# arabicsite2

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Guidelines_English_Final

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 College of Applied Medical Sciences Dept. of Radiological Sciences RAD 312 Ultrasound Physics                                 Sample Test and Answers (1) A)     Fill in the blanks: 1. Human being cannot hear sound with frequencies more than …20000………Hz. 2. The speed of sound in soft tissue is …1540 m/s……… 3. Rough surfaces cause sound to ……scatter…….. rather than be reflected. 4. U/S is attenuated in tissues by: …absorption… , …scatter…., and …reflection….. 5. When U/S is absorbed in a medium it is converted into …heat………. 6. The power of U/S passing through unit area perpendicular to the direction of propagation is known as …intensity…… 7. The speed of sound in air is …330 m/s………….. 8. If an U/S beam with a frequency of 2MHz has a speed of 1000 m/s in a certain medium. Another beam with a frequency of 4MHz passing through the same medium should have a speed of …1000 ….. m/s. 9.  1µs = …1/1000000……… s 10. The wavelength of an U/S beam with a frequency of 3.5MHz is …0.4mm…………. B)     Indicate whether the statements are True or False: 1. For 1MHz U/S beam, the average attenuation coefficient in soft tissue is 70 dB/m …………………………….. (  F  ) 2. The frequency of sound is the number of cycles/second, and its unit is the Hz. ……………………………………( T ) 3. When the difference in acoustic impedance between two tissues is small, the degree of reflection of U/S will be large ……………………………………………………(F) 4. High frequency U/S beam gives better resolution ……………………………………………………….( T ) 5. Attenuation of an U/S beam in a medium is inversely related to its frequency …..………………………………….( F ) 6. The wave length = the speed of sound X the frequency ……………………………………………………(F) 7. One MHz = 1000,000 KHz …………………( F ) 8. As the frequency of U/S increases the period of the wave decreases …………………………………………….( T ) 9. In diagnostic U/S, as the frequency increases the acoustic impedance also increases …………………………….( F ) 10. Attenuation = Path length X Attenuation coefficient ………………………………………………………(  T )C)     Draw a figure showing two waves with different frequencies. Indicate the wavelength and the amplitude in each wave. -         (See the power point slide) D)     Draw a curve showing the effect of using different frequencies on the penetration ability of an U/S beam. -         (See the power point slide)