Digital radiography in dental x-ray l Oral radiology MCQs for dental students
.
d. photostimulable phosphor (PSP) technology.
3. Which is the significant clinical feature of solid-state detectors?
a. Ease of use.
b. Rapid image production.
c. Production of electron-hole pairs.
d. More sensitive to light than to x-rays.
4. Which is the purpose of the layer of scintillating material coated directly on the charge-coupled device (CCD) surface?
a. Decrease sensitivity to white light.
b. Increase x-ray absorption efficiency.
c. Enhance production of electron-hole pairs.
d. Transfer each row of pixel charges to the next row.
5. Which element is combined with a linear array of pixels for panoramic imaging?
a. Stationary mounting.
b. Wide column of pixels.
c. Slit-shaped x-ray beam.
d. Retrofitted CCD sensors.
6. Which is the main difference between the CCD technology and the complementary metal oxide semiconductor (CMOS) technology?
a. Pixel arrangement.
b. Flat panel detectors.
c. Manner in which pixels are read.
d. Production of electron-hole pairs.
7. Which is the purpose of an intensifying screen for indirect flat panel detectors?
a. Strengthen x-ray absorption.
b. Decrease image “unsharpness.”
c. Create diffusion of light photons.
d. Convert x-ray energy into visible light.
8. Which technique is used to eliminate PSP plate ghost images?
a. Flood the plate with a bright light.
b. Expose plate to scintillating material.
c. Use red filter safety lights when handling.
d. Have patients remove eyeglasses, jewelry, and partial dentures to eliminate artifacts.
9. Which BEST explains why PSP plates should be processed as soon as possible?
a. Prevents possibility of double exposures.
b. Underexposed images rapidly deteriorate.
c. Oral fluids permeate the polyvinyl envelope.
d. Trapped electrons are spontaneously released over time.
10. The ability of the digital detector to distinguish different densities in the radiographic image is called
a. attenuation.
b. spatial resolution.
c. fast scan direction.
d. contrast resolution.
11. Inaccuracies in image acquisition are called
a. noise.
b. details.
c. spatial resolution.
d. contrast resolution.
12. Which constitutes a line pair (lp)?
a. Two pixels.
b. A line and its associated space.
c. Two very fine radiopaque lines.
d. Bit depths of 8, 10, 12, or 16 to the power of 2.
13. All factors, EXCEPT one, lower the actual image resolution. Which one is the EXCEPTION?
a. Variety of sources of noise.
b. CCD pixel size of approximately 20 μm.
c. Diffusion of photons in scintillator coating.
d. Imperfect optical coupling in systems using fiber optics.
14. Which is responsible for different shades of gray, or the color hue and intensity of electron scans?
a. Cathode ray tube (CRT) design.
b. Red, blue, and green phosphors.
c. Conventional computer monitors.
d. Electron beam’s variable intensity.
15. The quality of hard copies of digital images is MOST important in which situation?
a. Caries detection.
b. Eruption assessment.
c. Evaluation third molars.
d. Bone assessment for implant placement.
16. Which printer has a higher resolution?
a. 12 bits.
b. 16 bits.
c. Lower dots-per-inch (DPI) number.
d. Higher dots-per-inch (DPI) number.
17. Any operation that acts to improve, restore, analyze, or change a digital image is called
a. analog dialogue.
b. image processing.
c. spatial resolution.
d. solid-state technology.
18. Subjective image enhancement includes all EXCEPT one. Which one is the EXCEPTION?
a. Reduction in noise.
b. Increasing contrast.
c. Optimizing brightness.
d. Preprocessing operations.
19. Which is the purpose of smoothing filters?
a. Support contrast inversion.
b. Enhance histogram equalization.
c. Substantially benefit contrast enhancement.
d. Improve image quality by removing blur or noise.
20. Which image enhancement process changes the gray values into colors?
a. Despeckling.
b. Pseudocolor.
c. Contrast inversion.
d. Subtraction radiography.
21. The accuracy of the digital imaging measurement tool is MOST dependent on the
a. clinician’s skill.
b. sharpening filters.
c. projection geometry.
d. accuracy and precision of the measurement tool.
22. Which is NOT a basic step of image analysis?
a. Segmentation.
b. Transformation.
c. Feature extraction.
d. Object classification.
23. Which basic image analysis step subdivides the image, separating the objects from the background?
a. Segmentation.
b. Transformation.
c. Feature extraction.
d. Object classification.
24. Methods of obtaining digital image include:
A. Direct digital imaging
B. . Indirect digital imaging
C. Reusable storage phosphor imaging
D. All of the above
25. Dental digital images require less radiation exposure than film-based images because digital images do not require chemical processing:
A. The statement is true but the reason is false
B. The statement is false but the reason is true
C. Both statements and reasons are false
D. Both statement and reasons are true but not related
E Both statement and reasons are true and related.jpg)
Digital radiography in dental x-ray l Oral radiology MCQs for dental students
IMPORTANT POINTS TO REMEMBER
- • Digital radiography may be defined as
a system for acquisition, processing and display of radiographic images using
modern data processing technology.
- • Components of a digital radiographic system: A digital
radiographic system consists of solid-state detector and storage phosphor plate.
- • Solid-state detectors: Solid-state
detectors are made of semiconductors such as silicon or germanium, which are doped
by other elements.
- • Pixel: A solid-state detector
contains a high number of mostly square-shaped small (side length:
approximately 20 mm) measurement devices made of the semiconductor material. These
small units are called ‘pixels’, an acronym derived from ‘picture elements’.
- • CCD sensors: Here, the electric charge
resulting from incident photons is collected over columns and rows.
- • CMOSs: In CMOS technology,
transistors are integrated into each pixel and the charge acquired by the pixel
is directly amplified and transferred.
- • Storage phosphors: Storage
phosphors are also semiconductors; they are completely different from a
chemical point of view. For instance, yttrium oxide doped with europium is a
material with the typical properties of a storage phosphor.
- • Digital image: A digital image is
composed of pixels of intraoral radiographic sensors which are currently approximately
19 mm wide. Consequently, a digital image is not at all continuous
but ‘discrete’ in nature.
- • Pixel binning: It should be noted,
however, that most of the manufacturers combine several physical pixels to one
software pixel, a process referred to as ‘pixel binning’.
- • Image processing: Computer may
manipulate the image in one or another way by simply calculating a new image from
the original one.
- • Convenient
advantage of digital image processing is the ability to suppress or partly
remove noise.
- • Digital subtraction radiography: In fact, the simple method of subtracting two radiographs is referred to as ‘digital subtraction radiography’.
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