CE Digital Imaging in Dentistry + The radiographic image

Question 1

The production of digital images requires a process called Analog to Digital Conversion. Digital images consist of pixels organized in a matrix of rows and columns.

A. Both statements are true.

B. The first statement is true. The second statement is false.

C. The first statement is false. The second statement is true.

D. Both statements are false.

Answer 1

A. Both statements are true.

Question 2

Depending on the radiographic film used in the dental practice, radiation exposure time can be reduced as much as _____% when changing from radiographic film to digital sensors.

A. 10

B. 50

C. 75

D. 90

Answer 2

D. 90

Question 3

Digital imaging reduces the amount of radiation to the patient due to the sensitivity of the sensors.
A. True
B. False

Answer 3

A. True

Question 4

The digital images are composed of pixels or rows and columns of images aligned to represent the intensity (gray level) of the image. There is a value assigned to each pixel that represents the intensity or gray level of each location in the image.

A. Both statements are true.

B. The first statement is true. The second statement is false.

C. The first statement is false. The second statement is true.

D. Both statements are false.

Answer 4

A. Both statements are true.

Question 5

Standard radiation safety procedures still require the dental provider be at least _______________ from the x-ray tubehead and the patient be covered in a lead apron with a thyroid collar.
A. 1 foot
B. 3 feet
C. 6 feet
D. 12 feet

Answer 5

C. 6 feet

Question 6

The silicon chip detector converts x-ray photons into an electrical charge. The electrons produced are deposited into small boxes called _______________.

A. transistors

B. voxels

C. semiconductor

D. pixels

Answer 6

D. pixels

Question 7

Despite proper care and handling of PSP plates, loss in spatial resolution may occur. To reduce PSP plate deterioration resulting in surface damage and contamination, PSP plates should be handled carefully and cleaned according to manufacturer instructions.

A. Both statements are true.

B. The first statement is true. The second statement is false.

C. The first statement is false. The second statement is true.

D. Both statements are false.

Answer 7

A. Both statements are true.

Question 8

If contaminated, the CDC recommends an EPA-registered _______________ disinfectant after removing the barrier and before using the sensor on the next patient.
A. low-level
B. intermediate-level
C. high-level
D. advanced-level

Answer 8

B. intermediate-level

Question 9

With digital imaging, barriers must be placed on the sensors. Sensors cannot be sterilized.
A. Both statements are true.
B. The first statement is true. The second statement is false.
C. The first statement is false. The second statement is true.

Answer 9

A. Both statements are true.

Question 10

One recent research study found a degradation in spatial resolution after the same PSP plates had been used ______ times.
A. 11
B. 48
C. 78
D. 98

Answer 10

B. 48

Question 11

Signs of malfunction of the laser scanner include lines across the image due to _______________.
A. scanner belt slippage
B. photomulitplier tube malfunction
C. vacuum seal enhancement
D. Both A and B

Answer 11

D. Both A and B

Question 12

Some of the primary reasons to replace PSP plates are _______________.

A. scratches on the plates

B. loss of spatial resolution

C. there is no reason to replace PSP plates

D. A and B only

Answer 12

D. A and B only

Question 13

Digital imaging uses up to _____ shades of gray compared radiographic film that shows only 16-25 shades of gray. This allows for better detection of disease.
A. 56
B. 99
C. 199
D. 256

Answer 13

D. 256

Question 14

What is/are the advantage(s) of digital imaging?
A. Image quality
B. Cost
C. Patient comfort
D. Medico-legal

Answer 14

A. Image quality

Question 15

What is/one disadvantage of digital imaging?
A. Time

B. Patient comfort

C. Spatial resolution

D. Image quality

Answer 15

B. Patient Comfort

Question 16

Which of the following statements related to the formation of a radiographic image is correct?

A. When an x-ray passes through an absorber, it is absorbed evenly by the absorber.

B. When the x-ray beam exits an absorber, it will have varying intensities. The radiographic receptor will register the intensities as different densities, generating the radiographic contrast.

C. Radiographic densities associated with thick absorbers will be darker than densities associated with thin absorbers.

D. Two different absorbers of the same thickness will have the same radiographic density.

Answer 16

B. When the x-ray beam exits an absorber, it will have varying intensities. The radiographic receptor will register the intensities as different densities, generating the radiographic contrast.

Question 17

Which of the following statements related to factors affecting radiographic density is correct?

A. When the mA or exposure time decreases, the number of photons generated increases linearly without increasing beam energy.

B. An increase in the mA or exposure time will result in a brighter radiographic image related to a reference radiographic image.

C. When the kVp decreases, the number and energy of x-ray photons generated decrease.

D. A decrease in kVp will result in a radiographic image with lower density when compared to a reference radiographic image.

Answer 17

C. When the kVp decreases, the number and energy of x-ray photons generated decrease.

Question 18

All of the following statements related to source to object distance or thickness of the absorber are correct EXCEPT which one?

A. When the source to object distance increases, the intensity of the x-ray beam decreases following the inverse square law.

B. When related to a reference radiographic image, increasing the source to object distance will result in a darker image.

C. When the thickness of the absorber increases, the number of photons absorbed increases.

D. When related to a reference radiographic image, an increase in absorber thickness will result in a brighter image.

Answer 18

B. When related to a reference radiographic image, increasing the source to object distance will result in a darker image.

