Doses to internal organs for various breast radiation techniques--implications on the risk of secondary XXXX and @entity296 .

@entity1 @entity296 @entity0 @entity5 @entity2073
BACKGROUND: @entity0 are more frequently diagnosed at an early stage and currently have improved long term outcomes. Late normal tissue complications induced by adjuvant radiotherapy like secondary @entity5 or @entity296 must now be avoided at all cost. Several new breast radiotherapy techniques have been developed and this work aims at comparing the scatter doses of internal organs for those techniques. METHODS: A CT-scan of a typical early stage left @entity0 @entity1 was used to describe a realistic anthropomorphic phantom in the MCNP Monte Carlo code. Dose tally detectors were placed in breasts, the heart, the ipsilateral lung, and the spleen. Five irradiation techniques were simulated: whole breast radiotherapy 50 Gy in 25 fractions using physical wedge or breast IMRT, 3D-CRT partial breast radiotherapy 38.5 Gy in 10 fractions, HDR brachytherapy delivering 34 Gy in 10 treatments, or Permanent Breast 103Pd Seed Implant delivering 90 Gy. RESULTS: For external beam radiotherapy the wedge compensation technique yielded the largest doses to internal organs like the spleen or the heart, respectively 2,300 @entity2073 and 2.7 Gy. Smaller scatter dose are induced using breast IMRT, respectively 810 @entity2073 and 1.1 Gy, or 3D-CRT partial breast irradiation, respectively 130 @entity2073 and 0.7 Gy. Dose to the lung is also smaller for IMRT and 3D-CRT compared to the wedge technique. For multicatheter HDR brachytherapy a large dose is delivered to the heart, 3.6 Gy, the spleen receives 1,171 @entity2073 and the lung receives 2,471 @entity2073 . These values are 44% higher in case of a balloon catheter. In contrast, breast seeds implant is associated with low dose to most internal organs. CONCLUSIONS: The present data support the use of breast IMRT or virtual wedge technique instead of physical wedges for whole breast radiotherapy. Regarding partial breast irradiation techniques, low energy source brachytherapy and external beam 3D-CRT appear safer than 192Ir HDR techniques.
