Edelman Ch 10 Axial & Lateral Resolution Review

What is the ability to accurately distinguish two structures lying close together called ?

resolution

(Ch 10, pg. 145, Question # 1)

The ability to distinguish two structures lying close together front - to - back or parallel to the sound beam is called

longitudinal , axial , range , radial , depth resolution .

(Ch 10, pg. 145, Question # 2)

Axial resolution is measured with units of

distance , such as mm .

(Ch 10, pg. 146, Question # 3)

If there are more cycles in a pulse , the numerical value of range resolution is [ greater , lesser , same ] .

greater .

(Ch 10, pg. 147, Question # 4)

If a new pulsed transducer has many more cycles in its pulse , the image accuracy [ improves , degrades , remains the same ] .

degrades

(Ch 10, pg. 147, Question # 5)

[ High , Low ] frequency transducers generally have the best range resolution .

High

(Ch 10, pg. 147, Question # 6)

Which of the following transducers has the poorest axial resolution ?

A. 1.7 MHz and 4 cycles / pulse

B. 2.6 MHz and 3 cycles / pulse

C. 1.7 MHz and 5 cycles / pulse

D. 2.6 MHz and 2 cycles / pulse

C. This is the longest pulse . It has the lowest frequency and the most ringing ( more cycles / pulse ) .

(Ch 10, pg. 148, Question # 7)

In soft tissue , a 3 cycle , 1 MHz pulse has a pulse length equal to 4.5 mm . What is the axial resolution ?

In this setting , the axial resolution is 2.25 mm . Axial resolution is one - half of the spatial pulse length 4.5 mm / 2 = 2.25 mm ) .

(Ch 10, pg. 147, Question # 8)

Which of the following transducers has the best axial resolution ?

A. 1.7 MHz and 4 cycles / pulse

B. 2.6 MHz and 3 cycles / pulse

C. 1.7 MHz and 5 cycles / pulse

D. 2.6 MHz and 2 cycles / pulse

D. This is the shortest pulse . It has the highest frequency and the least ringing . ( fewest cycles / pulse ) .

(Ch 10, pg. 147, Question # 9)

Two different transducers create sound pulses . One transducer is labeled 5 MHz and the other , 3 MHz . Which transducer is more likely to create a more accurate image with respect to axial resolution ? Which transducer probably has a lower numerical value of axial resolution ?

The 5 MHz transducer is more likely to create an image with better axial resolution .

(Ch 10, pg. 147, Question # 10)

Two different transducers create pulses . Both transducers create sound with a frequency of 4 MHz . One transducer creates a pulse that comprises 6 cycles and the other , 3 cycles . Which transducer is more likely to create a more accurate image with respect to axial resolution ? Which transducer has a lower numerical value of axial resolution ?

The 3 - cycle pulse transducer is more likely to create an image with better axial resolution . Less ringing , or fewer cycles in a pulse , generally implies shorter pulses and improved axial resolution .

(Ch 10, pg. 147, Question # 11)

Two different transducers create pulses . One transducer is labeled 5 MHz and the other , 3 MHz . The 3 MHz transducer creates a more accurate image with respect to axial resolution . Explain .

Axial resolution is determined by pulse length . Shorter pulses have better axial resolution . In this question , the 3 MHz transducer has the best axial resolution , which means the 3 MHz pulse must be shorter than the 5 MHz pulse . Since 3 MHz sound has a longer wavelength than 5 MHz sound , the only way that the 3 MHz pulse is shorter is li the 3 MHz transducer rings less . Thus , the 3 MHz pulse has fewer cycles than the 5 MHz pulse .

(Ch 10, pg. 147, Question # 12)

The near zone length is 8 cm . The transducer diameter is 9 mm . What is the lateral resolution at a depth of 8 cm ?

4.5 mm . At the end of the near zone , the beam diameter is one half the transducer diameter .

(Ch 10, pg. 152, Question # 1)

The near zone length is 8 cm . The transducer diameter is 9 mm . What is the lateral resolution at a depth of 16 cm ?

9 mm . At a depth of twice the near zone , the beam is as wide as the transducer .

(Ch 10, pg. 152, Question # 2)

The near zone length is 8 cm . The transducer diameter is 9 mm . What is the best estimate for the resolution at 4 cm ?

