Author: Chan, King-chung Kenny
Title: Assessment of lung diseases in-vivo using acoustic transmission
Degree: M.Sc.
Year: 2009
Subject: Hong Kong Polytechnic University -- Dissertations.
Lungs -- Diseases -- Diagnosis.
Lungs -- Pathophysiology.
Department: Department of Health Technology and Informatics
Pages: vii, 84 p. : ill. (some col.) ; 30 cm.
Language: English
Abstract: A way of radiation free, non-invasive, real-time and continuous monitoring of patient"s chest condition is valuable to clinical patient care. A prototype system for such purpose was designed and built in this study. It consisted of 16-channels of thin piezoelectric transducers, connected to an amplifier and a laptop computer. By measuring the transit time of a short burst of 4kHz sound wave, an image can be generated in a phantom with simulated lung pathology. However, the sensitivity and the transmitting power of the prototype system were too low for use in adult patients. By changing the transmitter from a piezoelectric one to an electromagnetic driver, determination of transthoracic acoustic signal was achievable. Transthoracic signals were recorded in 5 healthy subjects and 11 patients with different pulmonary pathologies. The pattern of the received signal was complex, consisting of sound transmission through more than one path. The patterns were also different in patients with different types of pulmonary pathology. Measurement of the group velocity of peak sound pressure with 4kHz sound (sound speed) in the lung parenchyma was performed in the healthy subjects and the patients. The sound speed was 56 to 70m/s in healthy subject, depending on lung volume, 124m/s in patient with chronic obstructive airway disease, and 73m/s in patient with pneumonia Further refinement of the piezoelectric transducer, the algorithm of measuring transit time, the simultaneous measurement of distance between the transducers and the application of more sophisticated mathematical technique, such as waveform tomography, will be required for the further development of the system.
Rights: All rights reserved
Access: restricted access

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