Impact of patient positioning uncertainty in noncoplanar intracranial stereotactic radiotherapy.

Impact of patient positioning uncertainty in noncoplanar intracranial stereotactic radiotherapy.
J Appl Clin Med Phys. 2020 Jan 20;:
Authors: Tanaka Y, Oita M, Inomata S, Fuse T, Akino Y, Shimomura K
Abstract
The aim of this study is to evaluate the patient positioning uncertainty in noncoplanar stereotactic radiosurgery or stereotactic radiotherapy (SRS/SRT) for intracranial lesions with the frameless 6D ExacTrac system. In all, 28 patients treated with SRS/SRT of 70 treatment plans at our institution were evaluated in this study. Two X-ray images with the frameless 6D ExacTrac system were first acquired to correct (XC) and verify (XV) the patient position at a couch angle of 0º. Subsequently, the XC and XV images were also acquired at each planned couch angle for using noncoplanar beams to detect position errors caused by rotating a couch. The translational XC and XV shift values at each couch angle were calculated for each plan. The percentages of the translational XC shift values within 1.0 mm for each planned couch angle for using noncoplanar beams were 77.86%, 72.26%, and 98.47% for the lateral, longitudinal, and vertical directions, respectively. Those within 2.0 mm were 98.22%, 97.96%, and 99.75% for the lateral, longitudinal, and vertical directions, respectively. The maximum absolute values of the translational XC shifts among all planned couch angles for using noncoplanar beams were 2.69, 2.45, and 2.17 mm for the late...

Source: Journal of Applied Clinical Medical Physics - January 19, 2020 Category: Physics Authors: Tanaka Y, Oita M, Inomata S, Fuse T, Akino Y, Shimomura K Tags: J Appl Clin Med Phys Source Type: research