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Physics boards
| Question | Answer |
|---|---|
| Sound waves are | longitudinal, mechanical |
| The speed of US in soft tissue is closest to | 1,500 m/s |
| The frequency closest to the lower limit of US is | 15,000Hz |
| Which are acoustic variable? | density, pressure,distance |
| The effects of soft tissue on US are called? | Acoustic propagation properties |
| Two waves with identical frequencies must interfere constructively | False |
| Put in DECREASING order: deca,deci,micro,centi? | deca, deci,centi,micro |
| Is the time it takes to complete one cycle. | Period |
| Which of the following sound waves is ultrasonic and least useful in diagnostic imaging? | 30KHz |
| What is the frequency of a wave with 1 msec period? | 1KHz "Kiol-micro" |
| Is the distance covered by one cycle | wavelenigth = 1cycle |
| Which of the following is determined by the source and the medium? | propagation speed |
| Propagation speed =___ x wavelength | Frequency |
| As a result of ____ the propagation speed increases | decreasing compressibility and decreasing density |
| Put in decreasing order of propagation speed: gas, liquid,solid | Solid,liquid,gas |
| If the frequency of US is increased from 0.77MHZ to 1.54MHz, what happens to the wavelenigth | halved |
| A sound wave's frequency is 10 HMz. The wave is traveling in soft tissue. What is its wavelentgh | 0.15 |
| If the frequency of an US wave is doubled, what happens to the period? | doubles |
| if the frequency of US is increased from 0.77 MHZ to 1.54mhz what happens to the progation speed | remains the same |
| The units of pulse repetition frequency are | per minute |
| The time from the beginning of a pulse until its end is | pulse duration |
| what happens to the speed of sound in a medium when the bulk modulus of the medium increases | faster |
| ___resolution is determined by the sapatial pulse length.(SPL) | Radial and axial |
| If a wave amplitude is doubled, what happens to the power | quadrupled ( power=Amp2) |
| If the level if an acoustic variable ranges from 55 to 105, what is the amplitude? | 25 ( 55=25amp) _______ 105=25 |
| Power of sound has units of | watts |
| If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happened to the power | halved |
| Which of these intensities is the smallest: SATP,SPTP,SATA | SATA |
| The duty factor for continous wave ultrasound is | 1.0 ( duty factor for CW=1.0) |
| what is the minimum value of the duty factor? | 0.0% ( min value for DF for CW=0.0%) |
| What are the units of intensity? | watts/cm squared |
| What happens to the speed of sound in a medium when the bulk modulus of the medium decreases | slower ( bulk modulus/US decreases than sound gets slower) |
| the units of attenuation are __; this is a __ scale | dB, logarithmic |
| Sound intensity is decreased by 75%. How many decibles of attenuation is this? | 6dB |
| The fundamental frequency of a transducer is 2.5MHz. What is the second harmonic frequency? | 5HMZ ( harmonic=fundamenatal freq x2) |
| A pulse is emitted by a transducer and is traveling in soft tissue. The go-return time, or time-of-flight, of a sound pulse is 130 microseconds. What is the reflector depth | 10cm |
| If a 5HMz sound wave is traveling in the tissue listed below, which will have the longest wavelength: Fat,Air,Muscle or Bone | Bone ( because bone is an attenuator) |
| If a 5MHz sound wave is traveling in the tissue listed below, which will have the shortest wavelength? :Fat, Air, Muscle, or Bone? | Air |
| What is the approx attenuation coefficient of 1MHz US in soft tissue? | 0.5dB/cm ( attenuation coefficient = 1/2 MHz dB/cm) |
| The rayl is the unit of | impedance |
| Impedance is the ___of___and ___ | product, propagation speed, density |
| What are the attenuation's three components? | scattering,reflection and absorption |
| For soft tissue, the approximate attenuation coefficient in dB/cm is equal to one-half __in ____ | frequency,MHz |
| As the impedance of two media become vastly different the | reflection increases |
| The angel between an US pulse and the boundary between two media is 90. What is this called | Orthogonal incidence |
| The angel between and US pulse and the boundary between two media is 56. What is this called | Oblique incidence |
