic coloration and appearance. By utilizing the techniques described in this manual, the user can generate a composite visualization of the voxel data and the 3D mesh, facilitating spatial and anatomical orientation (:numref:`figVOX_8`). .. note:: A detailed video lesson has been made available on the official OrtogOnBlender course platform at https://ortogonline.eadplataforma.app/lesson/detail/5/168. However, in alignment with the principles of Open Science and open protocols, this material allows interested parties to replicate the procedure via text, provided they possess the necessary prior technical knowledge. While enrolling in the `complete training `__ supports the project's sustainability, this document aims to meet the needs of users who may not be able to acquire it at this time. ---------- Conclusion ---------- The implementation of this protocol demonstrates that complex comparative analyses can be efficiently performed within the OOB open-source ecosystem. By mastering hierarchy management and alignment tools, the specialist achieves greater precision in therapeutic monitoring and the evaluation of surgical outcomes. ---------- References ---------- .. raw:: latex \begingroup \def\section#1#2{} \def\chapter#1#2{} \begin{thebibliography}{1234} .. [Moraes_et_al_2021_d] Moraes, C., Graf, M., Dornelles, R., & Rosa, E. da. (2021). Reconstrução de Voxel Data no OrtogOnBlender. figshare. https://doi.org/10.6084/M9.FIGSHARE.13670134.https://ortogonline.com/doc/pt_br/OrtogOnLineMag/2/VoxelSlicer.html .. [Moraes_et_al_2021b_d] Moraes, C., Dornelles, R., & Rosa, E. da. (2021). Sistema de Reconstrução de Tomografia Computadorizada Baseado no Slicer 3D e no DicomToMesh. figshare. https://doi.org/10.6084/M9.FIGSHARE.13513890. https://ortogonline.com/doc/pt_br/OrtogOnLineMag/2/Slicer.html .. [Moraes_et_al_2021c_d] Moraes, C., Dakir, I., Dornelles, R., & Rosa, E. da. (2021). Reconstrução de Tomografias com o VTK Python, o SimpleITK e o Multiprocessing. figshare. https://doi.org/10.6084/M9.FIGSHARE.14370902. https://ortogonline.com/doc/pt_br/OrtogOnLineMag/3/VTK_ITK_multi.html .. [Moraes_et_al_2024_d] Moraes, C., Dakir, I., Startek, B., Dornelles, R., & Rosa, E. da. (2024). Ferramenta de Importação de Tomografia Computadorizada no OrtogOnBlender XP. figshare. https://doi.org/10.6084/M9.FIGSHARE.27648876. https://ortogonline.com/doc/pt_br/OrtogOnLineMag/10/CT_Scan.html .. [Moraes_et_al_2024b_d] Moraes, C., Dakir, I., Startek, B., Dornelles, R., & Rosa, E. da. (2024). Segmentação de Tomografias Computadorizadas por IA no OrtogOnBlender XP. figshare. https://doi.org/10.6084/M9.FIGSHARE.27761970. https://ortogonline.com/doc/pt_br/OrtogOnLineMag/10/AI.html .. [Moraes_et_al_2025_d] Moraes, C., Startek, B., Dakir, I., Schreiner, T., Dornelles, R., & Rosa, E. da. (2025). Sistema Unificado para a Criação de um Crânio Composto no OrtogOnBlender XP. figshare. https://doi.org/10.6084/M9.FIGSHARE.28135760. https://ortogonline.com/doc/pt_br/OrtogOnLineMag/11/Unificado.html .. raw:: latex \end{thebibliography} \endgroup