Comparison of the accuracy of positioning devices for radiation therapy ofcanine and feline head tumors

The purpose of this retrospective study was to evaluate the repositioning a ccuracy of different positioning devices In order to determine their applic ability for potential use in conformal radiation therapy for animals. Forty -four animals with spontaneous tumors of the head were included, The animal s were divided into 3 groups determined according to the positioning device used, Group 1 animals were positioned using a thermoplastic mask. Group 2 animals were positioned using a head holder. Group 3 animals were positione d using the head holder and an inflatable pillow, The time of presentation determined which position device was used, Port films of the 44 patients we re reviewed retrospectively, and the repositioning precision was recorded b y measurements in three orthogonal planes. Groups 2 and 3 had significantly better repositioning accuracy (P less than or equal to 0.05) compared to G roup 1. The position variation was not significantly different (P less than or equal to 0.05) between Groups 2 and 3 in the lateral and longitudinal d irection. Group 3 had a median reposition variation of 0.5 to 1.0 mm, with a standard deviation of 1.0 to 1.5 mm.