2 edition of Influence of phase cancellation in measurement of ultrasound attenuation in bone. found in the catalog.
Influence of phase cancellation in measurement of ultrasound attenuation in bone.
Mohammed Ali Ahmed Alnafea
Written in English
Dissertation (M.Sc.) - University of Surrey, 2002.
|Contributions||University of Surrey. School of Electronics and Physical Sciences. Department of Physics.|
SUBJECTS AND METHODS: We studied postmenopausal women older than 65 years of 4 US clinical centers. Broadband ultrasound attenuation (BUA), a measurement of the differential attenuation of sound waves transmitted through the calcaneus, and bone mineral density of the calcaneus and hip were by: Absorption (ultrasound) Dr Matt A. Morgan and Assoc Prof Craig Hacking et al. In ultrasound, absorption is the reduction in intensity of the sound waves as it passes through tissue.
Phase cancellation effects produced by the cortex have been reported previously. For example, Langton and Subhan () found that the curved lateral and medial surfaces of the calcaneus produced nBUA artefacts due to phase cancellation that ranged between dB MHz −1 cm − by: Transcranial attenuation for bone conduction as a function of frequency ( to 4 kHz.) was measured on a group of unilaterally deaf (n 15) and a group of normal (n = 35) by:
-Attenuation is the result of absorption, reflection, and refraction with absorption accounting for about 50% of attenuation. -Attenuation is greatest in tissues with high collagen content and with the use of high ultrasound frequencies. -Repulsiton is not a cause of ultrasound attenuation. Accounting for attenuation effects in ultrasound is important because a reduced signal amplitude can affect the quality of the image produced. By knowing the attenuation that an ultrasound beam experiences traveling through a medium, one can adjust the input signal amplitude to compensate for any loss of energy at the desired imaging depth.
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A scanning ultrasound measurement system was developed for bone assessment using a receiver with an ultra-small aperture size to limit the phase cancellation effects on the physical receiver itself.
Phase cancellation in ultrasound due to large receiver size has been proposed as a contributing factor to the inaccuracy of estimating broadband ultrasound attenuation (BUA), which is used to characterize bone quality. Transducers with aperture size ranging from 2 to 5 mm have been used in previous attempts to study the effect of phase by: Phase cancellation in ultrasound due to large receiver size has been proposed as a contributing factor to the inaccuracy of estimating broadband ultrasound attenuation (BUA), which is used to characterize bone quality.
Transducers with aperture size ranging from 2 to 5 mm have been used in previous attempts to study the effect of phase cancellation. The measurement of broadband ultrasonic attenuation (BUA) in cancellous bone at the calcaneus for the assessment of osteoporosis was first described within this journal 25 years ago.
Influence of Marrow on Ultrasonic Velocity and Attenuation in Bovine Trabecular Bone Article (PDF Available) in Calcified Tissue International 58(5) June with 48 Reads. Quantitative ultrasound (QUS) assessment, including broadband ultrasound attenuation (BUA), is an efficient technique for assessing bone quality in various statuses, e.g., osteoporosis.
While assessing trabecular bone loss is essential to bone quality, the existence of cortical bone can substantially reduce the accuracy of BUA measurement. In this study, we developed an approach to quantify Cited by: A scanning ultrasound measurement system was developed for bone assessment using a receiver with an ultra-small aperture size to limit the phase cancellation effects on the physical receiver itself.
Results show that phase cancellation does have a significant effect on BUA (e.g., PS nBUA is % higher than PI nBUA). The cause for this may be the influence of four factors—averaging, phase cancellation, diffraction and scattering—which are interactive and frequency dependent.
This means that values measured with different equipment and experimental set-up are not directly comparable and hence the introduction of measurement standards seems to be by: 4.
2 Introduction to the Physics of Ultrasound 31 MHz are used in bone clinical devices, alt hough higher frequencies have been tested experimentally, for example to investigate cancellous bone.
