The validation of tomotherapy dose calculations in low-density lung media

Summer R. Chaudhari, Olga L. Pechenaya, S. Murty Goddu, Sasa Mutic, Dharanipathy Rangaraj, Jeffrey D. Bradley, Daniel Low

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The dose-calculation accuracy of the tomotherapy Hi-Art II (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values ≤1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.

Original languageEnglish
Pages (from-to)2315-2322
Number of pages8
JournalPhysics in medicine and biology
Issue number8
StatePublished - Apr 20 2009


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