2026 PET Study Guide Positron Emission
Tomography Technologist Practice Questions Answer
Explanations • Radiopharmaceuticals • Imaging
Physics • Patient Preparation • Oncology • Clinical
Procedures Review
Domains Covered (NMTCB PET Content Outline): Diagnostic Procedures
(35%) • Instrumentation/Quality Control (30%) • Radiopharmaceuticals (25%) •
Radiation Protection (10%)
Domain I: Diagnostic Procedures (Questions 1–42)
1. The most commonly used PET radiopharmaceutical for oncology imaging is:
A) Tc-99m MDP
B) F-18 FDG
C) I-131 sodium iodide
D) Ga-68 DOTATATE
Rationale: F-18 FDG (fluorodeoxyglucose) is the most commonly used PET
radiopharmaceutical for oncology studies, exploiting the increased glucose
metabolism of malignant cells. Tc-99m MDP is used for bone scans (SPECT), I-
131 for thyroid imaging/therapy, and Ga-68 DOTATATE for neuroendocrine
tumors. FDG remains the workhorse of clinical PET oncology.
2. The primary physical principle behind PET imaging is:
A) Single photon emission
B) Annihilation coincidence detection
C) Compton scatter
D) Photoelectric absorption
Rationale: PET is based on annihilation coincidence detection of two collinear
511-keV gamma rays resulting from the mutual annihilation of a positron and an
electron. When a positron emitted from a radionuclide encounters an electron, both
are annihilated, producing two 511-keV photons emitted at approximately 180°
from each other.
3. How long must a lactating female wait before resuming breastfeeding after an F-
18 FDG PET scan?
,A) 4 hours
B) 12 hours
C) 9 hours
D) 48 hours
Rationale: The FDA label recommends that a lactating woman pump and discard
breast milk for 9 hours after F-18 FDG administration before resuming
breastfeeding. This allows sufficient decay of the radiopharmaceutical to minimize
infant exposure.
4. Normal F-18 FDG biodistribution would show the LEAST activity in the:
A) Brain
B) Myocardium
C) Bone
D) Kidneys
Rationale: Normal F-18 FDG distribution demonstrates high uptake in the brain
(high glucose metabolism), variable myocardial uptake, and renal excretion. Bone
normally shows minimal FDG uptake; focal skeletal uptake is abnormal and
warrants investigation for metastasis or fracture.
5. The standard fasting requirement before an F-18 FDG PET scan is:
A) 2 hours
B) 4 hours
C) 4–6 hours
D) 12 hours
Rationale: Patients are instructed to fast for 4–6 hours before F-18 FDG PET
imaging to lower serum insulin levels and blood glucose, which maximizes FDG
uptake into metabolically active tissues such as tumors. Eating before the exam
elevates insulin, which drives glucose (and FDG) into skeletal muscle, reducing
tumor-to-background contrast.
6. Which medication is administered before F-18 FDG dosing to DECREASE
uptake of the radiotracer by brown adipose tissue (BAT)?
A) Ephedrine
B) Propranolol
C) Caffeine
D) Nicotine
,Rationale: Propranolol, a beta-blocker, is administered to reduce brown adipose
tissue (BAT) uptake of F-18 FDG. BAT activation is mediated by sympathetic
nervous system stimulation, and beta-blockade suppresses this metabolic activity.
This is particularly important in pediatric and lean patients who may demonstrate
prominent BAT uptake.
7. The application of standardized uptake value (SUV) is LEAST useful in:
A) Prognosis of the disease
B) Diagnosis of the disease
C) Staging of the disease
D) Therapy monitoring of the disease
Rationale: SUV is a semi-quantitative measure of FDG uptake that is most
valuable for therapy monitoring, prognosis, and diagnosis. While SUV values can
support staging, staging is primarily determined by the anatomic distribution of
disease rather than the absolute SUV value. SUV measurements are subject to
variability from multiple technical and biological factors.
8. How soon after chemotherapy or radiation therapy should an F-18 FDG PET
scan be scheduled to avoid false-positive results?
A) Same day
B) Within one week
C) Several weeks to months following completion
D) Immediately after the last treatment
Rationale: F-18 FDG PET should be scheduled several weeks to months after
completion of chemotherapy or radiation therapy. Treatment-related inflammation
can cause increased FDG uptake that mimics residual or recurrent disease.
