Focused Nuclear Medicine Study Set

According to the NRC, imaging rooms should be posted with what sign?

"Caution: Radioactive Materials"

What is adenosine used for?

(Adenocard) cardiac stress/vasodilator; 140 ug/kg/min for 6 min

What is I-123 iobenguane (MIBG) used for?

(AdreView) imaging neuroendocrine/adrenal tumors, sympathetic nervous system; consider stopping hypertensive drugs

What is morphine sulfate used for?

(Astramorph, Duramorph) contracts sphincter of Oddi, forces traces through cystic duct into gallbladder thru pressure if it is not visualized

What is captopril used for?

(Capoten) ACE inhibitor/vasodilator; administered to assist in diagnosis of renovascular hypertension resulting from renal artery stenosis; 25-50 mg

What is acetazolamide used for?

(Diamox) vasodilator; used in conjunction w/ SPECT brain imging to identify ischemic areas in brain. Normal pts show increased perfusion w/Diamox, ischemic areas do not

What is dobutamine used for?

(Dobutrex) cardiac stress/contractile agent; indicated for pts w/ severe bronchospasm, contraindicated in pts w/ sever aortic stenosis; HL of a few mins

What is sincalide used for?

(Kinevac) synthetic form of CCK. Causes gallbladder to contract; used in hepatobiliary studies, can cause abdominal pain

What is furosemide used for?

(Lasix) diuretic used for kidney imaging to rule out ureteral obstruction

What is Sr-89 chloride used for?

(Metastron) relief of pain from cancer metastatic to bone; catheterization req'd for incontinent pts (HL: 50 d), pain relief after 7-20 d

Sr-89 (Decay type, HL, energy, production, use)

(Metastron) relief of pain from cancer metastatic to bone; catheterization req'd for incontinent pts (HL: 50 d), pain relief after 7-20 d; most common palliation nuclide in US

What is dipyridamole used for?

(Persantine) cardiac stress/vasodilator; reduces metabolism of endogenous adenosine

What is Samarium-153 lexidronam used for?

(Quadramet), palliative care for bone mets; can be imaged (103 keV); HL 1.9 d; quite rapid relief from symptoms

What is Sm-153 lexidronam (EDTMP) used for?

(Quadramet), palliative care for bone mets; can be imaged (103 keV); HL 1.9 d; quite rapid relief from symptoms

What is Tc-99m PYP (pyrophosphates) used for?

(TechneScan) acute cardiac infarction (accumulates w/ Ca in mitochondria), amyloidosis, altered osteogenesis imaging

With perfect scattering and randoms correction, what should the measured SUV be within the lung section of the NEMA PET Image Quality Phantom?

0

For transportation purposes, radioactive material is defined as any material which has a specific activity greater than...

0.002 uCi/g

Per NRC, what is the limit of removable activity for a sealed source leak test?

0.005 uCi/185 Bq

What is the MDA limit for a radionuclide?

0.005 uCi/185 Bq

NRC limit for Sr-82 and Sr-85 contamination and requirements for testing

0.02 kBq Sr-82 or 0.2 kBq Sr-85 /MBq of Rb-82 at time of administration & concentrations of these nuclides measured before 1st pt use each day

What is a typical 3D PET sensitivity?

0.02-0.1 cps/Bq/cc or 2-10%

Effective Dose Equivalent Dose Rate for F-18

0.143 uSv m2/MBq h = 5.3 uSv/h @ 1 m for 1 mCi

What are the maximum positron energies, positron ranges, and half-lives of F-18, C-11, O-15, N-13, Ga-68, and Rb-82?

0.6 MeV, 0.63 MeV, 0.74 MeV, 1.2 MeV, 1.9 MeV, 3.2 MeV (FCONGR) 110 m, 68 m, 20 m, 10 m, 2 m, 1.4 m (FGCNO) 2.4 mm, 4.2 mm, 5.4 mm, 8.2 mm, 8.4 mm, 17 mm (FCNGOR)

How thick are SPECT crystals designed for imaging low-energy radionuclides like Tc-99m or Tl-201?

0.635-cm (¼ inch)

What is the typical SUV for lung?

0.7

What fraction of Mo-99 decays to Tc-99m (BR =)?

0.876

1 R = __ rads

0.876, or 0.876 cGy

How thick are most SPECT camera crystals? What is the photopeak efficiency for Tc-99m and I-131?

0.95 cm (5/8 in). Photopeak efficiency is >80% for 140-keV gammas of Tc-99m, but <30% for 364-keV gammas of I-131

In a uniform concentration of F-18, assuming a tissue density of 1 g/cm, the SUV would be...

1

List wait times for I-123 uptake for 1) CTA 2) Synthyroid 3) Lugol's 4) kelp tablets 5) perchlorate

1) 1 mo 2) 3 w 3) 2 w 4) 2 w 5) 1 w

List wait times for I-123 uptake for 1) CTA 2) synthyroid 3) Lugol's 4) kelp tablets 5) perchlorate

1) 1 mo 2) 3 w 3) 2 w 4) 2 w 5) 1 w

What is the typical SUV for bone marrow?

1.0

How thick are SPECT crystals designed for imaging high-energy radionuclides like In-111?

1.27- to 2.5-cm (½ to 1 inch)

What is the typical SUV for the spleen?

1.9

About ___ of the photons reaching the photocathode of a PMT create an electron

1/5

What part of the federal code governs exposure notifications?

