TITLE:
Dosimetric Comparison of Different Prescription Modes in Lung Stereotactic Body Radiation Therapy
AUTHORS:
Hideharu Miura, Norihisa Masai, Ryoong-Jin Oh, Hiroya Shiomi, Kouichi Yamada, Junichi Sasaki, Muhammad Nauman Usmani, Toshihiko Inoue
KEYWORDS:
Dose Prescription; Monte Carlo Calculation; Stereotactic Body Radiation Therapy; Lung Cancer
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.3 No.1,
January
27,
2014
ABSTRACT:
The purpose of
this study was to compare the dose-volume statistics of stereotactic body radiotherapy (SBRT) for lung cancer between
planning target volume (PTV): D95 and gross tumor volume (GTV): D99 dose
prescriptions using Monte Carlo (MC) calculation. Plans for 183 patients
treated between October 2010 and April 2013 were generated based on four-dimensional (4D) computed tomography (CT) under
free breathing. A uniform margin of 8 mm was added to the internal target
volume (ITV) to generate PTV. A leaf margin of 2 mm was added to the PTV. The
plans were calculated with two different dose prescription methods: 40 Gy to
cover 95% of the PTV (PTV prescription) and 44 Gy to cover 99% of the GTV (GTV
prescription). A 6-MV photon beam was used. A dose-volume histogram (DVH) analysis was performed
for dose to the GTV using PTV and GTV dose prescriptions. For each treatment
plan, we evaluated the minimum dose to 99% of the GTV (D99).
The D99 of GTV was 44.5 ±
1.9 Gy and 44.0 ± 0.0 Gy for PTV and GTV prescriptions, respectively. The dose
to the GTV had wide variations with PTV prescription. We recommend that GTV
based dose prescription should be used to standardize dose to the tumor and to
achieve highly conformal dose distributions in SBRT for lung cancer.