Review

73 animations · 120 placements · 29 chapters

Animations

The hard concepts of nuclear medicine as interactive animations computed from real values. Each one runs in the book, in place of the figure it replaces; select a title to go there.

73 animations

  1. 01Characteristic X-rays and Auger electronsIn light atoms the vacancy is mostly filled with an Auger electron, in heavy atoms with an X-ray; I-125 releases ~25 Auger electrons per decay and can cause a double-strand break if close to DNA.Figure 1.4 · 5 steps
  2. 01The band of stability and decay directionsAs Z rises, stable nuclei need a higher neutron-to-proton ratio; nuclei outside the band decay in the direction that brings them towards it.Figure 1.7 · 5 steps
  3. 02Alpha and beta energy spectraIn alpha decay the energy is shared between two bodies, so the lines are discrete; in beta decay it is shared with a (anti)neutrino, the spectrum is continuous and the mean energy is about Emax/3.Figure 2.1 · 4 steps
  4. 02Positron, positronium and annihilationPositron range and the slight deviation of annihilation photons from 180° are physical limits of PET resolution.Figure 2.2 · 3 steps
  5. 02Electron capture and the β⁺ thresholdElectron capture can occur at any energy difference; β⁺ decay requires the energy difference between the nuclei to exceed 1.022 MeV.Figure 2.3 · 2 steps
  6. 02Tc-99m: isomeric transition and internal conversionIn an isomeric transition the energy leaves either as a γ photon or is transferred to a shell electron; internal conversion dominates in low-energy, high-multipolarity transitions.Figure 2.4 · 3 steps
  7. 02Decay curve, half-life and mean lifeThe remaining activity halves with each half-life and falls below one thousandth after 10 half-lives; the mean life is 1.443 × T½.Figure 2.5 · 3 steps

    Also in: Figure 27.11

  8. 02MIRD: effective half-life and cumulated activityThe effective half-life is shorter than both the physical and biological half-lives (1/Teff = 1/Tphys + 1/Tbiol); cumulated activity is the area under the curve, Ã = 1.443 × A₀ × Teff.Figure 2.7 · 3 steps

    Also in: Figure 10.3

  9. 02Transient equilibrium, secular equilibrium and no equilibriumIf the parent's half-life is somewhat longer than the daughter's, transient equilibrium forms; if much longer, secular equilibrium; if shorter, no equilibrium.Figure 2.8 · 3 steps
  10. 03Alpha track and the Bragg curve; comparison with betaAn alpha particle stops within a few cell diameters and deposits its energy most densely at the end of its path (Bragg peak); a beta electron ionises far more sparsely and travels millimetres.Figure 3.1 · 3 steps
  11. 03Radiation protection: time, distance, shieldingDose rate falls with the square of distance, dose rises in proportion to time, and each HVL of lead halves the photons passing; a beta source is shielded first with low-Z material.Figure 3.2 · 5 steps

    Also in: Figure 3.9, Figure 10.8, Figure 27.10

  12. 03Compton scatteringThe larger the scattering angle, the more energy the photon loses; photons scattered through small angles can fall inside the energy window.Figure 3.4 · 5 steps
  13. 03Photon interactions and regions of dominanceThe photoelectric effect dominates at low energy and high Z, Compton at intermediate energies, pair production well above 1.022 MeV; in tissue Compton prevails at nuclear medicine energies.Figure 3.5 · 6 steps

    Also in: Figure 3.6

  14. 03HVL, TVL and the build-up factorEach HVL halves the photons passing; HVL grows with photon energy; in a broad beam scattered photons are also measured, so transmission is higher than in a narrow beam.Figure 3.7 · 4 steps

    Also in: Figure 3.8

  15. 04Direct and indirect action, oxygen fixation and the timelineWith low-LET radiation most damage arises through OH• radicals (indirect); oxygen makes radical damage permanent, which is why hypoxic cells are more resistant.Figure 4.1 · 5 steps

    Also in: Figure 4.2

  16. 04DNA damage and repair pathwaysCells repair single-strand damage easily; the real danger is the few double-strand breaks, whose wrong or incomplete repair leads to cell death or mutation.Figure 4.3 · 5 steps
  17. 04Survival curve, LQ model, fractionation and LETLate-responding tissues have a small α/β and are more sensitive to dose per fraction; because sublethal damage is repaired between fractions, a split dose kills fewer cells than the same single dose.Figure 4.4 · 4 steps

    Also in: Figure 4.5

  18. 04LET, RBE and OERAs LET approaches about 100 keV/µm, ionisations become as close as the DNA diameter, double-strand breaks and RBE rise and the oxygen effect falls; at higher LET energy is wasted (overkill).Figure 4.9 · 3 steps
  19. 05Gas-filled detectorsAn ion chamber collects the charge as formed, a proportional counter multiplies it but keeps energy information, and a GM counter gives the same large pulse for every event and cannot discriminate energy.Figure 5.1 · 3 steps