The attenuation of ultrasound propagating through soft tissue is approximately dB/cm/MHz Reflection of the sound beam from a large interface with a rough surface is called.
Measured values of ultrasound attenuation in bone represent a combination of different loss mechanisms. As a wave is transmitted from a fluid into bone, reflections occur at the interface.
In the bone, mode conversion occurs between longitudinal and shear modes and the mechanical wave is scattered by its complex internal by: PURPOSE: Measured values of ultrasound attenuation in bone represent a combination of different loss mechanisms. As a wave is transmitted from a fluid into bone, reflections occur at the interface.
In the bone, mode conversion occurs between longitudinal and shear modes and the mechanical wave is scattered by its complex internal by: dependent intensity attenuation coeﬃcient (dB cm−1).
There are a number of attenuation processes involved in the propagation of ultrasound through bone, including ab-sorption, scattering, reﬂection , diﬀraction , , mode conversion, and phase cancellation ; although at-tenuation may be readily measured experimentally, it is.
The aim of this study was to evaluate the influence of immersion time and rotation of the heel around the leg axis on the reproducibility of measurements using an ultrasound bone imaging scanner (UBIS) with a temperature-controlled water bath.
Measurements were obtained in 10 men, 11 premenopausal women and 10 postmenopausal women. Ultrasound transmission velocity (UTV) and the slope of the linear dependence of broadband ultrasound attenuation on frequency (BUA) were measured in situ in 32 heels of 16 cadavers and in vitro in cores of calcaneal trabecular bone.
Results. After adjusting for Young's modulus, in Cited by: The attenuation measurements were also performed experimentally. The size of bone samples was 20 × 20 × 15 mm. The samples were obtained from the same part in the femoral head of 36 months old bovine.
During measurements, the bone sample was immersed in degassed water in an acoustical tube at room by: The aim of this cross-sectional study was to investigate whether two types of physical exercise affect the growing skeleton differently.
We used calcaneal quantitative ultrasound measurements (QUS) and dual-energy X-ray absorptiometry (DXA) for measurement of bone mineral density (BMD), and to test how QUS values reflect the axial DXA values in these various study Cited by: Wu J and Cubberley F Measurement of velocity and attenuation of shear waves in bovine compact bone using ultrasonic spectroscopy Ultrasound Med.
Biol. 23 –34 Crossref PubMed Google Scholar Xia Y, Lin W and Qin Y X The influence of cortical end-plate on broadband ultrasound attenuation measurements at the human calcaneus using Cited by: The measurements revealed a significant effect of bovine bone size on broadband ultrasound attenuation (BUA) and speed of sound (SOS) in vitro.
By normalizing the DXA and QUS results with bone thickness we could systematically improve their ability to predict bone strength. However, in bovine trabecular bone, Cited by: Ultrasound attenuation The attenuation of ultrasound wave that passed through tissues is unique and frequency dependant .
Previous study shows that ultrasound attenuation has a very high potential in characterizing biological tissue . In the field of breast cancer study, specific normal and. He, J. H. Sun, and P. Huang, “Bone measurements of infants in the first 3 months of life by quantitative ultrasound: the influence of gestational age, season, and postnatal age,” Pediatr Radiol 35(9), – ().Cited by: Ultrasound velocity (UV) and broadband ultrasound attenuation (BUA) were studied in human and bovine bone with a wide range of bone mineral density (BMD).
The BMD of 98 fresh specimens was measured by quantitative computed tomography: 42 cancellous specimens from women in the age group of 64±4 years; 51 bovine cancellous and 5 bovine by: Broadband ultrasound attenuation (BUA) on the os calcis has been proposed as a safe and reliable technique for evaluating skeleted status.
The present study provides preliminary normative BUA results on 93 female subjects divided into five age groups. These data can be used as a guide for comparing the results of individual studies. The diagnosis of osteoporosis was determined from lateral Cited by: