NUCLEAR CARDIOLOGY BOARDS EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026

NUCLEAR CARDIOLOGY BOARDS EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 Medications that inhibit binding of the technetium-99m pertechnetate to the hemoglobin molecule inside the RBCs. - Answers - hydralazine - prazosin - heparin - digoxin - doxorubicin - methyldopa - contrast media - quinidine If a gamma camera with parallel-hole collimator is moved farther away from the patient, how are resolution and sensitivity affected? - Answers Resolution worsens, and sensitivity remains approximately constant. The number of counts passing through the collimator does not change appreciably as distance increases. REMEMBER that more photons will strike the collimator further away from the source (just at different angles; giving you worse resolution). In Thallium-201 imaging, the photons detected in the 70-keV window are produced by which mechanism? - Answers Thallium-201 decays by electron capture to mercury-201. The mercury-201 is in an excited state and releases x-rays with energies near 70 keV. Electron capture - Answers Electron capture occurs when a nucleus combines with a proton to form a neutron. Following this, the excited state of the new element releases a characteristic x-ray. Energy peaking - Answers Should be performed DAILY! The technologist checks the peak of a known radioactive source by the camera's energy spectrum. Photomultiplier Tube (PMT) - Answers An apparatus that converts a photon of visible light into an electrical pulse, for example as part of a gamma camera. It is proportional to the amount of energy of the isotope interacting with the crystal. The voltage applied to the PMT must be very stable - a slight variation will greatly affect the pulse generated. To check if all the PMTs are working properly on a gamma camera, which of the following tests should be performed? - Answers Flood-field uniformity testing Uniformity Testing - Answers A uniform source of radioactive source (flood sheet can be Co-57) is placed on the camera detector to check if all the PMTs are operational. A blank spot is observed on the flood scan, if a PMT tube is malfunctioning. The interaction of a technetium-99m gamma photon with the scintillation camera is primarily by? - Answers Photoelectric effect Photoelectric effect - Answers Gamma-ray transfers all its energy to an orbital electron of the absorbing material and a photoelectron is ejected, which leaves a vacancy. The energy is converted 100% to the kinetic energy of the ejected photoelectron. Compton scatter - Answers Gamma photon transfers only part of its energy to an orbital electron. A photon and electron are ejected; however, only part of the energy is converted to the ejected electron (in the form of kinetic energy. The remaining energy takes the form of the energy-reduced ejected photon. Technetium-99m - Answers Clearance: Hepatic Cell uptake: Passive (stays concentrated in myocytes) Half-life: 6 hours Photon keV: 140 keV Origin: Generator (decays from Mo-99 to Tc-99m) Interaction: Compton Typical injection: 10mCi Rest (1.5 hours later 30mCi Stress Critical organ: Proximal colon Thallium-201 - Answers Clearance: Renal Half-life: 73 hours (leads to high dose) Cell uptake: Active Na-K ATPase, which allows it to function as a metabolic tracer for hibernating myocardium. Photon keV: 69-81, 10% @ 167 keV (low energy leads to poor resolution and more attenuation) some even @ 135keV. Newer cameras allow acquisition using several energy windows, and all three peaks should be utilized to increase counts and improve image quality. Interaction: Decays by electron capture to mercury-201. The mercury-201 (daughter) is in an excited state and releases x-rays with energies near 70 keV. Lung accumulation indicates LV failure Critical organ: kidneys Planar projections are first reconstructed into which body plane? - Answers Transaxial. From these images, the long axis of the heart is then defined. Effective half life - Answers (1/Te) = (1/Tp) + (1/Tb) Tetrofosmin (99mTc-tetrofosmin) - Answers Clearance: Hepatic Half-life: 6 hours Cell uptake: Passive Photon keV: 140 Origin: Generator Interaction: Compton Worst linearity & extraction fraction; May have decreased sensitivity compared to thallium Critical organ:?proximal colon? O2 is needed to oxidize the excess stannous ion after labeling with TcO4-. The excess tin will interfere with the ligand exchange reaction of tetrofosmin. A. 82Rb-- 15O-- 13N-- 11C-- 18F-- 99mTc -- 201Tl - Answers 75 sec-- 2min-- 10min-- 20min-- 110min-- 6hr --73hr 13N ammonia - Answers Clearance: Hepatic Half-life: 10 minutes Cell uptake: Passive Photon energy: 0.5 MeV Origin: Cyclotron Rubidium-82 (82Rb) - Answers Clearance: Renal Half-life: 75 seconds Cell uptake: Active Photon energy: 1.5 MeV Origin: Generator (decays from Sr-82 to Rb-82) via secular equilibrium. The half-life differences are ~1000 times has the least liver uptake compared to Mibi, Tetro, and