Bibliographic Metadata

Comparison of advanced treatment techniques for lung cancer / Marie-Theres Bsteh
Additional Titles
Vergleichsstudie zur Bewertung von komplexen Bestrahlungstechniken des Lungenkarzinoms
AuthorBsteh, Marie-Theres
CensorGeorg, Dietmar
PublishedWien, 2016
Description96 Seiten : Illustrationen, Diagramme
Institutional NoteTechnische Universität Wien, Diplomarbeit, 2016
Abweichender Titel nach Übersetzung der Verfasserin/des Verfassers
Zusammenfassung in deutscher Sprache
Document typeThesis (Diplom)
Keywords (DE)VMAT / 3D CRT / dynamic conformal arc / ARDOS Atmungsphantom / FF / FFF
Keywords (EN)VMAT / 3D CRT / dynamic conformal arc / ARDOS breathing phantom / FF / FFF
URNurn:nbn:at:at-ubtuw:1-92275 Persistent Identifier (URN)
 The work is publicly available
Comparison of advanced treatment techniques for lung cancer [8.17 mb]
Abstract (English)

This thesis discusses a variety of treatment methods for lung cancer using attend and unattened photon beams. Therefore, treatment plans for volumetric modulated arc therapy (VMAT) and dynamic conformal arc therapy (DCAT) using attend and unattened photon beams were generated using the treatment planning system Monaco 5.00.04 (Elekta AB, Stockholm, Sweden). For every treatment method two different dose prescriptions, following an in-house stereotactic body radiation therapy (SBRT) protocol as well as recommendations according to the ICRU 83 report, were applied. All plans were generated for ten dierent patients recently treated at the Medical University of Vienna as well as for an in-house developed breathing phantom and were compared to the clinically used unattened 3D conformal radiation therapy (3D-CRT) plans which were generated with the treatment planning system Oncentra (Elekta AB, Stockholm, Sweden). For four patients with the tumor in the left lung and for the phantom itself, all plans were irradiated to the breathing phantom. Thereby, it was possible to determine the inuence of the interplay between target motion and the leaf-motion of the multi-leafcollimator and the thereby induced change of the target dose. The in-house developed breathing phantom used for this study, called ARDOS, consists of tissue-equivalent solid water, bone equivalent tissue (to simulate the ribs) and lung-equivalent high density balsa wood. This phantom enables the simulation of chest motion, rib motion as well as longitudinal and rotational tumor motion. For the determination of the interplay effect, the plans were irradiated to the phantom without phantom motion, with longitudinal tumor motion and with a combination of longitudinal and rotational tumor motion. Due to their high spatial resolution in two dimensions radiochromic lms, in detail GAFChromic EBT3 lms (Ashland ISP, Wayne, NJ), were used. These films provided an optical dose range of 0.2 to 10Gy and a dynamic dose range of up to 20 Gy. Evaluation of the treatment plans showed that the SBRT VMAT plans provided best dose conformity and organ at risk sparing, compared to the other plans. In contrast, due to the higher prescribed doses, all ICRU plans exhibited a worse dose conformity and higher doses to the organs at risk. The comparison also showed that no significant dierences concerning dose coverage, dose conformity and dose to the organs at risk occurred for attened and unattened treatment plans. The main difference was the substantial reduced beam-on time for unattened treatment plans. Furthermore, the beam-on time was reduced by the use of 3D-CRT treatment plans compared to VMAT plans which was caused by the highly signicant increase of monitor units for VMAT plans. The measurements showed that for the used dose range of 15-27 Gy the use of the green channel led to a more accurate dose determination than the red channel. The evaluation of the interplay eect on realistic tumor motion and no tumor motion showed the lowest inuence on the mean dose of 2-3% for 3D-CRT and DCAT plans, with the 3D-CRT exhibiting a reduction of the mean dose to the target and the DCAT plans an respective increase. In contrast to that, VMAT plans showed an increase of the mean dose by 5-7% due to the interplay eect. However, it has to be mentioned that the uncertainty of measurement was estimated to be approximately 5% due to the use of the lms at the limits of their dose range. Since the improvements of treatment plan quality of SBRT VMAT plans were not signicant, the SBRT 3D-CRT plans provide the optimal type of therapy due to the shortest beam-on time and the lowest inuence of the interplay effect.