X-ray Vision: Diagnostic X-rays and CT Scans
Suzanne Amador Kane, Boris A. Gelman in Introduction to Physics in Modern Medicine, 2020
Conventional radiographic methods, including computed tomography and digital radiography, are based on detecting and measuring the reduction of intensity (the attenuation) of x-rays due to their absorption and scattering in the body. The image results from the variation of the x-ray attenuation in different parts of the body. The larger the attenuation variation, the greater is the image contrast. The difference in attenuation is the largest between the dense, strongly absorbing (bones, teeth) and soft, weakly absorbing (fat, muscle) tissues. Conventional radiography is less effective in delineating different kinds of soft tissues with similar attenuating properties. A particularly important example is the x-ray imaging for detecting possible cancers (see for example the discussion of mammography in Section 5.8). To overcome the low-contrast problem of soft tissue imaging, medical physicists and engineers are developing alternative x-ray techniques. In this section, we describe one such method, called x-ray phase contrast imaging. While still in the developmental stage, it has the potential to be used in clinical settings.
Introduction to medical imaging
David A Lisle in Imaging for Students, 2012
In the past, X-ray films were processed in a darkroom or in freestanding daylight processors. In modern practice, radiographic images are produced digitally using one of two processes, computed radiography (CR) and digital radiography (DR). CR employs cassettes that are inserted into a laser reader following X-ray exposure. An analogue-digital converter (ADC) produces a digital image. DR uses a detector screen containing silicon detectors that produce an electrical signal when exposed to X-rays. This signal is analysed to produce a digital image. Digital images obtained by CR and DR are sent to viewing workstations for interpretation. Images may also be recorded on X-ray film for portability and remote viewing. Digital radiography has many advantages over conventional radiography, including the ability to perform various manipulations on the images including: Magnification of areas of interest (Fig. 1.2)Alteration of densityMeasurements of distances and angles.
Reduction and Fixation of Sacroiliac joint Dislocation by the Combined Use of S1 Pedicle Screws and an Iliac Rod
Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White in Advances in Spinal Fusion, 2003
Functional integrity of fused vertebrae implies the absence of motion within the fused level despite manipulation of the fused area by flexion/extension or compression. These intervertebral translations of fused vertebrae are induced by a positional change of the patient and can be detected either by flexion-extension radiography or by roentgen stereometric analysis (RSA). Conventional radiography offers a low mean accuracy of 1-5 mm depending on the anatomical region and the number of investigators [6]. RSA is a precise quantifying method in evaluating the functional integrity of spinal arthrodesis. It provides information about persisting micromotion between fused vertebrae and is especially useful for testing the mechanical properties in vivo of different constructs within the unstable spine. RSA has already been proven to achieve an accuracy of 0.3-0.7 mm in spinal arthrodesis depending on the axis of motion [3,7-10]. In other orthopedic fields, RSA has gained wide acceptance in detecting early migration after prosthetic fixation in the hip or knee, in assessing joint stability, and in kinematics or fracture stability [6,11-14].
Cone-beam computed tomography, a new low-dose three-dimensional imaging technique for assessment of bone erosions in rheumatoid arthritis: reliability assessment and comparison with conventional radiography – a BARFOT study
Published in Scandinavian Journal of Rheumatology, 2018
Y Aurell, MLE Andersson, K Forslind
Early and accurate detection of erosions (cortical break) is important for treatment decisions and for monitoring the disease. So far, conventional radiography (CR) has been the reference method and has been used in both clinical trials and clinical practice for this purpose. The main drawback with CR is that it is a two-dimensional presentation of a three-dimensional volume. Therefore, different anatomical structures are superimposed on each other and small erosions may thus evade detection or be interpreted as cysts. To develop reliable imaging methods that have a high sensitivity to erosions, both magnetic resonance imaging (MRI) and ultrasonography scoring systems have been developed (2, 3). Detection, scoring, and volume assessment of bone erosions in RA by ultrasonography in comparison with computed tomography (CT) has been studied (4). In several studies, these methods have been compared to multi-detector computed tomography (MDCT), an imaging method that depicts small changes in the skeleton better than MRI and ultrasonography (5–7). However, MDCT has several disadvantages for this group of patients. One is that the patients have to stretch out the arms above the head in the prone position for imaging of the hands; another is the exposure to ionizing radiation.
Neuro-urological sequelae of lumbar spinal stenosis
Published in International Journal of Neuroscience, 2018
Jason Gandhi, Janki Shah, Gargi Joshi, Sohrab Vatsia, Andrew DiMatteo, Gunjan Joshi, Noel L. Smith, Sardar Ali Khan
Although numerous imaging modalities provide a more definitive diagnosis, a presumptive clinical diagnosis of LSS can be made based on the patient's history and physical examination [8]. The presence of a narrowed spinal canal on imaging studies does not necessarily define LSS [50–54]. While not routinely needed, conventional radiography may be used for an initial evaluation to rule out traumatic changes or other findings such as Paget's disease, spondylolisthesis or scoliosis. Radiography can also be used for post-surgical management to evaluate the integrity, correct position of fusion material and visualize signs of loosening of implanted fixating plates. The sensitivity and specificity of conventional radiographs are determined to be 66% and 98%, respectively [7]. Radiography can estimate the extent of disc space narrowing, facet joint hypertrophy and endplate sclerosis [8].
Impact of osteoarthritis disease severity on treatment patterns and healthcare resource use: analysis of real-world data
Published in Scandinavian Journal of Rheumatology, 2023
PG Conaghan, L Abraham, L Viktrup, JC Cappelleri, C Beck, AG Bushmakin, M Berry, J Jackson
In general, greater HCRU was observed among severe versus milder OA patients in terms of the use of imaging tests for diagnosis and monitoring, visits to HCPs, and hospitalization, primarily for surgery. When needed, conventional radiography should be used before other modalities, such as MRI, CT, or ultrasound (11). In line with guideline recommendations, X-rays were the most performed imaging for OA diagnosis and monitoring, and their use increased with greater disease severity. In only a small percentage of patients (4%), no imaging was performed for OA diagnosis, while MRI and CT were used in less than 20% of patients, with no significant differences in diagnosis or monitoring between disease severities. Imaging using these modalities is suitable where there is unexpected disease progression of symptoms or a change in clinical characteristics, and is not generally required for OA diagnosis (11).
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