Evaluation of robustness of optimization methods in breast intensity-modulated radiation therapy using TomoTherapy

Yuya Oki; Hiroaki Akasaka; Kazuyuki Uehara; Kazufusa Mizonobe; Masanobu Sawada; Junya Nagata; Aya Harada; Hiroshi Mayahara

doi:10.1007/s13246-023-01377-7

Evaluation of robustness of optimization methods in breast intensity-modulated radiation therapy using TomoTherapy

Phys Eng Sci Med. 2024 Jan 24. doi: 10.1007/s13246-023-01377-7. Online ahead of print.

Authors

Yuya Oki¹, Hiroaki Akasaka^{2

3}, Kazuyuki Uehara⁴, Kazufusa Mizonobe⁴, Masanobu Sawada^{5

6}, Junya Nagata^{5

7}, Aya Harada⁴, Hiroshi Mayahara⁴

Affiliations

¹ Division of Radiation Oncology, Kobe Minimally Invasive Cancer Center, 8-5-1 Minatojima-nakamachi, Chuo-ku, Kobe, Hyogo, 650-0046, Japan. yuya.oki1002@gmail.com.
² Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia.
³ Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuou-ku, Kobe, Hyogo, 650-0017, Japan.
⁴ Division of Radiation Oncology, Kobe Minimally Invasive Cancer Center, 8-5-1 Minatojima-nakamachi, Chuo-ku, Kobe, Hyogo, 650-0046, Japan.
⁵ Division of Radiological Technology, Kobe Minimally Invasive Cancer Center, 8-5-1 Minatojima-nakamachi, Chuo-ku, Kobe, Hyogo, 650-0046, Japan.
⁶ Division of Radiological Technology, Sanda City Hospital, 3-1-1 Keyakidai, Sanda, Hyogo, 669-1321, Japan.
⁷ Section of Medical Physics and Engineering, Kanagawa Cancer Center, Asahi-ku, Yokohama, Kanagawa, 241-8515, Japan.

PMID: 38265521
DOI: 10.1007/s13246-023-01377-7

Abstract

Intensity-modulated radiation therapy (IMRT) has become a popular choice for breast cancer treatment. We aimed to evaluate and compare the robustness of each optimization method used for breast IMRT using TomoTherapy. A retrospective analysis was performed on 10 patients with left breast cancer. For each optimization method (clipping, virtual bolus, and skin flash), a corresponding 50 Gy/25 fr plan was created in the helical and direct TomoTherapy modes. The dose-volume histogram parameters were compared after shifting the patients anteriorly and posteriorly. In the helical mode, when the patient was not shifted, the median D1cc (minimum dose delivered to 1 cc of the organ volume) of the breast skin for the clipping and virtual bolus plans was 52.2 (interquartile range: 51.9-52.6) and 50.4 (50.1-50.8) Gy, respectively. After an anterior shift, D1cc of the breast skin for the clipping and virtual bolus plans was 56.0 (55.6-56.8) and 50.9 (50.5-51.3) Gy, respectively. When the direct mode was used without shifting the patient, D1cc of the breast skin for the clipping, virtual bolus, and skin flash plans was 52.6 (51.9-53.1), 53.4 (52.6-53.9), and 52.3 (51.7-53.0) Gy, respectively. After shifting anteriorly, D1cc of the breast skin for the clipping, virtual bolus, and skin flash plans was 55.6 (54.1-56.4), 52.4 (52.0-53.0), and 53.6 (52.6-54.6) Gy, respectively. The clipping method is not sufficient for breast IMRT. The virtual bolus and skin flash methods were more robust optimization methods according to our analyses.

Keywords: Breast cancer; Intensity-modulated radiation therapy; Robust planning; Skin flash; TomoTherapy; Virtual bolus.