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IMAGING COMPILED QUIZZES FOR
GUARANTEE PASS
If a pixel has a bit depth of 2^6, the number of gray tones that pixel can produce is? a. 8 b. 16 c. 64 d. 256 - Correct answer c. 64 What pixel size has a 1024 x 1024 matrix with a 20-cm field of view (FOV)? 0.07 mm 0.2 mm 0.02 mm 5mm - Correct answer 0.2 mm In digital imaging, for the same FOV, as the digital image matrix size increases:
- Pixel size decreases.
- Spatial resolution decreases.
- Pixel depth decreases. - Correct answer 1 only How many pixels are in a 1024 x 1024 matrix? 512 1, 2, 1,048,576 - Correct answer 1,048, Which of the following matrix sizes in MOST LIKELY to produce the best image resolution? 128x 512x 1024x 2048x2048 - Correct answer 2048x The pixel bit depth has an effect on:
spatial resolution contrast resolution matrix size FOV - Correct answer Contrast resolution Which device converts the analog signal into digital data for input into a computer? Photomultiplier Tube (PMT) Analog-to-digital converter (ADC) Histogram LUT - Correct answer ADC Each pixel in a digital image: can have up to 3 gray scale values at a time. is composed of a matrix of up to 1024 x 1024 units. is the smallest picture element and has one gray scale value. is comprised of a small amount of analog data. - Correct answer is the smallest picture element and has one gray scale value. The field of view (FOV) and the matrix have what type of relationship? Indirect Direct Exponential They are not related - Correct answer They are not related How does the bit depth affect the digitally reproduced image? The more bits the better the reproduction of the original signal. The less bits the better the reproduction of the original signal The more bits the less true the reproduction of the original signal. The bits do not affect the reproduction of the original signal. - Correct answer The more bits the better the reproduction of the original signal. In which step of the digitizing process are the brightness levels assigned a number called a gray level? Scanning Sampling Quantization Conversion - Correct answer Quantization
The greater the dynamic range:
- The longer the gray scale.
- The shorter the gray scale.
- The more detail seen in the image.
- The less detail seen in the image a. 1 and 4 only b. 2 and 3 only c. 1 and 3 only d. 2 and 4 only - Correct answer 1 and 3 only What is used to express the contrast resolution provided by a particular imaging system? Matrix Line pairs/mm Frequency Modulation transfer function (MTF) - Correct answer Line pairs/mm The radiation dose received by the digital detector for each image is indicated by the: mA meter EI kV selector Histogram - Correct answer EI Which domain is used to view images by the radiographer? Spatial frequency Spatial location Fourier transformation Spatial resolution - Correct answer Spatial location Grayscale processing allows for adjustments in which image quality(s)? Brightness Contrast Resolution Both a and b - Correct answer Both a and b A histogram displays the useful signal by locating:
all pixel values maximum and minimum signal maximum signal only minimum signal only - Correct answer maximum and minimum signal The term windowing describes the practice of: varying the automatic brightness control changing the image brightness and/or contrast scale varying the FOV increasing resolution - Correct answer changing the image brightness and/or contrast scale The stored data that is applied when the image is processed to provide the proper grayscale (contrast) is called: histogram windowing LUT dynamic range compression - Correct answer LUT Changing the histogram will alter the: brightness of the image contrast of the image both a and b - Correct answer both a and b What is the term used to describe the numeric value of the exposure the IR receives in digital radiography? EI Exposure latitude Histogram analysis Signal to noise ratio - Correct answer EI Visual cues that an image has been overexposed are not easily seen in digital radiography because of: rescaling histogram analysis matrix size scintillators - Correct answer rescaling
both small structures and high contrast - Correct answer both small structures and high contrast If the radiographer applied an ankle LUT to a chest radiograph data set, the image would demonstrate: high contrast low contrast very high resolution low resolution - Correct answer high contrast If the number of pixels decrease in the matrix, what change occurs in the matrix and in the spatial resolution? increases, increases decreases, decreases increases, decreases decreases, increases - Correct answer decreases, decreases Which of the following matrix sizes in would produce the lowest image resolution? 128x 512x 1024x 2048x2048 - Correct answer 128x Which characteristic determines what object size can be seen in a digital image? matrix size pixel size bit depth dynamic range - Correct answer pixel size Which of the choices below would produce the highest spatial frequency and contrast? gallbladder contrast-filled urinary bladder 3mm renal calculi (stone) contrast filled appendix - Correct answer 3mm renal calculi (stone)
The measure of an imaging detector's overall efficiency, expressed as a ratio for the SNR out over the SNR in, is called its: sampling frequency K-edge effect conversion efficiency detective quantum efficiency (DQE) - Correct answer detective quantum efficiency (DQE) The dynamic range, or gray scale range is known as: bit depth pixels matrix brightness - Correct answer bit depth Exposure indicators used in digital radiography: represent exposure to a digital detector may be direct or indirect with regard to exposure and the number calculated can be used to assess image quality all of the above - Correct answer all of the above The exposure indicator number is an: accurate measure of the patient dose indication of radiation absorbed by the imaging plate both a and b neither a or b - Correct answer indication of radiation absorbed by the imaging plate When the quality of a digital detector is inspected for purchase, the preferred detector for purchase would have a: DQE of 65% and MTF of 0. DQE of 40% and MTF of 0. DQE of 68% and MTF of 0. DQE of 55% and MTF of 0.35 - Correct answer DQE of 68% and MTF of
60 keV 80 keV - Correct answer 35 keV When is the imaging plate in CR most sensitive to scatter radiation? Before the exposure after the exposure during the exposure both a and b - Correct answer both a and b A PSP in a metastable state will emit light ____.
