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Published on: May 8, 2018
Dosimetric Impact of Respiratory Motion During Breast Intensity-modulated Radiation Therapy Using Four-dimensional
Young Eun Choi1, Kihoon Sung2, Kap Sang Dong1
1Department of Radiation Oncology, Gachon University Gil Medical Center, Gachon University School of Medicine, Incheon, Republic of Korea.
Background/Aim:
The use of intensity-modulated radiation therapy (IMRT) in the treatment of breast cancer is increasing worldwide. Despite clear benefits concerning normal tissue sparing and dose homogeneity, the effects of breathing motion and setup error during breast IMRT should be considered. This study aimed to assess the dosimetric impact of respiratory motion on breast IMRT using four-dimensional (4D) dose calculations.
Patients And Methods:
Multiple computed tomography datasets acquired in three representative respiratory amplitudes, were retrospectively re-planned. Based on the reference dose distribution (RDD), motion-adjusted dose distributions (MDD) were recalculated. All 4D dose distributions were calculated by the voxel-based accumulation of RDD and MDD using five temporal probabilities. The dosimetric parameters of the 4D plans were compared to those of RDD.
Results:
The dosimetric parameters of the planning target volume (PTV) were not significantly different between the RDD and 4D plans. Of the parameters of tumor bed (TB) simultaneous-integrated boost (SIB), the mean dose and V95% for the 4D plans were significantly reduced compared to those of RDD, and the percentage difference in the TB V95% ranged from -1.1% to -5.7% (p<0.05).
Conclusion:
The breast IMRT plan was robust against respiratory motion during tidal breathing. However, special considerations should be made when designing the TB SIB.
