Immobilization effect of air-injected blanket (AIB) for abdomen fixation.

A new device for reducing the amplitude of breathing motion by pressing a patient's abdomen using an air-injected blanket (AIB) for external beam radiation treatments has been designed and tested. The blanket has two layers sealed in all four sides similar to an empty pillow made of urethane. The blanket is spread over the patient's abdomen with both ends of the blanket fixed to the sides of the treatment couch or a baseboard. The inner side, or patient side, of the blanket is thinner and expands more than the outer side. When inflated, the blanket balloons and effectively puts an even pressure on the patient's abdomen. Fluoroscopic observation was performed to verify the usefulness of AIB for patients with lung, breast cancer, or abdominal cancers. Internal organ movement due to breathing was monitored and measured with and without AIB. With the help of AIB, the average range of diaphragm motion was reduced from 2.6 to 0.7 cm in the anterior-to-posterior direction and from 2.7 to 1.3 cm in the superior-to-inferior direction. The motion range in the right-to-left direction was negligible, for it was less than 0.5 cm. These initial testing demonstrated that AIB is useful for reducing patients' breathing motion in the thoracic and abdominal regions comfortably and consistently.