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Influence of metallic dental implants and metal artefacts on dose calculation accuracy

Einfluss von metallischen Zahnimplantaten und Metallartefakten auf die Genauigkeit der Dosisberechnung

Strahlentherapie und Onkologie volume 191, pages 234–241 (2015)Cite this article

Abstract

Purpose

Metallic dental implants cause severe streaking artefacts in computed tomography (CT) data, which inhibit the correct representation of shape and density of the metal and the surrounding tissue. The aim of this study was to investigate the impact of dental implants on the accuracy of dose calculations in radiation therapy planning and the benefit of metal artefact reduction (MAR). A second aim was to determine the treatment technique which is less sensitive to the presence of metallic implants in terms of dose calculation accuracy.

Materials and methods

Phantoms consisting of homogeneous water equivalent material surrounding dental implants were designed. Artefact-containing CT data were corrected using the correct density information. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated on corrected and uncorrected CT data and compared to 2-dimensional dose measurements using GafChromic™ EBT2 films.

Results

For all plans the accuracy of dose calculations is significantly higher if performed on corrected CT data (p = 0.015). The agreement of calculated and measured dose distributions is significantly higher for VMAT than for IMRT plans for calculations on uncorrected CT data (p = 0.011) as well as on corrected CT data (p = 0.029).

Conclusion

For IMRT and VMAT the application of metal artefact reduction significantly increases the agreement of dose calculations with film measurements. VMAT was found to provide the highest accuracy on corrected as well as on uncorrected CT data. VMAT is therefore preferable over IMRT for patients with metallic implants, if plan quality is comparable for the two techniques.

Zusammenfassung

Ziel

Zahnimplantate aus Metall verursachen in Computertomographiedaten (CT) streifenförmige Artefakte. Diese verhindern eine korrekte Zuordnung von Form und Dichteeigenschaften des Metalls und des umgebenden Gewebes. Ziel dieser Studie war es, den Einfluss von Zahnimplantaten auf die Genauigkeit der Dosisberechnung in der Strahlentherapie zu untersuchen und zu überprüfen, ob eine reine Reduktion der Metallartefakte ohne Korrektur der Form und der Dichtewerte des Metallimplantats eine genauere Dosisberechnung ermöglicht. Als zweites Ziel sollte die Bestrahlungstechnik bestimmt werden, welche bei vorhandenen metallischen Implantaten, in Bezug auf die Dosisberechnungsgenauigkeit am wenigsten fehleranfällig ist.

Methoden und Material

Es wurden Phantome aus homogenem wasseräquivalentem Material mit Zahnimplantaten entworfen. CT-Daten welche Artefakte enthielten wurden mit den richtigen Dichtewerten korrigiert. Auf korrigierten und nichtkorrigierten CT-Daten wurden IMRT (intensity-modulated radiation therapy) und VMAT (volumetric modulated arc therapy)-Pläne berechnet und mit 2-dimensionalen Dosismessungen, welche mit GafChromic™-EBT2-Filmen durchgeführt wurden, verglichen.

Ergebnisse

Die Dosisberechnungsgenauigkeit ist für alle Pläne signifikant besser, wenn die Berechnungen auf korrigierten Daten durchgeführt wurden (p = 0,015). Berechnete und gemessene Dosisverteilungen stimmen für VMAT-Pläne signifikant besser überein als für IMRT-Pläne, sowohl bei Rechnungen auf nichtkorrigierten (p = 0,011) als auch auf korrigierten (p = 0,029) CT-Daten.

Schlussfolgerung

Für IMRT und VMAT wird die Übereinstimmung von berechneten und gemessenen Dosisverteilungen signifikant erhöht. Es wurde gezeigt, dass VMAT sowohl auf korrigierten als auch auf nichtkorrigierten CT-Daten die höchste Genauigkeit liefert. Wenn die Planqualität für beide Techniken vergleichbar ist, sollte bei Patienten mit Metallimplantaten die VMAT der IMRT vorgezogen werden.

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Notes

  1. NucletronTM, “Oncentra External Beam v4.0 – Physics and Algorithms.”

References

  1. Yazdi M, Lari MA, Bernier G et al (2011) An opposite view data replacement approach for reducing artifacts due to metallic dental objects. Med Phys 38:2275–2281

    Article  PubMed  Google Scholar 

  2. Bazalova M, Beaulieu L, Palefsky S et al (2007) Correction of CT artifacts and its influence on Monte Carlo dose calculations. Med Phys 34:2119–2132

    Article  CAS  PubMed  Google Scholar 

  3. Kim Y, Tomé WA, Bal M et al (2006) The impact of dental metal artifacts on head and neck IMRT dose distributions. Radiother Oncol 79:198–202

    Article  PubMed  Google Scholar 

  4. Roberts R (2001) How accurate is a CT-based dose calculation on a pencil beam TPS for a patient with a metallic prosthesis? Phys Med Biol 46:N227–N234

  5. Wei J, Sandison GA, Hsi W-C et al (2006) Dosimetric impact of a CT metal artefact suppression algorithm for proton, electron and photon therapies. Phys Med Biol 51:5183–5197

