Quantifying radiation dose delivered to individual shoulder muscles during breast radiotherapy

David B. Lipps*, Sean Sachdev, Jonathan B. Strauss

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Background and purpose Radiotherapy is an effective treatment for managing breast cancer, but patients may experience shoulder morbidity after completing radiotherapy. There is a knowledge gap regarding how the inclusion of the regional lymphatics in radiation treatment regimens influence the radiation dose delivered to the underlying shoulder musculature. Material and methods Five standardized radiation treatment regimens were developed from the computed tomography (CT) scans of 11 patients: tangent fields only (T), high tangent fields (HT), T + supraclavicular fossa and axillary apex with an anterior oblique beam (SCV), T + SCV + axillary nodes with an anterior oblique beam (SCV + AX), and T + SCV + AX with the nodal regions treated with a directly opposed beam configuration (DO). The muscle volumes for nine shoulder muscles anatomically located with the treatment regimens were segmented from the same CT scans. The effect of the nine muscles and five treatment regimens on the percentage of each muscle receiving at least 48 Gy (V48 Gy) was analyzed with two-way and one-way repeated measures ANOVAs. Results A statistically significant interaction existed between the nine shoulder muscles and five treatment regimens (p < 0.001) on the V48 Gy dose. Subsequent one-way analyses found statistically significant main effects of treatment plan on the V48 Gy dose for each muscle (p < 0.001). The pectoralis major and minor had the greatest V48 doses across the five treatments regimens. The HT, SCV + AX and DO treatment regimens produced statistically significant increases in the V48 dose of the latissimus dorsi and teres major. The infraspinatus, subscapularis, supraspinatus, teres minor, and trapezius only observed statistically significant V48 doses when treated with a DO plan. Conclusions These findings highlight the muscles (pectoralis major, pectoralis minor, latissimus dorsi, and teres major) that may exhibit future morbidity after radiation, and indicate that nodal RT delivered with a DO beam arrangement delivers the highest muscle dose.

Original languageEnglish (US)
Pages (from-to)431-436
Number of pages6
JournalRadiotherapy and Oncology
Volume122
Issue number3
DOIs
StatePublished - Mar 1 2017

Keywords

  • Axillary radiotherapy
  • Breast cancer
  • Computed tomography
  • Dose–volume histograms
  • Radiotherapy morbidity
  • Radiotherapy treatment planning

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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