Clinical application of vacuum bag immobilization of the trunk in malignant tumor patients

Objective: To evaluate the clinical application of vacuum bag immobilization of thorax and pelvis for patients with malignant tumors. Methods: Of 714 patients (fields) chosen randomly, 582(fields) were immobilized with vacuum bag, while the other 132 (fields) used only sand bags, tapes, and other simple immobilizing devices. The field movements were measured and compared before and after the setup, along with 56 patients immobilized twice with vacuum bag. Results: The variance of movement before and after the setup was 6.7% for patients with vacuum bag , while that was 26.5% for patients without the vacuum bag. It was even 32.1% for patients immobilized twice with vacuum bag. Conclusions: The variance of movement decreases significantly with vacuum bag immobilization. It should be used as frequently as possible. As the variance of movement rises obviously when vacuum bag is used twice, the semi-soft vacuum bag should be prepared afresh and checked under the simulator before the second use. (authors)