Comparing Two Forms of Head Immobilization for Stereotactic Radiotherapy

A Randomized Trial Comparing Two Forms of Immobilization of the Head for Fractioned 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.

Participant undergoes SRT using a GTC frame to immobilize the participant's heading during radiation therapy

Participant undergoes SRT using the BrainLab thermoplastic mask to immobilize the participant's head during radiation therapy

Distance From Ideal to Center of GTC Frame and BrainLab Thermoplastic Mask With Respect to Average and Variability

This study uses the ExacTRAC imaging system to assess positioning of frame or mask during SRT. Images yield lateral, longitudinal, and vertical deviations of the isocenter as well as head rotations about respective axes.

Inclusion Criteria: Patients who are eligible for fractionated stereotactic radiotherapy Exclusion Criteria: Severe claustrophobia

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