Acquisition of data: Casentini, Fornezza, Perini, Colombo. Analysis and interpretation of data: Casentini, Colombo. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Casentini. Statistical analysis: Perissinotto. Administrative/technical/material support: Perini. Study supervision: Colombo.
This work was partially presented as proceedings at the First European Conference on SRS/SBRT and IG-IMRT, “Radiation Oncology: can we still treat without image guidance?” Milan, Italy, February 22–23, 2013.