Quiz
Planar Gamma Camera
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Perguntas do quiz (52)
1Why must a gamma camera be "peaked" every morning before use?
- Ato ensure a proper correction factor is applied to each pixel
- Bto ensure there is no damage to the camera system
- Cto ensure the camera is performing consistently day-to-day
- Dto ensure a proper correction factor is applied to each PMT and the spaces between PMTs
- Eto ensure the PHA knows which energies to accept in imaging studies
2Which is the correct order of events that occur when a gamma ray is emitted from the patient?
1. A count is added at the x,y pixel location on the image matrix
2. The photocathode produces electrons which accelerate and multiply through the dynodes
3. The scintillation travels through the light pipe to the photocathode
4. The pulse travels through the PHA
5. A gamma ray passes through the collimator
6. The position circuit determines the x & y signal locations
7. A gamma ray interacts with the NaI(Tl) crystal to produce scintillation
8. The amplifier manipulates the Z-pulse- A5 > 7 > 3 > 2 > 6 > 8 > 4 > 1
- B7 > 5 > 3 > 2 > 8 > 6 > 4 > 1
- C5 > 7 > 4 > 6 > 1 > 3 > 2 > 8
- D5 > 7 > 3 > 2 > 6 > 1 > 8 > 4
- E5 > 7 > 3 > 2 > 6 > 4 > 8 > 1
3A nuclear medicine department receives a new gamma camera. The new camera has a larger number of smaller photomultiplier tubes than the older cameras currently in use. Which imaging characteristic will be most improved with the new camera?
- Auniformity
- Benergy resolution
- Cspatial resolution
- Dsensitivity
- Eminimum detectable activity
4 When determining the X and Y coordinates of a gamma event, the positional signals are divided by the energy signal (Z) to normalize the signal. Failure to normalize the positional signal may have what result on the resulting image?
- ATrue events may not be accepted by the pulse-height analyzer
- BAn event may be mapped to the wrong location on the image matrix
- CEdge packing will be increased
- DA ring artifact may occur
5Which of the following is the correct definition of spatial resolution as it relates to conventional nuclear medicine imaging?
- Athe ability of a gamma camera to produce a uniform image in response to a uniform source of gamma rays
- Bthe ability of a gamma camera to use the gamma rays available to it
- Cthe ability of a gamma camera to reproduce the details of a nonuniform source of gamma rays
- Dthe ability of a gamma camera to accurately reflect the different energies of a radionuclide source
- Ethe ability of a gamma camera to correct for attenuation in an object
6A static image is acquired with a 128x128 matrix. The minimum pixel value is 120 and the maximum pixel value is 18540. If using an 8-bit LUT array, what shade of grey will a pixel with a value of 18000 be assigned?
- A248
- B250
- C249
- D247
- E245
7To obtain high resolution images of a small organ, gland, or joint, which collimator would be most useful?
- Adiverging
- Bflat field
- Chigh-energy diverging
- Dlow-energy parallel-hole
- Epinhole
8A technologist changes the collimator on a gamma camera from a LEAP to a LEHR collimator. If the same number of counts is acquired, how will the acquisition time change when the high-resolution collimator is used?
- Athe acquisition time will be the same with both collimators
- Bthe acquisition time will decrease
- Cthe acquisition time will increase
- Dthe effect on acquisition time is unpredictable
- Ethe acquisition time is determined by the intrinsic sensitivity of the instrument
9For a parallel hole collimator, the best resolution is at:
- Athe collimator surface
- B10 cm
- C15 cm
- D20 cm
- Ethe focal distance
10Which of the following will increase the resolution of a "spot view" bone image obtained with a parallel hole collimator?
- Amoving the camera closer to the patient's body
- Bincreasing the PHA window width
- Cusing a high sensitivity collimator instead of a LEAP collimator
- Dusing fewer shades of grey to display the image
- Eusing a slant hole collimator
11A technologist forgets to change the LEAP collimator before imaging a patient who has been injected with I-131 for a whole body metastatic survey. The resulting image is most likely to be affected by:
- Aa star artifact
- Bpartial volume averaging
- Ca ring artifact
- Dedge packing
- EPMT visualization
12As a pinhole collimator is moved farther away from the thyroid, how will it affect the image?
- Athe gland will appear larger
- Bthe image will be flipped
- Cthe gland will appear smaller
- Dthere is no change in size or orientation
- Eright and left are reversed
13A gamma camera is equipped with a parallel hole collimator. Sensitivity is affected by all of the following except:
- APHA and window width
- Bcollimator design
- Cthickness of the camera crystal
- Dinstrument deadtime
- Edistance between the source and the collimator
14The following counts-per-pixel values were obtained from a count profile across a line-spread function. If the pixel dimension is 1.6 mm, what is the FWHM?
- A6.4 mm
- B4 mm
- C4.8 mm
- D14.4 mm
- E1.6 mm
15The modulation transfer function (MTF) is a quantitative measure of a camera system's spatial and contrast resolution capabilities. Which of the following will result in a higher MTF value?