    Article  PubMed  Google Scholar 

  6. Mail N, Albarakati Y, Ahmad Khan M et al (2013) The impacts of dental filling materials on RapidArc treatment planning and dose delivery: challenges and solution. Med Phys 40:081714

    Article  PubMed  Google Scholar 

  7. Spadea MF, Verburg J, Baroni G et al (2013) Dosimetric assessment of a novel metal artifact reduction method in CT images. J Appl Clin Med Phys 14:4027

    PubMed  Google Scholar 

  8. Spadea MF, Verburg JM, Baroni G et al (2014) The impact of low-Z and high-Z metal implants in IMRT: a Monte Carlo study of dose inaccuracies in commercial dose algorithms. Med Phys 41:011702

    Article  PubMed  Google Scholar 

  9. Paudel MR, Mackenzie M, Fallone BG et al (2013) Evaluation of normalized metal artifact reduction (NMAR) in kVCT using MVCT prior images for radiotherapy treatment planning. Med Phys 40:081701

    Article  CAS  PubMed  Google Scholar 

  10. Paudel MR, Mackenzie M, Fallone BG et al (2014) Clinical evaluation of normalized metal artifact reduction in kVCT using MVCT prior images (MVCT-NMAR) for radiation therapy treatment planning. Int J Radiat Oncol Biol Phys 89:682–689

    Article  PubMed  Google Scholar 

  11. Dobler B, Weidner K, Koelbl O (2010) Application of volumetric modulated arc therapy (VMAT) in a dual-vendor environment. Radiat Oncol 5:95

    Article  PubMed Central  PubMed  Google Scholar 

  12. Treutwein M, Hipp M, Koelbl O et al (2012) Searching standard parameters for volumetric modulated arc therapy (VMAT) of prostate cancer. Radiat Oncol 7:108

    Article  PubMed Central  PubMed  Google Scholar 

  13. Alvarez-Moret J, Pohl F, Koelbl O et al (2010) Evaluation of volumetric modulated arc therapy (VMAT) with Oncentra MasterPlan(R) for the treatment of head and neck cancer. Radiat Oncol 5:110

    Article  PubMed Central  PubMed  Google Scholar 

  14. Palma D, Vollans E, James K et al (2008) Volumetric modulated arc therapy for delivery of prostate radiotherapy: comparison with intensity-modulated radiotherapy and three-dimensional conformal radiotherapy. Int J Radiat Oncol Biol Phys 72:996–1001

    Article  PubMed  Google Scholar 

  15. Popescu CC, Olivotto IA, Beckham WA et al (2010) Volumetric modulated arc therapy improves dosimetry and reduces treatment time compared to conventional intensity-modulated radiotherapy for locoregional radiotherapy of left-sided breast cancer and internal mammary nodes. Int J Radiat Oncol Biol Phys 76:287–295

    Article  PubMed  Google Scholar 

  16. Vanetti E, Clivio A, Nicolini G et al (2009) Volumetric modulated arc radiotherapy for carcinomas of the oro-pharynx, hypo-pharynx and larynx: a treatment planning comparison with fixed field IMRT. Radiother Oncol 92:111–117

    Article  PubMed  Google Scholar 

  17. Clivio A, Fogliata A, Franzetti-Pellanda A et al (2009) Volumetric-modulated arc radiotherapy for carcinomas of the anal canal: A treatment planning comparison with fixed field IMRT. Radiother Oncol 92:118–124

    Article  PubMed  Google Scholar 

  18. Lagerwaard FJ, Meijer OW, Van Der Hoorn EA et al (2009) Volumetric modulated arc radiotherapy for vestibular schwannomas. Int J Radiat Oncol Biol Phys 74:610–615

    Article  PubMed  Google Scholar 

  19. Cozzi L, Dinshaw KA, Shrivastava SK et al (2008) A treatment planning study comparing volumetric arc modulation with RapidArc and fixed field IMRT for cervix uteri radiotherapy. Radiother Oncol 89:180–191

    Article  PubMed  Google Scholar 

  20. Pasler M, Georg D, Bartelt S et al (2013) Node-positive left-sided breast cancer: does VMAT improve treatment plan quality with respect to IMRT? Strahlenther Onkol 189:380–386

    Article  CAS  PubMed  Google Scholar 

  21. Pasler M, Wirtz H, Lutterbach J (2011) Impact of gantry rotation time on plan quality and dosimetric verification–volumetric modulated arc therapy (VMAT) vs. intensity modulated radiotherapy (IMRT). Strahlenther Onkol 187:812–819

    Article  PubMed  Google Scholar 

  22. Wiehle R, Knippen S, Grosu AL et al (2011) VMAT and step-and-shoot IMRT in head and neck cancer: a comparative plan analysis. Strahlenther Onkol 187:820–825

    Article  PubMed  Google Scholar 

  23. Kim Y, Tomé WA (2007) On the radiobiological impact of metal artifacts in head-and-neck IMRT in terms of tumor control probability (TCP) and normal tissue complication probability (NTCP). Med Biol Eng Comput 45:1045–1051