    Also in: Figure 5.2

  20. 05Scintillation detector and PMTIn a scintillation detector the energy passes through several conversions and carriers are lost at each; at 140 keV ~900 photoelectrons give ~10% resolution, CZT's ~30,000 carriers ~5–6%.Figure 5.3 · 3 steps

    Also in: Figure 5.4

  21. 05Energy spectrum, resolution and the PHA windowThe photopeak is full energy absorption; Compton, backscatter, escape and X-ray peaks are partial or secondary events. The energy window rejects photons scattered in the patient; a narrower window means less scatter but also fewer counts.Figure 5.6 · 3 steps

    Also in: Figure 5.7, Figure 5.8

  22. 06Anger logic and crystal thicknessThe weighted mean of the PMT signals gives the position and their sum the energy; a thick crystal catches more photons but spreads the light wider, so the position becomes less certain.Figure 6.2 · 2 steps

    Also in: Figure 6.3

  23. 06Collimator types and the effect of distanceThe collimator sets the image geometry; with a parallel-hole collimator resolution worsens with distance while sensitivity stays the same; a pinhole inverts the image and magnifies nearby objects.Figure 6.5 · 5 steps

    Also in: Figure 6.10, Figure 9.2

  24. 06SPECT acquisition and orbitsTwo opposed heads collect 360° of data in a 180° rotation; in cardiac imaging L-mode covers only the anterior 180° near the heart; a body-contour orbit keeps the detector close to the patient and preserves resolution.Figure 6.7 · 3 steps

    Also in: Figure 8.10

  25. 06Cardiac SPECT slice planesThe heart's long axis is oblique to the body axes, so transaxial slices cut the left ventricle obliquely; the data are reoriented to the long axis and SA, VLA and HLA slices are taken relative to it.Figure 6.8 · 3 steps
  26. 07Positron, annihilation and coincidenceWhen two 511 keV photons are detected within the timing window the event is placed on the line joining the two detectors; scatter and randoms create false lines, and TOF narrows the position along the line.Figure 7.1 · 6 steps

    Also in: Figure 7.2, Figure 7.3, Figure 7.7, Figure 9.9, Figure 28.8

  27. 07Coincidence timing window and count ratesTrue coincidences rise linearly with activity and level off once the window covers the arrival difference; randoms rise linearly with window width and with the square of activity, so noise grows at high activity and with a wide window.Figure 7.4 · 2 steps
  28. 072D and 3D PET acquisitionRemoving the septa lets cross-ring coincidences count and raises sensitivity ~4–8×; the price is more scatter and randoms and a more complex reconstruction.Figure 7.9 · 2 steps
  29. 07Respiratory misregistrationCT is a snapshot, PET a breathing average; a CT in deep inspiration gives a cold band at the liver dome, a diaphragm higher than in PET a hot artefact at the lung base; CT in shallow breathing or gating prevents this.Figure 7.12 · 2 steps

    Also in: Figure 9.8

  30. 07SUVmax, SUVpeak, MTV and TLGSUVmax is a single voxel and sensitive to noise, SUVpeak is more stable; the partial volume effect lowers the true value of a small lesion; MTV and SUVmean depend on the threshold chosen, and TLG = MTV × SUVmean.Figure 7.15 · 2 steps

    Also in: Figure 21.7

  31. 08Tomographic reconstructionSimple backprojection gives a star artefact and blurring; the ramp filter corrects this but raises noise; iterative methods fit the image step by step to the measured projections.Figure 8.1 · 4 steps

    Also in: Figure 8.2, Figure 8.4

  32. 08Attenuation: SPECT and PETIn SPECT attenuation depends on source depth (deep structures look faint); in PET the attenuation of the photon pair depends only on total thickness, so a transmission (CT) measurement corrects it exactly and correction is mandatory.Figure 8.6 · 3 steps
  33. 08ECG and respiratory gatingGating freezes motion by sorting counts by cardiac or respiratory phase; with irregular R-R, beat rejection costs counts, and with phase-based respiratory binning irregular breaths blur the image; end-expiration is the most stable phase.Figure 8.8 · 3 steps
  34. 09Counting statistics and noisePoisson noise dominates in nuclear medicine; relative noise falls as 1/√N and SNR rises as √N; detectability depends on CNR, and a low-contrast lesion needs many more counts.Figure 9.3 · 2 steps
  35. 09Partial volume effectWhen the lesion is smaller than 2-3 × FWHM a hot lesion is underestimated (spill-out) and a cold lesion overestimated (spill-in); the loss is described by the recovery coefficient and can be corrected.Figure 9.4 · 2 steps

