Comprehensive PET/CT and Radiopharmaceuticals: Production, Imaging, and Quality Control

How do samples and doses for testing get from the cell to the QC room?

Via a pass through window.

Why is radiopharmaceutical synthesis and dispensing performed in classified cleanroom environments under GMP conditions?

To ensure sterility, product quantity, and patient safety.

Which target material is most commonly used to produce F-18 for FDG production?

O-18 enriched water.

What is one advantage of automated synthesis modules used in PET radiopharmaceutical production?

They reduce operator radiation exposure and improve reproducibility.

What is the physical half-life of Rubidium-82?

75 seconds.

What is an immediate stop use limit for the Sr/Rb generator?

17L of cumulative eluate volume.

What is the eluent for the Ge/Ga generator?

Hydrochloric Acid.

Which regulation specifically addresses the production of PET radiopharmaceuticals?

21 CFR 212.

Which device compounds PET radiopharmaceuticals?

Synthesis module.

What happens to the mass and atomic number of a nuclide that undergoes positron decay?

The mass stays the same but the atomic number decreases by one.

What principle of positron physics results in degradation of spatial resolution in PET images?

Effective positron range.

Are most PET radiopharmaceuticals produced in a reactor or generator?

False.

Which PET radionuclide is produced via a generator?

Ga-68.

What is the stop use limit for the Sr-82 generator?

17L cumulative eluate volume.

Which radionuclide has the longest half-life?

Cu-64.

What is a lead-shielded device used to reduce radiation exposure during the tagging process for PET radiopharmaceuticals?

Hot cell.

Which quality control test for F-18 involves thin-layer chromatography to ensure the radiopharmaceutical is at least 90% bound?

Radiochemical purity.

What is the half-life of Ge-68?

271 days.

What type of particles do negative ion PET cyclotrons accelerate?

Negatively charged hydrogen atoms.

What quality must detectors have for Time of Flight to be accomplished?

Short decay time.

Which detector material is the most dense?

LSO.

What is a CT image essentially a map of?

Attenuation/tissue density.

In CT, voxel values are given in terms of what?

Hounsfield units, which express the attenuation of a given tissue relative to that of water.

What effect causes a small cold lesion to appear to have less count density than it really has?

Partial volume effect.

What is seen in a blank scan when there is a failure of a detector block?

A diagonal blank line.

What is the term for the travel distance of the CT scan table per 360° rotation of the x-ray tube divided by the x-ray beam collimation width?

Pitch.

What is a drawback of using thicker CT slices when imaging?

They increase the likelihood of missing very small objects.

If the range of Hounsfield numbers on the image is 0 to 200, what color will a value of 250 display as?

White.

What characteristics improve PET sensitivity?

Thicker crystal, higher timing resolution, lower energy threshold.

What image quality characteristics do PET scanners with smaller crystal elements improve?

Spatial resolution.

What generally happens when increasing crystal thickness?

Increase sensitivity but slightly degrade spatial resolution.

Which PET/CT QC test verifies that the x-ray tube is correctly calibrated on all kVp and mAs settings?

Air Calibration.

Which CT scanner test evaluates the standard deviation of a phantom to determine the extent of noise and accuracy of CT numbers?

Daily water phantom scan.

What is the typical rotation speed of most modern CT scanners?

0.5 seconds per rotation.

What artifact is seen in the image?

Beam hardening.

What imaging artifact is seen in this image?

Misalignment.

Does PET/MR for FDG imaging provide superior anatomic localization and image contrast compared to PET/CT?

True.

When used for imaging a patient post-stroke, what will 18F-FDG uptake in areas of ischemia or necrosis appear as?

Decreased uptake.

What are the indications for FDG neurology listed in the SNMMi procedure guidelines?

Neurooncology, movement disorders, Parkinson's syndromes, Alzheimer's and dementia, epilepsy, encephalitis.

What is the outermost layer of the cerebrum where matter lives?

Cerebral cortex.

Which type of cell controls neurotransmitter levels around synapses?

Astrocytes.

How long should patients receiving FDG brain imaging stay quiet in a dimly lit room before injection?

20-30 minutes.

What is the main function of the blood-brain barrier?

Protect the brain from pathogens and toxins.

Which cell type acts as the brain's immune cell and is associated with neuroinflammation?

Microglia.

What do the external carotid arteries supply blood to?

Face.

Why must FDG brain patients be kept in a quiet, dimly lit room?

To prevent overstimulation of certain areas of the brain, which could result in a false positive or false negative study.

What is a contraindication for FDG brain imaging?

A blood glucose over 200 mg/dL.

What is NOT required during the uptake of FDG for brain imaging?

Sedation should be given immediately after injection.

What is the most appropriate imaging time for a 2D acquisition of an FDG brain study for Ictal scanning?

20 minutes.

What is the appropriate positioning for an F18 FDG brain scan?

Supine arms down.

