Helical tomotherapy for locoregional irradiation including the internal mammary chain in left-sided breast cancer: dosimetric evaluation.
OBJECTIVE
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
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.
Caudrelier
Jean-Michel
JM
Department of Radiation Oncology, The Ottawa Hospital Cancer Centre, Ont., Canada. jcaudrelier@ottawahospital.on.ca
Morgan
Scott C
SC
Montgomery
Lynn
L
Lacelle
Manon
M
Nyiri
Balazs
B
Macpherson
Miller
M
D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000528:radiation effects*; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D016896:Treatment Outcome