Use of digital fluoroscopy as an on-line verification device in radiation therapy.

We have applied digital fluoroscopy technology to the radiation therapy environment, and developed a real-time fluorescent dosemeter (RFD). Our aim was to utilise this system as an on-line treatment verification device. We have found that the system behaves basically as a large array (512 X 512) of dosemeters. Using this device, instantaneous information about the actual treatment beam can be obtained simultaneously with the commencement of irradiation. As an array of dosemeters, it provides a detailed description of the dose distribution (exit dose) throughout the treatment. Furthermore, by applying image enhancement techniques to this measured information, good quality portal images are produced instantaneously and continuously during the entire irradiation for visual evaluation. The availability of this system should lead to improvements in precision in present dose delivery procedures.