10 CFR 19

What part of the federal code governs radiation protection, surveys, exposure limits, and personnel monitoring?

10 CFR 20

What part of the federal code governs reporting and records requirements?

10 CFR 30

What federal code governs nuclear medicine materials?

10 CFR 35

What part of the federal code governs leak testing of sealed sources?

10 CFR 39

Typical SPECT spatial resolution

10 mm at center for 30 cm orbit and Tc-99m

Recommended activity for ACR SPECT Phantom

10-15 mCi Tc-99m (5-10 mCi S phantom)

What is the energy resolution for NaI well counters for Cs-137 vs non-well detectors?

10-15% FWHM vs 6.5-7%, due to scattering w/in well

What dose rate requires a "Caution: Very High Radiation Area" sign?

100 mrem/hr 30 cm from src or any surf. radiation penetrates

A modern PET system can simultaneously acquire as many as ____ transverse images over _____ cm of axial distance

109, 21.6

Typical dead time for GM counters

10s to 100s of us

SPECT ACR Phantom Pass Criteria

11.1 mm rods (spat. res.), 19.1 mm sphere resolved (contrast)

What is a typical coincidence time window for a PET system with BGO and LSO detectors?

12 ns, 4.5 ns

Conversion efficiency (sensitivity) of BGO (Relative to NaI)

12-14%

How long should a patient avoid breastfeeding after being administered F-18?

12-24 h

What is the matrix size for the ACR SPECT Phantom Image Acquisition?

128x128

TVL of 511-keV photons in lead, narrow-beam

13.5 mm

Typical efficiencies (sensitivities) of well counters (low energy, high energy, cesium)

140 (Tc-99m/Co-57) = ~88% 360 (I-131/Ba-131) = ~31% 660 (Cs-137) = ~12%

What is the approximate effective dose of a CT scan with PET or SPECT for diagnostic quality, or only for attenuation correction and anatomic correlation?

16 mSv vs 7 mSv

What are common spatial resolution intervals in a lead bar phantom?

2, 2.5, 3, 4 mm wide bars; at least 2 sets should be visible

For diagnostic studies, the dose rate at 1 m from the patient immediately after injection is about...

2-20 Gy/h

Typical thickness of a PET scintillation crystal

2-3 cm

1 uCi =____ dpm

2.22 x 10^6

What is the typical SUV for a blood pool?

2.3

In the ACR PET phantom, what is the ideal ratio between each "hot" cylinder and background?

2.5

What is the typical SUV for liver>?

2.5

PET Phantom Dose

2.5 concentration ratio. For 10 mCi pt dose, A = 0.35, B = 0.83. Dose A + 1000 mL water/saline. Reserve 60 ml, use 40 ml for fillable cylinders. Dose B = phantom bkgd

Planar Gamma Camera ACR Spatial Resolution Criteria for four-quadrant bar phantom (Tc-99m/Co-57)

2.5-2.9 mm bars. (intr.) 3.0-3.4 mm bars (extr.)

About ___ of the photons created by an x- or gamma ray reach the photocathode of the PMTs

2/3

What is the typical scatter to primary percentage for brain and body SPECT?

20-30% and 30-40% respectively

What is the total effective dose for a clinical PET/CT exam? Which component has the highest dose?

20-40 mSv, CT (2-3x)

How many particles are administered in a typical MAA perfusion scan?

200,000 - 500,000

Approximately how long does it take for Tc-99m to reach transient equilibrium with Mo-99?

23 h

PET ACR Phantom Pass Criteria

25 mm cylinder 1.8-2.8, Bkgd 0.85-1.15, Ratio of 16/25 mm sphere > 0.7, 12 mm vial resolved (contrast), 9.5 mm rods resolved (spat. res.)

What is a typical SPECT pixel size?

3 mm

How long after Tl-201, Ga-67, and I-125 imaging should patients top breastfeeding?

3 weeks

A daily uniformity flood for a gamma camera should have at least how many counts?

3-5 million

K-shell binding energy of iodine

33.2 keV

How much does a patient self-attenuate F-18?

36%

1 mCi = ___ MBq

37

The average energy required to create an ion pair in air

37 eV

What is the approximate maximum amount of activity that can be measured on a well counter?

37 kBq (1 uCi) or 5kcps (I-125 and Co-57 <~0.2 μCi)

Radiation induced cancer risk

3x higher for 10 y.o. vs 50 y.o., 40% higher for females

How long after Tc-99m RBCs, DTPA, and MDA should patients stop breastfeeding?

4 h

What are activity limits of Y-90 after patient death?

4 mCi = autopsy/embalming, 27 mCi = cremation

What is approximate increase in sensitivity in 3D pet compared to 2D?

4-6x

α particle typical kinetic energy and range in body tissue

4-8 MeV, 0.03 mm

HVL of 140-keV photons in Water, narrow-beam

4.6 cm

Typical Tl-201 stress-redistribution protocol schematic

45° RAO -> 45° LPO for single head

What part of the federal code governs transportation of sealed sources?

49 CFR 40 (DOT CFR 49)

What ratios of activity concentrations are tested in the NEMA PET Image Quality Phantom?

4:1 and 8:1

What dose rate requires a "Caution: Radiation Area" sign?

5 mrem/h 30 cm from src or any surf. radiation penetrates

When measured using the NEMA standard, modern PET scanners have a resolution slightly better than ____ in the center of the detector ring

5-mm

The smallest bars in a bar pattern should be ~__% of the expected intrinsic resolution

50%

Approximately half of the maximum yield of a Mo-99 generator will be available ___ h after the last elution

6 h

How long after I-131 therapy should a patient wait to become pregnant?