5 mm

(Ch 10, pg. 152, Question # 3)

The near zone length is 8 cm . The transducer diameter is 9 mm What is the best estimate for the resolution at 7 cm ?

5 mm

(Ch 10, pg. 152, Question # 4)

The near zone length is 8 cm . The transducer diameter is 9 mm . What is the best estimate for the resolution at 21 cm ?

14 mm

(Ch 10, pg. 152, Question # 5)

The ability to distinguish two structures lying close together is called

resolution

(Ch 10, pg. 145, Question # 6)

The ability to distinguish two structures lying close together front - to - back is called

axial , longitudinal , range , radial , or depth resolution .

(Ch 10, pg. 145, Question # 7)

The ability to distinguish two structures lying close together side by side is called

lateral angular , transverse or azimuthal resolution .

(Ch 10, pg. 151, Question # 8)

Axial resolution and lateral resolution are both measured with units of

distance , such as mm .

(Ch 10, pg. 151, Question # 9)

When the number of cycles in a pulse increases while the frequency remains the same , the numerical value of the range resolution [ increases , decreases , remains the same ] .

Increases . With more cycles in a pulse , the pulse becomes longer . The numerical value of the range resolution increases .

(Ch 10, pg. 147, Question # 10)

When the number of cycles in a pulse increases ( more ringing ) while the frequency remains the same , the image quality [ improves , degrades , remains the same ] .

Degrades . When the number of cycles increases , the spatial pulse length increases and the image quality degrades .

(Ch 10, pg. 148, Question # 11)

High , Low ] frequency transducers have the best range resolution .

High frequency

(Ch 10, pg. 148, Question # 12)

Name the 4 synonyms for axial resolution

longitudinal , axial , range , radial , and depth ( mnemonic : LARRD ) .

(Ch 10, pg. 146, Question # 13)

Name the 3 synonyms for lateral resolution .

lateral , angular , transverse , and azimuthal ( mnemonic : LATA )

(Ch 10, pg. 151, Question # 14)

The length of a pulse is 8 mm . What is the minimum distance between two reflectors , positioned one in front of the other , that still produces two echoes on our image ?

B. 4 mm : This value is one - half the pulse length .

(Ch 10, pg. 147, Question # 15)

Axial resolution describes the accuracy related to visualizing two structures that are __________ to a sound beam's main axis

parallel

(Ch 10, pg. 147, Question # 258)

You are purchasing a diagnostic ultrasound system . System X has axial resolution of 0.7 mm whereas System D's is 0.4 mm . Based on this information , which system will produce the better quality picture ?

A. System X

B. System D

C. they have the same quality

D. cannot be determined

Resolution is reported in units of distance , such as cm or mm . Higher image quality is achieved by systems with lower numerical values for resolution . System D has a lower numerical value for longitudinal resolution , and will produce more detailed , higher quality pictures .

(Ch 10, pg. 147, Question # 259)

The axial resolution of an imaging system is reported to be 0.85 mm at the beam's focus . What is the closest estimate of the system's radial resolution at a location that is 5 cm deeper than the focus ?

A. less than 0.85 mm

B. equal to 0.85 mm

C. greater than 0.85 mm

B. Radial resolution is determined by the spatial pulse length or the pulse duration These variables remain constant , regardless of the depth of the pulse . The radial resolution is the same at all imaging depths .

(Ch 10, pg. 146, Question # 260)

Two systems are undergoing evaluation . System A has 1,000,000 pixels , each with 4 bits . System B has 750,000 pixels , each with 12 bits . Which system has the best longitudinal resolution ?

A. System A

B. System B

C. both are the same

D. cannot be determined

D. The longitudinal resolution of an ultrasound system is determined primarily by the pulse duration or the spatial pulse length . Since no information is provided on the length of the pulse , it is impossible to determine which of the systems will have superior longitudinal resolution .

(Ch 10, pg. 147, Question # 261)

True or False ? The lower the numerical value of the longitudinal resolution , the worse the picture .

False

(Ch 10, pg. 147, Question # 262)

True or False ? One way that a sonographer can alter the axial resolution achieved during an exam is to adjust the maximum imaging depth .

False

(Ch 10, pg. 146, Question # 263)