Test 8 (Chapter 15 & 16)

An uncompressed signal within the receiver of an ultrasound system has a dynamic range of 110 dB. The signal undergoes 40 dB of compression. What is the dynamic range of the compressed signal?

The dynamic range of the compressed signal is 110 dB- 40 dB = 70 dB

An uncompressed signal has a dynamic range of 85 dB. The signal undergoes 30 dB of compression. What is the dynamic range of the compression signal?

The dynamic range of the compressed signal is 85 dB-30 dB = 55 dB

A signal within a system;s receiver has a dynamic range of 60 dB after compression. The original signal was compressed by 50 dB. What is the dynamic range of the original, uncompressed signal?

The dynamic range of the original signal is 60 dB + 50 dB = 110 dB.

After compression, a signal within the ultrasound system has a dynamic range of 70 dB. The original signal was compressed by 40 dB. What is the dynamic range of the original, uncompressed signal?

The dynamic range of the original signal is 70 dB + 40 dB = 110 dB

True or false? A digital representation of a number can achieve only specific fixed values.

True

True or false? For digital image information to be displayed on conventional television screen, the data must be processed by a digital-to-analog converter.

True

True or false? Postprocessing of image data occurs after the data has been stored in the scan converter.

True

True or false? The assignment of different shades of gray to the digital numbers stored in the scan converter acts to improve the diagnostic value of an ultrasound exam.

True

True or false? The greater the number of bits assigned to each pixel of a digital image, the greater the number of shades of gray the image has.

True

How many gray shades can be represented by a group of - 4 bits? - 2 bits?

- 4 bits represent 16 shades - 2 bits represent 4 shades (multiple 22 by itself as many times as there are bits)

What is the number of shades that can be represented by 10 bits?

1024 different shades

What is the number of shades that can be represented by 3 bits?

2 x 2 x 2 = 8 (Eight different shades are stored using 3 bits)

What is the number of shades that can be represented by 8 bits?

256 different shades

What is the number of shades tat can be represented by n bits?

2^n different shades (2 is multiplied by itself n times)

With frequency compounding, how many pulses are transmitted down each scan line? A. 1 B. 2 C. 4 D. cannot be determined

A. 1

A signal with a 120 dB dynamic range is compressed by 40 dB. What is the dynamic range of the original uncompressed signal? A. 160 dB B. 120 dB C. 3 dB D. 80 dB

A. 160 dB

Two digital scan converters are undergoing evaluation. Both produce images of the same size. System A has 1,000,000 pixels, with 10 bits assigned to each. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to have the capability to display very small details in an image? A. System A B. System B C. both are the same D. cannot be determined

A. System A

What is the smallest amount of digital storage called? A. bit B. byte C. pixel D. fractel

A. bit

Which of the following technologies uses long sound pulses to create an image? A. coded excitation B. harmonics C. pulse inversion D. rendering

A. coded excitation

Which of the following components typically has the lowest dynamic range? A. display B. pulsar C. amplifier D. demodulator

A. display

Which of the these statements regarding a bit of computer memory is false? A. it is the smallest element of an image B. it is bistable C. eight bits combine to make a byte. D. it is a component of a digital scan converter

A. it is the smallest element of an image

Are the following procedures usually pre- or postprocessing? A. modifying a frozen image B. read zoom C. write zoom D. adjusting the brightness on the monitor E. increasing the receiver gain

A. postprocessing B. postprocessing C. preprocessing D. postprocessing E. preprocessing

All of the following are true of read zoom except: A. preprocessing function of a receiver B. same number of pixels are in the original ROI and the zoomed image C. on the screen, the pixels in the zoomed image are larger than those in the ROI D. the same number of ultrasound pulses are used to create the original ROI and the zoomed image

A. preprocessing function of a receiver

What happens to a digital image when the pixel density increases? A. spatial detail improves B. temporal resolution increases C. the field of view expands D. there are more shades of gray

A. spatial detail improves

Why is it neccessary for the receiver to perform compression on the electrical signals that it processes? A. the dynamic range of the system's electronics is less than the dynamic range of the received sound reflection B. the display's dynamic range exceeds the transducer's dynamic range C. the dynamic range of the receiver is less than the dynamic range of the image processor D. the dynamic range of the display exceeds the dynamic range of all other components if the ultrasound system

A. the dynamic range of the system's electronics is less than the dynamic range of the received sound reflection

Which of the following is best described as an analog number? A. the weight of a person B. the number of people in a room C. the number of stars in the sky D. the number of tires on a car

A. the weight of a person

Which of these is a binary number? A. 12211221 B. 10000000 C. 98765432 D. 01010102

B. 10000000

What is the approximate number of frames that must be presented each second for the human eye to perceive the display without flickering? A. 2 B. 30 C. 100 D. 500

B. 30

What is the number of binary digits required to store 29 levels of gray? A. 4 B. 5 C. 6 D. 29

B. 5

A byte is composed of ___ bits. A word is composed of _____ bytes. A. 2,2 B. 8,2 C. 16,16 D. 8,16

B. 8,16

Two digital scan converters are undergoing evaluation. Both produce images of the same size. System A has 1,000,000 pixels, and the picture size is 100 square inches. System B has an image size of 10 square inches composed of 250,000 pixels. Which image is more likely to display very small details? A. System A B. System B C. both are the same D. cannot be determined

