Úvod a cíl: Množství publikací a investic do 3D tisku jsou důkazem nárůstu zájmu o tuto výrobní metodu. Za objevitele s prvním patentem v oboru se považuje Američan Charles W. Hull. Principem 3D tisku je tisk žádaného předmětu ve vrstvách na základě jeho předlohy, nejčastěji ve formátu .stl (stereolitografie). Existuje sedm základních technologických procesů tisku, pět z nich má využití v zubním lékařství. Text se blíže zabývá třemi nejčastěji využívanými metodami Vat Polymerisation, Material Extrusion a Powder Bed Fusion. Ve stomatologii má strojová aditivní výroba významnou úlohu již delší dobu. Zejména v implantologii pro tisk chirurgických šablon a v ortodoncii pro tisk studijních modelů a takzvaných neviditelných rovnátek. Aditivní výroba umožňuje také tisk retenčních aparátů a usnadňuje autotransplantace zubů, přičemž postupně získává na důležitosti i v jiných sektorech stomatologie, jako v konzervačním zubním lékařství při dostavbě IV. Blackovy třídy, v navigované endodoncii a také v protetickém zubním lékařství při tisku kovových konstrukcí a dalších komponent, ať již ve fixní, nebo snímatelné protetice v zubní laboratoři. Mezi aktuální aplikace patří také tisk příslušenství, jako například ochranných masek a štítů, nebo tisk 3D modelů skutečných zubů a demonstračních modelů za účelem zlepšení pregraduálního, postgraduálního a kontinuálního vzdělávání. V medicíně se tisk používá například pro výrobu biomateriálů. Využití je tedy rozsáhlé a vliv 3D tisku na stomatologii nezpochybnitelný. Nedostatky tisku jsou podrobovány neustálému výzkumu a je tedy jenom otázka, kdy a do jaké míry nahradí konvenční postupy. Cílem tohoto přehledového článku bylo roztřídit základní informace o 3D tisku týkající se jeho historie, principu a typech tisku, ale hlavně shrnout jeho užití v zubním lékařství.
Introduction, aim: The rise of research papers and investments made into 3D printing are the proof of the increased interest about this manufacturing method. The American Charles W. Hull is considered to be the inventor with the first patent in the field. The principle of 3D printing is printing the desired item in layers according to its template, most often present in .stl format. There are seven main technological processes of 3D printing, five of them are used in dentistry. Text deals with the three methods that are used the most: Vat Polymerisation, Material Extrusion and Powder Bed Fusion. In dentistry, additive manufacturing already has an important role for a longer period of time especially in implantology for the printing of surgical guides and in orthodontics for printing of study models and so-called invisible aligners. Additive manufacturing also allows to print retention appliances, and it facilitates the autotransplantation of teeth, while its importance is slowly rising in other sectors of dentistry such as in conservative dentistry in Class IV reconstruction or in guided endodontics and in prosthetic dentistry for printing of metal substructures and other components either in fixed or removable prosthetics in dental laboratory. Printing of accessories such as protective masks and face-shields or printing of 3D models of the real teeth and demonstration models in order to improve undergraduate, postgraduate and continuous education are among current applications. In medicine the printing is used for example for the production of biomaterials. The range of applications is therefore vast and the impact of 3D printing on dentistry is unquestionable. Shortcomings of printing are undergoing constant research and therefore it is just a matter of time until 3D printing will replace the conventional methods. The objective of this review paper was to sort the basic information about 3D printing with regards to its history, principle and types of printing but more importantly to summarise its use in dentistry.
- MeSH
- Printing, Three-Dimensional * MeSH
- Humans MeSH
- Imaging, Three-Dimensional MeSH
- Dental Implants MeSH
- Models, Dental * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
Angiogenesis is the process of new blood vessels growing from existing vasculature. Visualizing them as a three-dimensional (3D) model is a challenging, yet relevant, task as it would be of great help to researchers, pathologists, and medical doctors. A branching analysis on the 3D model would further facilitate research and diagnostic purposes. In this paper, a pipeline of vision algorithms is elaborated to visualize and analyze blood vessels in 3D from formalin-fixed paraffin-embedded (FFPE) granulation tissue sections with two different staining methods. First, a U-net neural network is used to segment blood vessels from the tissues. Second, image registration is used to align the consecutive images. Coarse registration using an image-intensity optimization technique, followed by finetuning using a neural network based on Spatial Transformers, results in an excellent alignment of images. Lastly, the corresponding segmented masks depicting the blood vessels are aligned and interpolated using the results of the image registration, resulting in a visualized 3D model. Additionally, a skeletonization algorithm is used to analyze the branching characteristics of the 3D vascular model. In summary, computer vision and deep learning is used to reconstruct, visualize and analyze a 3D vascular model from a set of parallel tissue samples. Our technique opens innovative perspectives in the pathophysiological understanding of vascular morphogenesis under different pathophysiological conditions and its potential diagnostic role.
