[A fast procedure of patient set-up verification in pelvic radiotherapy]

Accuracy of patient positioning is an important aspect in radiation therapy. The present paper presents a new procedure for the determination of set-up errors in radiotherapy, which is based on a special form of the Fast Fourier Transform (FFT), i.e., the Fast Hartley Transform (FHT). The use of this method allows to compare in short time verification and simulator films, and to calculate the translation vector or the in-plane rotation of the patient. Standard deviations < 1 mm for shifting measurements and < 1 degree for measurements of the rotation were detected, provided that the positioning remained within the common clinical range. The present results were in good agreement with data obtained using a landmark-based method.