Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5814_Библиотеки_им_академика_М_И_Перельмана
.pdf
T
Non-focused Be
am
Focused Beam
φ
z
261Chapter eleven: Methods for measuring speed, attenuation, absorption
ransducer
z
0
Figure 11.13 Only a nonfocused transducer can be approximated as a point
source for far-eld measurements. This approximation cannot be applied to
focused transducers.
φ
therefore much more computing intensive, was developed by Madsen
et al. (1984).
For scattering measurements in highly absorptive media and at
higher frequencies, a particulate reference medium whose scattering
properties are well known may be used when the utilization of a focused
transducer is necessary to achieve the required signal-to-noise ratio (Chen
and Zagzebski, 1996; Wang and Shung, 1997).
11.3.2 In vivo methods
The gray level of a tissue in an ultrasonic B-mode image obtained by a
scanner or the echogenicity of a tissue is related in a nonlinear manner
to the ultrasonic backscattering coefcient of a tissue resulting from such
signal processing steps as time-gain-compensation, echo amplitude to
gray-scale mapping, etc., in a scanner. Only if these processing schemes
can be adequately compensated, but it is extremely difcult to do, is there
a one-to-one correspondence between echogenicity and the backscattering coefcient. By merely quantitating the gray level or echogencity of
a tissue in video images acquired by a scanner in vivo following appropriate standardization procedures, a number of studies have shown that
it is possible to differentiate diseased tissues from normal tissues in a
variety of organs. More quantitative data can be retrieved by acquiring
and analyzing radio frequency (RF) or raw data before signal processing, rather than the video data. In fact, there is a commercial system now
that is equipped with an RF output for users who have need the RF data.
Both backscattering coefcient and integrated backscatter (IB) have been
measured from a number of tissues in vivo (Shung and Thieme, 1993). The
262 Diagnostic ultrasound: imaging and blood ow measurements
most notable achievements have been made in the heart (Miller et al., 1985;
Shung and Thieme, 1993) and the eye (Coleman and Lizzi, 1983; Shung
and Thieme, 1993) for the purpose of tissue characterization.
References and Further Reading Materials
Busse LJ and Miller JG. Response characteristics of a nite aperture, phase insensi-
tive ultrasonic receiver based upon the acoustoelectric effect. J Acoust Soc Am
1981; 70: 1370–1376.
Chen CF, Robinson DE, Wilson LS, Grifths KA, Manoharan A, and Doust BD.
Clinical sound speed measurement in liver and spleen in vivo. Ultrasonics
Imaging 1987; 9: 221–235.
Chen JF and Zagzebski JA. Frequency dependence of backscatter coefcient versus
volume fraction. IEEE Trans Ultrasonics Ferroelect Freq Cont 1996; 43: 345–353.
Coleman DJ and Lizzi FL. Computerized ultrasonic tissue characterization of ocu-
lar tumors. Am J Ophthalmol 1983; 96: 165–175.
Greenleaf JA. Tissue characterization with ultrasound. Boca Raton, FL: CRC Press, 1986.
Kondo M, Takamizawa K, Hirama M, Okazaki K, Inuma K, and Takehara Y. An
evaluation of an in vivo local sound speed estimation technique by the cross
beam method. Ultrasonics Med Biol 1990; 16: 65–72.
Kuo IY, Hete B, and Shung KK. A novel method for the measurement of acoustic
speed. J Acoust Soc Am 1990; 88: 1679–1682.
Madsen EL, Insana MF, and Zagzebski JA. A method for data reduction for accu-
rate determination of acoustic backscatter coefcients. J Acoust Soc Am 1984;
75: 913–923.
Miller JG, Perez JE, and Sobel BE. Ultrasonic characterization of myocardium.
Progr Cardiovasc Dis 1985; 28: 85–110.
Parker KJ. The thermal pulse decay technique for measuring ultrasonic absorption
coefcients. J Acoust Soc Am 1983; 74: 1356–1361.
Schwan HP. Biological engineering. New York: Wiley, 1969.
Shung KK and Thieme GA. Ultrasonic scattering by biological tissues. Boca Raton,
FL: CRC Press, 1993.
Sigelmann RA and Reid JM. Analysis and measurement of ultrasound backscatter-
ing from an ensemble of scatterers excited by sinewave bursts. J Acoust Soc
Am 1973; 53:1351–1355.
Wang SH and Shung KK. An approach for measuring ultrasonic backscattering
from biological tissues with focused transducers. IEEE Trans Biomed Eng
1997; 44: 549–554.
Yuan YW and Shung KK. The effect of focusing on ultrasonic backscattering mea-
surements. Ultrasonics Imaging 1986; 8: 212–219.
Biomedical Imaging
Offers an Extensive Discussion on High Frequency Ultrasound
Based on a course taught and developed by a foremost expert in diagnostic
ultrasound technology, Diagnostic Ultrasound: Imaging and Blood Flow
Measurements, Second Edition covers cutting-edge developments, along
with the fundamental physics, instrumentation, system architecture, clinical
applications, and biological effects of ultrasound. This text addresses the
technical side of diagnostic ultrasound and begins with an overview of the
eld of ultrasonic imaging and its role in diagnostic medicine relative to other
imaging modalities. The author describes the fundamental physics involved
in ultra sonic transducers, as well as in conventional imaging approaches
and Doppler measurements, including contrast imaging and 4D imaging. He
reviews the current status and standards on ultrasound bioeffect and discusses
methods that have been used to measure ultrasonic properties of tissues. He
also provides a list of relevant references and further reading materials at the
end of each chapter.
New in the Second Edition
• Details the latest advances in ultrasound technology related to biomedical
applications, including elastrography, portable scanners, ultrasound
molecular imaging, preclinical high frequency imaging, 2D array, and 4D
imaging techniques
• Updates and expands each chapter
• Adds a new chapter on new developments such as elastography and
miniature scanners
• Includes new case studies and examples throughout the book
Diagnostic Ultrasound: Imaging and Blood Flow Measurements, Second
Edition covers recent advances in ultrasound technology related to biomedical
applications. Intended for senior- to graduate-level coursework in ultrasonic
imaging, this text also serves practicing physicists, engineers, clinicians, and
sonographers.
K189 46
ISBN: 978-1-4665-8264-4
9 781466 582644
90000
Соседние файлы в папке Библиотека им академика М.И. Перельмана