6 months

Cardiac polar map

6 segments at base

How long before and after I-131 therapy should a patient stop breastfeeding?

6 wks before, until next pregnancy after

What % injected FDG is taken up by the brain?

6%

A 1 g sample of a radionuclide has approximately ____ atoms

6.023 x 10^23 (Avogadro's number) divided by the atomic weight A

What is the minimum PET uptake time by minimum best practice?

60 m

Example gamma camera crystal size specifications

60 x 45 cm, with a field-of-view of about 50 by 40 cm

Approximately how many coincidences in a 3D abdomen acquisitions are from scatter?

60-70%; Compton is predominant interaction at 511 keV in detector

Self-attenuation of Tc-99m in water

63%

The intravenous administration of 370 MBq (10 mCi) of F-18 FDG to an adult imparts an effective dose of about...

7 mSv

What is the volume of the NEMA PET Image Quality Phantom?

70,000 mL

Conversion efficiency (sensitivity) of LSO (relative to NaI)

75%

What is a normal patient glucose level?

75-110 mg/dL (PET contraindicated if >200 mg/dl)

K and L shell binding energies of lead

80-90 keV, ~13-16 keV; May appear in spectra of shielded detector

What is a typical SPECT energy resolution for Tc-99m?

9-11%

According to USP, most Tc-99m labeled radiopharmaceutical purity of at least ___% before being administered to patients

90%

According to the USP, most Tc-99m labeled pharmaceuticals should have a radiochemical purity of at least __%

90%

What is the limit to the size of MAA particles, and who determines it?

90% of particles should be 10-90 um in size. No particles should be > 150 um; USP

Immediate release for I-131 patients

< 7 mrem/h or < 33 uCi

What is the USP limit on aluminum contamination?

<=10 μg alumina /mL of Tc-99m eluate.

What is the definition of a major spill?

>100 mCi of Tc-99m or Tl-210, >10 mCi of Ga-67 and In-111, >1 mCi of I-131

What quantitative method did Sokoloff et al. develop?

A physiological model that enables rate of local tissue glucose utilization to be calc from amount of F-18 FDG that accumulates in tissue. Has been used extensively in research studies of brain, heart, and other organs but requires blood sampling

How does a modern SPECT camera (w/o CT) get a map of nonuniform attenuation characteristics of a pt?

A sealed line src (commonly Gd-153, which emits 97 and 103-keV) acq. transmission data from proj. around pt. After acq., transmission projection data are reconstructed to provide maps of tissue attn. characteristics across transverse sections of pt, similar to x-ray CT imgs

3.1.1B. Example: SPECT uniformity simulation — non-uniformity at the center of the axis of rotation

A simulated -5% defect was introduced btwn pix 63 & 65 (center of FOV). Center of FOV and AOR will coincide as shown here only when care is taken in setup. Effect of defect on reconstructed uniformity is always greatest at AOR. Depth of non-uniformity (BR) decrease w/ increasing dist. from AOR.

Spectrum of Cs-137 as produced and pulse-height spectrum measured by a detector

A) 662-keV γ completely absorbed B) Compton continuum from scattered 662-keV γ escaping crystal, each part corresponding to a diff. angle C) Compton edge, upper limit of Compton D) Backscatter peak caused by photons 180 deg scattering from lead casing into det. E) Ba (decay of Cs-137) K-shell x-rays (31- 37 keV). F) lead K-shell x-rays (72-88 keV) from shield. Since E from BS (γ) and CE (e-) are both a result of Compton scatter, Eγ = Eb + Ece

Decay scheme/spectrum of Tc-99m Diagram

A) caused by total absorption of 140-keV γ. B) escape peak caused by 140-keV gammas that interact w/ the crystal by PE but with/ resultant iodine K-shell x-rays (28-33 keV) escaping crystal. C) caused by the absorption of lead K-shell x-rays from shield.

What is Y-90 used for?

AKA TheraSphere (20-30 u glass) or SIR-Spheres (40-60 u resin), ~81 mCi, ~2 mm β range. Used for treating hepatocellular carcinoma, metastatic colorectal cancer, or metastatic neuroendocrine tumors

2.5.4. Example: Uniformity — poor image — misplaced events

Accumulation of cts towards center indicating misplaced events. Can also be observed in hi-act., new Co-57 sheet sources placed directly on coll. Effect of hi-E components from decay of Co-57, Co-56, and Co-58 can lead to a hi flux of photons onto det. and a hi dead time, even tho cts in 122 keV E window of Co-57 will not indicate this.

Tl-201 Rest SPECT Imaging Protocol Schematic

After acute MI. Can also review after 3-4 hrs.

What is propylthiouracil?

Anti-thyroid medication, should be discontinued before imaging

What is theophylline used for?

Asthma, COPD; discontinue 24-36 h before dipyridamole or adenosine

How is scattered radiation corrected for in PET?

Bergstrom's method, "smeared out" image based on transmission studies with a water phantom. Works best when SF < 20-25%

2.1.1. Example: Wrong energy setting — uniformity

Both imgs show non-uniformity because the Co-57 source was imgd w/ a Tc-99m E window. A shows poor tuning and visible PM tubes. B shows discrete small cold spots (the white on the grey) due to crystal hydration

In most gas-filled detectors, the ____ is the wall of the container that holds the gas or a conductive coating on the inside of the wall, and the ____ is a wire inside the container.

