"Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has."

Margaret Mead
Technical report
peer-reviewed

Field-Specific Intensity-modulated Proton Therapy Optimization Technique for Breast Cancer Patients with Tissue Expanders Containing Metal Ports



Abstract

This report aims to propose and present an evaluation of a robust pencil beam scanning proton multi-field optimized treatment planning technique for postmastectomy radiation of breast cancer patients with implanted tissue expanders containing an internal metal port. Field-specific split targets were created for optimization to prevent spots from traveling through the metal port, while providing uniform coverage of the target with the use of a multi-field intensity modulated optimization approach. Two beam angles were strategically selected to provide complementary target coverage and plan robustness. The plan was compared with an independently developed photon plan and evaluated for robustness with respect to isocenter shifts, range shifts, and variation of the water-equivalent thickness of the port. The proton plan resulted in clinically acceptable target coverage and dosage to neighboring normal tissues. The D95% coverage was 95.3% in the nominal proton plan, with a worst-case coverage of 90.1% (when considering 0.3 cm isocenter shifts combined with 3.5% range uncertainty), and the coverage varied less than 1% under a hypothetically extreme variation of the port density. The proton plan had improved dose homogeneity compared with the photon plan, and reduced ipsilateral lung and mean heart doses. We demonstrated that a practical, field-specific intensity-modulated proton therapy (IMPT) optimization technique can be used to deal with the challenge of metal port in breast cancer patients with tissue expanders. The resulting proton plan has superior dosimetric characteristics over the best-case scenario photon plan, and is also robust to setup and proton range uncertainties.



Want to read more?

Create a free account to continue reading this article.

Already a member? Login.



Technical report
peer-reviewed

Field-Specific Intensity-modulated Proton Therapy Optimization Technique for Breast Cancer Patients with Tissue Expanders Containing Metal Ports


Author Information

Maura Kirk Corresponding Author

Radiation Oncology, University of Pennsylvania, Perelman Center for Advanced Medicine

Gary Freedman

Radiation Oncology, Perelman School of Medicine, University of Pennsylvania

Thorsten Ostrander

Radiation Oncology, Scripps Proton Therapy Center

Lei Dong

Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania


Ethics Statement and Conflict of Interest Disclosures

Human subjects: Consent was obtained by all participants in this study. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: Lei Dong is a member of Varian Proton Therapy Advisory Board.


Technical report
peer-reviewed

Field-Specific Intensity-modulated Proton Therapy Optimization Technique for Breast Cancer Patients with Tissue Expanders Containing Metal Ports


Figures etc.

Share
Technical report
peer-reviewed

Field-Specific Intensity-modulated Proton Therapy Optimization Technique for Breast Cancer Patients with Tissue Expanders Containing Metal Ports

Maura Kirk">Maura Kirk , Gary Freedman">Gary Freedman, Thorsten Ostrander">Thorsten Ostrander, Lei Dong">Lei Dong

  • Author Information
    Maura Kirk Corresponding Author

    Radiation Oncology, University of Pennsylvania, Perelman Center for Advanced Medicine

    Gary Freedman

    Radiation Oncology, Perelman School of Medicine, University of Pennsylvania

    Thorsten Ostrander

    Radiation Oncology, Scripps Proton Therapy Center

    Lei Dong

    Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania


    Ethics Statement and Conflict of Interest Disclosures

    Human subjects: Consent was obtained by all participants in this study. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: Lei Dong is a member of Varian Proton Therapy Advisory Board.

    Acknowledgements


    Article Information

    Published: September 18, 2017

    DOI

    10.7759/cureus.1698

    Cite this article as:

    Kirk M, Freedman G, Ostrander T, et al. (September 18, 2017) Field-Specific Intensity-modulated Proton Therapy Optimization Technique for Breast Cancer Patients with Tissue Expanders Containing Metal Ports. Cureus 9(9): e1698. doi:10.7759/cureus.1698

    Publication history

    Received by Cureus: August 08, 2017
    Peer review began: August 14, 2017
    Peer review concluded: September 13, 2017
    Published: September 18, 2017

    Copyright

    © Copyright 2017
    Kirk et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 3.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

    License

    This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

This report aims to propose and present an evaluation of a robust pencil beam scanning proton multi-field optimized treatment planning technique for postmastectomy radiation of breast cancer patients with implanted tissue expanders containing an internal metal port. Field-specific split targets were created for optimization to prevent spots from traveling through the metal port, while providing uniform coverage of the target with the use of a multi-field intensity modulated optimization approach. Two beam angles were strategically selected to provide complementary target coverage and plan robustness. The plan was compared with an independently developed photon plan and evaluated for robustness with respect to isocenter shifts, range shifts, and variation of the water-equivalent thickness of the port. The proton plan resulted in clinically acceptable target coverage and dosage to neighboring normal tissues. The D95% coverage was 95.3% in the nominal proton plan, with a worst-case coverage of 90.1% (when considering 0.3 cm isocenter shifts combined with 3.5% range uncertainty), and the coverage varied less than 1% under a hypothetically extreme variation of the port density. The proton plan had improved dose homogeneity compared with the photon plan, and reduced ipsilateral lung and mean heart doses. We demonstrated that a practical, field-specific intensity-modulated proton therapy (IMPT) optimization technique can be used to deal with the challenge of metal port in breast cancer patients with tissue expanders. The resulting proton plan has superior dosimetric characteristics over the best-case scenario photon plan, and is also robust to setup and proton range uncertainties.



Want to read more?

Create a free account to continue reading this article.

Already a member? Login.



Maura Kirk, M.Sc.

Radiation Oncology, University of Pennsylvania, Perelman Center for Advanced Medicine

For correspondence:
maura.kirk@uphs.upenn.edu

Gary Freedman

Radiation Oncology, Perelman School of Medicine, University of Pennsylvania

Thorsten Ostrander

Radiation Oncology, Scripps Proton Therapy Center

Lei Dong, Ph.D., Professor

Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania

Maura Kirk, M.Sc.

Radiation Oncology, University of Pennsylvania, Perelman Center for Advanced Medicine

For correspondence:
maura.kirk@uphs.upenn.edu

Gary Freedman

Radiation Oncology, Perelman School of Medicine, University of Pennsylvania

Thorsten Ostrander

Radiation Oncology, Scripps Proton Therapy Center

Lei Dong, Ph.D., Professor

Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania