نوع مقاله: مقاله کامل پژوهشی

نویسندگان

1 دانشجوی دکتری مهندسی پزشکی، گروه بیوالکتریک، دانشکده مهندسی برق و کامپیوتر، دانشگاه تربیت مدرس، تهران

2 دانشیار، گروه بیوالکتریک، دانشکده مهندسی برق و کامپیوتر، دانشگاه تربیت مدرس، تهران

10.22041/ijbme.2014.13292

چکیده

درین تحقیق، روش جدیدی برای بازسازی تصاویر التراسوند پزشکی به شیوه‌ی روزنه‌ی مصنوعی ارائه شد. امروزه تصویربرداری به شیوه‌ی ساده‌ی بازسازی در حوزه‌ی زمان(DAS) و به صورت خط­به­خط انجام می‌شود. ازجنبه­ی دیگر، تصویربرداری به شیوه‌ی روزنه‌ی مصنوعی امکان فوکوس دینامیکی و دست­یابی به حدّاقل دوبرابر رزولوشن جانبی را با هزینه‌ی حجم محاسبه­های بیش­تر فراهم می‌کند. برای کاهش بار محاسباتی، روش­هایی برای بازسازی بلوکی تصویر در حوزه‌ی رادار معرفی شده که هنوز برای حوزه‌ی پزشکی ناشناخته است. برای تعمیم این روش­ها به حوزه‌ی پزشکی باید تفاوت پارامترهایی چون عمق هدف، فرکانس مرکزی، پهنای باند سیگنال ارسالی و عرض پرتو در نظر گرفته شود. درین پژوهش، نوع ساده‌ی مونواستاتیک با استفاده­از الگوریتم بلوکی عدد موج، مدل­سازی شد که می‌تواند معادلات را به نوع پیچیده‌تر مالتی‌استاتیک تعمیم دهد. به علاوه، برای کاهش اثرهای مخرّب ناشی­از تفاوت پارامترها از پالس ارسالی chirp به همراه فیلتر تطبیقی، پنجره‌گذاری و الگوریتم spotlighting استفاده شد. برای ارزیابی الگوریتم،‌ داده‌های شبیه‌سازی شده با نرم‌افزار FieldII انجام شد و نتایج نشان داد که استفاده الگوریتم عدد موج، با حفظ رزولوشن جانبی، در حدود 20 برابر سریع­تر از الگوریتم استاندارد DAS است.
 

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Synthetic Aperture Ultrasound Imaging Using Frequency-Domain Reconstruction to Reduce Computational Complexity

نویسندگان [English]

  • Elahe Moghimirad 1
  • Ali Mahloojifar 2
  • Babak Mohammadzadeh Asl 2

1 Ph.D Student, Electrical and Computer Engineering Department, Faculty of Engineering, Tarbiat Modares University

2 Associate Professor, Electrical and Computer Engineering Department, Faculty of Engineering, Tarbiat Modares University

چکیده [English]

A new implementation of a synthetic aperture focusing technique is presented in the paper. Standard medical ultrasound imaging is done using line-by-line transmission with classical Delay-and-Sum (DAS) image reconstruction. Synthetic aperture imaging, however, has a better resolution and frame rate in cost of more computational load. To overcome this problem, block processing algorithms are used in radar and sonar which are relatively unknown in medical. To extend the methods to medical field, one should concern the parameters difference such as carrier frequency, signal band width, beam width and depth of imaging. In this paper, we extended one of these methods called wavenumber to medical ultrasound imaging with a simple model of synthetic aperture focus. We have also used chirp pulse excitation followed by matched filtering, windowing and spotlighting algorithm to compensate the effect of differences in parameters between radar and medical imaging. Computational complexity of the two reconstruction methods, wavenumber and DAS, have been calculated. Field II simulated point data has been used to evaluate the results in terms of resolution and contrast. Evaluations with simulated data show that for typical phantoms, reconstruction by wavenumber algorithm is almost 20 times faster than classical DAS while retaining the resolution.

کلیدواژه‌ها [English]

  • ultrasound imaging
  • real aperture
  • synthetic aperture
  • time domain image recounstruction
  • frequency domain image recounstruction

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