It has been reported and discussed that electrical current can be produced when an insulating material interacts with ionizing radiation. We have found that high-resolution images can be obtained from insulating materials if this current is guided by an electric field to the pixels of a TFT array. The charge production efficiency of insulators is much smaller than that of photoconductor materials such as selenium, silicon, or other conventional semiconductors. Nevertheless, when the intensity of the ionizing radiation is sufficiently high, a charge sensitive TFT imaging array with only dielectric material can produce high MTF images with contrast resolution proportional to the intensity of the radiation. The function of the dielectric in this new detector may be similar to that of an ionization chamber. Without the semiconductor charge generating material, the dielectric imaging detector does not exhibit charge generation fatigue or charge generation saturation. Prototype detectors have been tested using diagnostic x-ray beams with energy ranging from 25 kVp to 150 kVp, and therapeutic 2.5MV, 6MV, 10MV, and 15MV photon beams (with and without an electron built-up layer), electron beams, broad area proton beams, and proton pencil beams in the energy range of 150 MeV. High spatial resolution images up to the Nyquist frequency have been demonstrated. The physics, structure, and the imaging properties as well as the potential application of this detector will be presented and discussed.
Total Skin Electron Therapy (TSET) utilizes high-energy electrons to treat cancers on the entire body surface. The otherwise invisible radiation beam can be observed via the optical Cherenkov photons emitted from interaction between the high-energy electron beam and tissue. Using a specialized camera-system, the Cherenkov emission can thus be used to evaluate the dose uniformity on the surface of the patient in real-time. Each patient was also monitored during TSET via in-vivo detectors (IVD) in nine locations. Patients undergoing TSET in various conditions (whole body and half body) were imaged and analyzed, and the viability of the system to provide clinical feedback was established.