- Agreater collimator-source distance
- Bhigher photon energy
- Cchanging the collimator from a LEHR to a LEAP
- Dlonger source wavelength
- Ehigher source frequency
16Temporal resolution is related to which of the following acquisition parameters?
- Apercentage energy window
- Bmatrix size
- Cframing rate
- Dcollimator
- Ecrystal size
17It would be appropriate to apply temporal smoothing in which of the following studies?
- Agated-equilibrium cardiac function study
- BSPECT study of the brain
- CSPECT study of the liver
- Dthyroid image
- Ewhole-body bone image
18If an image is acquired into a 128x128 matrix on a scintillation camera with a 350mm diameter field of view, what are the dimensions of each pixel?
- A2.73x2.73
- B3.14x3.14
- C5.92x5.92
- D6.51x6.51
- E7.83x7.83
19Static frame mode acquisition is the most appropriate type of image acquisition for which of the following procedures?
- Afirst phase of a 3-phase bone study
- Bthyroid imaging
- CLVEF determination
- Drenal function imaging
- Ehepatobiliary imaging
20Which of the following matrix sizes and acquisition modes would be most appropriate for a blood flow study of the feet?
- A64x64 word
- B64x64 byte
- C256x256 byte
- D256x256 word
- E512x512 byte
21When performing a whole-body bone scan, why is it important to have a 5 minute delay before the bed/detectors start(s) moving over the length of the patient after the acquisition is started?
- ATo ensure counts are acquired for the same length of time over each section of the patient's body
- BBecause tracer uptake in the skull is delayed due to the blood brain barrier
- CTo allow time for the tracer to distribute through the patient's body
- DTo visualize blood flow to the skull
- EThere is no specific reason for this
22Background correction is sometimes employed to enhance which of the following image characteristics?
- Aspatial resolution
- Blinearity
- Ccontrast resolution
- Duniformity
- Eability to detect small lesions
23Image resolution may be improved when imaging small objects by all of the following EXCEPT:
- AZoom applied pre-acquisition
- BUse of a pinhole collimator
- CDecreasing collimator-patient distance
- DIncreasing the matrix size
- EZoom applied post-acquisition
24Perform a 9-point weighted smooth on the image matrix. What will be the new value of the highlighted pixel?
- A58
- B102
- C62
- D35
- E42
25A static image of the femur is acquired to 100k counts on a 128x128 matrix. The average pixel noise is 6%. If the technologist wants to improve resolution by repeating the image with a 256x256 matrix, how many counts must be acquired to avoid increasing the average pixel noise?
- A100k
- B200k
- C50k
- D400k
- E800k
26A 50 cm camera with an image matrix of 128x128 is used to acquire an image of the spine. Information density in the region of the spine is 1850 cts/cm^2. What is the average count density per pixel?
- A722 cts/pixel
- B1129 cts/pixel
- C71 cts/pixel
- D281 cts/pixel
- E361 cts/pixel
27The image on the left was likely acquired with:
- AA zoom factor with the image on the right having no zoom applied
- BA larger image matrix than the image on the right
- CA smaller image matrix than the image on the right
- DA pinhole collimator, and the image on the right was acquired with a parallel hole
- EA parallel hole collimator, and the image on the right was acquired with a pinhole
28The system resolution of a gamma camera is 9.5 mm. What is the largest pixel dimension that should be used with this system if we are to take full advantage of the system resolution?
- A19 mm
- B9.5 mm
- C4.75 mm
- D2.38 mm
- E7.8 mm
29Which of the following statements about an image acquired with zoom is true?
- Aimage resolution is increased
- Bbackground counts are increased
- Cmore memory is required
- Dcontrast is decreased
- Especificity is increased
30In which scenario may a logarithmic grey scale enhance visualization of the organ of interest?
- AVisualization of the gallbladder in a hepatobiliary study
- BVisualization of the stomach in a gastric emptying study
- CVisualization of the kidney in a renal function study
- DVisualization of the sternum in a whole-body bone scan
- EVisualization of the myocardium in a myocardial perfusion study
31A MUGA study is performed and the ROIs drawn by the technologist yield the following results:
ED counts: 143908
ES counts: 78094
Background counts: 7564
ED ROI size: 645 pixels
ES ROI size: 323 pixels
Background ROI size: 102 pixels
Calculate the LVEF.- A44%
- B48%
- C46%
- D50%
- E42%
32How much memory will be needed for a MUGA study that is acquired in 30 frames with a 128x128 matrix in byte mode?
- A3840 bytes
- B16,384 bytes
- C491,520 bytes
- D546 bytes
- E256 bytes
33A daily uniformity flood for a scintillation camera should contain a minimum of how many counts?