B. System B

Two digital scan converters are undergoing evaluation. System A has 1,000,000 pixels, with 4 bits assigned to each. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to display images with very subtle differences in gray scale? A. System A B. System B C. both are the same D. cannot be determined

B. System B

A video display that is limited to black and white only, with no shades of gray, is called A. binary B. bistable C. monochrome D. inchworm

B. bistable

What is the primary storage device on a PACS system? A. magneto-optical system B. hard disc drives C. solid state memory D. compact disc

B. hard disc drives

All of the following are true of read zoom except: A. preprocessing function of a receiver B. same number of pixels are in the original ROI and the zoomed image C. the pixel size in the zoomed image and the ROI are the same D. in comparison to the zoomed image, fewer ultrasound pulses are used to create the original ROI

B. same number of pixels are in the original ROI and the zoomed image

What is the primary disadvantage of video tape and computer disc methods of image archiving? A. these methods are very costly B. the information is vulnerable to erasure when exposed to strong magnetic fields C. only low resolution images are stored D. only black and white images are stored

B. the information is vulnerable to erasure when exposed to strong magnetic fields

With 6 bits, what is the largest number of different gray shades that can be stored? A. 8 B. 16 C. 64 D. 256

C. 64

In modern elastography, how are the tissues deformed? A. by pressing the transducer into the skin B. with the use of a second probe C. automatically D. as a result of respiration

C. automatically

Which display is limited to a single pair of brightness or display levels? A. CRT B. binary C. bistable D. gray scale

C. bistable

Which of the following terms is not associated with a wide dynamic range image? A. low contrast B. many shades of gray C. bistable

C. bistable

The relationship between the largest and the smallest signal amplitudes processed by a component of an ultrasound system is called the ______ and has units of _______. A. decibels, watts B. intensity, W/cm^2 C. dynamic range, dB D. proportionality, dB

C. dynamic range, dB

Which of the following techniques is used to create image data where none really exists? A. edge enhancement B. temporal compounding C. fill-in interpolation D. spatial compounding

C. fill-in interpolation

Where does coded excitation take place? A. in the transducer B. in the receiver C. in the pulser D. in the PACS system

C. in the pulser

Which of the following statements regarding pixel is false? A. it is the smallest part of a digital image B. a collection of bits, assigned to each pixel, stores the shade of gray C. it displays up to 3 gray shades simultaneously D. image quality is improved when the number of pixels is high

C. it displays up to 3 gray shades simultaneously

What is the smallest part of a digital picture called? A. bit B. byte C. pixel D. fractel

C. pixel

All of the following are consistent with an image containing black and white only with no shades of gray except: A. bistable B. high contrast C. wide dynamic range

C. wide dynamic range

Which of the following scan converters will provide the best spatial resolution? A. 256 x 256 pixels B. 512 x 512 pixels C. 128 x 128 pixels D. 1000 x 1000 pixels

D. 1000 x 1000 pixels

What is the maximum number of shades of gray that are represented with 4 bits? A. 4 B. 8 C. 12 D. 16

D. 16

How many bits are required to display 10 different shades of gray? 14 shades? 15 shades? A. 4 bits, 5 bits, 6 bits B. 10 bits, 14 bits, 15 bits C. 4 bits, 4 bits, 2 bits D. 4 bits, 4 bits, 4 bits

D. 4 bits, 4 bits, 4 bits

A signal with a 120 dB dynamic range is compressed by 40 dB. What is the dynamic range of the compressed signal? A. 40 dB B. 120 dB C. 3 dB D. 80 dB

D. 80 dB

All of the following area advantages of PACS systems except: A. data is collected from different viewing angles B. frame rates are reduced C. shadowing artifact can be eliminated D. can be performed with a mechanical transducer

D. can be performed with a mechanical transducer

Which of the following is not true about spatial compounding? A. data is collected from different viewing angles B. frame rates are reduced C. shadowing artifact can be eliminated D. can be performed with a mechanical transducer

D. can be performed with a mechanical transducer

What happens to an image when the number of bits allocated to each pixel increases? A. spatial detail improves B. frame rate increases C. field of view expands D. more shades of gray

D. more shades of gray

What is DICOM? A. standards for transducer design B. standards for patient exposure C. protocols for two-dimensional imaging D. protocols for medical image data

D. protocols for medical image data

Which electronic component is required for gray scale imaging? A. VCR B. non-interlaced display C. computer memory D. scan converter

D. scan converter

What was the original purpose for the ultrasound system's analog scan converter? A. to increase the dynamic range of ultrasound systems B. to make real-time imaging possible C. to increase the sensitivity of ultrasound systems D. to allow for gray scale imaging

D. to allow for gray scale imaging

True or false? Digital scan converters do not use computer technology to process electronic data into images.

False

True or false? Preprocessing of image data occurs after the data has been stored in the scan converter.

False

True or false? The greater the number of bits assigned to each pixel of a digital image, the greater the spatial resolution of the image is.

False

How many bits are needed to store: - 10 shades of gray? - 11 shades of gray? - 15 shades of gray?

Four bits are required to store from 9 to 16 shades of gray