RT Journal Article
SR Electronic
T1 Assessment of tumor size and movement trajectories using CT scans with different pitch settings
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP P658
VO 40
IS Suppl 56
A1 Paul Martin Putora
A1 Marciana Nona Duma
A1 Florent Baty
A1 Michal Devecka
A1 Martin Brutsche
A1 Ludwig Plasswilm
YR 2012
UL http://erj.ersjournals.com/content/40/Suppl_56/P658.abstract
AB Introduction: Pitch Settings of CT scanners have an influence on the way moving lesions are reconstructed. These images have an impact on target definition in radiotherapy planning, therefore the Planning-CT settings are of central importance for correct tumor irradiation and normal tissue sparing.Method: A water filled 40mm table tennis ball serving as a tumor phantom was moved along an elipsoid trajectory by a custom-assembled Lego(c) based device with a cycle duration of 4.2 seconds. The pitch/slice settings tested were termed "fast" (2.5mm, standard pitch), "intermediate" (2.5mm, half pitch), and "slow" (0.625mm, half pitch).Results: The volume of the ball was overestimated with the volume of the tumor-phantom growing from 82% for the fast CT, 171% for the intermediate CT and 300% for the slow CT. The phantom trajectory could best be reconstructed in the slow CT. The different sizes can be seen here:Conclusion: The custom lung phantom proved to work well for the specified task. The effect of CT settings during planning-CT acquisition on the resulting volumes was significant. Acquisition of slow-CT images for radiotherapy planning enables a better targeting of the moving tumor and sparing of normal lung tissue specifically when respiratory gating is not available.