Cathode, anode. After reaching anode, the e- travel thru circuit to cathode, where they recombine w/ cations

2.2.10.1A. Examples: Fillable flood sources — air bubble

Changing position of flood source, position of cold area also moved

PET ACR Phantom Setup

Choose A & B dose based on std. pt. dose. Add A to hot cylinders, add B to phant. B/A concentration should be ~2.5 (similar to lesion/bkgd). 1 cm thick slices.

2.2.1B. Example: Symmetric 10%, 15% and 20% energy window nonuniformity

Comparison of 3 imgs shows a degradation in uniformity as the window width is decreased. At 10% E window, a pattern of PMTs is seen in the right 1/2 of uniformity img

According to the NRC, how often must radiation surveys be performed in areas of radionuclide use?

Daily

I-123 (Decay type, HL, energy, production, use)

Decay: EC (100%), HL: 13 h, γ: 159 keV (83%) Produced by: Cyclotron ($$$), Used for: Imaging thyroid when in chemical form NaI (lower dose), of neuroendocrine tumors/tremors in form mIBG; 80% eff. on 1/2" crystal

I-125 (Decay type, HL, energy, production, use)

Decay: EC (100%), HL: 2 mo (60 d), γ: 35 keV (6%), 27 keV (39%), 28 keV (76%), 31 keV (20%), Produced by: n activation, Used for: Occasionally for plasma volume studies and basic research. Previously the most common isotope used in radioimmunoassays

Ga-67 (Decay type, HL, energy, production, use)

Decay: EC (100%), HL: 3 d (78 h), γ: 94 keV (40%), 184 keV (24%), 296 keV (22%), 393 keV (4%), 494 keV (<1%) Produced by: Cyclotron, Used for: Not commonly used, used to be for tumor staging, abscesses, inflammatory sites. Similar to Fe, binds to plasma protein

Tl-201 (Decay type, energy, production, use)

Decay: EC (100%), HL: 3 d, γ: 69~80 keV Hg-201 x-rays, 135 keV (2%), 167 keV (8%), (94%) Produced by: cyclotron, Used for: imaging of myocardial perfusion using a K analog, diagnosing parathyroid adenomas and the most malignant brain tumors; potassium analog; 3-5% of dose to heart; kidney crit. organ; Teff = 55 h

Gd-153 (Decay type, HL, energy, production, use)

Decay: EC (100%), HL: 8 mo (242 d), γ: 97 keV (29%), 103 keV (21%), HL: 9 mo ( 271 d), Produced by: cyclotron, Used for: transmission scans, attn. maps

Cr-51 (Decay type, HL, energy, production, use)

Decay: EC (100%), Metastable (9%, γ: 320 keV), HL: 1 mo (28 d), Produced by: cyclotron, Used for: RBC labeling

Co-57 (Decay type, HL, energy, production, use)

Decay: EC (100%), γ: 122 keV (86%), 136 keV (11%), HL: 9 mo ( 271 d), Produced by: cyclotron, Used for: flood source, constancy cource

F-18 (Decay type, HL, energy, production, use)

Decay: EC (3%), β+ (97%), HL: 110 min, γ: 511 keV (180%), Produced by: Cyclotron, Used for: tumor staging, imaging hibernating myocardium, a lot of other things; glucose analog

In-111 (Decay type, HL, energy, production, use)

Decay: EC, HL: 3 d, γ: 173 keV (89%), 247 keV (94%), Produced by: Cyclotron, Used for: bound to antibodies, polypeptides, WBCs for diagnostic studies/radioimmunoassays (Fe analog)

Ra-223 (Decay type, energy, production, use)

Decay: α, α: 5.975 MeV, Produced by: Ac-227 generator, Used for: Palliation to bones from prostate Ca metastases

N-13 (Decay type, HL, energy, production, use)

Decay: β+ (100%), HL: 10 m, β: 1.2 MeV, Produced by: cyclotron, Used for: organ blood flow, cardiology

O-15 (Decay type, HL, energy, production, use)

Decay: β+ (100%), HL: 2 m, β: 735 MeV, Produced by: cyclotron, Used for: cardiac/cerebral blood flow

C-11 (Decay type, HL, energy, production, use)

Decay: β+ (100%), HL: 20 m, β: 633.5 keV, Produced by: cyclotron, Used for: prostate Ca imging

Rb-82 (Decay type, HL, energy, production, use)

Decay: β+, HL: 75 s, β+:3.15 MeV , Produced by: Sr-82 generator, Used for: Cardiac PET

P-32 (Decay type, HL, energy, production, use)

Decay: β- (100%), HL: 2 wk (14 d), no photons, Produced by: n activation, Used for: bone pain from metastaic disease and polycythemia (sodium phosphate), peritoneal or pleural effusions from metastatic disease (chromic phosphate)

Mo-99 (Decay type, HL, energy, production, use)

Decay: β- (100%), HL: 2.75 d (66 h), γ: 181 (6%), 740 (12%), 780 (4%) keV, Produced by: Fission of U-235, Used for: Tc-99m generation

I-131 (Decay type, HL, energy, production, use)

Decay: β- (100%), HL: 8 d, γ: 364.4 keV (82%), 284 keV (6%), 637 keV (7%), Produced by: Fission of U-235, Used for: whole body metastatic survey for thyroid Ca, thyroid scan in pt w/ substernal thyroid, therapy for hyperthyroidism or thyroid Ca

