BIoE 1330 Ch 10-11

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0 [{"id":310557,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:17:02","updated_at":"2017-12-13 20:31:30","questionName":"In ultrasound, the space being imaged is organized into three regions. In each region, a particular approximation best describes the beam pattern. Those approximations are I - the Fraunhofer approximation II - the geometric appoximation (the very near field) III - the Fresnel approximation In what order do the corresponding regions of space occur, as one moves away from the transducer?","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":3,"explanation":"The order is geometric (very near field), Fresnel (near field), and then Fraunhofer (far field).","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310567,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:24:49","updated_at":"2017-12-13 20:31:31","questionName":"Which of the following statements is (are) true about the pulse-echo mode of operation in a phased array ultrasound scanner? I. The same transducers usually generate and receive the ultrasound pulses. II. The beam is steered by changing the duration of the transmit pulse envelope. III. Color Doppler is possible with pulse-echo ultrasound.","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":13,"explanation":"The beam is steered by changing the relative delay for each of the elements of the array, not the duration of the transmit pulse envelope","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310561,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:20:25","updated_at":"2017-12-13 20:31:31","questionName":"In ultrasound, which of the following is not true about the field pattern, an example of which is shown below (the figure actually shows a field pattern for light, but is analogous to that found with ultrasound).","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":"uploads\/bioe-1330-ch-10-11\/Chap10-11Q8.JPG","position":7,"explanation":"The Fraunhofer zone, otherwise known as the far field is labeled \u201cD.\u201d","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310568,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:25:23","updated_at":"2017-12-13 20:31:31","questionName":"Posterior enhancement (through transmission) is a type of ultrasound artifact often used in diagnosis because","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":14,"explanation":"Posterior enhancement makes tissue beyond a fluid filled structure appear brighter.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310556,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:16:27","updated_at":"2017-12-13 20:31:30","questionName":"The following are true about the waves used in clinical ultrasound imaging, except","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":2,"explanation":"Clinical ultrasound uses compression waves.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310558,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:17:39","updated_at":"2017-12-13 20:31:31","questionName":"Which of the following statements is false about the Fraunhofer zone? (or all are true)","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":4,"explanation":"These are all true. Null points on the axis do occur in the Fresnel zone, but in the far field the aperture appears small enough that the field pattern is only fall off with distance squared and otherwise only varies with angle off the axis.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310562,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:21:01","updated_at":"2017-12-13 20:31:31","questionName":"In ultrasound, with an incident planar wave that is not perpendicular to a boundary where the acoustic impedance Z changes, which of the following is (are) TRUE? I. Refraction will always occur. II. Reflection will always occur. III. Particle velocity v is generally much less than wave velocity c.","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":8,"explanation":": Refraction requires a non-perpendicular angle and a change in the speed of propagation, c = \u03c1Z, where \u03c1 is density. Therefore, c can still be the same in two materials, even though Z is different, if \u03c1 is also different. Therefore I is false. Reflection","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310554,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:14:30","updated_at":"2017-12-13 20:31:30","questionName":"In ultrasound, with an incident planar wave that is not perpendicular to a boundary where the acoustic impedance Z changes, the following are true: I. Reflection will always occur. II. Refraction will occur if and only if the wave velocity c changes. III. Particle velocity v will always equal wave velocity c on either side of the boundary","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":0,"explanation":"Refraction depends only on c. Reflection depends only on Z and the angle of incidence. Particle velocity v is generally much slower than wave velocity c.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310564,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:22:13","updated_at":"2017-12-13 20:31:31","questionName":"The following are true about the waves used in clinical ultrasound imaging, except","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":10,"explanation":"Absorption in biological tissue is roughly proportional to frequency and thus inversely proportional to wavelength, given that velocity (in soft tissue) is fairly constant at around 1540 meters\/second.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310559,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:18:27","updated_at":"2017-12-13 20:31:31","questionName":". Which of the following statements is false about the use of the complex exponential in modeling ultrasound?","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":5,"explanation":"The use of complex exponentials instead of real sinusoids encapsulates phase in such a way that algebra and calculus are straightforward, and is the heart of not only ultrasound design, but of modern optics. A linear system with superposition of the waves","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310566,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:24:12","updated_at":"2017-12-13 20:31:31","questionName":". Which of the following statements is false about resolution in ultrasound?","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":12,"explanation":"Lateral resolution generally decreases (gets worse) with increasing range.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310555,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:15:47","updated_at":"2017-12-13 20:31:30","questionName":"The following are true about theoretical plane waves in ultrasound, except","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":1,"explanation":"Whereas spherical waves spread out attenuating pressure by 1\/r, planar waves do not spread out, and thus maintain their full amplitude.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310560,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:19:08","updated_at":"2017-12-13 20:31:31","questionName":"Which of the following statements is false about the piezoelectric crystals used in ultrasound transducers?","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":6,"explanation":"The transmitting constant and receiving constants don\u2019t even have the same physical units, so they will certainly not have the same numerical values.","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310565,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:22:55","updated_at":"2017-12-13 20:31:31","questionName":"Which of the following statements is false about the use of the complex exponential in modeling ultrasound, (or all are true)?","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":11,"explanation":"The use of complex exponentials instead of real sinusoids encapsulates phase in such a way that algebra and calculus are straightforward, and is the heart of not only ultrasound design, but of modern optics. A linear system with superposition of the waves","question_score_id":null,"lang":null,"questionAudioPath":null},{"id":310563,"quiz_id":"15767","answer_id":null,"answerType_id":"0","created_at":"2017-10-27 20:21:38","updated_at":"2017-12-13 20:31:31","questionName":"The following are true about theoretical plane waves in ultrasound, except","questionTimeSeconds":"0","questionTimeMinutes":"2","questionImagePath":null,"position":9,"explanation":"They are approximated within the Very Near Field of the transducer, not in the Fraunhofer zone. In the Fraunhofer zone the waves diverge at a constant angle acting more like spherical waves","question_score_id":null,"lang":null,"questionAudioPath":null}]
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In ultrasound, the space being imaged is organized into three regions. In each region, a particular approximation best describes the beam pattern. Those approximations are I - the Fraunhofer approximation II - the geometric appoximation (the very near field) III - the Fresnel approximation In what order do the corresponding regions of space occur, as one moves away from the transducer?

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