Question 19

Which of the following statements related to radiographic contrast, i.e., the difference in the degree of grayness between areas of the radiographic image, is correct?

A. When the x-ray beam is attenuated by 2 different thicknesses of the same object, the thicker part will attenuate less x-rays than the thinner part.

B. An important contributing factor is the density of the object - high density material will attenuate more x-rays than low density material.

C. Higher kVp will make the x-ray beam less penetrating resulting in lower contrast.

D. Higher kVp will make the x-ray beam less penetrating resulting in higher contrast.

Answer 19

B. An important contributing factor is the density of the object - high density material will attenuate more x-rays than low density material.

Question 20

Which of the following statements related to receptor contrast, i.e., the ability of a receptor to show adequately the information that the photons transmitted through the subject is incorrect?

A. In conventional radiography, receptor contrast depends on the size of the grains, development time, concentration and temperature of the developing solution, and overall film density.

B. In digital imaging, contrast depends on the bit-depth of the receptor, i.e., the number of possible grey values that can be stored in an image.

C. In digital imaging, the higher the bit-depth of the receptor, the less gray values it can store.

D. In digital imaging, a 1-bit receptor can only store one of two values, 0 (white) and 1 (black).

Answer 20

C. In digital imaging, the higher the bit-depth of the receptor, the less gray values it can store.

Question 21

Factors that affect radiographic contrast include scatter radiation, which will decrease the contrast of the radiograph; however, collimation can counterbalance this effect.

A. True

B. False

Answer 21

A. True

Question 22

All of the following statements related to contrast resolution are correct EXCEPT which one?

A. Contrast resolution is the ability of an imaging system to distinguish between multiple densities in the radiographic image.

B. In digital imaging, contrast resolution depends on the bit-depth of the system - an 8-bit system can show 256 gray values as opposed to a 12-bit system, which shows 4096 gray values.

C. In digital imaging, an 8-bit system shows less gray values than a 12-bit system and is, generally, a low contrast system.

D. In digital imaging, a 12-bit system that shows more gray values than an 8-bit system and is, generally, a low contrast system, but if it can clearly show two near-by gray value intensities, the system will have a high contrast resolution.

Answer 22

C. In digital imaging, an 8-bit system shows less gray values than a 12-bit system and is, generally, a low contrast system.

Question 23

All of the following statements related to special resolution are correct EXCEPT which one?

A. Spatial resolution in radiology refers to the ability of an imaging system to differentiate between two near-by objects.

B. In digital imaging, special resolution depends on the size of the pixel used.

C. Larger the pixel size, the more likely that the system will resolve two near-by structures, i.e., will have a higher special resolution as compared to a small pixel size system.

D. Spatial resolution is measured in line-pairs per millimeters.

Answer 23

C. Larger the pixel size, the more likely that the system will resolve two near-by structures, i.e., will have a higher special resolution as compared to a small pixel size system.

Question 24

Which of the following statements related to image magnification is correct?

A. Image magnification refers to the proportional increase in the dimensions of a radiographed object relative to the actual dimensions of that object.

B. Increasing object to film distance only will result in an decrease in magnification of the radiographic image

C. Increasing source to object distance only will result in a increase in magnification of the radiographic image.

D. Decreasing source to object distance only will result in a decrease in magnification of the radiographic image

Answer 24

A. Image magnification refers to the proportional increase in the dimensions of a radiographed object relative to the actual dimensions of that object.

Question 25

Which of the following statements related to image distortion is incorrect?

A. It refers to the proportional increase in the dimensions of a radiographed object relative to the actual dimensions of that object

B. It can be seen when there is a change in the angle of the incidence x-ray beam

C. It can be seen when the receptor is parallel to the object

D. It is not affected by the Source-Object or Object receptor distance

Answer 25

C. It can be seen when the receptor is parallel to the object

would have to say is NOT parallel to be correct

Question 26

Image sharpness is considered a major factor in determining image quality as it is the factor that determines the amount of detail an imaging system can reproduce.

A. True

B. False

Answer 26

A. True

Question 27

Image sharpness is defined by the dimensions of the partially shaded outer region or the penumbra of an object– an image with a narrow penumbra is less sharp.

A. True

B. False

Answer 27

B. False

Question 28

All of the following statements related to image sharpness are correct EXCEPT which one?

A. The larger is the size of the apparent focal spot, the larger is the penumbra, resulting in a less sharp image.

B. The greater is the source-to-object distance, the greater is the penumbra, resulting in a less sharp image.

C. The greater is the object-to-receptor distance, the larger is the penumbra, resulting in a less sharp image.

D. If the tube moves when the x-ray image is being taken, the apparent focal spot size will become larger resulting in a larger penumbra and a less sharp image.

Answer 28

B. The greater is the source-to-object distance, the greater is the penumbra, resulting in a less sharp image.

just remember
The apparent focal spot size: The larger the size of the apparent focal spot, the larger the penumbra, resulting in a less sharp image.
Source-to-object distance: The greater is the source-to-object distance, the smaller is the penumbra, resulting in a sharper image.
Object-to-receptor distance: The greater is the object-to-receptor distance, the larger is the penumbra, resulting in a less sharp image.
X-ray tube motion-related un-sharpness: If the tube moves during image acquisition, the apparent focal spot size will become larger, resulting in a larger penumbra and a less sharp image.