1
PET CT REVIEW COMPLETE QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED
ANSWERS)
QUESTION: How do you correct for attenuation?
Ans: CT AC Map
Cs137/Ge68 Transmisson
QUESTION: Why is CT better for attenuation correction in PET?
Ans: Decrease noise on attenuation map
Decrease acquisition time
Better anatomic info.
QUESTION: How are x-rays produced?
Ans: Bremsstrahlung radiation - (braking radiation) A charged particle interacts
with an atom by entering the electron shell, slowing down, and changing direction
before exiting the electron shell. The atom emits the Brems Ray in the form of an
x- ray to get rid of the excess energy.
Characteristic radiation - electron ejected from inner shell, energy released as
characterisic x-rays as outer shell electrons drop into vacancies.
Master01 | 2025/2026 | Latest update
, 2
QUESTION: How are x-rays produced in an x-ray tube
Ans: Current is applied to the filament of the cathode (-), this produces an
electron cloud (and increases mAs). The electron cloud is accelerated towards
anode (+) when voltage is applied to the anode (increasing kVp). The electrons
strike the anode on the target producing x-rays.
QUESTION: When you increase kVp =
Ans: Increase x-ray energy
Increase penetration of object
Decrease noise
Decrease beam hardening
Increase pt. dose
Decrease contrast
QUESTION: When you increase mA =
Ans: Increase # of x-rays
Decrease noise
Increase contrast
Increast pt. dose
Master01 | 2025/2026 | Latest update
, 3
QUESTION: Hounsfield unit for water?
Ans: 0
QUESTION: Hounsfield unit for air?
Ans: -1000
QUESTION: Hounsfield unit for bone?
Ans: 1000
QUESTION: What is reconstruction kernel?
Ans: An algorithm applied to raw data that determines the amount of smoothing
during reconstruction process. It is necessary to use more than one reconstruction
kernel because of the different densities in the body.
QUESTION: What is the window width and level?
Ans: It controls how the image is displayed. The gray scale and filter is set by
the operator to help differentiate tissue densities like soft tissue or bone.
QUESTION: What is the DAILY QC for CT?
Master01 | 2025/2026 | Latest update
PET CT REVIEW COMPLETE QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED
ANSWERS)
QUESTION: How do you correct for attenuation?
Ans: CT AC Map
Cs137/Ge68 Transmisson
QUESTION: Why is CT better for attenuation correction in PET?
Ans: Decrease noise on attenuation map
Decrease acquisition time
Better anatomic info.
QUESTION: How are x-rays produced?
Ans: Bremsstrahlung radiation - (braking radiation) A charged particle interacts
with an atom by entering the electron shell, slowing down, and changing direction
before exiting the electron shell. The atom emits the Brems Ray in the form of an
x- ray to get rid of the excess energy.
Characteristic radiation - electron ejected from inner shell, energy released as
characterisic x-rays as outer shell electrons drop into vacancies.
Master01 | 2025/2026 | Latest update
, 2
QUESTION: How are x-rays produced in an x-ray tube
Ans: Current is applied to the filament of the cathode (-), this produces an
electron cloud (and increases mAs). The electron cloud is accelerated towards
anode (+) when voltage is applied to the anode (increasing kVp). The electrons
strike the anode on the target producing x-rays.
QUESTION: When you increase kVp =
Ans: Increase x-ray energy
Increase penetration of object
Decrease noise
Decrease beam hardening
Increase pt. dose
Decrease contrast
QUESTION: When you increase mA =
Ans: Increase # of x-rays
Decrease noise
Increase contrast
Increast pt. dose
Master01 | 2025/2026 | Latest update
, 3
QUESTION: Hounsfield unit for water?
Ans: 0
QUESTION: Hounsfield unit for air?
Ans: -1000
QUESTION: Hounsfield unit for bone?
Ans: 1000
QUESTION: What is reconstruction kernel?
Ans: An algorithm applied to raw data that determines the amount of smoothing
during reconstruction process. It is necessary to use more than one reconstruction
kernel because of the different densities in the body.
QUESTION: What is the window width and level?
Ans: It controls how the image is displayed. The gray scale and filter is set by
the operator to help differentiate tissue densities like soft tissue or bone.
QUESTION: What is the DAILY QC for CT?
Master01 | 2025/2026 | Latest update
