Deck 6: Charge-Coupled Devicecomplementary Metal Oxide Semiconductor Image Capture

Question 1

Quantum efficiency is a measurement of the

A) amount of electron-hole pairs held by the electrostatic force.
B) percentage of light that is absorbed.
C) amount of electrons produced relative to the incident light from the scintillator.
D) total amount of light that is absorbed.

Answer 1

amount of electrons produced relative to the incident light from the scintillator.

Question 2

Which of the following statements about scintillators is true?

A) All scintillators absorb the same amount of x-ray photons.
B) The amount of x-rays absorbed depends on the type of scintillator.
C) Structured phosphors produce more light spread.
D) Unstructured phosphors are more efficient.

Answer 2

The amount of x-rays absorbed depends on the type of scintillator.

Question 3

The indirect conversion detector system that requires optical coupling and image size reduction is known as a

A) CCD.
B) field-effect transistor.
C) CMOS.
D) thin-field transistor.

Answer 3

CCD.

Question 4

Which of the following flat-panel detector technologies was developed by NASA?

A) CCD
B) Field-effect transistor
C) CMOS
D) Thin-field transistor

Question 5

The most popular base material used in integrated circuits is

A) selenium.
B) sulfur.
C) silicon.
D) tellurium.

Question 6

When specialized pixels in a complementary metal oxide silicon system are struck with x-ray photons

A) the x-ray photons are converted into light.
B) light photons are stored in capacitors.
C) light photons are converted into electrical charges.
D) All of the above

Question 7

A device that acts like a camera in an indirect conversion detector is known as a

A) CCD.
B) field-effect transistor.
C) CMOS
D) thin-field transistor.

Question 8

When compared with a CMOS,CCDs

A) are less light sensitive.
B) are more susceptible to noise.
C) use more than 100 times the power.
D) are inexpensive to manufacture.

Question 9

Which statement best describes a capacitor?

A) It converts x-ray photons to light.
B) It converts light to an electrical charge and stores it.
C) It converts x-ray photons to light and stores it.
D) It stores light and converts it from an analog to a digital signal.

Question 10

Which of the following statements is true?

A) Quantum efficiency and detective quantum efficiency are the same.
B) Quantum efficiency will affect detective quantum efficiency.
C) Quantum efficiency has no effect on detective quantum efficiency.
D) Quantum efficiency is the absolute efficiency of the amount of light collected.

Question 11

A detector in which each pixel has its own amplifier is known as a

A) CCD.
B) field-effect transistor.
C) CMOS.
D) thin-field transistor.

Question 12

The readout process requires that _______ and _______.

A) electrons flow freely when the gates are open;voltage stays consistent
B) the flow of electrons is timed;voltage stays consistent
C) electrons flow freely when the gates are open;multiple voltage changes occur
D) the flow of electrons is timed;multiple voltage changes occur

Question 13

Clinical applications for CCDs include all of the following except

A) digital fluoroscopy.
B) computed tomography fluoroscopy.
C) digital mammography.
D) general radiography.

Question 14

Demagnification is

A) reducing the phosphor output image to the size of the active area of the CCD.
B) reducing the field size of the CCD detector.
C) reducing the amount of light spread from the scintillator.
D) None of the above

Question 15

Which statement best describes a charge-coupled device (CCD)?

A) It is the oldest direct conversion technology that is still in use today.
B) It is the oldest direct conversion technology with limited use today.
C) It is the oldest indirect conversion technology that is no longer used in medical imaging.
D) It is the oldest indirect conversion technology used in a variety of image capture applications.

Question 16

A highly efficient indirect conversion system that takes up less fill space than CCDs is known as a(n)

A) analog to digital converter.
B) field-effect transistor.
C) CMOS.
D) thin-field transistor.

Question 17

The components that focus the signal from the scintillators to the CCD are called

A) detector elements.
B) capacitors.
C) fiber optics.
D) analog-digital converters.

Question 18

Detector elements are formed by voltage gates that _____ at readout to _____ the flow of electrons.

A) close;allow
B) open;allow
C) close;stop
D) open;stop

Question 19

The most common types of noise that affects image quality include all of the following except

A) quantum noise.
B) statistical noise.
C) "dark" current noise.
D) amplification noise.

Question 20

Some advantages to CCDs include

A) less expensive to manufacture.
B) module design makes repairs and upgrades easy.
C) demagnification capabilities.
D) a and c only.
E) All of the above

Question 21

The number of electron-hole pairs produced is related to the amount of light absorbed.

Question 22

_______ turn semi-conductors into full electrical conductors.

A) Dopants
B) Amplifiers
C) Positive transistors
D) Negative transistors

Question 23

CCDs use more power than CMOS.

Question 24

The polysilicon layer within a CCD acts as an insulator.

Question 25

All of the following are considered impurities except

A) gallium arsenide.
B) indium antimonide.
C) tellurium.
D) most metal oxides.