The aim of our study was to detect the possible uncertainties arising from tumor movements in the daily routine treatment planning, in extreme breathing conditions. Ten patients with lung cancer were enrolled into the study. According to tumor location, five patients had periferial and five had central tumor. After the normal planning CT scan, two more scans were made with the same CT parameters in maximal exhalation and in maximal inhalation. For planning, the normal breathing scans were used with the fusion of the maximal inhalation and maximal exhalation scans. After the fusion in all breathing phases the gross tumor volumes were contoured (GTV1, GTV2, GTV3). Around the GTV1 (normal breathing phase GTV) 3 planning target volumes (PTV) were generated with the margin of 0.5 cm, 1.5 cm and 2.5 cm (PTV1, PTV2, PTV3). Individual plans were generated to all PTVs. All GTV volumes were registered. In all cases volume deviations were registered in different breathing phases (min: 1.5%, max: 35.6%). For GTV coverage comparison the coverage index (CI) was used. In case of extreme breathing conditions, using 0.5 cm margin was sufficient to reach good coverage for central tumors. For periferal tumors 1.5 cm margin had to be used for the acceptable coverage (CI: 0.85-1.00). In our study, extreme breathing conditions were analyzed. According to our results, CT scans used in the daily routine do not exactly represent the tumor midposition and the true tumor volume. Due to breathing synchron tumor movements, 0.5 cm margin must be used for planning in central location. In periferal tumors wider margin should be used.
|Translated title of the contribution||Tumor movements detected by multi-slice CT-based image fusion in the radiotherapy of lung cancer patients|
|Number of pages||5|
|Publication status||Published - Dec 1 2007|
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