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THE DEVELOPMENT OF NEW ULTRASONIC IM...

FOSTER, FRANCIS STUART.

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THE DEVELOPMENT OF NEW ULTRASONIC IMAGING TECHNIQUES FOR THE EARLY DETECTION OF BREAST CANCER.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	THE DEVELOPMENT OF NEW ULTRASONIC IMAGING TECHNIQUES FOR THE EARLY DETECTION OF BREAST CANCER./
Author:	FOSTER, FRANCIS STUART.
Notes:	Source: Dissertation Abstracts International, Volume: 41-02, Section: B, page: 0446.
Contained By:	Dissertation Abstracts International41-02B.
Subject:	Biophysics, Medical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NK47047

THE DEVELOPMENT OF NEW ULTRASONIC IMAGING TECHNIQUES FOR THE EARLY DETECTION OF BREAST CANCER.
FOSTER, FRANCIS STUART.

THE DEVELOPMENT OF NEW ULTRASONIC IMAGING TECHNIQUES FOR THE EARLY DETECTION OF BREAST CANCER.

Source: Dissertation Abstracts International, Volume: 41-02, Section: B, page: 0446.

Thesis (Ph.D.)--University of Toronto (Canada), 1980.

Ultrasound is the basis of a varied and rapidly expanding group of medical diagnostic procedures. Although the breast is well situated and contains no structures that obstruct the propagation of ultrasound, this organ has proved to be one of the most difficult to adequately image. Investigation in this field has recently been stimulated by reports indicating that a significant decrease in mortality due to breast cancer could be achieved using a safe, effective screening procedure. While mammography is an effective means of detecting small breast tumours, many critics feel that its use would result in as many new breast cancers as were detected in the screening program. For this reason the use of ultrasound is a particularly appealing alternative. A number of groups have demonstrated the capability of ultrasound in breast imaging but several problems remain to be solved before it can be used in routine clinical imaging or as a screening tool. Two of the most fundamental problems are addressed in this thesis. The first concerns the improvement of lateral resolution throughout the image and the second relates to the development of comfortable and effective clinical scanning procedure.Subjects--Topical Terms:

1017681
Biophysics, Medical.

THE DEVELOPMENT OF NEW ULTRASONIC IMAGING TECHNIQUES FOR THE EARLY DETECTION OF BREAST CANCER.
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035 $a (UMI)AAINK47047
035 $a AAINK47047
040 $a UMI $c UMI
100 1 $a FOSTER, FRANCIS STUART. $3 1297213
245 1 4 $a THE DEVELOPMENT OF NEW ULTRASONIC IMAGING TECHNIQUES FOR THE EARLY DETECTION OF BREAST CANCER.
500 $a Source: Dissertation Abstracts International, Volume: 41-02, Section: B, page: 0446.
502 $a Thesis (Ph.D.)--University of Toronto (Canada), 1980.
520 $a Ultrasound is the basis of a varied and rapidly expanding group of medical diagnostic procedures. Although the breast is well situated and contains no structures that obstruct the propagation of ultrasound, this organ has proved to be one of the most difficult to adequately image. Investigation in this field has recently been stimulated by reports indicating that a significant decrease in mortality due to breast cancer could be achieved using a safe, effective screening procedure. While mammography is an effective means of detecting small breast tumours, many critics feel that its use would result in as many new breast cancers as were detected in the screening program. For this reason the use of ultrasound is a particularly appealing alternative. A number of groups have demonstrated the capability of ultrasound in breast imaging but several problems remain to be solved before it can be used in routine clinical imaging or as a screening tool. Two of the most fundamental problems are addressed in this thesis. The first concerns the improvement of lateral resolution throughout the image and the second relates to the development of comfortable and effective clinical scanning procedure.
520 $a The lateral resolution is directly related to the focussing of the ultrasound beam. The physics of ultrasound focussing in breast and other human tissues is examined using a unique variable aperture, variable focal length transducer. Focussing is tested as a function of lens f-number (focal length/diameter), tissue type and thickness. The causes of defocussing are investigated and the crucial role of ultrasound attenuation and system bandwidth are discussed. A frequency of 3.5-4.0 MHz and an f-number of 2.0-3.0 are recommended for breast imaging.
520 $a The use of low f-number lenses results in a reduction of the region in which the image remains sharp (depth of field). One way to solve this problem is to divide the image range into a number of well focussed "zones", each scanned separately, and summed to generate the final image. An instrument called the Demonstration Scanner is used to assess the validity of this approach. Significant resolution gains are demonstrated and a rule for selecting zone width is derived.
520 $a A new concept in ultrasound image formation, called the Cylindrical Transducer Scatter Scanner, has been invented. With it, the depth of field problem is attacked directly by replacing the traditional point focus with a line focus generated by a cylindrical transducer. Right-angle scatter, detected by a transducer aimed along the axis of the cylinder, is used to generate the image. This approach achieves an extremely sharp focus, with a depth of field essentially equal to the length of the cylinder. The ultrasonic field of the cylindrical transducer is examined experimentally and theoretically. Preliminary images of simple phantoms and in vitro tissue samples are exceptionally encouraging and a program for the development of scatter imaging technology is described.
520 $a Breast II is a simple ultrasound breast scanner designed for clinical use. Emphasis is placed on the development of a comfortable and acceptable scanning procedure, not on resolution. The rationale behind this design is discussed. Clinical results indicate that a simple linear scanning regime is sufficient to provide high quality images of normal and pathological tissues. The design of Breast III, a zone focussed rectilinear scanner is outlined briefly.
590 $a School code: 0779.
650 4 $a Biophysics, Medical. $3 1017681
690 $a 0760
710 2 0 $a University of Toronto (Canada). $3 1017674
773 0 $t Dissertation Abstracts International $g 41-02B.
790 $a 0779
791 $a Ph.D.
792 $a 1980
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NK47047