5) Image Processing and Reconstruction
1.
Automatic segmentation of the 18F-FDG PET signal is …
A) Not necessary; visual interpretation of the PET signal is sufficient.
B) Best accomplished using a fixed threshold of the maximum tumor signal intensity(40% or 50%).
C) Compulsory and best achieved using adaptive thresholding through the signal-to background ratio.
D) Very important but still a subject of ongoing research.
Answer:
D) Very important but still a subject of ongoing research.
2.
In which of the following brain regions is glucose metabolism as measured by 18F-FDG PET not affected in AD?
A) Cerebellum.
B) Visual cortex.
C) Both A and B.
D) Neither A nor B
Answer:
A) Cerebellum.
3.
Although many of the drawbacks of software fusion techniqes have been addressed by the hardware approach, which one of the following is still a strength of software fusion?A) The mismatch due to patient respiration can be solved.
B) The total scanning time for CT and PET is less than for combined PET/CT.
C) Any 2 imaging modalities can be coregistered.
D) Separate scans registered post hoc are more tolerable for the patient.
Answer:
C) Any 2 imaging modalities can be coregistered.
4.
The use of CT images to generate attenuation correction factors for the PET data is a major advantage of PET/CT scanners. The significant advantages of CT-based attenuation correction, compared with a standard PET transmission scan, include all except which of the following?
A) CT images are acquired much more rapidly than a standard PET transmission scan.
B) The higher x-ray flux results in much lower noise in the CT images.
C) The spatial resolution of the CT scan is much higher than that of the PET scan.
D) A simple threshold is required by the energy scaling algorithm.
Answer:
C) The spatial resolution of the CT scan is much higher than that of the PET scan.
5.
Photon attenuation:
A) Affects both the quality and quantitative accuracy of PET data
B) Generates artifacts in reconstructed images.
C) Make it difficult to spot a hot or cold deep lesion in oncological PET studies.
D) D. All of the above.
Answer:
D) D. All of the above.
6.
The total linear attenuation coefficient is:
A) A measure of the number of primary photons which have had no interactions.
B) Same as the absorption coefficient which measures the energy absorbed by the medium.
C) The probability of survival of a photon traversing a given amount of absorber without any kind of interaction
D) None of the above
Answer:
C) The probability of survival of a photon traversing a given amount of absorber without any kind of interaction
?? I would have said its the probability of interacting with the absorber
I think they meant the answer to be B)
The linear attenuation coefficient (m) represents the probability of a photon undergoing an interaction per unit thickness of the material and is units of reciprocal distance (e.g. cm-1). Therefore, the linear attenuation coefficient is a measure of the fraction of primary photons which interact while traversing an absorber and is expressed in units of inverse centimeters (cm-1).
7.
Segmented attenuation correction allows to:
A) Reduce noise propagation from transmission to emission data
B) Reduce transmission scanning time
C) Restore the uniform uptake in some organs e.g. the liver
D) All of the above
Answer:
D) All of the above
8.
The attenuation coefficient E(cm-1) for a given energy E can be derived from x-ray CT by:
A) Assigning theoretical energy and tissue-dependent attenuation coefficients to X-ray CT images
B) Using established tissue-dependent calibration curves between Hounsfield (HU) units and E(cm-1)
C) Assuming linear relationship between HU and E(cm-1)
D) None of the above
Answer:
B) Using established tissue-dependent calibration curves between Hounsfield (HU) units and E(cm-1)
9.
The necessity of attenuation correction is:
A) Well-accepted by the nuclear medicine community for all clinical PET procedures
B) Still controversial in oncological PET studies
C) Not needed in clinical brain PET studies
D) All of the above
Answer:
A) Well-accepted by the nuclear medicine community for all clinical PET procedures
10.
Iterative reconstruction algorithms are:
A) Computationally intensive compared to analytic reconstruction techniques
B) Allow the incorporation of other physical degrading factors in the reconstruction process
C) Produce smoother images compared to analytic reconstruction techniques
D) All of the above
Answer:
D) All of the above