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Perthes Disease
Published in Benjamin Joseph, Selvadurai Nayagam, Randall T Loder, Anjali Benjamin Daniel, Essential Paediatric Orthopaedic Decision Making, 2022
To prevent deformation of the femoral head: Achieve containment of the femoral head by any one of the following methods: Abduction cast/brace (A-frame orthosis)2Femoral varus derotation osteotomy3Pelvic osteotomy (Salter, Triple, Shelf)4–6
Image Registration, Segmentation and Virtual Simulation
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Vibeke Nordmark Hansen, J.-C. Rosenwald
As adaptive on-line planning is becoming more popular (see Section 48.4), improvement of automatic image segmentation is required. However, for on-line adaptation, the best starting point is to use the outline set from the patient's own original planning CT as the reference. This can already be done on many planning systems and generally yields an accurate segmentation based on deformation of the patient. This deformation is likely to be minor, as the patient is set up in the same position, and only internal anatomy changes may have happened.
Roller Compaction Technology
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Ronald W. Miller, Vishwas Nesarikar
When powder granules undergo an applied force or stress, a stress force is released from the granules. The granules attempt to return to their original shape or form; this is described as elastic deformation. A deformation that does not totally recover after the stress is released is a plastic deformation. Elastic and plastic deformations can occur simultaneously, but one effect usually predominates.
Finite element simulation of multilayer model to simulate fine needle insertion mechanism into iliac crest for bone marrow biopsy
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Rahul Nadda, Ramjee Repaka, Ashish Kumar Sahani
Nevertheless, the studies described above have not used human BMB in practice. This is due to inevitable fracture of bone and damage of tissue caused by extensive deformation. Hence, clinicians need novel methods. To overcome this needle insertion medical challenge, a technique is needed to measure tissue deformation during needle insertion to help clinicians learn needle-tissue interactions and increase target precision. FEA has the potential to address this problem in explicit dynamic needle-tissue and bone damage examination. However, this is particularly tough because element deletion methods are needed to represent it. FEA with element deletion method is generally recognized as Lagrangian-based FEA for structural studies. Although, it is difficult to achieve consistent results because mesh in FEM requires the structure to be reversed or to discard specific nodes when damage or needle-tissue interaction occurs. Therefore, we employ a Lagrangian approach for simulation, which is also appropriate for bone damage and large tissue deformation while using the continuum models.
Compression–decompression modulus (CDM) – an alternative/complementary approach to Heckel’s analysis
Published in Pharmaceutical Development and Technology, 2022
Devang B. Patel, Vivek D. Patel, Yash Patel, John C. Sturgis, Robert Sedlock, Rahul V. Haware
A low YPel implies less pressure requirement of a compact for the possible axial elastic recovery after the release of compression pressure. As the majority of the deformation gets recovered easily (low YPel) during the unloading process, such materials are termed as a ‘predominantly elastic material’. This can lead to a reduction in the bonding area followed by a bonding strength of the deformed particles. These events eventually translate into the formation of weaker tablets. Due to this, elastic materials are known to form the weaker tablets compared to the fragmenting and plastic materials. This trend was mirrored with a statistically significant negative impact of YPel on the TMS. However, it is important to note that, unlike a decompression modulus, this elastic recovery indicator Heckel descriptor is about to become statistically insignificant though these different parameters are derived from the same compression profile generated under similar experimental settings.
Shape-constrained Gaussian process regression for surface reconstruction and multimodal, non-rigid image registration
Published in Journal of Applied Statistics, 2022
Thomas Deregnaucourt, Chafik Samir, Sebastian Kurtek, Anne-Francoise Yao
There is a large number of applications demanding image registration including medical imaging, biology, computer vision, robotics, and many others [26]. In general, the registration problem consists of mapping a target image to a reference image under certain smoothness and boundary constraints. For 2D and 3D image registration, the estimated deformation can be based on pixel/voxel intensity values (i.e. gray-scale level correspondences), geometric features (e.g. landmark points or curves), or both (usually referred to as hybrid methods) [24,26]. As a result, image registration methods can be roughly categorized into two groups: (1) intensity-based, which integrate spatial information over the entire image domain, and (2) feature-based, which require a representation of the image data in terms of relevant geometric features. Feature-based methods offer more robust registration when the intensity distribution varies due to artifacts or differences in the imaging protocols. Generally, automatic segmentation of geometric structures in Ultrasound (US) images is inaccurate due to intensity changes. But, fairly accurate segmentation of distinctive structures, such as those considered in this paper, is achievable by a medical expert. The most distinctive anatomical structures in such images are easily distinguished organs. We use the boundaries of these structures, which form parameterized curves, as geometric features in the proposed registration framework.