TU-H-BRC-08: Use and Validation of Flexible 3D Printed Tissue Compensators for Post-Mastectomy Radiation Therapy

Authors

  • Craft D,

    1. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX
    2. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
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  • Woodward W,

    1. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
    2. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
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  • Kanke J,

    1. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
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  • Kry S,

    1. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX
    2. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
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  • Salehpour M,

    1. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX
    2. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
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  • Howell R

    1. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX
    2. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
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Abstract

Purpose:

Patient-specific tissue equivalent compensators can be used for post-mastectomy radiation therapy (PMRT) to achieve homogenous dose distributions with single-field treatments. However, current fabrication methods are time consuming and expensive. 3D-printing technology could overcome these limitations. The purposes of this study were to [1] evaluate materials for 3D-printed compensators [2] design and print a compensator to achieve a uniform thickness to a clinical target volume (CTV), and [3] demonstrate that a single-field electron compensator plan is a clinically feasible treatment option for PMRT.

Methods:

Blocks were printed with three materials; print accuracy, density, Hounsfield units (HU), and percent depth doses (PDD) were evaluated. For a CT scan of an anthropomorphic phantom, we used a ray-tracing method to design a compensator that achieved uniform thickness from compensator surface to CTV. The compensator was printed with flexible tissue equivalent material whose physical and radiological properties were most similar to soft tissue. A single-field electron compensator plan was designed and compared with two standard-of-care techniques. The compensator plan was validated with thermoluminescent dosimeter (TLD) measurements.

Results:

We identified an appropriate material for 3D-printed compensators that had high print accuracy (99.6%) and was similar to soft tissue; density was 1.04, HU was - 45 ± 43, and PDD curves agreed with clinical curves within 3 mm. We designed and printed a compensator that conformed well to the phantom surface and created a uniform thickness to the CTV. In-house fabrication was simple and inexpensive (<$75). Compared with the two standard plans, the compensator plan resulted in overall more homogeneous dose distributions and performed similarly in terms of lung/heart doses and 90% isodose coverage of the CTV. TLD measurements agreed well with planned doses (within 5 %).

Conclusions:

We have demonstrated that 3D-printed compensators make single-field electron therapy a clinically feasible treatment option for PMRT.

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