| Refraction only occurs if there are | oblique incedence and different propagation speeds |
| With normal incidence, which of these factors affect refraction of US: propagation speed, frequncy, attenuation coefficients | none of the above |
| With right angle incidence, reflections are always generated at a boundary if the propagation speed of a media are deifferent | False |
| ___is a redirection of US in many direction as a result of a rough boundary between two media. | scattering |
| Which if the following tissue is most likely to create Rayleigh scattering? | RBC |
| With normal incidence the angle is 189 | False |
| Under which condition is axial resoulition improved | decreased spatial pulse lentgh |
| Snell's law describes physics of | refraction ( Snells=refraction) |
| The most likely amount of reflection at a boundary between soft tissue is | 1% ( soft tissue =1%) |
| The most typical amount of transmission at a boundary in biologic media is | 99% ( biologic media=99%) |
| Sound is traveling from medium 1 to medium 2. PS of M1 and M2 are 1,600m/s and 1,500m/s, respectively. There is oblique incidence. | angle of incidence =angle of reflection |
| Doppler shift always occurs if the sound source and receiver are in motion | False |
| Which of the following is associated with power mode Doppler | poor temporal resolution adn flash artifact |
| The Doppler shift is a measure of | difference between incident and reflected frequency |
| The sonographer cannot change, directly or indirectly, the duty factor of an US machine | False |
| There have not been biological effect from the US found in the lab | false |
| In an analog scan converter, what component stores the image data? | dielectric matrix |
| Correct order for mega-milli-kilo-micro | |
| How many cm are 60 millimeters? | 6 |
| Lateral resolution is also called | 68 azimuthal =lateral |
| Which had the correct units? Freq- speed -intens -atten | mHz - m/sec - W/cm2 - dB |
| What increases patient exposure? | exam time |
| Shadowing may result from high amounts of reflection of US energy | True |
| Where are harmonics created | in the tissues |
| How is range ambiguity artifact eliminated | lower the PRF |
| For Doppler, which incident angle results in no shift? | 90 |
| Which transducer would be best to image superficial structures | small diameter, high frequency |
| A transducer with more than one active element is called | array |
| How many bits are needed to represent 16 shades of gray | 4 |
| What information does Doppler shift provide | velocity |
| A sound wave is a pressure wave made of compressions and rarefactions | True |
| A hydrophone is used to measure | Frequency and intensity |
| Image on a videotape are stored using | magnetism |
| Circumferences may be measured in unit of | cm |
| Decimal uses a base of 10 and binary uses a base of | 2 |
| If the frame rate increases and the lines per frame is unchanged, what else must happen? | Depth decreases ( frame rate up depth down |
| Which of these cannot be performed by a sonographer? | Clean pixels |
| Which of the following is not a beam steering technique for a mechanical scanhead? | Phased beam |
| A system which was working well now does not display clear images in the far field. This may be a problem with the: transducer, receiver,monitor, scan converter | True |
| How many decibles is related to a 90% decrease in imaging power? | -10dB ???? |
| If the output of an US machine is calibrated in dB and the output is increased by 20dB the beam intensity is increased | 100 times |
| Which has the greatest amount of attenuation? | Bone |
| Which of the following will result in the greatest number of shades of gray in a digital image display | Large pixel with many bits/pixel |
| What is not the responsibility of the sonographer | adjust converter matrix |
| With good images on the display but not on the printer one should | adjust the recorder |
| To measure the US beam intensity, use a | calibrated hydrophone |
| When the US machine displays only strong reflecting objects and nothing else, the sonographer should | increase output power |
| Compression is used to | decrease the range of amplitudes |
| Reject is used to | adjust the appearance of lowly reflective object |
