The effect of respiratory motion on forward intensity modulated radiotherapy for breast cancer.
This study evaluated the effect of respiratory movement on field-in-field (FIF) forward intensity-modulated radiotherapy (IMRT) for the treatment of breast cancer. FIF forward IMRT was performed on ten patients receiving radiotherapy to the whole breast after conservation surgery. Assuming that breast motion follows a sophisticated cyclic function, the changes in hot and cold region, dose homogeneity index (DHI), and skin dose were examined at different respiration amplitudes of 1 cm, 2 cm, and 3 cm. FIF forward IMRT significantly improved the hot region, DHI, and skin dose, but slightly worsened the cold region, compared to the two wedged tangential technique (TWT). Interestingly, we found that the respiration amplitude affected the DHI and cold region but had no effect on the hot region and skin dose. The DHI was slightly improved at 1 cm of amplitude probably due to the blurring effect, remained unchanged at 2 cm of amplitude, and was worsened at 3 cm of amplitude. FIF forward IMRT significantly increased the cold region at 2 cm and 3 cm of respiration amplitude compared to the TWT. At 3 cm of respiration amplitude, an average cold region of 3.27 cm(3) was observed. In summary, our data indicate that during FIF forward IMRT, respiration movement has an important effect on various endpoints depending on the respiration amplitude of the patient.
Song
Taesoo
T
Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea.
Suh
Chang-Ok
CO
Lee
Ikjae
I
Jeong
Kyoungkeun
K
Keum
Kichang
K
Lee
Chang Geol
CG
Seong
Jinsil
J
Cho
Jae Ho
JH
D016477:Artifacts; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D009068:Movement; D050397:Radiotherapy, Intensity-Modulated; D012119:Respiration