A real-time treatment guidance system for Pleural PDT.

Intrapleural photodynamic therapy (PDT) has been used as an adjuvant treatment with lung-sparing surgical treatment for mesothelioma. In the current intrapleural PDT protocol, a moving fiber-based point source is used to deliver the light and the light dose are monitored by 7 detectors placed in the pleural cavity. To improve the delivery of light dose uniformity, an infrared (IR) camera system is used to track the motion of the light sources. A treatment planning system uses feedback from the detectors as well as the IR camera to update light fluence distribution in real-time, which is used to guide the light source motion for uniform light dose distribution. We have reported previously the success of using IR camera to passively monitor the light fluence rate distribution. In this study, the real-time feedback has been implemented in the current system prototype, by transferring data from the IR camera to a computer at a rate of 20 Hz, and by calculation/displaying using Matlab. A dual-correction method is used in the feedback system, so that fluence calculation can match detector readings. Preliminary data from a phantom showed superior light uniformity using this method. Light fluence uniformity from patient treatments is also shown using the correction method dose model.