| If a reflector is moved twice as far away from the transducer, how will this affect the time-of-flight of sound pulse? | double it ( deeper or farther away doubles) |
| A singleelement transducer is focused | by the manufacture |
| An US machine has a digital scan converter but has an analog input signal. The machine needs to have a | Analog to digital converter |
| Under which of the following conditions is lateral resoulution improved | decreased beam diameter |
| In which way is an annular phased array transducer different than a linear phased array transducer | the annular is steered mechanically |
| In which of these biologic tissues will sound waves propagate most quickly | tendon |
| Which of the following best describes a sound beam? | a collection of mechanical vibrations in the form of compressions and rarefactions |
| You are performing a quality assurance study on an US system using a tissue equivalent phantom. You make an adjustment using a knob on the system console that changes the appearance of reflector brightness from fully bright to barely visible. What are you | System sensitivity |
| Which of the following best describes the features of a sound wave and medium that determine the speed of sound in the medium | Density of the medium and stiffness of the medium |
| While scanning in a water tank, what location in a sound beam has the highest intensity | focal point |
| Which of these factor has the greatest influence on pulse repetition period | display depth |
| Which of the following choices best describes an ideal epidemiologic bioeffects study | randomized and prospective |
| Which of the following will result in the highest mechanical index | low frequency and high signal amplitude |
| All of teh following statements regarding in-vitro bioeffects are tur except | in-vitro bioeffects conclusions are clinically relevant ( not true) |
| Under which circumstance is the mechanical index highest | Low frequency and high signal amplitude |
| What is the accuracy of reflector depth position on an A-mode,B-mode or M-mode display called | Depth calibration |
| Pre-processing occurs | when the patient is scanned |
| Post processing occurs when the image | entered the A/D converter but before display |
| The region from the transducer to the minimum beam cross section area is the | Fresnel zone |
| Biologic effects have not been documented below what intensity (SPTA) | 100mW/m2 |
| What is the standard for communication between medical imaging computers? | A to D conversion |
| The Cuire temperature has which effect | the ferroelectic material is depolarized |
| What happens to venous blood flow to the heart during expiration? | decreased |
| Which of the following has a propagation speed closest to soft tissue | muscle |
| In a B-mode display, which of the following axes are used for the amplitude of the reflection | z-axis |
| What is displayed on the x-axis of an M-mode image? | time |
| What is displayed on the y-axis of an m-mode image | time-of-flight |
| A sonographer's education ends when they become registered | false |
| The dynamic range is the ratio of teh smallest t teh largest__ that a system can process without distortion | amplitude |
| When may a patient revoke their consent to be treated? | any time |
| If the intensity is increased by 3dB, it: | doubles |
| What determins the frequency of a sound beam from a pulsed transducer? | PZT thickness |
| While propagation, a sound wave is refracted. Finally,it returns to the transducer. The system processes the sound wave as if it has: | traveled in a straight line, reflected and returned |
| What measures the output of a transducer | hydrophone |
| Put in increasing order of propagation speed: | air,water,bone |
| Which type of artifact appears most commonly with highly reflective objects | shadowing |
| What can pulsed Doppler measure that continuous wave cannot | location |
| What is the fraction of time that a transducer is trasmitting | Duty factor |
| Which of the following clinical modalities has the lowest output intensity? | gray scale imaging |
| What is the location of the minimum cross-section area of the US beam called | focus |
| The dB is defined as the __of two intensities | ratio |
