Algorithm Validation for Treatment Planning Systems in Lung Region

Accurate dose calculation in radiotherapy is crucial for effective treatment of cancer while minimizing radiation exposure to normal tissues. In this study, the accuracy of anisotropic analytical algorithm (AAA) in radiotherapy treatment planning systems (RTPSs) for lung cancer is evaluated by comparing calculated and measured dose distributions using CIRS Thorax Phantom (Model No.: 002 LFC, CIRS Inc., Norfolk, VA). Three treatment planning techniques—3D conformal radiation therapy (3D CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT)—were compared using two X-ray energies (6 MV and 10 MV). Absolute dosimetry was performed on a one-dimensional (1D) water phantom under standard conditions, and dose delivery was checked using a DOSE-1 reference class electrometer. The percentages of error between calculated and measured doses for 6 MV beams were 0.31% for 3D CRT, 2.52% for IMRT, and 0.15% for VMAT. For 10 MV beams, the errors were 0.21%, 0.26%, and 1.41%, respectively. These results demonstrate strong agreement between calculations and measurements, remaining within the 3% tolerance for the lung region. The causes of differences were inhomogeneity of lung tissue, scatter effects, and limitations of the dose algorithm. High-energy beams (10 MV) with increased scattering affecting dosing precision were seen in this study. Among the three techniques, VMAT and 3D CRT exhibited better agreement with planned doses compared to IMRT. These findings confirm the validity of modern treatment planning algorithms for handling tissue heterogeneity and precise dose delivery in lung cancer radiotherapy.