Effects of Rotational Motion on Dose Coverage in Single Isocenter Multiple Target Stereotactic Radiosurgery
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Authors
Sova, Adam
Issue Date
2019-05-24
Volume
Issue
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Stereotactic radiosurgery using a single isocenter multiple target technique is being used widely today. However, not much is known about the extent to which rotational patient motion effects dose coverage. This study investigated this issue by first developing a geometric model to predict dose coverage loss with rotational motion. The model varied tumor volume and distance from isocenter. It was shown that small tumor volumes and large distances from isocenter increase the rate at which dose coverage is lost with rotations. Adding 1 mm margins around the tumor allowed for slight (< 1.5 degrees) rotations before losing
dose coverage. A clinical experiment was then carried out using the StereoPHAN phantom from Sun Nuclear and the Varian Eclipse treatment planning system to simulate patient rotations. Rotational errors of 0.5 , 1.0, 2.0, and 3.0 degrees were introduced and delivered the same treatment plan in Eclipse keeping dose output fixed. Results fit the geometric model for dose coverage. These results show that rotational motion needs to be considered during treatment planning and treatment delivery, as it can have an effect on dose coverage to the tumor volume and excessive dose to healthy tissue.
Description
Citation
Publisher
Creighton University
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Copyright is retained by the Author. A non-exclusive distribution right is granted to Creighton University and to ProQuest following the publishing model selected above.