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Scanning Techniques and Image Processing
Published in Yongjie Jessica Zhang, Geometric Modeling and Mesh Generation from Scanned Images, 2018
Different from CT, magnetic resonance imaging (MRI) does not use ionizing radiation to scan images. An MRI scanner is a sophisticated facility consisting of a large magnet, a microwave transmitter, a microwave antenna, and several electronic components to decode the signal and reconstruct crosssectional images. The cost of an MRI system is more expensive than a CT system, ranging from $500,000 to $2,000,000 or even $3,000,000. In an MRI scanner, the bore is often 6 to 8 feet or 2 meters long. During the image acquisition, patients are positioned in the middle of the magnetic field. Due to large Faraday cages and substantial iron masses surrounding the magnet, the environments for MRI scanners must be well shielded like CT facilities to avoid possible magnetic and radiofrequency interference.
3D Printing in Medicine
Published in Rafiq Noorani, 3D Printing, 2017
MRI is the technique of taking pictures of various parts of the body without the use of x-rays. An MRI is safe for most patients. People who are claustrophobic and who have implanted medical devices such as a eurysim clip in the brain, heart pacemakers, and cochlear implants may not be able to have an MRI. An MRI scanner employs a large and very strong magnet which envelopes the patient. A radio wave antenna is used to send “radio wave signals” to the body and then receive the signals back. These returning signals are converted into pictures by a computer attached to the scanner. MRI is a powerful and versatile tool that generates thin-section images of any part of the body including the heart, arteries and veins, from any angle and any direction without surgical intervention. MRIs can also be used to create “maps” of biochemical compounds within any cross-section of the body. These maps provide valuable biomedical and anatomical information for new knowledge and for early diagnosis of many diseases.
A Survey of Medical Imaging Systems
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
An MRI is also called magnetic resonance tomography (MRT) because one of the display modes is tomographic slices. An MRI scanner is basically a very large magnet with a hole in its center into which the patient is put. Before describing the physical details of how MRI works, let us examine some of the pros and cons of this NI imaging method. MRI advantages include: (1) MRI is totally NI and essentially risk free. Unlike PET and CAT methods, there are no ionizing radiations from within or without. (2) MRI gives excellent contrast for soft tissues including the brain, breasts, lungs, and liver. (3) MRI images blood vessels with high contrast because of the high-water content of blood. This feature enables the detection of aneurisms, stenoses, areas of high perfusion in parts of the brain during specific tasks, and the vascularization accompanying tumors. Some disadvantages of MRI are: (1) An MRI scan takes a long time; ∼30 min, during which the patient must remain motionless to avoid image blurring. (2) MRI does not image bone well; tissue calcification is not easily seen. (3) MRI is acoustically noisy. The gradient magnets are switched on and off, producing loud “thunks” from magnetostriction. In some cases, this noise can reach 95 dB. A patient should wear earplugs to prevent possible hearing loss. (4) Because of the very high-magnetic fields involved, patients wearing pacemakers or cochlear implants, or having implanted metal joints, cannot undergo MRI. MRI is also avoided during the first trimester of pregnancy, although there are no reported harmful effects to the fetus. An MRT has pixel resolution between ∼0.5 and 1 mm (Petridou et al. 2012).
Hospital design principles implementation: Reflections from practitioners in Thailand
Published in Journal of Asian Architecture and Building Engineering, 2023
Traiwat Viryasiri, Vikrom Laovisutthichai, Kullathida Sangnin, Kawin Dhanakoses, Pakwan Roopkaew, Pundharee Viryasiri
In Thailand, a “form – follow–function” design approach has been widely adopted. Some efficient and practical solutions are implemented, including providing a service corridor behind all examination rooms for medical equipment logistics and supply chain management. With the rapid development of medical service procedures and technologies, these spatial demands, requirements, and arrangements have been shifted. Thai practitioners have recognized these changes and already considered them in their design practice, suggesting that they introduce both opportunities and challenges to the design. In the past, a pneumatic tube for delivering blood, drugs, and documents must be designed carefully, as the noise from its operation may disturb patients and medical staff. Currently, the new pneumatic tube system with lab automation technology for blood delivery requires only around one inch in diameter for operations. It reduces noise, improves working productivity, and requires less space. The Magnetic Resonance Imaging (MRI) scanner is a massive magnetic scanner, producing human body images. It should not be located underground to lessen the risk of flood, avoid high humidity rates, and reduce the machinery maintenance cost. These examples explain new design requirements that emerged from technological advancements. In response to these shifts, many existing buildings require B3) additional budget and resources for renovation (see Figure 4), while the new building design should be able to accommodate future changes in the industry.