| If the power of a sound wave is increased by a factor of 8, how many decibles is this | 9dB |
| An US system is set at 0dB and is transmitting at full intensity. What is the output power when the system is transmitting at 50% of full intensity? | -3dB |
| An US system is aet at 0dB & is transmitting at full intensity. What is the output power when the system is transmitting at 10% full intensity | -10dB |
| The Doppler shift is the __ of two frequencies | difference |
| What is PS determined by | density and elasticity |
| If 300,000 cycles occur in a second, what is the wave's frequency | 0.3 Mhz |
| (154) What would be the brightest B-mode spot when scanning the following | |
| A Doppler exam is performed with a 5MHz probe and a PRF of 15 kHZ. Which of these Dopller shift will creat aliasing? | 14 kHz ( any probe that is above 1/2 PRF) |
| Which of the following choices determines the signal amplitude in the transducer of an US system | reflected intensity of teh sound beam |
| In an air-tissue interface, what percentage of the US is reflected? | near 100% ( air tissue 100% reflected) |
| Traveling through the same medium, if the frequency is doubled,the wavelength is | haved |
| Traveling through the same, if teh frequency is doubled, the progation speed is: | unchanged |
| Increasing the frequency increases the penetration depth | false |
| Axial resolution is affected by focusing | false |
| If a manufacturer changed the lines per frame and kept the imaging depth the same , what else would change | frame rate |
| Which of the following has the greatest influence on temporal resolution | PS and the imaging depth |
| In a real time scanner, which of these choices determines the maximum frame rate? | depth of view |
| Multiple reflections that are equally spaced are called | reverberations |
| What artifact has a grainy appearance and is caused by the interferance effects of scattered sound | speckle |
| All of the following improve temporal resolution: 1. increased line density 2. single rather than multi focus 3. higher frame rate 4. shallower depth of view 5. slower speed of sound in a medium | increased line density |
| Impedance is the product of ___ and ___ | Density / PS |
| The manufacture increases the number of lines per frame. As a result, which of the following may have to be decreased. ( true or false) | |
| Frequency | false |
| Frame rate | True |
| sector angle | True |
| imaging depth | True |
| power output | false |
| How many bits are needed to represent 1024 gray shades | 10 |
| Gray scale can be changed by the sonographer | True |
| The distance to a target is doubled. The time-of-flight for a pulse to travel to the target and back is | 2 times |
| If 3MHz sound has 2dB of attenuation in 1cm of tissue, what is the amount of attenutaion of 6MHz sound in 0.5 cm of the same tissue | 2dB |
| Volume has which of the following units | cm3 |
| Which of the following is proportional to the square of the amplitude? | power |
| What are the typical clinical Doppler frequencies | 1-10,000 Hz |
| What Doppler angle is most inaccurate | 60-75 degrees |
| Changing which of the following would not cause any change in a hard copy image output? | display brightness and contrast |
| A quality assurance program: | is needed by all labs |
| What is the actual time that an US machine is creating a pulse | pulse duration |
| The angle of incidence of an US beam is perpendicular to an interface. The two media have the same propagation speeds. What process cannot occur | refraction |
| What component of the US unit contains the memory bank | scan converter |
| An US wave travels through two media and has attenuation of 3dB in the first and 5dB int eh second. What is the total attenuation | 8dB |
| According to the AIUM statment on bioeffect, there have been no confirmation bioeffects below internsites of ___ watts per square centimeter SPTA | 0.1 ( 0.1 NO CONFIRMED BIOEFFECTS) |
| Fill in of an anechoic structure such as a cyst is know as all of the following except? | ghosting artifact |
| What is the range of frequencies created by medical diagnostic Doppler transducer | 2-10MHz |
| What is the significance of gray scale variation in the spectrum of a pulsed wave Doppler display | it represents the number of red blood cells creating the reflection |
