TITLE:
Planning and Dosimetric Comparisons of IMRT Lung Cancers with Three Advanced Optimization Algorithms
AUTHORS:
Yie Chen, Jie Qu, Jack Yang, Mitch Weiss, Sang Sim, Xiongfei Liao
KEYWORDS:
MCO; DMPO; Tomotherapy; Lung IMRT
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.2 No.2,
May
24,
2013
ABSTRACT: Purpose: To evaluate planning quality and dosimetric differences of
clinically deliverable Intensity-modulated Radiation Therapy lung
plans generated from Tomotherapy, Pinnacle3, and RayStationTM treatment planning systems. Method and
Materials: Ten patients diagnosed with non-small-cell lung carcinoma
(NSCLC) previously treated with plans on Pinnacle using Direct Machine
Parameter Optimization were randomly selected and re-planned with Tomotherapy
dose volume constraints and same beam geometry with RayStation Multi Criteria
Optimization (MCO) equivalent uniform dose (EUD) or dose volume
constraints, respectively. Prescription
was established as 60 Gy to cover > 95% of PTV. Planning outcomes such as D95 (95% of volume of PTV receiving the prescribed dose), D5, D33, mean heart and lung doses, V20 (volume of lung receiving 20
Gy), and max cord dose of 1cm3 were evaluated according to our departmental clinical protocols. Conformity
index (CI = PTV / prescription isodose volume) and homogeneity index (HI = D5/D95)
were also reported simultaneously. All plans were successfully uploaded for
delivery verification. Results: Mean
volume of calculated PTV was 356 ± 141 cm3.
The planning results indicated that CI, HI, D95 and D5 of
PTV, V20 of lung, and 1cm3 max cord dose were comparable but with
better overall dosimetric distributions with conformity and homogeneity index
from Tomotherapy plans in comparison to both Pinnacle and RayStation
planning outcomes. Conclusions: Tomotherapy plans achieved better uniform tumor coverage with fewer hot spots
while sparing more critical structures with superior dose fall-off. RayStation
plans with MCO automatically generated a set of Pareto optimized solutions with
given objectives to allow tradeoffs between targets and critical organs and
tended to achieve better tumor coverage compared to Pinnacle. All three
planning algorithms can generate clinical deliverable IMRT lung plans while
Tomotherapy plans provide superior dosimetric indexes compared to Pinnacle and
RayStation due to its unique beamlet optimization process with high modulation.