Impact of image registration surrogates on the planning target volume geometry for bladder radiation therapy

Lipiodol is the optimal image registration surrogate for partial bladder radiation therapy. However, for patients who are contraindicated for Lipiodol injection, BWS is the preferred noninvasive surrogate because the derived PTV has a smaller geometric variation from the Lipiodol-PTV when compared with COB, especially when the CTV was located at the dome or the base of the bladder.