An International Peer - Reviewed Journal by Nuclear Science & Technology Research Inistitute

Document Type : Research paper


1 Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran

2 Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Postcode: 14155-1339, Iran

3 3Research Center for Nuclear Medicine, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran


[68Ga] DOTATATE as a radiolabeled tracer is used for in vivo detection of neuroendocrine tumors in the PET/CT examinations. This study aims to calculate S-values in various organs in a voxelized-based Monte Carlo simulation approach for each patient individually. PET/CT images of 9 patients suspected of neuroendocrine cancer were acquired 60 minutes after injection of [68Ga] DOTATATE. After reshaping and registering CT images to the size of PET images, GATE/GEANT4 Monte Carlo (MC) toolkit was used with two inputs of CT images as voxelized attenuation map and PET images as a voxelized activity map for the calculation of the different organs dose. Voxelized dose maps were extracted in the target organs for different source organs. S-value volume histogram and absolute S-values based on the MIRD formalism were calculated. The highest S-values were observed for spleen, bladder, kidneys, liver, pituitary, and the lung with 6.26E-05 ± 1.47E-05, 5.17E-05 ± 3.08E-05, 3.41E-05 ± 7.68E-06, 2.08E-05 ± 4.12E-06, 1.62E-05 ± 5.74E-06 and 8.47E-06 ± 2.47E-06 mGy/MBq.S, respectively. The difference between the amounts of the calculated S-values and those presented in OLINDA software is mainly related to the anatomical difference of the patients with the standard phantom in OLINEDA software. This study showed that patient-specific dosimetry is necessary to calculate S-values.


  1. 1.    G. Fink, D.W. Pfaff, J.E. Levine, Handbook of neuroendocrinology, Academic Press (2012).

    2.    J.F. Tierney, C. Kosche, E. Schadde, et al., 68Gallium-DOTATATE positron emission tomography–computed tomography (PET CT) changes management in a majority of patients with neuroendocrine tumors, Surg. (United States). 165, 178 (2019).

    3.    E.M. Wolin, The expanding role of somatostatin analogs in the management of neuroendocrine tumors, Gastrointest. Cancer  Res. 5, 161 (2012).

    4.    M. Pavel, D. O’Toole, F. Costa, et al., ENETS consensus guidelines update for the management of distant metastatic disease of intestinal, pancreatic, bronchial neuroendocrine neoplasms (NEN) and NEN of unknown primary site, Neuroendocrinology. 103, 172 (2016).

    5.    W.A.P. Breeman, A.M. Verbruggen, The 68Ge/68Ga generator has high potential, but when can we use 68Ga-labelled tracers in clinical routine?, Eur. J. Nucl. Med. Mol. Imaging. 34, 978 (2007).

    6.    H.R. Maecke, M. Hofmann, U. Haberkorn, (68)Ga-labeled peptides in tumor imaging., J. Nucl. Med. 46, 172 (2005).

    1. A.R. Jalilian, An overview on Ga-68 radiopharmaceuticals for positron emission tomography applications, Iran. J. Nucl. Med. 24, 1 (2016).

    8.    S. Zolghadri, A. Jalilian, H. Yousefnia, Absorbed dose assessment of 177 Lu-zoledronate and 177 Lu-EDTMP for human based on biodistribution data in rats, J. Med. Phys. 40, 102 (2015).

    9.    I. Virgolini, V. Ambrosini, J.B. Bomanji, et al., Procedure guidelines for PET/CT tumour imaging with 68Ga-DOTA- conjugated peptides: 68Ga-DOTA-TOC, 68Ga-DOTA-NOC, 68Ga-DOTA-TATE, Eur. J. Nucl. Med. Mol. Imaging. 37, 2004 (2010).

    10.  M. Sandstrom, I. Velikyan, U. Garske-Roman, et al., Comparative Biodistribution and Radiation Dosimetry of 68Ga-DOTATOC and 68Ga-DOTATATE in Patients with Neuroendocrine Tumors,J. Nucl. Med. 54, 1755 (2013).

    11.  T.D. Poeppel, I. Binse, S. Petersenn, et al., 68Ga-DOTATOC Versus 68Ga-DOTATATE PET/CT in Functional Imaging of Neuroendocrine Tumors,
    J. Nucl. Med. 52, 1864 (2011).

    12.  M. Fallahpoor, M. Abbasi, F. Kalantari, et al.,  Practical nuclear medicine and utility of phantoms for internal dosimetry: Xcat compared with zubal, Radiat. Prot. Dosimetry. 174, 191 (2017).

     13.  B. Quinn, Z. Dauer, N. Pandit-Taskar, et al.,  Radiation dosimetry of 18F-FDG PET/CT: Incorporating exam-specific parameters in dose estimates,BMC Med. Imaging. 16, 1 (2016).

    14.  A. Josefsson, R.F. Hobbs, S. Ranka, et al., Comparative Dosimetry for 68 Ga-DOTATATE: Impact of Using Updated ICRP Phantoms, S Values, and Tissue-Weighting Factors,J. Nucl. Med. 59, 1281 (2018).

    15.  D. Scheme, N. Data, E.C. Transitions, Table of radionuclides - 68Ga, pp. 1–7 (2012).

    16.  M. Ljungberg, K. Gleisner, Hybrid Imaging for Patient-Specific Dosimetry in Radionuclide Therapy, Diagnostics. 5, 296 (2015).

    17.  W.E. Bolch, L.G. Bouchet, J.S. Robertson, MIRD pamphlet No. 17: the dosimetry of nonuniform activity distributions--radionuclide S values at the voxel level. Medical Internal Radiation Dose Committee., J. Nucl. Med. 40, 11S (1999).

    18.  R.E. Drzymala, R. Mohan, L. Brewster, Dose-volume histograms., Int. J. Radiat. Oncol. Biol. Phys. 21, 71 (1991).

    19.  L. Bodei, V. Ambrosini, K. Herrmann, I. Modlin,  Current Concepts in 68 Ga-DOTATA­­TE Imaging of Neuroendocrine Neoplasms: Interpretation, Biodistribution, Dosimetry, and Molecular Strategies , J. Nucl. Med. 58, 1718 (2017).

    20.  R.C. Walker, G.T. Smith, E. Liu, et al., Measured Human Dosimetry of 68Ga-DOTATATE, J. Nucl. Med. 54, 855 (2013).

    21.  M.G. Stabin, R.B. Sparks, E. Crowe, OLINDA/EXM: The Second-Generation Personal Computer Software for Internal Dose Assessment in Nuclear Medicine., J Nucl Med. 46, 1023 (2005).

    22.  M. Stabin, J Siegel, J. Hunt, et al., The radiation dose assessment resource—an online source of dose information for nuclear medicine and occupational radiation safety [abstract]. J Nucl Med. 42, 243 (2002).

    23.  W. Snyder, M. Ford, G. Warner, et al. Estimates of absorbed fractions for monoenergetic photon sources uniformly distributed in various organs of a heterogeneous phantom. J Nucl Med. 5, suppl 3 (1969).

    24.  M.G. Stabin, R.B. Sparks, E. Crowe. OLINDA/EXM: The Second-Generation Personal Computer Software for Internal Dose Assessment in Nuclear Medicine.J Nucl Med. 46, 6 (2005).

    25.   M.G. Stabin, J.A. Siegel. RADAR Dose Estimate Report: A Compendium of Radiopharmaceutical Dose Estimates Based on OLINDA/EXM Version 2.0. J Nucl Med. 59, 154–160 (2018).