Figure 1

Image acquisition and guidance process. (a) Imaging acquisition process at simulation. A simulation CT was acquired (CT1) followed by a single 3DUS scan (US1). US1 picture shows the 3D US probe. CT1 was contoured offline by a single RO while US1 was contoured by a single RT. (b) Image guidance process at ‘treatment’. A second CT was acquired (CT2) followed by three subsequent 3DUS scans made by three different RTs (US2a, US2b, US2c). CT2 was contoured by a single RO and a seroma shift was determined based on implicit registration of CT coordinates. US2a, US2b, and US2c were each contoured by 5 RTs and a seroma shift was calculated by comparing each contour with the initial US1. This study design allowed for an analysis of scanning variability (dashed line) and contouring variability (dotted line).