- Immediately.
- When stimulated by light.
- Over time. 1 only 2 only 2 and 3 only 1,2 and 3 - Correct answer 1,2 and 3 A latent image is stored in the CR imaging plate, similar to a latent image on film, but with: higher speed higher contrast wider latitude narrower latitude - Correct answer wider latitude Photostimulated luminescence (PSL) refers to the process by which: The laser beam is converted into a usable electronic signal Radiation is absorbed into the lattice of a fluorescent crystal The photomultiplier tube converts the electronic signal into a laser image. The trapped energy of the electronic latent image is released as visible light. - Correct answer The trapped energy of the electronic latent image is released as visible light Throughout the entire imaging sequence for a CR system, how many times is the PSP caused to glow? once twice
3 times a CR plate does not give off light, but conducts electricity - Correct answer twice Europium is the ____ of the PSP. image buffer scintillator phosphor activator - Correct answer activator The luminescence of blue-violet light from a CR fluorohalide due to laser stimulation: is proportional to the xray energy exposure is inversely related to the xray energy exposure is not related to the xray exposure is directly related to the rescaling process - Correct answer is proportional to the xray energy exposure Readout of CR data from the imaging plate is a line-by-line process which creates a: detector array grid raster pattern a series of sensitivity specks linear array - Correct answer raster pattern This is defined as the physical distance between pixels. pixel depth pixel pitch pixel size pixel space - Correct answer pixel pitch The computer algorithms that are designed to correct for flaws and limitations in the acquisition of a digital image are known as: post-processing pre-processing analysis windowing - Correct answer pre-processing
amorphous selenium amorphous silicon gadolinium oxysulfide - Correct answer amorphous silicon Spatial resolution in digital imaging systems is primarily limited by: speed of the exam amount of collimation scatter size and number of detectors (pixels) - Correct answer size and number of detectors (pixels) The component that converts light to an electronic signal in a digital detector is the: TFT scintillator photoconductor detector element (DEL) - Correct answer photoconductor In direct digital detectors, the electronic readout of a signal is accomplished by the: amorphous selenium TFT photoconductor reflective layer - Correct answer TFT In indirect-conversion DR systems, the dispersion of light emitted from molecules of cesium iodide is reduced by using: light guides turbid phosphor structure crystalline phosphor structure amorphous phosphor structure - Correct answer crystalline phosphor structure In a digital detector, the term "fill-factor" refers to the: size of the DEL load capacity of the detector surface file size of the total data
sensing area of the detector element - Correct answer sensing area of the detector element DR panels that are connected to the radiographic unit with a "hard wired" connection cable: are considered to be "tethered" can operate throughout the hospital operate in a wireless mode have excellent positioning flexibility - Correct answer are considered to be "tethered" Of the choices below, select the DR panel that would provide the highest spatial resolution. DEL size 200 microns, 75% fill factor. DEL size 125 microns, 95% fill factor. DEL size 110 microns, 75% fill factor. DEL size 140 microns, 95% fill factor. - Correct answer DEL size 125 microns, 95% fill factor The relationship between detector "fill-factor" and spatial resolution is: direct. indirect. not a factor in detector quality. indirect based on the DEL depth. - Correct answer direct Which of the following is a possible ill effect of edge enhancement? Excessive noise. Segmentation failure. Saturation. Excessive overall brightness. - Correct answer excessive noise As a radiographer, you are looking at an image you had just taken, on the review monitor. The image looks marginally noisy. Your next step should be to: refer to the exposure index number to confirm the image appearance. return to the patient and repeat the image at a higher kVp. send the image for interpretation since the radiologist's monitor will correct the noise.