    Also in: Figure 27.6

  36. 09SPECT artefactsSPECT assumes all projections are consistent; patient motion gives a break and double contour, a fixed detector defect a ring, and a centre-of-rotation shift a blurred or ring-shaped point source.Figure 9.5 · 3 steps

    Also in: Figure 9.7, Figure 27.4

  37. 11Negative-ion cyclotronIn a cyclotron a charged particle circling in a magnetic field is accelerated by RF at each crossing and spirals outwards; in a negative-ion cyclotron a carbon foil turns H⁻ into a proton to extract the beam; the products are proton rich (β⁺, EC).Figure 11.2 · 3 steps
  38. 11Mo-99/Tc-99m generatorTc-99m in the column peaks at about 23 hours; after elution it builds up again and in transient equilibrium decreases together with Mo-99.Figure 11.5 · 5 steps

    Also in: Figure 11.6

  39. 12Radiochemical purity by ITLCAcetone measures free pertechnetate (moves to the front), saline measures colloidal Tc (stays at the origin); RCP = 100 − free TcO₄⁻ − colloidal Tc, and for most kits it must be at least 90%.Figure 12.12 · 3 steps

    Also in: Figure 27.9

  40. 13Iodine metabolism in the thyroid and drug effectsPerchlorate blocks trapping, thionamides organification and lithium release; if organification is defective, unbound iodide leaves the gland after perchlorate.Figure 13.1 · 3 steps
  41. 13MIBI parathyroid imaging: dual phase and subtractionDual phase relies on differential washout between thyroid and adenoma, subtraction on a second agent taken up by the thyroid only; each has its own false results.Figure 13.7 · 2 steps
  42. 14Flow, extraction and uptakeUptake is flow × extraction; extraction falls with flow, so uptake plateaus at high flow and the defect looks milder than it is; the relation is most linear for O-15 water and N-13 ammonia.Figure 14.1 · 2 steps
  43. 14Polar map, 17 segments and SSS/SRS/SDSThe polar map gathers short-axis slices into one circle with the apex in the centre and the base outside; the sum of stress scores (SSS) gives risk and the stress–rest difference (SDS) the amount of ischaemia.Figure 14.4 · 3 steps
  44. 14Tl-201 redistribution and reinjectionViable ischaemic myocardium keeps taking up Tl-201 from the blood, so the defect fills with time; some defects that look fixed at 4 h prove viable with reinjection or a 24 h late image.Figure 14.6 · 2 steps
  45. 15Uptake and distribution of bone agentsDiphosphonate is retained by chemisorption driven by osteoblastic activity, NaF by forming fluorapatite; imaging waits for soft-tissue background to clear (MDP 2-4 h, NaF 45-60 min).Figure 15.1 · 2 steps
  46. 15Three-phase bone scintigraphyPhases 1-2 show hyperaemia, phase 3 shows bone formation; osteomyelitis and cellulitis separate on phase 3, and a ratio that rises at 24 h supports a bone lesion.Figure 15.2 · 2 steps
  47. 16Renal agents along the nephronDTPA is filtered (GFR, ~20%), MAG3 is secreted (ERPF, ~55%), DMSA stays in the tubular cell (cortex); the route of the agent decides what it measures.Figure 16.1 · 3 steps
  48. 16Renogram and the diuretic responseThe renogram's shape reflects the transit of the tracer through the kidney; after furosemide a T½ under 10 minutes excludes obstruction, over 20 minutes suggests obstruction.Figure 16.2 · 2 steps

    Also in: Figure 16.4, Figure 23.3

  49. 16GFR by plasma samplingClearance is dose / area under the curve; the slope-intercept method misses the early distribution component, overestimates GFR and is corrected with Brøchner-Mortensen.Figure 16.6 · 2 steps
  50. 17MAA particles and right-to-left shuntMAA particles lodge in the precapillary arteriole that matches their size; with a right-to-left shunt particles that bypass the lung appear in brain and kidneys and the shunt fraction is systemic / total.Figure 17.1 · 2 steps

    Also in: Figure 17.9

  51. 17Xe-133 ventilation phasesAir trapping shows reduced filling on single breath, filling at equilibrium and delayed clearance on washout; washout is the key phase.Figure 17.2 · 3 steps
  52. 18Gastric emptying: solids and liquidsThe solid meal is first ground in the antrum (lag), then empties roughly linearly; >10% at 4 h is gastroparesis and <30% at 1 h is rapid emptying.Figure 18.3 · 2 steps
  53. 18Hepatobiliary (HIDA) scintigraphyNo gallbladder at 60 minutes and 30 minutes after morphine means acute cholecystitis; no bowel even at 24 hours means complete obstruction or biliary atresia; GBEF <38% with sincalide is dyskinesia.Figure 18.8 · 4 steps