| Which one of the following sets of properties of a test phantom is most relevant when assessing depth calibration accuracy? | reflector spacing and propagation speed |
| Assuming a constant frequency, what happens if the diameter of an unfocused circular transducer is increased? | the beam width in the near field is increased |
| From a safety standpoint, which one of the following methods is best | low transmit output and high receiver gain |
| The relative output of an US instrument is calibrated in dB and the operator increases the output by 60dB. The beam intensity is increased by which of the following | one million times |
| What is the most typical Dopppler shift measured clinically? | 2kHz |
| Doppler shift always occurs if the source and receiver are in motion relative to each other. | False |
| Doppler shift always occurs if the source and observer are in motion relative to each other and the angle between the motion and the sound beam is not 90 degrees | True |
| When the sound source and the receiver are not moving directly towards or away from each other, the ___ of the angle between them enters into the calculation of Doppler shift | cosine |
| The range equation relates distance from the reflector to __ and __ | time-of-flight, PS |
| In soft tissue: Distance traveled=__x round trip time | PS |
| With the presence of __we see more boundaries than there are reflecting surfaces. | reverberations |
| What is another name for longitudinal resolution? | depth |
| What are the units of longitudinal resolution? | feet |
| Which of the following is the best lateral resolution: 15mm, 6mm, 0,06cm or 2cm | 0.06cm |
| If the spatial pulse length is 10mm, what is the axial resolution | 0.5cm |
| If the frequency is decreased the numerical value of the radial resoultion is | increased ( freq down radial resol up) |
| A transducer__one form of ___ into another | converts /energy |
| The production of a voltage from deformation is called | piezeoelectricity |
| What is the production of deformation from voltage called | piezeoelectricity |
| Which is not a part of a transducer | A/D converter |
| What is the fraunhofer? | Far zone |
| If we increase the frequency in the near zone length is: | increased ( freq up nearzone length up) |
| If the transducer diameter increases, the lateral resolution at its smallest dimension is | increased |
| At the focus, the beam diameter is___ the transducer diameter | half |
| Lateral resoultion can be improved by: | focusing |
| The digital scan converter has a number of pixels assigned to each bit | false |
| The more bits per pixel | the more shades of gray |
| The more pixels per inch | the better spatial resolution |
| Rectification and smoothing are components of which of the following | demobdulation |
| What is the eliminaltion of voltages that do not exceed a certain level | reject |
| What is the name of the receiver function that corrects for attenuation | compensation |
| The process of reducing the difference between the smallest and largest voltages is called | compressions |
| If the lines per frame is increased while the image depth is unchanged then: | the frame rate decreases |
| A mirror image artifact can appear along side of the true anatomy | false |
| Enhancement, multipath and side lobes result in | artifact |
| The PS of US in the AIUM test object is | 1.54mm/us |
| If wires in an AIUM test object do not appear in the same place as on the display, what is amiss? | registration accuracy |
| How many data bits are needed to represent 46 gray shades | 6 ( 2x1=2;2x2=4; 4x2=8; 8x2=16; 16x2=32; 32x2=64 ) |
| The Fresnel is the | near zone |
| Which of the following is associated with cavitation? | Mechanical index |
| Which of the following best describes the mechanistic approach to the study of bioeffect? | cause-effect |
| Which of the following best describes the empirical approach to the study of bioeffect? | exposure-response |
| The interaction of microscopic bubbles and US form the basis for cavitation bioeffects. Which of the following forms of cavitaion are more likely to produce microstreaming in the intracellullar fluid and shear stresses | stable cavitation |
| The consolidation of many images into a single frame best describes which of the following | dynamic range |
