4-Jun-161 ULTRASOUND IMAGING Lec 1: Introduction Ultrasonic Field Wave fundamentals. Intensity, power and radiation pressure.

4-Jun-162 Introduction: Why Medical Imaging? Earlier diagnosis Easier diagnosis More accurate diagnosis Less invasive diagnosis and treatments Greater sharing of knowledge

4-Jun-163 The field of diagnostic radiology has undergone tremendous growth in the past several decades: Angiography developed in the 1950’s Nuclear Medicine in the 1960’s Ultrasound and CT in the 1970’s MRI and interventional radiology in the 1980’s PET in the early 1990’s

4-Jun-164 Image Capturing Technique Radiography Magnetic Resonance Imaging Computed Tomography Ultrasound Nuclear Imaging

4-Jun-165 Radiography Process of creating an image by passing x-rays through a patient to a detector. Relies on natural contrast between radiographic densities of air, fat, soft tissue and bone. Most advantageous in parts of the body with inherently high contrast, e.g. the lungs and the heart.

4-Jun-166 Fluoroscopy Uses the x-ray beam continuously. Physician can: Evaluate the dynamic processes (e.g. diaphragmatic excursion or bowel peristalsis). Watch contrast medium (e.g. in the blood vessels, bowel, kidneys, or joint spaces). Follow the path of an opaque object (e.g. feeding tube or intravascular cathether).

4-Jun-167 Mammography Plain film study that uses specially designed equipment with low voltages and a film-screen combination to evaluate breast tissue and calcification with high contrast resolution for detail at a low radiation dose. Breast compression is to reduce radiation exposure and improve image quality.

4-Jun-168 Ultrasound Ultrasound uses high frequency sound waves 1-10 MHz and their corresponding echoes to create images of the internal structures of patients. The sound waves are directed into the body reflected by various body structures.

4-Jun-169 The time taken for the reflected waves to return determines the depth of the structures. The amount of beam absorption determines the intensity of the returning wave. Echoes from interfaces between tissues with different acoustic properties yield information on the size, shape, and internal structure of organs and masses.

4-Jun-1610 Why ultrasound is popular? The advantages are the: Portability Lack of ionizing radiation Ability to scan the body in any plane Disadvantages are: Operator dependency Limited usage for imaging the lungs and skeleton

4-Jun-1611 Ultrasound © Radiology Info © Photo Dynamic Imaging Limited Ref: Amy Schnelle, Computer Science, Univ. of Wisconson-Platteville

4-Jun-1612 Sound Frequency, (Hz. or c/s.) Number of oscillations per second performed by the particles of the medium in which the ultrasound is propagating. Audible sound: 20 Hz – 18 kHz Ultrasound: > 18 kHz Bats:120 kHz Grasshoppers:100 kHz Diagnostic ultrasound: 0.5 – 25 MHz Abdominal scanning:3 MHz Opthalmology:10 MHz