Xe-133 (Decay type, HL, energy, production, use)

Decay: β-, HL: 5 d, γ: 81 keV (37%), Produced by: Fission of U-235, Used for: pulmonary ventilation studies (or dissolved in saline for special blood flow studies), charcoal filter req'd

Y-90 (Decay type, energy, production, use)

Decay: β-, β: 937 keV, Produced by: Fission of U-235, Used for: treating hepatocellular carcinoma, metastatic colorectal cancer, or metastatic neuroendocrine tumors

Tc-99m (Decay type, HL, energy, production, use)

Decay: γ, HL: 6 h, γ: 140 keV (90%), Produced by: Mo-99 generator, Used for: 85% of all scans

Decay scheme of Cs-137

Decays by β- to Ba-137m, which decays w/ 662-keV gamma (90%) or IC (10%), followed by emission of ~32 keV K-shell characteristic x-ray

What is required to be tested annually on a well counter (& our specs)?

E res. (FWHM <= 15%), Chi-Square (3.33-16.9 or 90% CI), MDA (~200 dpm Cs-137), Cs-137 Efficiency (~7%)

What is required to be tested annually on a thyroid probe (& our specs)?

E resolution (FWHM <= 10%), Chi-Square (3.33-16.9 or 4.17-14.68 90% CI), MDA (~200 dpm Cs-137, < 200 dpm I-131), Efficiency (~13% Cs-137)

Why does Tc-99m (140 keV) have better resolution than Tl-201 (69-80 keV)?

Each gamma produces approximately 2x as many photons, significantly reducing err.

How is SR-82/85 concentration testing performed?

Eluate is allowed to decay for 1 h so only Sr-82 and Sr-85 remain. Sample then assayed in dose cal., and amounts of Sr-82 and Sr-85 are estimated from an assumed ratio

What is the RMS effective range and what are typical values?

Estimate of e+ range on ACD spat. res., typically about 0.25 mm (F-18) - 3 mm (R-82)

False Positive Fraction

FP/(TN+FP) = 1 - specificity

Example filter image in frequency space

Filter Kernel A = Butterworth filter of 5th order w/ a critical freq. of 0.15 Nyquist, B = Butterworth filter of 5th order w/ critical freq. of 0.27 Nyquist. Filter A provides more smoothing than B

Diagram of PET detector thickness causing LOR uncertainty

For coincident interactions in det. A & B, there is little uncertainty in LOR. When coincidences occur in det. B & C, there is greater uncertainty in LOR.

What is the difference between frame and list mode?

Frame mode acquires images in real time based on signal measured, list mode formats data into large tables that can be formatted and reconstructed later

Which components in a GM counter and multichannel analyzers have the longest dead time?

GM counter: Detector MCA: ADC

What SPECT radiopharmaceutical emits a gamma ray that is within the energy range of PET?

Ga-67 (494 keV)

Whole-body dose from Ga-67, Tl-201, F-18, Tc-99m

Ga-67 − 0.26 rad/mCi Tl-201 - 0.21 rad/mCi F-18 − 0.04 rad/mCi Tc-99m - 0.017 rad/mCi

Which decays by positron emission? Ge-68 or Ga-68?

Ge-68, produced by accelerator, decays to Ga-68 via electron capture, which then decays by positron emission.

Typical dose to thyroid from I-131, I-123, Tc-99m

I-131: 1 rad/uCi I-123: 1 rad/100 uCi Tc-99m: 1 rad/5000 uCi

What artifact results from soft tissue scatter?

Images appear darker on arm + chest wall

3.1.6. Example: SPECT uniformity — dual head SPECT — partial ring artifacts

In multihead SPECT sys, each head will contribute to non-uniformity. Since non-uniformity in each head will be diff., resultant pattern will not be rings but partial rings.

What is Zevalin (Ibritumomab Tiuxetan) used for?

In-111 imaging (5 mCi) and then Y-90 injection (HL = 64 h) with rituximab chemo used to image and then treat non-Hodgkin's lymphoma. β path ~ 5 mm; requires CBC, bone marrow biopsy, CD20 expression; before administration a non-labeled antibody is injected to saturate CD20 epitope of non-malignant B cells

chemotaxis examples

In-111 leukocytes accumulating at reaction site

What is likely to cause aliasing or a Moire pattern in the bar phantom image?

Incorrect collimator

2.3.2.3. Example: High energy collimator and line source

Individual holes of the coll. appear the img of line source. Nevertheless, by using a wide profile, effect of the individual holes is smoothed and a continuous LSF is obtained for quantitative assessment of spat. res.

2.2.2C3. Example: Asymmetric energy window — poor tuning

L shows a reasonably uniform hexagonal pattern of PMT. R shows v patchy uniformity. The wide variation in response is indicative of v poor tuning

What is a normal Ejection fraction for left and right ventricles?

L: 50-70%, R: >40%

2.2.6.6. Example: Problems with linearity correction

L: no contrast enhancement, R: contrast enhancement. Caused by coordinates not aligned w/ coordinates of linearity correction, so linearity correction is not properly applied

When performing a gated equilibrium cardiac study, which view best separates right and left ventricles?

LAO (horizontal long axis); view of septal, inferoapical, and lateral walls

2.2.9.3. Examples: Collimator septa and hole alignment assessed by a distant point source — low energy collimator problems

LEHR artifact due to hole misalignment w/ respect to crystal face

SPECT Daily Uniformity - What/Why/How

Looks for contamination on camera and can reveal noise in electronics. Tc-99m photopeak, 128 x 128, 100 s

How can you identify a Ga-68 dotatate study rather than a normal F-18 FDG study?

