Comparing Two Forms of Head Immobilization for Stereotactic Radiotherapy

Fractionated stereotactic radiotherapy (SRT) requires extremely precise and reproducible immobilization of the patient's head. This randomized study compares the efficacy of two commonly used forms of immobilization used for SRT.

PRIMARY OBJECTIVE: 1\) To compare the efficacy of two commonly used, generally accepted forms of immobilization for the treatment of lesions in the head with fractionated stereotactic radiotherapy. Specifically, this study will use the ExacTRAC kilovoltage imaging system to assess positioning accuracy for these two systems. OUTLINE: Two routinely used methods of immobilization, which differ in their approach to reproduce head position from day-to-day are the Gill-Thomas-Cosman (GTC)frame and the BrainLab thermoplastic mask. The GTC frame fixates on the patient upper detention and thus us in direct mechanical contact with the cranium. The BrainLab mask is a two-part masking system custom-fitted to the front and back of the participant's head. After patients sign an IRB-approved informed consent form, eligible participants are either randomized to either the GTC frame or the mask for their course of SRT. Participants are treated as per standard procedure; however, prior to each treatment, a set of digital kV images (ExacTrac, BrainLabAB, Germany) is taken. These images are fused with reference digitally constructed radiographs obtained from treatment planning CT to yield lateral, longitudinal, and vertical deviations of isocenter and head rotations about respective axes. The primary endpoint of the study is to compare the two systems with respect to mean and standard deviations (SDs) using the distance to isocenter measure.