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Assessment of emission data and transmission factors supporting radiation protection in the use of 225Ac

Published:October 13, 2022DOI:https://doi.org/10.1016/j.ejmp.2022.10.007

      Highlights

      • Gamma ray emission with all the series at equilibrium is much higher than that due to 225Ac only.
      • Shielding cannot be evaluated according to a simple mono-exponential model.
      • Accurate fitting parameters are provided, allowing to easily interpolate transmission factors.

      Abstract

      Purpose

      225Ac is the most promising alpha emitter for radiopharmaceutical therapy. Labeling PSMA, it showed to be effective in the treatment of prostate cancer and research is undergoing in order to improve its production capacity.
      Currently, there are still few data published concerning operational radiation protection in its use, both in clinics and in radiopharmacy, and even some basic data are not readily available. This papers aims to estimate the emission gamma-ray constant of 225Ac when at equilibrium with its descendants, and the transmission factors for a broad beam of the gamma-rays emitted by 225Ac and its descendants.

      Materials & methods

      Monte Carlo simulations were performed using FLUKA 4.2, considering firstly the source in air, in absence of any shielding, and secondly by adding an increasing thicknesses of Lead, Concrete or Tungsten. In order to obtain statistically meaningful results, high-statistics simulations were performed by sampling up to 1010 primary decay events. As the shielding thickness increased, an appropriate variance reduction technique (importance biasing) was applied.

      Results

      The specific gamma ray emission constant for 225Ac at equilibrium with descendants resulted (3.26 ± 0.03) × 10-5 mSv/h per 1 MBq at a distance of 100 cm. The transmission factors are presented in detail and data have been appropriately interpolated and fitting parameters are reported.

      Conclusions

      The attenuation curves show a clear bi-exponential trend: performing shielding calculations by adopting a simple approach based on a single value of Half Value Layer (HVL) or Tenth Value Layer (TVL) cannot provide adequate results.
      In conclusion, our results may be useful in the design of shielded hot cells or accessories necessary for operational radiation protection.

      Keywords

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      References

        • Morgenstern A.
        • Apostolidis C.
        • Kratochwil C.
        • Sathekge M.
        • Krolicki L.
        • Bruchertseifer F.
        An overview of targeted alpha therapy with 225Actinium and 213Bismuth.
        Curr Radiopharm. 2018; 11: 200-208https://doi.org/10.2174/1874471011666180502104524
        • Radchenko V.
        • Morgenstern A.
        • Jalilian A.R.
        • Ramogida C.F.
        • Cutler C.
        • Duchemin C.
        • et al.
        Production and Supply of α-Particle-Emitting Radionuclides for Targeted α-Therapy.
        Nucl Med. 2021; 62: 1495-1503https://doi.org/10.2967/jnumed.120.261016
        • Kratochwil C.
        • Bruchertseifer F.
        • Giesel F.L.
        • Weis M.
        • Verburg F.A.
        • Mottaghy F.
        • et al.
        225Ac-PSMA-617 for PSMA targeting alpha-radiation therapy of patients with metastatic castration-resistant prostate cancer.
        J Nucl Med. 2016; 57: 1941-1944https://doi.org/10.2967/jnumed.116.178673
        • Sathekge M.
        • Bruchertseifer F.
        • Vorster M.
        • Lawal I.O.
        • Knoesen O.
        • Mahapane J.
        • et al.
        Predictors of Overall and Disease-Free Survival in Metastatic Castration-Resistant Prostate Cancer Patients Receiving 225Ac-PSMA-617 Radioligand Therapy.
        J Nucl Med. 2020; 61: 62-69https://doi.org/10.2967/jnumed.119.229229
        • Apostolidis C.
        • Molinet R.
        • McGinley J.
        • Abbas K.
        • Möllenbeck J.
        • Morgenstern A.
        Cyclotron production of Ac-225 for targeted alpha therapy.
        Appl Radiat Isot. 2005; 62: 383-387https://doi.org/10.1016/j.apradiso.2004.06.013
        • Melville G.
        • Allen B.J.
        Cyclotron and linac production of Ac-225.
        Appl Radiat Isot. 2009; 67: 549-555https://doi.org/10.1016/j.apradiso.2008.11.012
        • Nagatsu K.
        • Suzuki H.
        • Fukada M.
        • Ito T.
        • Ichinose J.
        • Honda Y.
        • et al.
        Cyclotron production of 225Ac from an electroplated 226Ra target.
        Eur J Nucl Med Mol Imaging. 2021; 49: 279-289https://doi.org/10.1007/s00259-021-05460-7
        • Smith D.S.
        • Stabin M.G.
        Exposure rate constants and lead shielding values for over 1,100 radionuclides.
        Health Phys. 2012; 102: 271-291https://doi.org/10.1097/HP.0b013e318235153a
        • Ahdida C.
        • Bozzato D.
        • Calzolari D.
        • Cerutti F.
        • et al.
        New Capabilities of the FLUKA Multi-Purpose Code.
        Front Phys. 2022; 9788253https://doi.org/10.3389/fphy.2021.788253
        • Lo Meo S.
        • Cicoria G.
        • Campanella F.
        • Mattozzi M.
        • Panebianco A.S.
        • Marengo M.
        Radiation dose around a PET scanner installation: Comparison of Monte Carlo simulations, analytical calculations and experimental results.
        Phys Med. 2014; 30: 448-453https://doi.org/10.1016/j.ejmp.2013.12.004
        • Zagni F.
        • Cicoria G.
        • Lucconi G.
        • Infantino A.
        • Lodi F.
        • Marengo M.
        Monte Carlo modeling provides accurate calibration factors for radionuclide activity meters.
        Appl Radiat Isot. 2014; 94: 158-165https://doi.org/10.1016/j.apradiso.2014.07.021
        • Infantino A.
        • Cicoria G.
        • Lucconi G.
        • Pancaldi D.
        • Vichi S.
        • Zagni F.
        • et al.
        Assessment of the neutron dose field around a biomedical cyclotron: FLUKA simulation and experimental measurements.
        Phys Med. 2016; 32: 1602-1608https://doi.org/10.1016/j.ejmp.2016.11.115
        • Vichi S.
        • Infantino A.
        • Zagni F.
        • Cicoria G.
        • Braccini S.
        • Mostacci D.
        • et al.
        Activation studies for the decommissioning of PET cyclotron bunkers by means of Monte Carlo simulations.
        Radiat Phys Chem, Radiat Phys Chem. 2020; 174108966https://doi.org/10.1016/j.radphyschem.2020.108966
      1. CERN. https://fluka.cern, accessed 29/09/2022 .