even Tl-201 Critical organ: kidneys Linear transfer energy - Answers The amount of energy deposited per unit length of the absorber and units are expressed as keV/μm. Electromagnetic and beta particles have low LET, since they lose little energy per interaction. Alpha particles are heavy particles and lose energy very rapidly and have high LET. Fraction of nonattenuated gamma rays - Answers Given by e^−μx where μ is the attenuation coefficient and x is the length. Semiconductor solid-state detector - Answers Electrons produced by the absorption of an emission photon are amplified and detected directly. This is much more efficient compared to a scintillation detector, which involves several steps: conversion of electrons to scintillation photons, transport of scintillation photons to the photomultiplier tubes (PMTs), conversion of scintillation photons into electrons in the photocathodes of the PMTs, and amplification and detection of electrons in the PMTs. As a result, the detected electrons in the solid-state detector have better statistical accuracy, and the energy resolution is higher. Higher spatial resolution Higher energy resolution Smaller size Linearity Correction - Answers Smooths out the the uniformity. Transmission scan - Answers Scan used for attenuation correction (CT, etc) Uniformity Correction Testing - Answers This is necessary as most gamma cameras exhibit non-uniformity of distortions at the edge of the detector field of view. Gamma Camera Collimation - Answers Usually made of lead. Designed to limit the detection of gamma rays traveling in certain directions Determines: - Field of view - Spatial resolution - Sensitivity - Image distortion Collimator hole size - Answers Resolution and sensitivity are inversely related. Bigger: Resolution goes down, but sensitivity goes up. Smaller: Resolution goes up, but sensitivity goes down. LEHR Collimator sensitivity value - Answers 150 cts/min/microCi Increase collimator hole diameter - Answers resolution decrease sensitivity increases Increase collimator hole length - Answers resolution increase sensitivity decrease Increase septal thickness of collimator hole - Answers resolution no change sensitivity decrease The septal thickness determines which energy of gamma emitter can be used for imaging. Increasing septal thickness allows for the use of higher energy gamma emitter. The septa absorb most gamma rays that do no emanate for the direction if interest; therefore, a collimator for high energy gamma rays has a much thicker septa than does a collimator for low-energy rays. Measurement of Spatial Resolution - Answers Use bar phantoms. You can assess for degradation over time. Quality Control Procedure testing frequency - Answers Uniformity - Daily Energy peaking - Daily Planar Resolution - Weekly Linearity bar phantoms - Weekly SPECT (plexiglass phantoms) - quarterly Useful for quality assurance and calibration of PET scanners - Answers Germanium-68 Decays to the positron-emitting gallium-68 (half-life = 68 minutes), so a sealed germanium-68/gallium-68 source behaves in effect like a long-lived positron emitter. Measuring Activity Calculation - Answers A = A0^-0.693(time elapsed)/(half life time) Measuring Half Value layer - Answers Exp = Exp0^-0.693(time elapsed)/(half life time) Very High Radiation Area High Radiation Area Radiation Area - Answers Very high = 500 rads/hr at 1 m from the source. High = 100mRem/hr (1mSv) at 30 cm from a source Radiation area = 5mRem/hr at 30 cm from a source. Transportation index - Answers Exposure measurement at 1 m from the surface of the package. Annual Radiation Exposure limit (occupational worker) - Answers NRC limits a radiation occupational worker to receive a total whole-body dose of 5 rem per year (50mSev) Annual Radiation Exposure limit (pregnant occupational worker) - Answers 500mREM (5mSv) over the gestation period. Why is 99Mo a bad tracer? - Answers 67 hour half-life decays by beta and gamma emission (740 and 780 keV - very high) Long half life with beta emissions is dangerous 99Mo/ 99mTc generator - Answers Moly is stuck to aluminum columns. As it decays to Tc, it is less tightly stuck (valence change) so you can elute Tc off with saline (moly stays). The chlorine in saline (Na+Ci-) changes places with the TcO4- ion yielding sodium pertechnetate (Na+TcO4) -99Mo is the parent radionuclide -99mTc is the daughter radionuclide Alumnia test - Answers Dipping a dipstick into the elute to see there is any Mb99 (attached to aluminum) as this would suggest Mb99 contamination. Very rare to be positive. Actually not regulated by the NRC. The aluminum concentration limit is 10 ug per mL of the eluate. This is a test of chemical purity. Radioactive contamination on the skin is best removed by? - Answers Cleaning with luke warm water and soap. DOT Label White I - Answers Surface (mR/h): 0.5 At 1 m: Not detectable Surface wipe test 6600dpm/300cm^2 DOT Label Yellow II - Answers Surface (mR/h): 50 At 1 m: 1.0 