Dosimetric evaluation near lung and soft tissue interface region during respiratory-gated and non-gated radiotherapy: A moving phantom study. (October 2017)

• Record Type: Journal Article
• Authors: Jong, W.L.; Ung, N.M.; Vannyat, Ath; Rosenfeld, A.B.; Wong, J.H.D.
• Is Part Of: Physica medica. Volume 42(2017)
• Page Start: 39
• Page End: 46
• Publication Date: 2017-10
• Subjects: MOSFET -- Radiochromic film -- EBT2 -- Quality assurance -- Margin -- Inhomogeneity -- Gating technique; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2017.08.011
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: The interface dosimetric characteristics in a moving phantom during gated and non-gated radiotherapy was investigated. Dose smearing effect was observed during non-gated radiotherapy but was reduced with gated radiotherapy. The "Edge-on" MO Skin detector concurred with EBT2 film measurements in terms of dose profiles. Abstract: Challenges in treating lung tumours are related to the respiratory-induced tumour motion and the accuracy of dose calculation in charged particle disequilibrium condition. The dosimetric characteristics near the interface of lung and Perspex media in a moving phantom during respiratory-gated and non-gated radiotherapy were investigated using Gafchromic EBT2 and the MO Skin detector. The MO Skin detectors showed good agreement with the EBT2 films during static and gated radiotherapy. In static radiotherapy, the penumbral widths were found to be 3.66 mm and 7.22 mm in Perspex and lung media, respectively. In non-gated (moving) radiotherapy with 40 mm respiratory amplitude, dose smearing effect was observed and the penumbral widths were increased to 28.81 mm and 26.40 mm, respectively. This has been reduced to 6.85 mm and 9.81 mm, respectively, in gated radiotherapy with 25% gating window. There were still some dose discrepancies as compared to static radiotherapy due to the residual motion. This should be taken into account in the margin generation for the target tumour.