        • Stránský C.
        • Theis A.
        • Tsinganis R.
        • Versaci V.
        • Vlachoudis A.
        • Waets M.
        Widorski, “New Capabilities of the FLUKA Multi-Purpose Code”.
        Front Phys. 2022; 9788253https://doi.org/10.3389/fphy.2021.788253
      2. Vlachoudis V. “FLAIR: A Powerful But User Friendly Graphical Interface For FLUKA”Proc Int. Conf. on Mathematics, Computational Methods & Reactor Physics (M&C 2009) 2009 Saratoga Springs, New York ISBN: 9780894480690.

      3. CERN, FLUKA manual, available online: https://flukafiles.web.cern.ch/manual/index.html, accessed 29/09/2022.

      4. Wolfmet 2019. Tungsten Alloys Technical Information. Available online at: https://www.wolfmet.com/resources/ . Accessed on 29/09/2022.

      5. Unger LM, Trubey DK. Specific gamma-ray dose constants for nuclides important to dosimetry and radiological assessment. Oak Ridge, TN: Oak Ridge National Laboratory; ORNL/RSIC-45/R1; 1982.

        • Tschurlovits M.
        • Leitner A.
        • Daverda G.
        Dose rate constants for new dose quantities.
        Radiat Prot Dosim. 1992; 42: 77-82https://doi.org/10.1093/oxfordjournals.rpd.a081281
        • Delacroix D.
        • Guerre J.P.
        • Leblanc P.
        • Hickman C.
        Radionuclide and radiation protection data handbook.
        Radiat Prot Dosim. 2002; 98: 1-168https://doi.org/10.1093/oxfordjournals.rpd.a006705
        • Cicoria G.
        • Zagni F.
        • Infantino A.
        • Corazza A.
        • Pancaldi D.
        • Marengo M.
        “Initial experience in the management of radiation protection in clinical use of Ra-223 “. EANM’15.
        Eur J Nucl Med Mol Imaging. 2015; 42: S269https://doi.org/10.1007/s00259-015-3198-z
        • Della Gala G.
        • Bardiès M.
        • Tipping J.
        • Strigari L.
        Overview of commercial treatment planning systems for targeted radionuclide therapy.
        Phys Med. 2021; 2: 52-61https://doi.org/10.1016/j.ejmp.2021.11.001
        • Marengo M.
        • Martin C.J.
        • Rubow S.
        • Sera T.
        • Amador Z.
        • Torres L.
        Radiation Safety and Accidental Radiation Exposures in Nuclear Medicine.
        Semin Nucl Med. 2022; 52: 94-113https://doi.org/10.1053/j.semnuclmed.2021.11.006