Evaluation of four surface surrogates for modeling lung tumor positions over several fractions in radiotherapy.

Patient breathing during lung cancer radiotherapy reduces the ability to keep a sharp dose gradient between tumor and normal tissues. To mitigate detrimental effects, accurate information about the tumor position is required. In this work, we evaluate the errors in modeled tumor positions over several fractions of a simple tumor motion model driven by a surface surrogate measure and its time derivative.

Evaluation of irregular breathing effects on internal target volume definition for lung cancer radiotherapy.

Purpose: Irregular breathing may compromise the treated volume for free-breathing lung cancer patients during radiotherapy. We try to find a measure based on a breathing amplitude surrogate that can be used to select the patients who need further investigation of tumor motion to ensure that the internal target volume (ITV) provides reliant coverage of the tumor.

Material And Methods: Fourteen patients were scanned with four-dimensional computed tomography (4DCT) during free-breathing.