Helical tomotherapy for locoregional irradiation including the internal mammary chain in left-sided breast cancer: dosimetric evaluation

Radiother Oncol. 2009 Jan;90(1):99-105. doi: 10.1016/j.radonc.2008.09.028. Epub 2008 Nov 1.

Abstract

Purpose: To compare a standard 3- or 4-field technique to intensity modulated radiotherapy with helical tomotherapy (IMRT-HT) in the planning of locoregional breast radiation including the internal mammary chain (IMC).

Methods and materials: For 10 women with stage III left-sided breast cancer with a planning target volume (PTV) defined by the breast/chest wall and regional nodes, radiotherapy to a dose of 50 Gy in 25 fractions was planned using a standard 3- or 4-field technique and using IMRT-HT. Various metrics were extracted from dose-volume histograms, and were compared using the paired Student's t-test.

Results: The PTV receiving at least 95% of the prescribed dose did not differ between the two plans, but the VD115% was significantly lower with IMRT-HT. The dose conformality was significantly better with IMRT-HT. The cardiac V30(Gy) was reduced with IMRT-HT. The mean lungs dose was lower with IMRT-HT, as well the V20(Gy). With IMRT-HT, a greater volume of contralateral breast was irradiated to 5 Gy, but a smaller volume of soft tissue received dose above 50 Gy.

Conclusions: Compared to a standard technique, IMRT-HT provides similar target coverage, improves dose conformality and dose homogeneity within the PTV, decreases mean lung dose and spares heart, lung and soft tissue from high dose exposure.

Publication types

  • Comparative Study

MeSH terms

  • Breast Neoplasms / pathology
  • Breast Neoplasms / radiotherapy*
  • Dose Fractionation, Radiation
  • Female
  • Humans
  • Lymph Nodes / radiation effects*
  • Neoplasm Staging
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted / methods
  • Radiotherapy, Computer-Assisted / methods*
  • Radiotherapy, Intensity-Modulated / methods*
  • Treatment Outcome