Lots of skeletal/muscle uptake, liver and gallbladder hot, pituitary gland visualized, low contrast

4.1.3. Example: Clinical Whole body bone scan — change of scan speed during scan

Motion of scan was from head to feet. Whole body scan started correctly as electronic shutter opened, but during subsequent motion scan speed changed.

What is diazepam used for?

Muscle relaxant to decrease uptake of F-18

DOT Transport Categories

NM radioRx use groups III and IV. Most hazardous are I

What is the name for the collaboration between the ACR, AMI, and ACRIN to ensure access to Medicare reimbursement for PET?

National Oncologic PET Registry (NOPR)

How can you identify an Axumin/fluciclovine study rather than a normal F-18 FDG study?

No brain uptake, hepatic uptake

Table: Properties of PET detector scintillators (Decay constant, density, conversion efficiency relative to NaI)

Note: LYSO is similar to LSO in every regard except the density and attenuation coefficient are less

Figure 10-2, Elements of an ideal Cs-137 γ-ray pulse-height spectrum over time and pulse amplitude

Only the photopeak in B represents deposition of full E of γ in det.

Which isotopes does the NRC not require measurement of due to being pure β emitters?

P-32 and Sr-89

What medical isotopes are produced by nuclear reactor?

P-32, Cr-51, Sr-89, I-125, Sm-153

What is N-13 ammonia used for?

PET cardiac rest-stress perfusion exams; passive/active entrance, stays trapped in heart myocytes by glutamine synthetase pathway; near 100% extraction

What is Ga-68 dotatate used for and what is the critical organ?

PET neuroendocrine (somatostatin) tumor imaging, identifying candidate for Lutathera (Lu-177); kidney is the critical organ

White I Label Requirements

Pkg surf. < 0.5 mrem/h, dose at 1 m < 0.05 mrem/h (TI < 0.05), act. listed in Bq, Isotope listed as common name (F-18). Most research materials

Yellow III Label Requirements

Pkg surf. < 200 mrem/h, dose at 1 m < 10.0 mrem/h (TI < 10), act. listed in Bq, Isotope listed as common name (F-18)

Yellow II Label Requirements

Pkg surf. < 50 mrem/h, dose at 1 m < 1.0 mrem/h (TI < 1), act. listed in Bq, Isotope listed as common name (F-18)

What is the definition of specific activity?

Radioisotope Activity/Total Mass of Element Present

Leveen Shunt Patency Protocol (Route, activity, prep, wait, imaging time, collimator, notes)

Radionuclide: Tc-99m MAA; Activity: 1 mCi; Route: intraperitoneal; Special Prep: Void b4 exam, anesthesia at inj; Wait: 0 h, 1 h, 4 h; Imaging time: 1 h; Collimator: LEHR; Notes: lung/liver act. should be seen by 4 h

Typical Random Fraction and Scatter Fractions for Brain/Abdomen

Random/True ~ 0.1-0.2 (brain) Random/True ~ >1 (lg activity/abdomen) Scatter/True ~ 0.2-0.5 (brain) Scatter/True ~ 0.4-2.0 (abdomen)

Which study has the greatest dose? O-15, N-13, or Rb-82 rest/stress?

Rb-82 (~13 mSv)

What medical isotopes are produced by a generator, besides technetium?

Rb-82, Ga-68, Y-90

What is rituximab used for?

Recombinant monoclonal chimeric antibody against CD20 on B cells. For treatment of B cell Lymphoma

Typical SPECT Intrinsic Spatial Resolution/Linearity

Res typically 3-4 mm FWHM, 6.5-9 mm FWTM. relative linearity typically 0.2-0.6 mm, absolute < 1.5 mm. x and y dirs.

What do physicists check on annual PET QC?

Resolution, Count Rate Performance, Dead Time Correction, Sensitivity, Uniformity, Image Quality Phantom, CT # Accuracy, SUV accuracy, Image Co-Registration, Acquisition Monitor, Safety, Quality Control Program (Dose calibrator, Daily PET, Daily CT, ACR Phantom)

Right to Left vs Left to Right shunt

RtL: deoxygenated blood returns to circulation; causes uptake in brain, kidneys; reduction in MAA particles needed for perfusion, can also be imgd w/ MAA LtR: oxygenated blood goes back to lungs, imgd w/ DTPA

What is the Rose criterion?

SNR of 3-5 to distinguish a lesion; CSP takes this value as 4

What kind of equilibrium is each generator in? Rb-82, Ga-68, Mo-99

Secular, Secular, (mostly) transient

ROC Plot Illustration

Sensitivity vs FPF

Bowel Activity Impinging on Myocardium

Sometimes caused by FBP

I-125 decay and spectrum illustration

Spectrum acquired w/ well counter shows a "sum peak" caused by 2 photons simultaneously striking detector. Similar effect is not seen w/ other geometry as the interaction is much less likely

3.5.2. Example: Head tilt — offset point source — comparison of increasing head tilt

T row no head tilt, each subsequent row more tilt

5.4.2. Example: Gated SPECT data acquisition — arrhythmia problems

T row not corrected for arrhythmia

3.1.1A. Example: SPECT uniformity simulation — Effect of 64x64 vs 128x128 matrix

T row: 64x64 matrix, 64 projections. B row: 128 x 128 matrix, 128 projections. Note sampling in top is inadequate for nose-free data

Components of EKG diagram

TP segment = early diastole P wave = depolarization (activation) of atria; immediately precedes atrial contraction PR interval = increases w/ increase in vagus nerve input PR segment = blood flows from atria to ventricles QRS Complex = depolarization ventricles and immediately precedes ventricular contraction; entirely negative = QS wave ST segment = blood flows to lungs and body; ischemia may be demonstrated by depression below the baseline T wave = ventricle repolarization

How long after Technetium-99m and I-123 imaging can a parent resume breastfeeding?

