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Musculoskeletal system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The patient lies supine in the middle of the scanner table, ensuring that the anterior superior iliac spines are equidistant from the table top and the arms are placed across the chest. The selected hip is abducted to move the lesser trochanter away from the ischium of the pelvis and medially rotated through 25°, bringing the femoral neck parallel to the scanner table. By doing so the greater trochanter is rotated forward and the lesser trochanter backwards, to ensure the long axis of the femur is parallel to the long axis of the table, thus avoiding foreshortening of the neck due to normal femoral neck anteversion and giving adequate bone for analysis (Fig. 3.60a). The patient’s foot is placed using the manufacturers’ foot positioner, which provides support to maintain the required position for the duration of the scan. Using the positioning laser, the scanner arm is centred over the femur 2 cm below the lower border of the symphysis pubis. From this start point, scanning continues cranially covering a maximum distance of 200 mm. The patient is asked to keep still and breathe normally. Although the procedure may be stopped by the operator at any time, scanning must commence at least 2 cm below the lesser trochanter and end no less than 3 cm above the greater trochanter to give adequate coverage for accurate measurements (Fig. 3.60b). Scan time varies depending on the equipment and the supporting software used. A typical scan time is 15–60 seconds.
Optimization and Dose Reduction in Hybrid Imaging: PET/CT and SPECT/CT
Published in Lawrence T. Dauer, Bae P. Chu, Pat B. Zanzonico, Dose, Benefit, and Risk in Medical Imaging, 2018
Adam M. Alessio, Frederic H. Fahey
As in SPECT/CT, an optimal PET/CT imaging protocol would result in images with sufficient diagnostic quality at a minimum of risk. For PET/CT, images often must be of sufficient image quality to perform a variety of tasks (detection, staging, and quantitative monitoring), not just a single binary detection task of a single disease. Images that can perform all of these tasks, without compromising clinically relevant information, have full diagnostic utility. In general, increased scan duration and injected activity leads to increased, favorable count levels, although it is very challenging to determine the “image quality” of an acquisition protocol and therefore challenging to determine if it provides sufficient image quality.69 On the other hand, there are risks associated with the scan duration and injected activity. Specifically, longer scan durations are associated with issues such as motion artifacts, patient discomfort, and complications from potential sedation. Likewise, increased injected activity is linked to a potentially increased risk of radiation-induced cancer.
Swarm Optimization and Machine Learning to Improve the Detection of Brain Tumor
Published in Shikha Agrawal, Manish Gupta, Jitendra Agrawal, Dac-Nhuong Le, Kamlesh Kumar Gupta, Swarm Intelligence and Machine Learning, 2022
Diagnostic steps play and an important role in disease management and help in determining a specific condition a patient is suffering from. When a doctor observes symptoms like long term headaches and loss of balance, he may prescribe scans for the brain and suggest the patient to visit a neurologist or neurosurgical oncologist for further treatment. A scan helps to determine the presence of a tumor, its location and size. Sometimes the patient may require more than one type of scan for better diagnosis of its type and location. Some of the commonly used scanning techniques are CT scans and MRIs [2, 4].
Experimental and numerical studies on the repeated low-velocity impact response and damage accumulation in woven S2-glass fibre/epoxy composites
Published in Advanced Composite Materials, 2023
F. Fulginiti, M. Rezasefat, A. Xavier da Silva, S. C. Amico, M. Giglio, A. Manes
An 8-harness satin S2-glass (302 g/m2, 0.24 mm, 22 threads per cm) fabric from Hexcel® and an epoxy resin AR260 with AH260 hardener (AR/AH260) – 100/26 g/g ratio from Barracuda Advanced Composites were used. Composite laminates were manufactured by vacuum infusion and characterized as previously described in [25,26]. In brief, Figure 1a. illustrates the process with a one-sided mould, 16 layers of stacked dry fabrics (630 × 320) mm, a peel-ply layer and a flow mesh to promote resin distribution. The mould was sealed using tacky tape and a vacuum bag, after accommodating inlet and outlet gates for the resin. After infiltration, driven by an imposed vacuum of 100 kPa, the material was left to cure for 24-h at room temperature, followed by post-curing at 65 °C for 16 h. The plates were later inspected using C-scan ultrasound, as in [25].
Failure patterns of solder joints identified through lifetime vibration tests
Published in Nondestructive Testing and Evaluation, 2023
Kangkana Baishya, David M. Harvey, Teresa Partida Manzanera, Guangming Zhang, Derek R. Braden
A method for non-destructive examination of solder joint degradation as they progress through their operational life comprising of exposure to vibration. Moreover, since all flip chip solder joints are hidden under the flip chip, an imaging system that can penetrate the die is required to successfully ‘see’ the joints. An advanced acoustic imaging system was used, having the capability to image through the top of the chip with sufficient accuracy to collect degradation information at each solder connection. The ultrasound imaging selected was based on a gated 2D C-scan. These Acoustic Micro Imaging (AMI) C-scans [18] are relatively fast but for a doubled-sided populated PCB scanning all the individual flip chips can still take several hours. The measurements to test solder joint integrity were based on the reflection of the ultrasound from the solder joint to flip chip mechanical connection as this is where cracks usually develop. Two metrics were used to track the degradation of joints, the reflected ultrasound intensity, and the reflected ultrasound area, as they both show measurable growth through-life.
Thermal management of an interventional medical device with double layer encapsulation
Published in Experimental Heat Transfer, 2022
Nu Bich Duyen Do, Erik Andreassen, Stephen Edwardsen, Anders Lifjeld, Knut E. Aasmundtveit, Hoang-Vu Nguyen, Kristin Imenes
Ultrasound imaging plays an important role in the diagnosis of cardiovascular diseases. Imaging the heart with a probe inside the esophagus, known as trans-esophageal echocardiography (TEE), has the capability of providing high quality images of the heart. The TEE probe passes through the mouth of the patient into the esophagus, and provides 3D images of the heart in real time [1]. The tip of a TEE probe, referred to as ‘scan head’ in this paper, contains the ultrasound transducer and electronics. The thermal management of a TEE scan head is important with respect to patient safety, since the transducer and the electronics in the scan head generate heat during imaging. Therefore, the temperature distribution on the surface of the scan head must be well controlled to avoid hot spots. According to the standard for the safety and performance of ultrasonic medical diagnostic equipment, IEC 60601-2-37, the temperature of medical devices in contact with the patient for 10 minutes or more must not exceed 43°C, to avoid thermal damage to biological tissue [2]. Thermal management is also critical for the performance, lifetime and reliability of the device [3, 4].