Dosimetric comparison of left-sided whole breast irradiation with 3DCRT, forward-planned IMRT, inverse-planned IMRT, helical tomotherapy, and topotherapy

• Published in: Radiotherapy and oncology 2011-08, Vol.100 (2), p.241-246
• Main Authors: Schubert, Leah K, Gondi, Vinai, Sengbusch, Evan, Westerly, David C, Soisson, Emilie T, Paliwal, Bhudatt R, Mackie, Thomas Rockwell, Mehta, Minesh P, Patel, Rakesh R, Tomé, Wolfgang A, Cannon, George M
• Format: Article
• Language: English
• Subjects: Breast - radiation effects; Breast cancer; Breast Neoplasms - radiotherapy; Female; Hematology, Oncology and Palliative Medicine; Humans; IMRT; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Radiotherapy, Intensity-Modulated - instrumentation; Radiotherapy, Intensity-Modulated - methods; Tangents; Tomotherapy; Topotherapy
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2011.01.004

Abstract Background and purpose To compare left-sided whole breast conventional and intensity-modulated radiotherapy (IMRT) treatment planning techniques. Materials and methods Treatment plans were created for 10 consecutive patients. Three-dimensional conformal radiotherapy (3DCRT), forward-planned IMRT (for-IMRT), and inverse-planned IMRT (inv-IMRT) used two tangent beams. For-IMRT utilized up to four segments per beam. For helical tomotherapy (HT) plans, beamlet entrance and/or exit to critical structures was blocked. Topotherapy plans, which used static gantry angles with simultaneous couch translation and inverse-planned intensity modulation, used two tangent beams. Plans were normalized to 50 Gy to 95% of the retracted PTV. Results Target max doses were reduced with for-IMRT compared to 3DCRT, which were further reduced with HT, topotherapy, and inv-IMRT. HT resulted in lowest heart and ipsilateral lung max doses, but had higher mean doses. Inv-IMRT and topotherapy reduced ipsilateral lung mean and max doses compared to 3DCRT and for-IMRT. Conclusions All modalities evaluated provide adequate coverage of the intact breast. HT, topotherapy, and inv-IMRT can reduce high doses to the target and normal tissues, although HT results in increased low doses to large volume of normal tissue. For-IMRT improves target homogeneity compared with 3DCRT, but to a lesser degree than the inverse-planned modalities.