Human face is a dynamic system where facial expressions can rapidly modify geometry of facial features. Facial expressions are believed to be universal across world populations, but only a few studies have explored whether grimacing is sexually dimorphic and if so to what extent. The present paper explores inter- and intra-individual variation of human facial expressions with respect to individual's sex based on a set of neutral and expression-varying 3D facial scans. The study sample composed of 20 individuals (10 males and 10 females) for whom 120 scans featuring grimaces associated with disgust, surprise, "u" sound, smile and wide smile were collected by an optical scanner Vectra XT. In order to quantify the dissimilarity among 3D images, surface comparison approach based on aligned 3D meshes and closest point-to-point distances was carried out in Fidentis Analyst application. The study revealed that sexual dimorphism was indeed one of the factors which determined the extent and characteristics of facial deformations recorded for the studied expressions. In order to produce a grimace, males showed a tendency towards extending their facial movements while females were generally more restrained. Furthermore, the facial movements linked to the wide smile and "u" sound were revealed as the most extensive relative to the other expressions, while the smile and surprise were shown indistinguishable from the neutral face.
- MeSH
- Analysis of Variance MeSH
- Models, Anatomic MeSH
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Face anatomy & histology MeSH
- Sex Characteristics * MeSH
- Smiling MeSH
- Facial Expression * MeSH
- Imaging, Three-Dimensional MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Typical time intervals between acquisitions of three-dimensional (3-D) images of the same cell in live cell imaging are in the orders of minutes. In the meantime, the live cell can move in a water basin on the stage. This movement can hamper the studies of intranuclear processes. We propose a fast point-based image registration method for the suppression of the movement of a cell as a whole in the image data. First, centroids of certain intracellular objects are computed for each image in a time-lapse series. Then, a matching between the centroids, which have the maximal number of pairs, is sought between consecutive point sets by a 3-D extension of a two-dimensional fast point pattern matching method, which is invariant to rotation, translation, local distortion, and extra/missing points. The proposed 3-D extension assumes rotations only around the z axis to retain the complexity of the original method. The final step involves computing the optimal fully 3-D transformation between images from corresponding points in the least-squares manner. The robustness of the method was evaluated on generated data. The results of the simulations show that the method is very precise and its correctness can be estimated. This article also presents two practical application examples, namely the registration of images of HP1 domains and the registration of images of telomeres. More than 97% of time-consecutive images were successfully registered. The results show that the method is very well suited to live cell imaging.
- MeSH
- Algorithms MeSH
- Artifacts MeSH
- Financing, Organized MeSH
- Microscopy, Fluorescence methods MeSH
- Image Interpretation, Computer-Assisted methods MeSH
- Cells, Cultured cytology MeSH
- Humans MeSH
- Cell Movement MeSH
- Reproducibility of Results MeSH
- Pattern Recognition, Automated methods MeSH
- Sensitivity and Specificity MeSH
- Subtraction Technique MeSH
- Information Storage and Retrieval methods MeSH
- Artificial Intelligence MeSH
- Microscopy, Video methods MeSH
- Image Enhancement methods MeSH
- Imaging, Three-Dimensional methods MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Evaluation Study MeSH
- MeSH
- Microscopy, Confocal methods utilization MeSH
- Humans MeSH
- Specimen Handling methods utilization MeSH
- Computers MeSH
- Image Processing, Computer-Assisted methods utilization MeSH
- Programming Languages MeSH
- Software MeSH
- Statistics as Topic MeSH
- Models, Theoretical MeSH
- Imaging, Three-Dimensional methods instrumentation utilization MeSH
- Check Tag
- Humans MeSH
BACKGROUND: Although the etiology of chronic lymphocytic leukemia (CLL), the most common type of adult leukemia, is still unclear, strong evidence implicates antigen involvement in disease ontogeny and evolution. Primary and 3D structure analysis has been utilised in order to discover indications of antigenic pressure. The latter has been mostly based on the 3D models of the clonotypic B cell receptor immunoglobulin (BcR IG) amino acid sequences. Therefore, their accuracy is directly dependent on the quality of the model construction algorithms and the specific methods used to compare the ensuing models. Thus far, reliable and robust methods that can group the IG 3D models based on their structural characteristics are missing. RESULTS: Here we propose a novel method for clustering a set of proteins based on their 3D structure focusing on 3D structures of BcR IG from a large series of patients with CLL. The method combines techniques from the areas of bioinformatics, 3D object recognition and machine learning. The clustering procedure is based on the extraction of 3D descriptors, encoding various properties of the local and global geometrical structure of the proteins. The descriptors are extracted from aligned pairs of proteins. A combination of individual 3D descriptors is also used as an additional method. The comparison of the automatically generated clusters to manual annotation by experts shows an increased accuracy when using the 3D descriptors compared to plain bioinformatics-based comparison. The accuracy is increased even more when using the combination of 3D descriptors. CONCLUSIONS: The experimental results verify that the use of 3D descriptors commonly used for 3D object recognition can be effectively applied to distinguishing structural differences of proteins. The proposed approach can be applied to provide hints for the existence of structural groups in a large set of unannotated BcR IG protein files in both CLL and, by logical extension, other contexts where it is relevant to characterize BcR IG structural similarity. The method does not present any limitations in application and can be extended to other types of proteins.