Objectionable quantum noise on an image that makes its acceptance marginal, generally indicates an underexposure of: 25% 50% 100% 200% - Correct answer 25% As a radiographer, you are using a DR system that displays EI numbers as part of the DICOM header. The EI# is calculated as directly proportional and linear to exposure. The image you have created shows marginal quantum noise and an EI# of 140. The exposure technique you used was 85 kVp and 15 mAs. To improve image quality and eliminate the objectionable noise, your next step should be to: repeat the exposure at 85 kVp and 20 mAs. post process the image using high pass filtering. repeat the exposure at 85 kVp and 12 mAs. repeat the exposure at 72 kVp and 30 mAs. - Correct answer repeat the exposure at 85 kVp and 20 mAs A radiographic image that demonstrates image receptor electronics on the final image, superimposed over patient anatomy, is likely the result of: overexposure data drop. improper radiographic grid alignment. backscatter radiation. dexel saturation. - Correct answer backscatter radiation When the exposure absorbed by the image receptor surpasses the level at which the image receptor can respond, what is said to occur? Saturation. Quantum mottle. Photon starvation. Data saturation. - Correct answer saturation The artifact that can occur when incomplete erasure occurs in CR is: Aliasing. Moiré effect. Ghosting. Both a and b. - Correct answer Ghosting
The increased sensitivity of the receptor to a wider dynamic range of remnant radiation energies that allow materials not seen on film screen systems to be seen on CR and DR detectors is a feature known as: diagnostic acuity. low contrast resolution. image fidelity. diagnostic yield. - Correct answer low contrast resolution Fine white lines appearing on a soft copy of CR image may be caused by: dirt on the light guide in the plate reader. double exposure. cracks in the imaging plate. debris on the mirror in the laser printer. - Correct answer dirt on the light guide in the plate reader Backscatter radiation artifacts can occur more readily in digital imaging because of the: large data file sizes. techniques used. highly sensitive receptors. partitioning errors. - Correct answer highly sensitive receptors Pre-programmed exposure techniques provided by the equipment manufacturer: should be viewed as exact for all situations. should be viewed as a starting point for technique selection. are based upon a national standard and widely accepted by everyone. consider the age of the system and modify techniques accordingly. - Correct answer should be viewed as a starting point for technique selection The optimal kVp must ensure: sufficient penetration of the subject. acceptable radiographic contrast. the availability of diagnostic information. All of the above. - Correct answer All of the above
How much over-exposure is required before a digital imaging system becomes overwhelmed with data, causing saturation to occur: 2-3 times 4-5 times 8-10 times 20-22 times - Correct answer 8-10 times What is the recommended technique for digital imaging? Increasing kVp by 15% with a reduction in mAs. Using higher mAs with lower kVp. Always using AEC. Never using AEC. - Correct answer Increasing kVp by 15% with a reduction in mAs Which of the post processing functions allows text to be added to the image? Image inversion. Electronic masking. Image stitching. Annotation. - Correct answer Annotation What is the post processing function that serves to protect the viewer's eyes from extraneous illuminator light? Electronic masking. Image stitching. Annotation. Image inversion. - Correct answer electronic masking What should be the first consideration when assessing noise on a digital image? The kVp and mAs used for the exposure. The exposure indicator number. The thickness of the body part. The SID used when positioning the body part. - Correct answer The exposure indicator number
A network of computers, servers, and storage devices for the distribution and display of medical images is referred to as a(n) ______________ system. EMR PACS VNA RIS - Correct answer PACS The DICOM standard has established two classes of information. They are: digital class and analog class. service class and object class. software class and hardware class. medical class and nonmedical class. - Correct answer service class and object class The luminance of a digital display device is measured in: lumens. candelas per meter squared. candelas. lumen and candela/meter squared. - Correct answer lumen and candela/meter squared The adoption of a DICOM standard in the medical imaging industry was designed to: allow various venders to share digital data without proprietary software constraints. eliminate small vendors from the medical marketplace based upon product quality and reliability. protect patient's medical records and information. establish common exposure dosage values for various medical imaging procedures. - Correct answer allow various vendors to share digital data without proprietary software constraints For LCD display monitors, the response time is the time required for a(n): pixel to change brightness. next frame to be reconstructed. next field to be reconstructed.
