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Int J Radiat Oncol Biol Phys. 2009 May 1;74(1):275-82. doi: 10.1016/j.ijrobp.2008.11.028.

Investigation of helical tomotherapy for partial-breast irradiation of prone-positioned patients.

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1
Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, USA.

Abstract

PURPOSE:

To investigate whether helical tomotherapy can provide conformal, uniform target-dose coverage for partial-breast irradiation (PBI) of patients positioned prone while achieving organ-at-risk sparing compliant with National Surgical Adjuvant Breast and Bowel Project (NSABP) B-39/Radiation Therapy Oncology Group (RTOG) 0413 guidelines; and to report our initial experience with the delivery of prone-breast PBI treatments using tomotherapy.

METHODS AND MATERIALS:

For our pilot study, we generated helical tomotherapy plans upon the images of 10 prone-positioned patients previously treated using conventional techniques. We also generated plans for 4 left-breast prone-positioned PBI patients who were treated using helical tomotherapy, and recalculated the planned sinograms upon the pretreatment megavoltage computed tomographic images. Of the planning target volume (PTV), 95% was prescribed to receive 38.5 Gy, administered twice daily for 5 days.

RESULTS:

For our pilot study, on average the maximum point dose to the PTV was 41.3 Gy, and 99% or more of the PTV received 90% or more of the prescribed dose. RTOG 0413 dose-volume histogram objectives were fulfilled for all organs at risk except the contralateral breast, which received a maximum point dose as high as 3.2 Gy in 1 case. For the prospective prone-positioned tomotherapy PBI plans, all objectives were met except the contralateral-breast maximum dose, which was 3.7 Gy on average. Dose calculation using the planned sinogram upon the pretreatment megavoltage computed tomographic images indicated consistency with the planned dose distributions.

CONCLUSIONS:

Helical tomotherapy can provide conformal and uniform target-dose coverage simultaneous with adequate sparing of critical structures; in this study only the contralateral breast dose exceeded RTOG 0413 guidelines. Dosimetric results for our 4 prospective patient cases were consistent with those for our 10-case pilot study.

PMID:
19362247
DOI:
10.1016/j.ijrobp.2008.11.028
[Indexed for MEDLINE]

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