    Article  PubMed  Google Scholar 

  24. Li H, Noel C, Chen H et al (2012) Clinical evaluation of a commercial orthopedic metal artifact reduction tool for CT simulations in radiation therapy. Med Phys 39:7507–7517

    Article  PubMed Central  PubMed  Google Scholar 

  25. Webster GJ, Rowbottom CG, Mackay RI (2009) Evaluation of the impact of dental artefacts on intensity-modulated radiotherapy planning for the head and neck. Radiother Oncol 93:553–558

    Article  PubMed  Google Scholar 

  26. Dobler B, Pohl F, Bogner L et al (2007) Comparison of direct machine parameter optimization versus fluence optimization with sequential sequencing in IMRT of hypopharyngeal carcinoma. Radiat Oncol 2:33

    Article  PubMed Central  PubMed  Google Scholar 

  27. Snyder WS, Cook MJ, Nasset ES, Karkhausen LR, Howells GP,Tipton IH (1974) “Report of the task group on reference man,”Technical Report 23, International Commission on Radiological Protection, 1974

  28. Tissue substitutes in radiation dosimetry and measurement (1989) International Commission on Radiation Units and Measurements Bethesda, Md., U.S.A.: International Commission on Radiation Units and Measurements (ICRU report, 44)

  29. Menegotti L, Delana A, Martignano A (2008) Radiochromic film dosimetry with flatbed scanners: a fast and accurate method for dose calibration and uniformity correction with single film exposure. Med Phys 35:3078–3085

    Article  CAS  PubMed  Google Scholar 

  30. Micke A, Lewis DF, Yu X (2011) Multichannel film dosimetry with nonuniformity correction. Med Phys 38:2523–2534

    Article  PubMed  Google Scholar 

  31. Schneider F, Polednik M, Wolff D et al (2009) Optimization of the gafchromic EBT protocol for IMRT QA. Z Med Phys 19:29–37

    Article  PubMed  Google Scholar 

  32. Lewis D, Micke A, Yu X et al (2012) An efficient protocol for radiochromic film dosimetry combining calibration and measurement in a single scan. Med Phys 39:6339–6350

    Article  PubMed  Google Scholar 

  33. Low DA, Harms WB, Mutic S et al (1998) A technique for the quantitative evaluation of dose distributions. Med Phys 25:656–661

    Article  CAS  PubMed  Google Scholar 

  34. Ezzell GA, Burmeister JW, Dogan N et al (2009) IMRT commissioning: multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119. Med Phys 36:5359–5373

    Article  PubMed  Google Scholar 

  35. Hayashi N, Watanabe Y, Malmin R et al (2012) Evaluation of triple channel correction acquisition method for radiochromic film dosimetry. J Radiat Res 53:930–935

    Article  PubMed Central  PubMed  Google Scholar 

  36. Dobler B, Walter C, Knopf A et al (2006) Optimization of extracranial stereotactic radiation therapy of small lung lesions using accurate dose calculation algorithms. Radiat Oncol 1:45

    Article  PubMed Central  PubMed  Google Scholar 

  37. Otto K (2008) Volumetric modulated arc therapy: IMRT in a single gantry arc. Med Phys 35:310–317

    Article  PubMed  Google Scholar 

  38. Bortfeld T (2006) IMRT: a review and preview. Phys Med Biol 51:R363–R379

    Article  PubMed  Google Scholar 

  39. Carolan M, Dao P, Fox C et al (2000) Effect of hip prostheses on radiotherapy dose. Australas Radiol 44:290–295

    Article  CAS  PubMed  Google Scholar 

Download references

Compliance with ethical guidelines

Acknowledgements

The work was supported by the Wilhelm Sander Foundation. We want to thank Walter Schäffer for providing the teeth implant material.

Conflict of interest

M. März, O. Kölbl and B. Dobler state the following: the department has a research cooperation with Elekta GmbH Hamburg. The accompanying manuscript does not include studies on humans or animals.

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Authors and Affiliations

  1. Department of Radiotherapy, Regensburg University Medical Center, 93042, Regensburg, Germany

    Manuel Maerz M.Sc., Oliver Koelbl M.D. & Barbara Dobler Ph.D.

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  1. Manuel Maerz M.Sc.
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  2. Oliver Koelbl M.D.
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  3. Barbara Dobler Ph.D.
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Correspondence to Manuel Maerz M.Sc..

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Maerz, M., Koelbl, O. & Dobler, B. Influence of metallic dental implants and metal artefacts on dose calculation accuracy. Strahlenther Onkol 191, 234–241 (2015). https://doi.org/10.1007/s00066-014-0774-2

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  • DOI: https://doi.org/10.1007/s00066-014-0774-2

Keywords

  • Computed tomography
  • Metal artifacts
  • Dental implants
  • Radiotherapy
  • Intensity modulated radiation therapy
  • GafChromic

Schlüsselwörter

  • Computertomographie
  • Metallartefakte
  • Zahnimplantate
  • Strahlentherapie
  • Intensitätsmodulierte Strahlentherapie
  • GafChromic