| Identify one of the advantages of coded excitation | improves excitation |
| All of the following are true of normal cavitation except: | harmful bioeffects are commonly observed |
| Where does coded excitaion originate? | the pulser |
| Which of the following has the greatest output intensity? | pulsed Doppler |
| You enter a hospital room to preform an US exam. Which of the following should you do 1st | check the PT writband for ID |
| You entera room only to find that the Pt does not speak english. Which of the following is best to obtain informed consent | call for a hospital interpreter |
| The creation of an image by scanning grom different angles best describes | spatial compounding |
| What is the meaning of a thermal index =3? | tissue temperaure may rise 3 degrees Celsius |
| Identify one of the advantages of coded excitation | penetration |
| Which of these boundaries will create the strongest reflection? | air-soft tissue |
| Which of these boundaries will create the strongest refelction | air soft tissue |
| US physics is nothing to fear and can almost be fun if you remember to | pay your dues |
| Can be used to measure area | ellipse |
| Know that 0.000001 is | 10`6 or micro |
| How many hertz is 3Mhz | 3,000,000 |
| How much bigger is a billion than a million | 1,000 times |
| Macro means | bigger |
| Micro means | smaller |
| What is a sound wave | compressions and rare factions |
| particles move in a perpendicular direction, rt angle or 90 degree | transverse wave |
| Particels move in the same direction as the wave | longitudinal wave |
| Regions of higher density and pressure, molecules squeezed together | compressions |
| Regions of lower density and pressure, molecules spaced apart | rarefactions |
| Time to complete a single cycle or time from start of a cycle to the next. | period |
| Typical value for period | 0.06 to 0.5 usec |
| Number of certain events that occur in a particular time duration. can not be changed | Frequency |
| Frequency values | 2-15mhz |
| Freq exceeding 20,000hz (20khz)can not be heard by man | US |
| Heard by man freq of 20 -20,000 Hz | Audible sound |
| Freq less than 20hz, cannot be heard by man | infrasound |
| BOARDS QUESTION | WAVELENGTH (MM) = PS(MM/US) / FREQ (MHZ) |
| IF U GET A QUESTION LIKE: WHAT IS THE WAVELENGTH OF SOUND IN SOFT TISSUE, YOU TAKE | 1.54MM/FREQ EX: 1.54/2MHZ =0.77MM |
| AVERAGE SPEED OF SOUND NO MATTER WHAT IN SOFT TISSUE | 1.54KM/S = 1,540M/S =1.54MM/US |
| SPEED GENERAL RULE: | GAS(SLOWER)< LIQUID<SOLID (FASTER) |
| TISSUE AND SPEED IN INCREASING ORDER | AIR=SLOW @330 LUNG 300-1,200 FAT 1,450 SOFT TISSUE BLOOD 1540 TENDON 1850 BONE 2000-4000 ( DECREASING ORDER GOES UP HERE) |
| SLOWEST | GAS |
| MEDIUM | LIQUID |
| FAST | SOLID |
| STIFFNESS | CHANGES IN SHAPE |
| DENSITY | WRIGHT, HEAVER=MORE DENSE |
| STIFFNESS AND SPEED SAME LETTER | SAME DIRECTION |
| DENSITY AND SPEED DIFFERENT LETTERS | DIFFERENT DIRECTION |
| UNIT FOR WAVELENGTH | MM |
| UNIT FOR FREQ | HERTZ |
| UNIT FOR INTENSITY | WATTS/CM2 |
| UNIT FOR PS | METERS/SEC |
| UNIT FOR PERIOD | SECOND |
| UNIT FOR POWER | WATTS |
| CAN BE CHANGED BY SONOGRAPHER | AMP,POWER,INT |
| WHAT IS SPTA | SPATIAL PEAK TEMPROL AVERAGE |
| FIVE KEY WORDS | PEAK=BIGGEST; AVERAGE; SPATIAL; TEMPLORAL; PULSE |
| SPTA | IMPORTANT FOR THERMAL BIOEFFECTS |
| PEAK IS GREATER | THAN AVERAGE |
| HIGHEST INTENSITY | SPTP |
| LOWEST INTENSITY | SATA |
| FOR CW SOUND ( IMPORTANT ) | SPTA=SPPA AND SATA=SAPA |
| WHAT IS THE SAME AS SPTA | SPPA |
| WHAT IS THE SAME AS SATA | SAPA |
| WHAT IS THE SAME AS SPPA | |
| SPTA IS RELATED TO | TISSUE HEATING |
| SPTP IS RELATED TO | GREATEST |
| SATA IS RELATED TO | SMALLEST |
| A NOVEL WAY OF RATING NUMBERS, COUNT THE ZEROS | LOGARITHMS |
| LOG OF 10 LOG OF 100 LOG OF 1000 | =1 =2 =3 |
| WHAT IS A RELATIVE ANYTHING? EX: WHAT ARE THE UNITS OF RELAIVE AMPLITUDE? | DB |
| POSTIVE DB MEANS GETTING BIGGER, EX: EVERY 3DB = | 2X BIGGER SO 9DB = 2X2X2 |
| 3DB 10DB | 2X BIGGER 10X BIGGER |
| 6DB MEANS | 2X2 SO 4X BIGGER |
| 9DB MEANS | 2X2X2 SO 8X BIGGER |
| 20DB MEANS | 10X10 SO 100 X BIGGER |
| 30DB MEANS | 10X10X10 SO 1000 X BIGGER |
| WHAT DOES 50DB MEAN!!!! | 100,000X BIGGER |
| DECIBEL = | LOGARMITHIC SCALE |
Created by:
yovana2011