Research ArticleSpecial Contribution

MIRD Pamphlet No. 24: Guidelines for Quantitative 131I SPECT in Dosimetry Applications

Yuni K. Dewaraja, Michael Ljungberg, Alan J. Green, Pat B. Zanzonico, Eric C. Frey, SNMMI MIRD Committee, Wesley E. Bolch, A. Bertrand Brill, Mark Dunphy, Darrell R. Fisher, Roger W. Howell, Ruby F. Meredith, George Sgouros and Barry W. Wessels
Journal of Nuclear Medicine December 2013, 54 (12) 2182-2188; DOI: https://doi.org/10.2967/jnumed.113.122390

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Images corresponding to 131I pointlike source measured in air at 20 cm with medium-energy (left) and high-energy (right) collimators. Images are shown on a logarithmic gray scale (individually normalized). System planar sensitivities for a 364-keV window were 319 cps/MBq for the medium-energy collimator and 82 cps/MBq for the high-energy collimator, but the fraction of unwanted penetration and scatter events was much higher with the medium-energy collimator than with the high-energy collimator, 85% versus 49%, based on Monte Carlo simulation.

  • FIGURE 2.
    FIGURE 2.

    Energy spectrum corresponding to a radioimmunotherapy patient imaged 2 d after administration of 2.8 GBq of 131I. Windows for TEW (310–332 keV and 405–427 keV) are shown by dashed lines, and the trapezoidal scatter estimate is indicated in the 332–405 keV photopeak window.

  • FIGURE 3.
    FIGURE 3.

    Measurement of RCs discussed in patient example 1. (A) Phantom set-up. (B) SPECT/CT image. (C) RC as function of OSEM iteration number. (D) RC as function of volume at 35 iterations. RCs that were determined with commercial OSEM reconstruction are also shown.

  • FIGURE 4.
    FIGURE 4.

    SPECT/CT imaging based tumor dosimetry in a non-Hodgkin lymphoma patient undergoing 131I radioimmunotherapy. (A) Inguinal tumor outline shown on superimposed SPECT/CT images. Tumor volumes at the 3 time points were 77, 63, and 39 mL. (B) Tumor time–activity curves. (C) Tumor-absorbed dose map, showing isodose contours in units of cGy. (D) Tumor dose–volume histogram.

  • FIGURE 5.
    FIGURE 5.

    SPECT/CT imaging–based biodistribution measurement in sarcoma patient undergoing radioimmunotherapy with 131I-L19SIP. (A) SPECT/CT images of upper thorax, with tumor indicated by arrows. (B) Time–activity concentration curves for tumor and normal organs.

Tables

  • TABLE 1

    Phantom and In Vivo Validation Studies of Quantitative 131I SPECT

    StudyApplication/potential applicationStudySystemReconstructionQuantification accuracy*
    Song 2011 (14)RIT dosimetryPhantom simulationsSimulation studyOSEM with ESSE SC, AC, CDRC<5% error for larger organs; 10%–15% for smaller organs
    Dewaraja 2010 (4)RIT dosimetryPhantom measurements/simulationsSPECT/CTOSEM with TEW SC, CT-based AC, CDRC<17% error for 8- to 95-mL spheres; 31% for 4-mL sphere
    Pereira 2010 (28)DosimetryPhantom measurementsSPECT/CTOSEM with TEW SC, CT-based ACMeasured-to-true ratios of >90% for 11.5-mL sphere, 13%–63% for 1.4- and 2.2-mL spheres
    Shcherbinin 2008 (29)MIBG dosimetryPhantom measurementsSPECT/CTOSEM with analytic scatter model, CT-based AC, CDRC3%–4% error for 32-mL volumes
    Koral 2005 (24)RIT dosimetryPhantom measurementsSPECT and CT separatelyOSEM with TEW SC, CT-based AC, CDRC<7% average error for 100-mL sphere
    Gonzalez Trotter 2001 (13)Brain tumor RITPhantom measurementsSPECT with specialized collimatorOSEM with TEW SC, AC, CDRC<20% error for 6- to 11-mL spheres
    Alaamer 1993 (18)MIBG dosimetryPhantom measurementsSPECT and CT separatelyReconstruction with SC and ACSE = 0.24 MBq for 6–600 mL
    Israel 1990 (19)MIBG and thyroid carcinoma dosimetryPhantom measurements and in vivo patient study of 131I concentration in urinary bladderSPECTFBPPhantom: good correlation with truth (r = 0.98, SEE = 20.94 counts/voxel); patients: good correlation with concentration in urine (r = 0.98, SEE = 25.049 kBq/mL)
    Riggs 1988 (30)RITPhantom measurements and in vivo patient study of 131I concentration in heartSPECTFBP with DEW SC, Chang ACPhantom: <10% error; patients: good correlation with concentration in serial blood

    • ↵* Percentage difference between SPECT estimated activity and truth.

    • RIT = radioimmunotherapy; ESSE = effective scatter source estimation; SC = scatter correction; AC = attenuation correction; CDRC = CDR compensation; MIBG = metaiodobenzylguanidine; FBP = filtered backprojection; DEW = dual energy windows, SE = standard error; SEE = standard error of the estimate.

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