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Establishing the impact of temporary tissue expanders on electron and photon beam dose distributions

Published:February 15, 2015DOI:https://doi.org/10.1016/j.ejmp.2015.01.015

      Highlights

      • Accuracy of treatments can be compromised by temporary tissue expanders.
      • Discrepancies in literature between backscatter and dose reduction measurements.
      • Film measurements taken for different phantoms, and beam setups.
      • An accurately modelled high-density implant in the TPS is required.

      Abstract

      Purpose

      This study investigates the effects of temporary tissue expanders (TTEs) on the dose distributions in breast cancer radiotherapy treatments under a variety of conditions.

      Methods

      Using EBT2 radiochromic film, both electron and photon beam dose distribution measurements were made for different phantoms, and beam geometries. This was done to establish a more comprehensive understanding of the implant's perturbation effects under a wider variety of conditions.

      Results

      The magnetic disk present in a tissue expander causes a dose reduction of approximately 20% in a photon tangent treatment and 56% in electron boost fields immediately downstream of the implant. The effects of the silicon elastomer are also much more apparent in an electron beam than a photon beam.

      Conclusions

      Evidently, each component of the TTE attenuates the radiation beam to different degrees. This study has demonstrated that the accuracy of photon and electron treatments of post-mastectomy patients is influenced by the presence of a tissue expander for various beam orientations. The impact of TTEs on dose distributions establishes the importance of an accurately modelled high-density implant in the treatment planning system for post-mastectomy patients.

      Keywords

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      References

        • Partridge M.
        • Trapp J.
        • Adams E.
        • Leach M.
        • Webb S.
        • Seco J.
        An investigation of dose calculation accuracy in intensity-modulated radiotherapy of sites in the head & neck.
        Phys Medica. 2006; 22: 97-104
        • Moni J.
        • Graves-Ditman M.
        • Cederna P.
        • Griffith K.
        • Krueger E.A.
        • Fraass B.A.
        • et al.
        Dosimetry around metallic ports in tissue expanders in patients receiving postmastectomy radiation therapy: an ex vivo evaluation.
        Med Dos. 2004; 29: 49-54
        • Damast S.
        • Beal K.
        • Ballangrud A.
        • Losasso T.J.
        • Cordeiro P.G.
        • Disa J.J.
        • et al.
        Do metallic ports in tissue expanders affect postmastectomy radiation delivery?.
        Int J Radiat Oncol Biol Phys. 2006; 66: 305-310
        • Chatzigiannis C.
        • Lymperopoulou G.
        • Sandilos P.
        • Dardoufas C.
        • Yakoumakis E.
        • Georgiou E.
        • et al.
        Dose perturbation in the radiotherapy of breast cancer patients implanted with the Magna-Site: a Monte Carlo study.
        J Appl Clin Med Phys. 2011; 12: 58-70
        • Thompson R.C.
        • Morgan A.M.
        Investigation into dosimetric effect of a MAGNA-SITE™ tissue expander on post-mastectomy radiotherapy.
        Med Phys. 2005; 32: 1640-1646
        • Srivastava S.P.
        • Chee-Wai C.
        • Andrews J.
        • Das I.J.
        Dose perturbation due to metallic breast expander in electron and photon beam treatment of breast cancer.
        J Radiat Oncol. 2014; 3: 65-72
        • Kairn T.
        • Crowe S.B.
        • Fogg P.
        • Trapp J.V.
        The appearance and effects of metallic implants in CT images.
        Australas Phys Eng Sci Med. 2013; 36: 209-217
        • Barnett G.C.
        • Wilkinson J.
        • Moody A.M.
        • Wilson C.B.
        • Sharma R.
        • Klager S.
        • et al.
        A randomised controlled trial of forward-planned radiotherapy (IMRT) for early breast cancer: baseline characteristics and dosimetry results.
        Radiother Oncol. 2009; 92: 34-41
        • Donovan E.M.
        • Yarnold J.R.
        • Adams E.J.
        • Morgan A.
        • Warrington A.P.J.
        • Evans P.M.
        An investigation into methods of IMRT planning applied to breast radiotherapy.
        Br J Radiol. 2014; 81: 311-322
        • Al-Rahbi Z.S.
        • Al Mandhari Z.
        • Ravichandran R.
        • Al-Kindi F.
        • Davis C.A.
        • Bhasi S.
        • et al.
        Dosimetric comparison of intensity modulated radiotherapy isocentric field plans and field in field (FIF) forward plans in the treatment of breast cancer.
        J Med Phys. 2013; 38: 22-29
        • Kairn T.
        • Aland T.
        • Kenny J.
        Local heterogeneities in early batches of EBT2 film: a suggested solution.
        Phys Med Biol. 2010; 55: 37-42
        • Aland T.
        • Kairn T.
        • Kenny J.
        Evaluation of a Gafchromic EBT2 film dosimetry system for radiotherapy quality assurance.
        Australas Phys Eng Sci Med. 2011; 34: 251-260