Dosimetric comparison of four different external beam partial breast irradiation techniques: Three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, helical tomotherapy, and proton beam therapy
Received 29 May 2008; received in revised form 11 September 2008; accepted 13 September 2008. published online 07 November 2008.
Abstract
Background and purpose
As an alternative to whole breast irradiation in early breast cancer, a variety of accelerated partial breast irradiation (APBI) techniques have been investigated. The purpose of our study is to compare the dosimetry of four different external beam APBI (EB-APBI) plans: three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), helical tomotherapy (TOMO), and proton beam therapy (PBT).
Methods and materials
Thirty patients were included in the study, and plans for four techniques were developed for each patient. A total dose of 30Gy in 6Gy fractions once daily was prescribed in all treatment plans.
Results
In the analysis of the non-PTV breast volume that was delivered 50% of the prescribed dose (PD), PBT (mean: 16.5%) was superior to TOMO (mean: 22.8%), IMRT (mean: 33.3%), and 3D-CRT (mean: 40.9%) (p<0.001). The average ipsilateral lung volume percentage receiving 20% of the PD was significantly lower in PBT (0.4%) and IMRT (2.3%) compared with 3D-CRT (6.0%) and TOMO (14.2%) (p<0.001). The average heart volume percentage receiving 20% and 10% of the PD in left-sided breast cancer (N=19) was significantly larger with TOMO (8.0%, 19.4%) compared to 3D-CRT (1.5%, 3.1%), IMRT (1.2%, 4.0%), and PBT (0%, 0%) (p<0.001).
Conclusions
All four EB-APBI techniques showed acceptable coverage of the PTV. However, effective non-PTV breast sparing was achieved at the cost of considerable dose exposure to the lung and heart in TOMO.
aProton Therapy Center, National Cancer Center, Gyeonggi-do, Republic of Korea
bCenter for Breast Cancer, National Cancer Center, Gyeonggi-do, Republic of Korea
Corresponding author. Address: Proton Therapy Center and Center for Breast Cancer, National Cancer Center, 809 Madu-1-dong, Ilsandong-gu, Goyang-si, Gyeonggi-do 411-769, Republic of Korea.
ABSTRACT