What substances may alter glucose metabolism in the brain and lead to false results in an FDG brain study?

Caffeine, alcohol, and some psychiatric medications.

What is the half-life for 18-Fluorine?

109 minutes.

Does PET/MR for FDG brain imaging provide superior anatomic localization and image contrast compared to PET/CT?

True.

What should be taken into consideration in the timing of the scan at the end of the uptake time?

Mental status of the patient.

Which cells provide structural stability, maintain the chemical environment, and regulate repair processes?

Glia.

What anatomical marker should be used for positioning in dementia imaging?

Camthomeatal line.

What information is needed to calculate accurate SUV calculations for dementia imaging?

Patient height, patient weight, and amount of injected activity.

What is the purpose of dementia imaging with FDG as an adjunct to amyloid imaging?

Assisting in differentiation in the type of dementia.

What is the major difference in imaging protocols between FDG and amyloid agents for dementia imaging?

Patients do not need a quiet dimly lit room with reduced stimulation for amyloid.

What is amyloid plaque?

Insoluble fibrous protein aggregates.

What recreational drugs interfere with 18F-dopa uptake?

Methamphetamines.

Which reconstruction method is recommended for F-dopa according to practice guidelines?

Iterative reconstruction with OSEM (ordered subset expectation maximization).

What do tau tangles disrupt communications between?

Dendrites.

What is the most appropriate choice for imaging a patient with parkinsonian syndrome?

18F-Flurodopa.

Do 18F-Flurodopa and I-123 Ioflupane have the same mechanism of action?

False.

What is the method of localization for amyloid brain imaging?

Receptor binding.

What dietary restrictions are there for 18F-Dopa scanning?

Withhold amino-acid containing foods for 4 hours.

What adjunctive medication is given 60-90 minutes prior to F-dopa injection?

To increase the bioavailability of DOPA to the brain and reduce the radiation dose to the bladder.

What is the recommended acquisition time for F-18 Flortaucipir Imaging?

20 minutes

What type of dementia is marked by a loss of dopamine receptors in the striatum?

Lewy-Bodies

What is visually characteristic of Parkinson's Disease in F-dopa imaging?

Asymmetric pattern of reduced putamen and preserved caudate uptake

What is the appropriate uptake time from injection to scanning for tau imaging?

80 minutes

Will amyloid and tau always accumulate in the same areas of the brain if the same patient is scanned with both imaging agents?

False

Is tumor heterogeneity often a sign of tumor progression/aggression?

True

What does TAM stand for?

Tumor associated macrophages

Do all malignant cells metabolize glucose at an increased rate?

False

How is N-13 produced?

Via cyclotron

What factors affect the value obtained for the SUV?

Partial volume correction, count rate determination, region of interest definition

Why is knowledge of a PET tomograph's spatial resolution necessary?

To determine resolution recovery coefficients

What is created by accelerating electrons into an anode?

X-rays

What is seen as a diagonal blank line in a blank scan?

Failure of a detector block

What are the half-lives of Cu-64, Rb-82, C-11, N-13, Ga-68, and F-18?

Cu-64 → 12.8 hours, Rb-82 → 75 seconds, C-11 → 20.4 minutes, N-13 → 9.9 minutes, Ga-68 → 68 minutes, F-18 → 109 minutes

What quality must detectors have for Time of Flight?

Short decay time

What do values higher than 2,000 HU on the Hounsfield scale represent?

Very dense materials

How can artifacts caused by anatomy 'moves' be remedied?

Gating

What is the appropriate slice thickness for FDG brain imaging?

2-4mm

Which radiopharmaceutical is used to evaluate depression and other issues of brain metabolism?

18F-FDG

Why must patients be placed in a quiet dimly lit room before their 18F-FDG study?

To relax the brain for even distribution/uptake

Did the technologist make a mistake by using a previous weight for the FDG oncologic study?

True

What radionuclides are possible radioactive contaminants in the eluent of a Rb-82 generator?

82Sr and 85Sr

What is the term for the chance detection of photons from unrelated annihilation events?

Random coincidence

What is the most common irradiation process of producing 18F?

18O(p,n)18F

Which radionuclide accumulates in the brain based on the presence of neurofibril tangles?

F-18 Flortaucipir

What does the term 'attenuation' refer to?

The loss of gamma rays as they pass through tissue

Which is the most appropriate radiopharmaceutical for a patient being evaluated for Huntington's Disease?

F-18 Fluorodopa

What is the target material for F-18 production?

O-18 enriched water

Which of the following is a contraindication for FDG PET/CT imaging?

Hyperglycemia, severe claustrophobia, ocular metal shrapnel

What is O-18 enriched water used for?

It is used in PET imaging.

What is a contraindication for FDG PET/CT imaging?

Glucose level above 200.

Which medication may reduce skeletal muscle uptake in head and neck cancer patients?

Alprozolam.