Design, fabrication, and validation of patient-specific electron tissue compensators for postmastectomy radiation therapy. (October 2018)

• Record Type: Journal Article
• Authors: Craft, Daniel F.; Balter, Peter; Woodward, Wendy; Kry, Stephen F.; Salehpour, Mohammad; Ger, Rachel; Peters, Mary; Baltz, Garrett; Traneus, Erik; Howell, Rebecca M.
• Is Part Of: Physics and imaging in radiation oncology. Volume 8(2018)
• Page Start: 38
• Page End: 43
• Publication Date: 2018-10
• Subjects: 3D printing -- Compensator -- PMRT -- Electrons; Radiotherapy -- Periodicals; Radiation dosimetry -- Periodicals; Cancer -- Imaging -- Periodicals; Oncology -- Periodicals; 615.842
• DOI: 10.1016/j.phro.2018.11.005
• Languages: English
• ISSNs: 2405-6316

Abstract

Abstract: Background and purpose: Postmastectomy radiotherapy (PMRT) is complex to plan and deliver, but could be improved with 3D-printed, patient-specific electron tissue compensators. The purposes of this study were to develop an algorithm to design patient-specific compensators that achieve clinical goals, to 3D-print the planned compensators, and validate calculated dose distributions with film and thermoluminescent dosimeter (TLD) measurements in 3D-printed phantoms of PMRT patients. Materials and methods: An iterative algorithm was developed to design compensators corresponding to single-field, single-energy electron plans for PMRT patients. The 3D-printable compensators were designed to fit into the electron aperture, with cerrobend poured around it. For a sample of eight patients, calculated dose distributions for compensator plans were compared with patients' (multi-field, multi-energy) clinical treatment plans. For all patients, dosimetric parameters were compared including clinical target volume (CTV), lung, and heart metrics. For validation, compensators were fabricated and irradiated for a set of six 3D-printed patient-specific phantoms. Dose distributions in the phantoms were measured with TLD and film. These measurements were compared with the treatment planning system calculated dose distributions. Results: The compensator treatment plans achieved superior CTV coverage (97% vs 89% of the CTV receiving the prescription dose, p < 0.0025), and similar heart and lung doses (p > 0.35) to the conventional treatment plans. Average differences between calculated and measured TLD values were 2%, and average film profile differences were <2 mm. Conclusions: We developed a new compensator based treatment methodology for PMRT and demonstrated its validity and superiority to conventional multi-field plans through end-to-end testing.