Abstract
PURPOSE: Patients with body weights close to or above 400 lbs present unique challenges in radiation therapy since the weight limit of most treatment couches decreases as the couch-top extends toward the treatment gantry. The purpose of this work was to develop a small footprint couch-top support platform to safely perform image-guided radiotherapy (IGRT) for extremely heavy patients. METHODS: One way to protect the couch-top from damage and prevent a catastrophic breakdown is to provide additional support as the couch extends toward the treatment gantry. To allow a maximal range of gantry movement, a small-footprint adjustable jack stand, placed underneath the couch-top, was chosen and modified from a commercial jack stand (with 1100 lbs capacity). The couch could be easily extended longitudinally and laterally with a modified 8-ball-transfer plate mounted at the top. The operation of a couch-top support platform was used for two heavy patients after phantom testing. kV and MV imaging options and ranges were quantified. RESULTS: The custom-constructed couch-top support platform was found to provide stable support with smooth couch shifts. The small footprint allowed gantry rotation from 133° to 227°, which would allow both fixed beam radiotherapy and partial-arc volumetric modulated arc therapy (VMAT). For IGRT, orthogonal 2D kV-kV image pairs with source angles of 40(o) and 130(o) were acquired and tested successfully. With the support platform, two clinical cases with patient weights greater than 415 lbs were successfully treated with image-guided partial arc VMAT radiotherapy. The study demonstrated the safety and efficiency of using this new couch-top support platform to prevent couch failure from treating heavy patients. CONCLUSIONS: A new couch-top support platform has been designed, assembled, and tested for IGRT. The new support platform is easy to use, cost-effective, and allows extremely heavy patients to be treated safely and robustly with IGRT and VMAT.