Surface wipe test 6600dpm/300cm^2 DOT Label Yellow III - Answers Surface (mR/h): 200 At 1 m: 10 How long after the resting injection should the acquisition be performed (using Tc99m)? Stress? - Answers Rest: 30-60 minutes Stress: 10-20 minutes The maximum permissible activity concentration of molybdenum-99 to technetium 99m as stipulated by NRC is? - Answers 0.15 μCi/mCi at the time of administration to the patient. When a radioactivity package is delivered to the hot lab of a nuclear medicine department, when must the package be monitored for radioactive contamination? - Answers Within 3 hours after receiving in the hot lab or within 3 hours from the beginning of the next working day, if received after working hours. How much is radiation exposure are Americans exposed to annually from all sources? - Answers 620 millirem (6.2 mSv) per year Roughly half of ionizing radiation exposure is from natural sources. Adenosine binds to what receptor? - Answers A2A causes vasodilatation A1, A2B, and A3 receptors cause side-effects. A1 causes AV conduction delay/nodal block A2B/A3 induce bronchospasm by facilitating mast cell degranulation. Cardiovascular effects of adenosine? - Answers Rapidly taken up by RBCs and endothelial cells Potent vasodilator Vagal inhibition at low doses leading to an increase in heart rate Bradycardia and AV block at high doses Reduced adrenergic activity Adverse events with adenosine use are second-degree AV block (4.1%), hypotension (1.8%), bradycardia (0.2%), and third-degree AV block (0.8%). Dipyridamole and dosing - Answers Blocks reuptake of adenosine Metabolized in the liver (use cautiously in liver patients) Half-life is 30-45 minutes (longer half-life makes it a good agent for PET - does not need to be given over a long period of time) Chest pain occurs in 20% of patients undergoing dipyridamole pharmacologic stress testing Administered intravenously at a dose of 0.14 mg/kg per minute for approximately 4 minutes. Total dose of 0.56 mg/kg. The radiotracer is administered intravenously 3-4 minutes after the dipyridamole infusion is completed. Regadenoson - Answers Relatively selective A2a receptor agonist Can be given by a single bolus (same dose for everyone!) Fewer side effects compared to adenosine A more common symptom is a headache. Most adverse reactions began soon after dosing and generally resolved within ~15 minutes, except for headache, which resolved in most patients within 30 minutes. Use of nitrates during technetium-99m sestamibi SPECT MPI - Answers The use of nitrates in conjunction with rest technetium-99m sestamibi SPECT MPI has been shown to improve the detection of viable myocardium, similar to the results observed with thallium-201. Compared with resting technetium-99m sestamibi studies alone, nitrate-enhanced SPECT has a greater ability to predict improvement of regional function after revascularization and to provide important prognostic information. The demonstration of "defect reversibility" on nitrate-enhanced compared to resting images may have better accuracy than either technique alone. Advantage of dual-isotope SPECT MPI? - Answers Improved efficiency in the nuclear cardiology laboratory. Dual-isotope studies can be performed in a much shorter time period as there is no waiting for liver clearance as is required with the technetium-99 tracers and the studies can be completed in a much shorter time interval. So there is less time between rest injection and acquisition. The radiation exposure of dual-isotope imaging is 25 to 30 mSv, while single-isotope rest/stress technetium-99 imaging is ~8 to 15 mSv. Attenuation correction to determine attenuation artifact has been validated for technetium-based imaging agents but not thallium-201. Dobuatmine pharmacologic stress testing over vasodilator stress - Answers Dobutamine is a stress inotropic agent that can be used for pharmacologic stress testing in patients with active airway disease or in patients being treated with theophylline. In such patients, dipyridamole, adenosine, or regadenoson may cause further airway decompensation by stimulation of adenosine A2B or A3 receptors that mediate bronchospasm. Risk factors for serious hypotension in patients receiving regadenoson for SPECT MPI - Answers Autonomic dysfunction Hypovolemia Left main coronary artery stenosis Stenotic valvular heart disease Pericarditis or pericardial effusions Stenotic carotid artery disease with cerebrovascular insufficiency Absolute contraindications for exercise testing include: - Answers acute MI (within 2-4 days) unstable angina decompensated heart failure uncontrolled cardiac arrhythmias uncontrolled hypertension with systolic blood pressures greater than 200 or diastolic blood pressures greater than 110 recent myocardial infarction within the prior 2 days severe pulmonary hypertension acute pulmonary embolus myocarditis/pericarditis aortic dissection severe symptomatic aortic stenosis. Exercise physiology - Answers Increase peripheral