    Also in: Figure 18.9

  54. 19Brain perfusion agents and the blood-brain barrierLipophilic HMPAO and ECD cross the BBB and are trapped in the cell as a hydrophilic form; with no redistribution the image freezes perfusion at the moment of injection.Figure 19.1 · 3 steps
  55. 19Ictal SPECT and SISCOMIctal SPECT freezes the moment of injection: injection within the first 20 seconds shows the focus hyperperfused; SISCOM fuses the ictal − interictal difference with MRI to localize it.Figure 19.6 · 2 steps

    Also in: Figure 19.7

  56. 20Deauville scoreThe Deauville score compares residual uptake with blood pool and liver: 1-3 is negative (CMR); with 4-5, comparison with baseline gives PMR, NMR or PMD.Figure 20.3 · 2 steps
  57. 20Dilution principle: red cell mass and plasma volumeAfter mixing, the concentration in a sample gives the volume; high RCM is absolute and normal RCM with low PV is relative erythrocytosis.Figure 20.5 · 2 steps
  58. 21Metabolic trapping of FDG in the cellFDG enters and is phosphorylated like glucose, but FDG-6-P can neither enter glycolysis nor be reversed, so uptake reflects the cell's glucose use.Figure 21.1 · 1 steps
  59. 22Lymphatic transport and the sentinel lymph nodeThe SLN is the first node reached by each lymphatic channel; smaller particles travel faster but are retained less, and the ideal size is 10-100 nm.Figure 22.1 · 2 steps

    Also in: Figure 22.2

  60. 22Gamma probe and the 10% ruleNarrow collimation and side shielding give the probe its directional sensitivity; every node with ≥10% of the highest ex vivo count is an SLN.Figure 22.6 · 3 steps

    Also in: Figure 22.7

  61. 23EANM paediatric dosage cardPaediatric activity = baseline activity × weight multiplier; if the result falls below the minimum activity, the minimum is given.Figure 23.1 · 2 steps
  62. 24Ga-67 uptake mechanismsGa-67 travels on transferrin; it accumulates at a focus through increased permeability, lactoferrin, siderophores and leukocytes, and enters tumour cells through the transferrin receptor cycle.Figure 24.1 · 3 steps
  63. 24Labelled leukocyte scintigraphyWith labelled leukocytes infection shows uptake that rises on late images, and is told from marrow by discordance with colloid.Figure 24.3 · 4 steps

    Also in: Figure 24.5, Figure 24.6

  64. 25DacryoscintigraphyDacryoscintigraphy shows drainage physiologically: pooling proximal to a block, delay without a block in functional epiphora.Figure 25.1 · 2 steps

    Also in: Figure 25.2

  65. 25Salivary gland scintigraphy and acid stimulationRapid washout after acid stimulation is normal; a stone preserves uptake but blocks washout, Sjögren and RAI damage reduce uptake.Figure 25.3 · 2 steps
  66. 26Lu-177 DOTATATE: targeting and kidney protectionLu-177 DOTATATE binds SSTR2, is internalised and stays in the lysosome; β⁻ travels tens of cell diameters and irradiates neighbours too; lysine-arginine protects the kidney by reducing megalin-mediated reabsorption.Figure 26.6 · 3 steps
  67. 26Y-90 radioembolisation and the MAA shuntY-90 microspheres lodge in arterially fed tumour and irradiate it in place; the lung shunt measured with MAA sets the dose (>20% contraindicated).Figure 26.11 · 2 steps

    Also in: Figure 26.12

  68. 27Gamma camera quality controlDaily energy peak and uniformity checks and the weekly bar phantom ensure the camera gives accurate, uniform and linear images.Figure 27.1 · 3 steps

    Also in: Figure 27.2, Figure 27.3

  69. 28Patient selection in theranosticsRadioligand therapy only treats lesions that show the target on imaging; a single lesion without the target (discordant) can decide the patient's outcome.Figure 28.3 · 2 steps
  70. 28Total-body PETThe ~40-fold sensitivity of total-body PET comes both from seeing the whole body at once and from catching oblique photon pairs, and it can be spent on lower dose, shorter time or better quality.Figure 28.7 · 2 steps
  71. 29Diagnostic test performanceSensitivity, specificity and likelihood ratios belong to the test; what a result means for a patient depends on the pre-test probability (prevalence) and the chosen threshold.Figure 29.1 · 3 steps

    Also in: Figure 29.2, Figure 29.3

  72. 29Power, confidence intervals and the forest plotFinding a significant result needs adequate power; power and narrow confidence intervals depend on sample size, and meta-analysis pools studies by weighting them for their precision.Figure 29.6 · 3 steps

    Also in: Figure 29.7

  73. 29Kappa and Bland-AltmanPercent agreement and correlation can overstate agreement: kappa corrects categorical readings for chance, and Bland-Altman shows systematic and proportional differences in continuous measurements.Figure 29.9 · 2 steps