- A10,000
- B1-2 million
- C3-5 million
- D6-10 million
- E20-30 million
34In quantitating scintillation camera detector uniformity, the central field of view (CFOV) is defined as the diameter of the useful field of view (UFOV) multiplied by:
- A0.95
- B0.75
- C0.33
- D0.25
- E0.15
35To perform pixel calibration, two capillary sources are placed on the camera surface 15 cm apart. From an image acquired using a 128x128 matrix, an activity profile is generated on the computer. If the profile shows that there are 45 pixels between the two activity peaks, the pixel size is:
- A0.02 cm
- B0.12 cm
- C0.20 cm
- D0.33 cm
- E0.42 cm
36If a PLES transmission phantom is used, how many images must be acquired to assess linearity over the entire field of view of a scintillation camera?
- A1
- B2
- C3
- D4
- E5
37Using a 125 MBq source, 30,500 cpm were collected during a camera sensitivity determination. If the background count is 1200 cpm, what is the sensitivity of the instrument?
- A234 cpm/MBq
- B244 cpm/MBq
- C29,300 cpm
- D3,662,500 cpm
- E300,500 cpm
38Which of the following radionuclide sources is used to acquire an extrinsic uniformity flood?
- ATc-99m point course with collimator removed
- BCo-57 sheet source with collimator removed
- CTc-99m point source with collimator in place
- DI-131 point source with collimator removed
- ECo-57 sheet source with collimator in place
39Extrinsic uniformity is performed daily on a gamma camera with a Co-57 sheet source and a LEAP collimator. From the data shown here, all the following may have caused the decreased sensitivity seen on June 5 except:
- Aincorrect photopeak/window setting
- Bincorrect collimator
- Ca cracked crystal
- Dincorrect acquisition matrix
- Ea malfunctioning PMT
40Sources of intrinsic non-uniformity include all of the following except:
- Amistuned PMTs
- Bregional variations in Z-pulse amplitude
- Cspatial distortion
- Dlinearity
- Eedge packing
41Extrinsic quality control on a gamma camera means the quality control is done:
- Aautomatically overnight
- Bwithout the collimator on
- Cinside the camera
- Doutside the camera
- Ewith the collimator on
42If a technologist is preparing a Tc-99m point source for an intrinsic uniformity flood, how much activity is sufficient for the image?
- A10 mCi
- B5 mCi
- C200 uCi
- D2 mCi
- E20 mCi
43Linearity correction involves:
- Adiagonal lines
- Bhorizontal lines
- Chorizontal and vertical lines
- Dvertical lines
- Ediagonal and vertical lines
44To repair the non-uniformity demonstrated on the intrinsic uniformity image the service engineer will need to:
- Areplace the crystal
- Bredo reference map calibration
- Crepair the collimator
- Dreplace a photomultiplier tube
- Ereplace the x,y localization barrel
45For the majority of physiologic studies, "cold" spots are areas on the image display that indicate:
- Anecrotic tissue
- Bmistuned PMTs
- Cincreased activity
- Dnonlinearity
- Ea cracked crystal
46A 1M count extrinsic flood is acquired with a Co-57 sheet source and is uniform in appearance, but it takes 2 minutes longer to acquire than normal. What is a possible explanation?
- AThe photopeak is centered on 140 keV
- BA high sensitivity collimator is installed when the extrinsic flood is usually acquired with a high resolution collimator
- CA brand new sheet source is being used
- DThe technologist selected the incorrect matrix size
- EThe technologist forgot to position the detectors as close as possible to the sheet source before acquiring the flood
47Image A was acquired with a 128 x 128 matrix. What matrix size was used to acquire Image B?
- A64 x 64
- B32 x 32
- C128 x 128
- D256 x 256
- E512 x 1024
48The acquired thyroid image appears as shown here. The patient received 3.7 MBq of I-131. What is a possible explanation for the poor resolution?
- AToo little activity was administered
- BThere is contamination on the bottom of the collimator
- CThe photopeak is set on 140 keV
- DA HEGP collimator is installed
- EUniformity corrections were not applied
49This intrinsic uniformity flood was acquired using an asymmetric window. What is the most likely explanation for the phenomenon seen here?
- ACracked crystal
- BLoss of automated corrections
- COff-peak windows
- DPoor coupling of PMTs to the crystal
- ELoss of the hermetic seal
50The non-uniformity seen here indicates:
- Aa cracked crystal
- Ba dented collimator
- Ca malfunctioning PMT
- Dthe wrong energy window was selected
- Ewater damage to the crystal
51This is the image acquired from the weekly bars quality control scan. What should the technologist do next?
- AUse the gamma camera for clinical studies
- BCall the repair technician
- CApply linearity and uniformity corrections
- DBuy a new gamma camera
- ECheck the collimator for damage
52Regarding the images, which of the following is/are true?
1. The results may be due to improper energy window setting
2. Energy peaking is typically done for every individual scan
3. The energy window should be 20% and set at 160 keV
4. A collimator defect was likely present on the posterior camera head
5. The posterior camera had may be too far from the patient
- A1, 2, and 5
- B1, 2, and 3
- C4 and 5
- D1 only
- E1 and 5
Informações
- Descrição
- QC, acquisition modes, instrumentation, and image quality
- Autor
- Siobhan Pett
- Idioma
- English
- Visualizações
- 335
- Etiquetas
- Avaliação
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