PURPOSE: This article reports experiences with 3T magnetic resonance imaging(MRI)-guided brachytherapy (BT) for cervical cancer focusing on late side effects. METHODS: Between June 2012 and March 2017 a total of 257 uterovaginal BT administrations were performed in 61 consecutive patients with inoperable cervical cancer. All patients were treated with BT combined with external beam radiotherapy. RESULTS: The mean HR-CTV (high risk-clinical target volume) D90 was 87 ± 5.1 Gy equivalent dose corresponding to the conventional fractionation using 2 Gy per fraction (EQD2, range 70.7-97.9 Gy). The mean doses in OAR (organs at risk), namely rectum, sigmoid and bladder were D2 cm3rectum = 62.6 ± 6.9 Gy EQD2 (range 38.2-77.2 Gy), D2 cm3sigmoid = 66.2 ± 6.8 Gy EQD2 (43.2-78.6 Gy) and D2 cm3bladder = 75.1 ± 8.3 Gy EQD2 (58.2-92.6 Gy). There were no signs of late gastrointestinal (GI) toxicity in 49 patients, grade 3 toxicity was seen in 2 patients and grade 4 toxicity in 3 patients. There were no signs of late genitourinary (GU) toxicity in 41 patients, grade 3 toxicity was seen in 4 patients and no signs of grade 4 toxicity were seen. After the treatment, 60 patients (98.4%) achieved locoregional remission. In 54 patients (88.5%) the remission was complete, whereas in 6 patients (9.8%) remission was partial. CONCLUSION: The use of 3T MRI-guided BT leads to achievement of high rates of local control with limited late morbidity as demonstrated in this series of patients.
- MeSH
- Brachytherapy adverse effects MeSH
- Radiotherapy Dosage * MeSH
- Colon, Sigmoid radiation effects MeSH
- Dose Fractionation, Radiation MeSH
- Combined Modality Therapy MeSH
- Organs at Risk radiation effects MeSH
- Humans MeSH
- Magnetic Resonance Imaging * MeSH
- Urinary Bladder radiation effects MeSH
- Uterine Cervical Neoplasms pathology radiotherapy MeSH
- Follow-Up Studies MeSH
- Radiation Injuries etiology MeSH
- Radiotherapy, Image-Guided adverse effects MeSH
- Rectum radiation effects MeSH
- Neoplasm Staging MeSH
- Check Tag
- Humans MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
PURPOSE: To develop an assumption-free methodology for aligning the geometry of on-board imagers with the geometry of medical linear accelerators applied in image-guided radiotherapy (IGRT). MATERIAL: Alignment of the on-board imaging (OBI) system with respect to the accelerator system is achieved using a multi-modular phantom described elsewhere (Tabor et al., 2017), enabling the geometry of the linear accelerator to be specified without any pre-assumptions. METHODS: The placement of two isocentres (of the on-board imager and of the therapeutic system) and of three frames of reference (those of the on-board imager, of the therapeutic system, and of the treatment table) is formulated as an optimization problem. It is solved by analysing the images of fiducial points positioned in 3D space in phantom modules attached to the treatment table and to the collimator of the accelerator. Fiducials are projected onto an imaging plane of unknown characteristics from a virtual source of unknown coordinates. CONCLUSIONS: An analytical framework exploiting projection images of the proposed multi-modular phantom has been developed, enabling precise alignment of the reference frame related to the on-board imager with the reference frame related to the therapeutic system. Within the proposed framework, the necessary corrections of treatment table positioning prior to patient irradiation, are delivered in the treatment table coordinates.
