CH. 15-REST FINAL EXAM QUESTIONS Flashcards
HOW DO YOU DESCRIBE THE PRP?
THE SUM OF THE PULSE’S ON TIME AND THE LISTENING OFF TIME
DO ALL SOUND WAVES TRAVEL IN THE SAME MEDIUM AT IDENTICAL SPEEDS?
YES
WHAT ESTABLISHES THE PRF?
THE SOURCE OF THE SOUND
WHAT IS THE TYPICAL VALUE FOR THE DUTY FACTOR OF PULSED SOUND WAVES USED IN U/S?
0.001
WITH PULSED U/S WHAT IS THE MAXIMUM VALUE OF THE DUTY FACTOR?
LESS THAN 100% (100% WOULD MEAN CONTINUOUS WAVE)
WHAT IS THE IMPORTANCE OF DESCRIBING SOUND BEAM INTENSITIES IN A VARIETY OF WAYS WITH REGARD TO SPACE AND TIME?
IT’S IMPORTANT WHEN STUDYING BIOEFFECTS
WHICH INTENSITY IS MOST CLOSELY CORRELATED TO TISSUE HEATING?
SPTA (REMEMBER SPCA)
WHAT DETERMINES ATTENUATION?
PATH LENGTH AND FREQUENCY OF SOUND
AN ACOUSTIC WAVE IS TRAVELING THROUGH SOFT TISSUE. ITS INTENSITY UNDERGOES 6 DECIBELS OF ATTENUATION. HOW DOES THE FINAL INTENSITY OF THE WAVE RELATE TO THE INTENSITY OF THE WAVE WHEN IT STARTED ITS JOURNEY?
IT IS NOW ONE-FOURTH AS LARGE (-3 DB IS ONE HALF, ANOTHER -3 WOULD BE ONE FOURTH)
WHEN IS A BOUNDARY CONSIDERED SMOOTH FOR SPECULAR REFLECTION?
WHEN IRREGULARITIES IN ITS SURFACE ARE SMALLER THAN THE WAVELENGTH OF THE INCIDENT ULTRASONIC BEAM
A SOUND WAVE REACHES A ROUGH OR IRREGULAR BORDER BETWEEN TWO MEDIA. UNDER THESE EXPLICIT CIRCUMSTANCES, WHICH PROCESS IS MOST LIKELY TO OCCUR?
BACKSCATTER / DIFFUSE REFLECTION (BOUNDARIES HAS IRREGULARITIES THAT ARE LARGER THAN THE WAVELENGTH OF THE INCIDENT ACOUSTIC PULSE, SO THE REFLECTIONS ARE DISPERSED IN MULTIPLE DIRECTIONS)
WHAT IS THE UNIFORM DISPERSION OF A SOUND WAVE IN MANY DIFFERENT DIRECTIONS AFTER STRIKING A VERY SMALL PARTICLE?
RAYLEIGH SCATTERING (THE DIMENSION OF THE REFLECTING PARTICLE IS USUALLY LESS THAN THE WAVELENGTH OF THE U/S WAVE) EX: BLOOD CELLS
HOW IS RAYLEIGH SCATTERING EXPRESSED?
FREQUENCY RAISED TO THE FOURTH POWER
WHAT IS THE CONVERSION OF ACOUSTIC ENERGY INTO HEAT CALLED?
ABSORPTION
WHAT IS THE AMOUNT OF ATTENUATION PER CM THAT A SOUND WAVE UNDERGOES CALLED?
ATTENUATION COEFFICIENT
WHAT HAS LOWEST ATTENUATION OF U/S?
WATER
WHAT HAS SECOND LOWEST ATTENUATION OF U/S?
BLOOD
WHAT HAS THIRD LOWEST ATTENUATION OF U/S?
FAT
WHAT HAS FOURTH LOWEST ATTENUATION OF U/S?
MUSCLE
WHAT HAS FIFTH LOWEST ATTENUATION OF U/S?
BONE
WHAT HAS HIGHEST ATTENUATION OF U/S?
AIR
ARE ATTENUATION AND PROPAGATION RELATED?
NO
WHAT ARE THE TWO ATTRIBUTES OF ACOUSTIC IMPEDANCE OF A MEDIUM?
DENSITY AND STIFFNESS
THE ANGLE BETWEEN THE DIRECTION OF PROPAGATION AND THE BOUNDARY BETWEEN 2 MEDIA IS 90 DEGREES. WHAT TERM DESCRIBES THE FORM OF INCIDENCE OF THE WAVE?
ORTHOGONAL
WHAT ARE SYNONYMS FOR ORTHOGONAL?
AT RIGHT ANGLES, 90 DEGREES, NORMAL, PERPENDICULAR
A SOUND WAVE STRIKES A BOUNDARY BETWEEN 2 MEDIA AT 60 D AND IS CALLED WHAT?
OBLIQUE INCIDENCE
HOW IS THE INTENSITY TRANSMISSION COEFFICIENT DEFINED?
THE PERCENTAGE OF AN U/S BEAM’S INTENSITY THAT IS TRANSMITTED AS THE SOUND WAVE PASSES THROUGH A BOUNDARY BETWEEN 2 MEDIA (NO UNITS USED!)
WHAT RESULTS WHEN REFLECTED INTENSITY IS DIVIDED BY INCIDENT INTENSITY?
INTENSITY REFLECTION COEFFICIENT
WHAT RESULTS WHEN THE INTENSITY TRANSMISSION COEFFICIENT AND THE INTENSITY REFLECTION COEFFICIENT ARE ADDED TOGETHER?
THEY EQUAL 1 OR 100%
WHAT DOES THE LAW OF CONSERVATION OF ENERGY STATE?
THE SUM OF THE PERCENTAGE OF TRANSMITTED SOUND AND THE REFLECTED SOUND EQUALS 100%
UNDER THE CONDITIONS OF ORTHOGONAL/NORMAL INCIDENCE, WHAT DOES REFLECTION DEPEND ON?
DIFFERENCES IN THE ACOUSTIC IMPEDANCES OF THE MEDIA ON EITHER SIDE OF THE BOUNDARY
WHAT DO GREATER DIFFERENCES BETWEEN 2 IMPEDANCES CREATE?
STRONGER REFLECTIONS (SLIGHTLY DIFFERENT IMPEDANCES WILL PRODUCE WEAK REFLECTIONS)
TRUE OR FALSE: LARGER REFLECTIONS OCCUR WITH GREATER IMPEDANCE DIFFERENCES
TRUE