Tc-99m: 12-24 h I-123: 2-3 d all cross placenta, fetal throid ~12 wks

3.1.1D. Example: SPECT uniformity simulation — 16 pixel wide non-uniformity offset from the axis of rotation

The 'ringing', sharp spikes on profile (BR), and increased central activity are artifacts due to sharp discontinuities in uniformity and FBP recon.

What intrinsically limits the spatial resolution of gamma cameras?

The QDE of the PMTs in detecting UV/visible light photons produced in crystal is most significant factor (typically only 20%-25% of UV/visible light photons incident on a photocathode contribute to signal). Also size of PMTs & crystal thickness

2.3.1.7. Example: Bar pattern — off-centered point source

The point source was centered in x-dir. but off-centered almost to the lower edge of FOV in y-dir. Flux was therefore decreased for the 2 quadrants w/ horiz. bars where crystal was shielded by bars. The impression is then created of 2 hot quadrants and 2 cold quadrants

2.2.6.1. Example: Illustration of the effect of no linearity or energy corrections being applied

This example illustrates the typical response when no linearity and energy corrections are applied

What causes a Chi-square value to be too high or too low?

Too much noise = too high, continuous extraneous signal/high ct rate = too low

What is a Schilling test?

Used to measure B-12 absorption. Uses oral Co-57 or Co-58 bound B-12.

Secular equilibrium

When HL of parent A is so long that decay is negligible during observation period (λp ~ 0) eg Sr-82/Rb-82

No equilibrium (plot and definition)

When daughter HL is > than parent HL, eg Te-131m (T = 30 h) -> I-131 (T = 8 d)

Transient equilibrium (plot and definition)

When parent HL is >> than daughter HL but not "infinite" (eg Mo-99 & Tc-99m)

3.9.8A. Example: FBP streak artifacts — hot organ activity outside of organ of interest — liver study

Zoomed liver transverse slices show distinct streaks due to extremely hot spleen & FBP

Typical dead time for non-GM counter radiation detectors, such as gamma cameras

a few us

What is a fatty meal used for?

alternative to CCK/Sincalide to empty gallbladder

Ramp filter

amplifies high frequencies to counter 1/r blurring

What is I-131 Bexxar (tositumomab) used for?

anti-CD20 antibody used for non-Hodgkin's lymphoma; before administration a non-labeled antibody is injected to saturate CD20 epitope of non-malignant B cells

What is quenching and how is it reduced?

any process that reduces the amount of scintillation light produced by sample or collected by PMTs, typically for liquid scintillation det. Caused by materials that absorb radiation w/o scintillating or dilution. Results in apparent shift of cts to lower E, possibly out of E window, resulting in inaccurate cting. Corrected by adding a sample of known act. and cting 2x, cting in 2 diff. windows, or both

Conversion efficiency (sensitivity) of NaI(Tl) crystal

approx. 13% of deposited E is converted into light. Because a light photon has an E of ~3 eV, approx. 1 light photon is emitted for every 23 eV absorbed by the crystal.

What areas of the body is spatial resolution in PET best?

best in dense tissue, worse in tissue like lungs

What is propanalol used for?

beta blocker for reducing blood pressure; also reduces brown fat uptake of FDG

How does Alzheimer's disease present in an FDG scan?

bilateral, symmetric decreased uptake in temporoparietal region

How long should you wait after biopsy, chemotherapy, and radiation therapy for a PET scan?

biopsy: 1 w chemotherapy: 2-4 w therapy: 2-6 mo

Figure 10-4, Iodine escape peak

caused by characteristic 30 keV I K-shell x-ray in NaI crystal from γ interaction. Occurs at γ - 30 keV, more pronounced in low-E radioRx due to greater likelihood of detection near surface of crystal

2.5.1. Example: Changes in uniformity at high count rates

clinical work unlikely to produce ct rates higher than lowest value here

Scintillation counter energy calibration process

confirm photopeaks at correct position on MCA w/ at least 2500 cts in the peak channel for all radioRx used

How is GFR determined and what is a normal value?

cts in both kidneys compared to cts of dose prior to inj.; Normal value 125 mL/ml

How is ERPF determined and what is a normal value?

cts of dose prior to inj./cts in a plasma sample taken at 45 mins post-injection; can also be purely camera-based; Normal value 500-600 mL/m

PET QC Frequency

daily: sinogram (blank scan) weekly: uniform phat. looking for bad dets. and normalization annual: cal. factor correction; a cylinder phantom w/ known act. in a known V scanned & meas. act. is compared to known

6.2.3A. Example: Intrinsic uniformity — interference from an external radioactive source

dark lines changed w/ change in orientation of cam head; were due to stray radiation from extraneous source

Pulse pile-up diagram

dashed lines represent signals produced by 2 interactions in det that occur at ALMOST the same time, solid line is actual pulse from det.; worse in hi ct rates