Scheduling too soon after therapy can lead to false-positive interpretations.
9. Which of the following is NOT a recognized indication for F-18 FDG PET/CT
in oncology?
A) Staging of lymphoma
B) Detection of Helicobacter pylori infection
C) Monitoring response to therapy
D) Evaluation of solitary pulmonary nodule
Rationale: F-18 FDG PET is not indicated for detecting Helicobacter pylori
infection, which is diagnosed by breath tests, stool antigen tests, or endoscopy.
, Established oncology indications include lymphoma staging, therapy response
monitoring, and characterization of solitary pulmonary nodules.
10. The Deauville criteria (5-point scale) are used for:
A) Brain tumor grading
B) Lymphoma response assessment
C) Cardiac viability assessment
D) Bone metastasis detection
Rationale: The Deauville criteria (5-point scale) are the standard for visual
interpretation of F-18 FDG PET/CT in lymphoma, particularly for treatment
response assessment. Scores range from 1 (no uptake) to 5 (markedly increased
uptake), with scores of 1–3 generally considered negative and 4–5 considered
positive.
11. For brain PET imaging with F-18 FDG, the patient should:
A) Be actively engaged in conversation
B) Rest quietly with eyes closed in a dimly lit room
C) Watch television during uptake
D) Listen to loud music
Rationale: During the FDG uptake phase for brain PET, the patient should rest
quietly with eyes closed in a dimly lit, quiet room to minimize sensory stimulation
and ensure consistent cerebral glucose metabolism. Sensory input can increase
regional cerebral blood flow and FDG uptake in visual and auditory cortices,
degrading image interpretation.
12. For cardiac FDG PET viability imaging, the patient should:
A) Fast for 12 hours
B) Receive a glucose load before FDG injection
C) Exercise vigorously before the study
D) Take beta-blockers immediately before the scan
Rationale: In the cardiology setting, administration of glucose-containing food or
liquids (e.g., 50–75 grams) prior to FDG injection facilitates localization of cardiac
ischemia. This shifts myocardial metabolism from fatty acid oxidation to glucose
utilization, improving FDG uptake in viable myocardium.
13. The recommended adult dose of F-18 FDG for oncology PET is:
Tomography Technologist Practice Questions Answer
Explanations • Radiopharmaceuticals • Imaging
Physics • Patient Preparation • Oncology • Clinical
Procedures Review
Domains Covered (NMTCB PET Content Outline): Diagnostic Procedures
(35%) • Instrumentation/Quality Control (30%) • Radiopharmaceuticals (25%) •
Radiation Protection (10%)
Domain I: Diagnostic Procedures (Questions 1–42)
1. The most commonly used PET radiopharmaceutical for oncology imaging is:
A) Tc-99m MDP
B) F-18 FDG
C) I-131 sodium iodide
D) Ga-68 DOTATATE
Rationale: F-18 FDG (fluorodeoxyglucose) is the most commonly used PET
radiopharmaceutical for oncology studies, exploiting the increased glucose
metabolism of malignant cells. Tc-99m MDP is used for bone scans (SPECT), I-
131 for thyroid imaging/therapy, and Ga-68 DOTATATE for neuroendocrine
tumors. FDG remains the workhorse of clinical PET oncology.
2. The primary physical principle behind PET imaging is:
A) Single photon emission
B) Annihilation coincidence detection
C) Compton scatter
D) Photoelectric absorption
Rationale: PET is based on annihilation coincidence detection of two collinear
511-keV gamma rays resulting from the mutual annihilation of a positron and an
electron. When a positron emitted from a radionuclide encounters an electron, both
are annihilated, producing two 511-keV photons emitted at approximately 180°
from each other.
3. How long must a lactating female wait before resuming breastfeeding after an F-
18 FDG PET scan?
,A) 4 hours
B) 12 hours
C) 9 hours
D) 48 hours
Rationale: The FDA label recommends that a lactating woman pump and discard
breast milk for 9 hours after F-18 FDG administration before resuming
breastfeeding. This allows sufficient decay of the radiopharmaceutical to minimize
infant exposure.
4. Normal F-18 FDG biodistribution would show the LEAST activity in the:
A) Brain
B) Myocardium
C) Bone
D) Kidneys
Rationale: Normal F-18 FDG distribution demonstrates high uptake in the brain
(high glucose metabolism), variable myocardial uptake, and renal excretion. Bone
normally shows minimal FDG uptake; focal skeletal uptake is abnormal and
warrants investigation for metastasis or fracture.
