Patient position reproducibility in fractionated stereotactic radiotherapy: an update after changing dental impression material

The reproducibility of patient positioning within the Gill-Thomas-Cosman re locatable stereotactic frame was re-evaluated following the substitution of a new, softer, dental impression material for the original hard acrylic co mpound. The average total displacement for a series of 10 patients was 1.1 mm ( +/- 0.6 mm). Rotational discrepancies were small. This technique canno t deliver accurate repositioning in the absence of patient co-operation. (C ) 1999 Elsevier Science Ireland Ltd. All rights reserved.