Resolution (increases/decreases) with the diameter of the PET detector ring. Why?

decreases due to worsening effect of non-colinearity

ion exchange example

diphosphonates locate in bone

Effective vs. equivalent dose

equivalent = mult. by rad. factor, effective = mult. by organ factors

What is granulocyte colony-stimulating factor (GCSF) used for?

febrile neutropenia after myelosuppressive chemotherapy; glycoproteins regulate production, differentiation, survival, and activation of hematopoietic cells; stimulates the bone marrow to produce more infection-fighting white blood cells called neutrophils. Wait ~10 d before FDG scan

Rank in order of particle size from smallest to largest: MAA, filtered sulfur colloid, unfiltered sulfur colloid, DTPA

filtered sulfur colloid (~0.1 um), unfiltered sulfur colloid (~1 um), DTPA (~1 um), MAA (~10 um)

What effect does high bilirubin levels have on hepatobiliary imaging?

high bilirubin = poorly functioning liver = more kidney uptake/excretion

proximal stomach FDG uptake is (higher/lower) than distal stomach uptake

higher

What is a typical dose for I-131 hyperthyroidism and thyroid cancer therapy?

hyperthyroidism: 20-30 mCi cancer: 150 - 200 mCi

What is metformin used for?

hypoglycemia for Type II diabetes; also causes intense bowel FDG uptake

Regions of the brain and what they control (diagram)

hypothalamus (tiny part, not shown) controls visceral functions, body temperature, and behavioral responses; other portion of cerebral cortex comprised of gray matter

2.2.6.2. Example: Effect of linearity and energy corrections but no uniformity correction

img shows a distinct pattern of non-uniformity that is characteristic of one particular mfr

2.2.3.1B. Example: Comparison of intrinsic uniformity for Tl-201, Ga-67, I-123, In-111 and I-131 on the same scintillation camera — Tc-99m uniformity correction map

imgs show loss of uniformity, especially at lo photon E (Tl-201, Ga-67)

ischemia vs infarction

ischemia = decreased blood flow infarction = dead

The sensitivity of the exercise SPECT myocardial perfusion imaging for recognizing disease in individual coronary arteries is the highest in which artery?

left anterior descending

What is the sensitivity/specificity of FDG PET for detecting malignant lung nodules > 1 cm and for lymphoma?

lung nodules: 96%/77% lymphoma: 90%/91%

Where does brown fat tend to accumulate the most?

neck

Example octreotide scan

note hot spleen, relatively hi cts, robust kidney uptake, lack of bone uptake

Example Ga-67 scan

note lachrymal gland uptake, bone uptake, lack of splenic and renal uptake

short axis view

note septal wall on left

The healthy heart under normal conditions derives more than two thirds of its energy from...

oxidative long-chain fatty acids metabolism; under fasting switches to anaerobic glucose

What radiopharmaceutical is used to bind to RBCs with Tc-99m?

pertechnetate

Dual-isotope parathyroid study

pertechnetate or I-123 thyroid img subtracted from sestamibi or Tl-201 parathyroid img; residual act. represents act. in abnormal parathyroid

What disease will show up in the lungs on a bone scan?

radiation pneumonitis

What is In-111 chloride used for?

radiolabeling OncoScint or ProstaScint used for tumor imaging and for radiolabeling Zevalin in radioimmunotherapy procedures

Dual Window Subtraction

scatter correction; coincidence events accumulated in 2 separate energy E. assumes scattered photons in the lower than photopeak E window are linearly proportional to scattered photons in photopeak window.

Intrinsic efficiency (sensitivity) by detector type

scintillators - varies by det. size semi-conductors - E dependent gas-filled - good for particles, <1% for γ, x-rays

Sestamibi vs tetrofosmin

sestamibi 1st pass extraction: 65%, tetrofosmin: 54%, both total uptake ~1-1.4% in myocardium

Name 4 tumors with low FDG uptake

signet-ring cell carcinoma, prostate carcinoma, mucinous adenocarcinoma, renal cell carcinoma

Cardiac Output

the blood pumped out of the ventricle after 1 min; CO = SV x HR

Because the singles rates in individual detectors, ignoring dead-time count losses, are approximately proportional to the activity in the patient, the rate of random coincidences is approximately proportional to...

the sq. of act. in pt. (2 det.)

How many PMTs are typically in a gamma camera, and what is their typical diameter?

typically 75-91 per camera, 2-3" diameter

Which tomographic plane of the heart displays all walls of the left ventricle?

vertical long axis

Stroke Volume

volume of blood pumped out by one ventricle with each beat (ESV - EDV)

What is roll-off in cardiac imaging?

when myocardial uptake plateaus at high enough blood flow rates. more pronounced for Tc-99m than Tl-201

NRC Requirements for opening nuc med packages

wipe test, surface survey w/in 3 h

PET sinogram

y-axis: sets of det. pairs x-axis: shift of LOR from center of gantry

FWHM = ___ x smallest bar pattern visible

~1.7. Eg, FWHM of 1 cm (10 mm) can resolve 5-7 (6) mm bar phantoms

Typical efficiency (sensitivity) of a low-energy high-resolution collimator

~1E-4 or 100 cps/MBq

Typical efficiency (sensitivity) a general-purpose low-energy collimator

~2E-4 or 200 cps/MBq

What sources are exempt from NRC leak testing requirements?

β or γ srcs w/ act. <= 100 uCi or α/n srcs w/ act. <= 10 uCi, srcs w/ HL <= 30 d