5. The standard fasting requirement before an F-18 FDG PET scan is:
A) 2 hours
B) 4 hours
C) 4–6 hours
D) 12 hours
Rationale: Patients are instructed to fast for 4–6 hours before F-18 FDG PET
imaging to lower serum insulin levels and blood glucose, which maximizes FDG
uptake into metabolically active tissues such as tumors. Eating before the exam
elevates insulin, which drives glucose (and FDG) into skeletal muscle, reducing
tumor-to-background contrast.
6. Which medication is administered before F-18 FDG dosing to DECREASE
uptake of the radiotracer by brown adipose tissue (BAT)?
A) Ephedrine
B) Propranolol
C) Caffeine
D) Nicotine
,Rationale: Propranolol, a beta-blocker, is administered to reduce brown adipose
tissue (BAT) uptake of F-18 FDG. BAT activation is mediated by sympathetic
nervous system stimulation, and beta-blockade suppresses this metabolic activity.
This is particularly important in pediatric and lean patients who may demonstrate
prominent BAT uptake.
7. The application of standardized uptake value (SUV) is LEAST useful in:
A) Prognosis of the disease
B) Diagnosis of the disease
C) Staging of the disease
D) Therapy monitoring of the disease
Rationale: SUV is a semi-quantitative measure of FDG uptake that is most
valuable for therapy monitoring, prognosis, and diagnosis. While SUV values can
support staging, staging is primarily determined by the anatomic distribution of
disease rather than the absolute SUV value. SUV measurements are subject to
variability from multiple technical and biological factors.
8. How soon after chemotherapy or radiation therapy should an F-18 FDG PET
scan be scheduled to avoid false-positive results?
A) Same day
B) Within one week
C) Several weeks to months following completion
D) Immediately after the last treatment
Rationale: F-18 FDG PET should be scheduled several weeks to months after
completion of chemotherapy or radiation therapy. Treatment-related inflammation
can cause increased FDG uptake that mimics residual or recurrent disease.
Scheduling too soon after therapy can lead to false-positive interpretations.
9. Which of the following is NOT a recognized indication for F-18 FDG PET/CT
in oncology?
A) Staging of lymphoma
B) Detection of Helicobacter pylori infection
C) Monitoring response to therapy
D) Evaluation of solitary pulmonary nodule
Rationale: F-18 FDG PET is not indicated for detecting Helicobacter pylori
infection, which is diagnosed by breath tests, stool antigen tests, or endoscopy.
, Established oncology indications include lymphoma staging, therapy response
monitoring, and characterization of solitary pulmonary nodules.
10. The Deauville criteria (5-point scale) are used for:
A) Brain tumor grading
B) Lymphoma response assessment
C) Cardiac viability assessment
D) Bone metastasis detection
Rationale: The Deauville criteria (5-point scale) are the standard for visual
interpretation of F-18 FDG PET/CT in lymphoma, particularly for treatment
response assessment. Scores range from 1 (no uptake) to 5 (markedly increased
uptake), with scores of 1–3 generally considered negative and 4–5 considered
positive.
11. For brain PET imaging with F-18 FDG, the patient should:
A) Be actively engaged in conversation
B) Rest quietly with eyes closed in a dimly lit room
C) Watch television during uptake
D) Listen to loud music
Rationale: During the FDG uptake phase for brain PET, the patient should rest
quietly with eyes closed in a dimly lit, quiet room to minimize sensory stimulation
and ensure consistent cerebral glucose metabolism. Sensory input can increase
regional cerebral blood flow and FDG uptake in visual and auditory cortices,
degrading image interpretation.
12. For cardiac FDG PET viability imaging, the patient should:
A) Fast for 12 hours
B) Receive a glucose load before FDG injection
C) Exercise vigorously before the study
D) Take beta-blockers immediately before the scan
Rationale: In the cardiology setting, administration of glucose-containing food or
liquids (e.g., 50–75 grams) prior to FDG injection facilitates localization of cardiac
ischemia. This shifts myocardial metabolism from fatty acid oxidation to glucose
utilization, improving FDG uptake in viable myocardium.
13. The recommended adult dose of F-18 FDG for oncology PET is:
