An air monitoring system includes a tubing having a metallic inner layer and an outer jacket to provide optimal transport of air samples. The node N may then also select an alternate parent node \u201cP\u2032\u201d that has connectivity to GP and N. The ion source is operable to generate an ion beam from the ionization of ion precursor gas present in the ion chamber by electrons emitted from the filament. The thin-film transistors have leakage current that rises relatively slowly with voltage across the transistor within a range that matches exposure through an object being imaged but rises at a sufficiently higher rate within a higher range to provide protection even when a corresponding region of the charge generator layer receives greater amounts of x-rays.