oxygen demand Increase venous return - increase EDV Increase (SV) small, increase HR Peripheral vasodilation Increase systolic pressure Increased MVO2 Duke Treadmill Score - Answers Score = Exercise time - (5 x ST depression) - (4 x angina index) - angina index: 0=none, 1=during test, 2= stopped Low +5 Moderate -10 to +4 High -10 If you do 10 min and don't stop for angina, you get a score of 10. Ramp filter artifact - Answers (think inferior defect) is seen during filtered back projection using a ramp filter and is caused by overlapping or adjacent liver or bowel activity and causes a loss of counts in the adjacent myocardial walls. The use of iterative reconstruction minimizes this artifact but does not make it go away completely. Waiting longer to get liver clearance or administration of small amounts of liquids to enhance peristalsis and move gastrointestinal activity may allow repeat imaging to improve image quality. Ring artifacts - Answers Seen with nonuniformity across the camera head, which may be due to problems with any of the following: photomultiplier tubes, damaged collimator, camera electronics, or sodium iodide crystal. Daily floods are critical to detecting problems at any of these levels. peak pixel count - Answers A minimum of 200 counts/pixel using technetium-99m and 100 counts/pixel using thallium-201 in the myocardium on an anterior projection is recommended. The count rate capability of most gamma cameras exceeds 70cps. What is the minimum number of acquisition projections or stops recommended for SPECT acquisition over 180 degrees using technetium-99m radiotracers? - Answers Minimum number of projections recommended is 60 to 64 For thallium-201 that has lower resolution, 32 projections are acceptable. During filtered back projection reconstruction of SPECT technetium-99m images, what effect does overfiltering have on the perfusion images? - Answers Leaves too little contrast Overfiltering SPECT perfusion images, which generally have a low signal-to-noise ratio, makes the images too smooth and leaves too little contrast so that there is a loss of information and a tendency to decrease sensitivity for detection of CAD. PET tracers can be used to quantitatively assess both myocardial perfusion and metabolism? - Answers 11C-acetate 8F-2-fluoro-2-deoxy-D-glucose, or FDG - Answers Cell uptake: active Half-life: 110 minutes Critical organ urinary bladder Cardiac PET studies for viability attempt to drive glucose into myocytes, and blood glucose levels are routinely checked at baseline. If levels are too low, D50 can be administered, and if they are too high, insulin on a sliding scale is administered so that when fluorine-18 FDG is administered, it is not diluted out by the high endogenous glucose levels. After administration of fluorine-18 FDG, glucose levels are again checked and an attempt is made to drive glucose into cells. Thus, 12-hour fasting assures that glucose levels are not too elevated. Longer fasts are not necessary. Hormesis - Answers Presumptive protective effect of exposure to low amounts of ionizing radiation, possibly on the basis of up-regulation of molecular cell repair mechanisms. Protocols that will stimulate myocardial glucose utilization in FDG PET - Answers Current guidelines recommend imaging under conditions in which glucose metabolism has been stimulated. Oral glucose loading with 50 g of dextrose prior to FDG injection IV glucose loading with D50W to which 20 mg of hydrocortisone has been added to administer a total of 25 g dextrose "Priming" the patient with 50 mL of 20% dextrose and 5 units of regular insulin IV Normal variant in the myocardial distribution of nitrogen-13 ammonia - Answers May be a decrease in nitrogen-13 ammonia uptake in the inferolateral region of the ventricle. 99mTc-phosphate derivatives - Answers 99mTc-phosphate derivatives also accumulate in the heart after an acute myocardial infarction. The radiotracer typically accumulates several days after an infarct, possibly related to calcium overloading of the mitochondria. Subsequently, 99mTc-DPD (technetium-3,3-diphosphono-1,2-propanodicarboxylic acid) and 99mTc-PYP (technetium pyrophosphate) have both been shown to accumulate in patients with cardiac amyloidosis. More recently, 99mTc-HDP (technetium-hydroxymethylene diphosphonate) has been similarly detected in patients with ATTR. Planar Imaging Scoring with 99mTc-PYP - Answers 0 = absent cardiac uptake and intense bone uptake 1= mild cardiac uptake, less than bone uptake 2 = moderated cardiac uptake, equal to bone uptake 3 = high cardiac uptake, greater than bone uptake ECG uninterpretable for the purpose of exercise stress testing? - Answers Pre-excitation with WPW Ventricular pacing LBBB Digoxin use Baseline ST segment changes 0.10 mV Pretest probability for CAD - Answers High: 90% pretest probability. Intermediate: between 10% and 90% pretest probability. Low: between 5% and 10% pretest probability. Very low: 5% pretest probability.