X-ray transparent multi-channel dosimeter based on organic photodiodes and plastic scintillators for real-time IVR monitoring

Interventional radiology (IVR) is a medical subspecialty of radiology to realize image-guided surgical procedures using imaging modalities, such as x-ray fluoroscopy. However, skin injuries by prolonged x-ray exposure in duration of procedure have been reported. Therefore, monitoring of skin dose is desired in clinical sites for reduction of excessive x-ray exposure. We are developing a real-time dose distribution monitoring system for the IVR in which only radiolucent materials were in the field of view not to interfere with the IVR procedure. The organic photodiode (OPD) is mainly composed of organic materials, which has good transparency for x-ray. As a result, the detector using the OPDs combined with a plastic scintillator connected to thin flexible cable is expected to have transparency to x-rays. In this paper, therefore, we developed a new detector based on the OPD connected to the thin flexible cable for the real-time monitoring of skin dose distribution in IVR. The device structure of the OPD was plastic scintillator (BC-408, 10 mm × 10 mm × 1 mm)/ IZO (100nm)/ PEDOT: PSS (30 nm) / PCBM: P3HT (200 nm) / Al (70 nm). The size of a sensing area is 6 mm × 4 mm on the plastic scintillator. The readout flexible cable was made of 25 μm polyimide board and 12 μm copper line. The length of the flexible cable is 30 cm and there are three readout electrodes to connect to the OPD electrode. We evaluated performance of the x-ray detectors for with a micro CT (R_mCT2, RIGAKU). As a result, the proposed x-ray detector had a enough transparency to be used in the IVR dosimeter. In addition, we obtained the sufficient detector responses for the various tube current, tube voltage and irradiation angle for x-ray irradiation in real-time with 1 s interval.2016IEEE NSS&MI