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Treatment planning
Published in Jing Cai, Joe Y. Chang, Fang-Fang Yin, Principles and Practice of Image-Guided Radiation Therapy of Lung Cancer, 2017
Yan Yu, Kamila Nowak Choi, Virginia Lockamy
The carina is the point where the trachea bifurcates into the right and left main stem bronchi. It is a useful landmark that can be used for CBCT registration, and carina matching has been shown to identify setup errors and provide superior nodal coverage and combined target coverage as compared to spine matching [85].
Elements of Continuum Mechanics
Published in Clement Kleinstreuer, Biofluid Dynamics, 2016
Fig.4.1.2 Nasal airways with specific flow regions (Shi, 2006). the projection of turbinates from the lateral wall (Fig. 4.1.2). Mucous layers on the passage walls condition the inhaled air and trap fine/ultrafine particles and microorganisms. The turbinates are bones with warm mucousmembrane surfaces that also contain sensitive nerves that detect odors or induce sneezing to expel irritating particles. The pharynx (or throat) is a muscular section where air flows from the nose to the larynx/ trachea and food slides from the mouth to the esophagus/stomach. The regulator is the epiglottis which closes during swallowing and is open during breathing. The larynx (or voice box) is a cartilaginous structure connecting the pharynx and trachea. It mainly contains the vocal cords which produce sound because of vibration when air passes through the opening, called the glottis. The trachea (or windpipe) is a smooth-muscle tube supported by incomplete, i.e., C-shaped, cartilaginous rings. After the airway constriction in the larynx, airflow in the trachea and below may become turbulent at elevated breathing rates. The trachea divides at the carina to form the left and right bronchi (or branches) leading to the lungs. Specifically, these bronchi bifurcate into three secondary bronchi in the right lung and into two in the left lung. This portion of the respiratory tract is also lined with mucous membranes where the cilia (i.e., fine hairs) sweep mucus and embedded particles toward the pharynx for clearing. Further repeat-bifurcations of the bronchi rapidly reduce the local airflow rate and geometric dimensions until the terminal bronchioles are reached which become the alveolar ducts. Clearly, even when the airflow in the trachea is turbulent, say, during exercise, continuous airflow rate division quickly reduces the local Reynolds number all the way to Re<1 in the alveolar region. At the end of the alveolar ducts millions of small sacs (the alveoli) are clustered, surrounded by capillary beds connected to both the pulmonary artery and the pulmonary vein. The thin-walled alveoli consist of a layer of epithelial cells for the O2−CO2 exchange, surfactant production to control the sac stability via variable surface tension, and scavenging of foreign material, such as bacteria.
Evaluating the biomechanical characteristics of cuffed-tracheostomy tubes using finite element analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Dhananjay Radhakrishnan Subramaniam, Liran Oren, J. Paul Willging, Ephraim J. Gutmark
The finite element model of the trachea was constructed from computed tomography (CT) scans obtained from a public repository (www.osirix-viewer.com), for a healthy 43-year-old subject with no history of lung disease. The images were acquired using a 16-detector CT scanner and consisted of 200 slices (each 2 mm thick) extending from the thyroid cartilage to the carina. The pixel spacing of the CT images was 0.7422 × 0.7422 mm (spatial resolution: 512 × 512 pixels). Due to challenges in accurately identifying the inner and outer surfaces of the trachea wall, a semi-automatic segmentation of the CT scans was performed using the Materialise Mimics 20.0 image processing software (Materialise NV, Leuven, Belgium) to reconstruct the airway wall. The cartilage rings were isolated based on their higher density, to precisely differentiate between cartilaginous and muscle tissue (Pérez del Palomar et al. 2010; Trabelsi et al. 2011). The resulting airway wall geometry consisted of 10 cartilage rings (including a circular section of the carina), 10 connective tissue segments between the individual cartilage rings, and the posterior wall smooth muscle, similar to that described in previous FEA studies (Bagnoli et al. 2011, 2013; Safshekan et al. 2020). As compared to previous computational studies that assumed a uniform airway wall thickness (Malvè et al. 2011a, 2011b), the trachea geometry in the present study was characterized by a non-uniform wall thickness.
Morphological changes in the respiratory system: an MRI investigation of differences between the supine and left lateral decubitus positions
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2021
J. Paige Little, Erin Chapman, Adam Parr, Gregory Moloney, Simon Bowler, Robert D. Labrom, Geoffrey N. Askin
The cross-sectional area and centroid of the left and right lungs were measured using a transverse plane through the carina of the trachea. This plane was the MRI slice where the bifurcation of the trachea into left and right main bronchi was just visible (Figure 3). The following measurements were obtained for each participant, on both the left and right lung, in both positions: Transverse cross-sectional Area: The main borders of the lung were traced, excluding heart tissue (Figure 3(a)).Transverse Centroid: Calculated as the centre of area of the demarcated transverse lung area. The location of the centroid was defined relative to the position of the carina (Figure 3(b)).
Aerosol deposition in 3D models of the upper airways and trachea of rhesus macaques
Published in Aerosol Science and Technology, 2020
Jana S. Kesavan, Valerie J. Alstadt, Beth L. Laube
The 3D file was modified by closing the mouth opening and attaching an exit tube at the end of the trachea using Geomagic Design X (3D systems). The mouth opening was closed in order to isolate particle deposition to nasal breathing alone. The 3D file was also sectioned into four segments using the SLA system. Four holes were inserted into the file around the periphery of each of the segments using Geomagic Design X. None of the holes passed through the model airways. When the model was printed, four rods were passed through these holes to hold the segments together. We chose to divide the upper airways into segments in order to quantify regional deposition within each segment in future experiments. Files were saved as STL files for 3D printing. Each model included the animal’s face with nostrils, nasal passages, pharynx, larynx and entire length of trachea to carina. We chose to include the trachea in our UAT models because the scans we used to generate each model provided complete images of the trachea and we decided that inclusion of the trachea would provide additional information regarding deposition estimates.