The invention features compositions and methods for treating or preventing a neoplasia. A masking circuit performs masking of the first rectangular wave signals Pu to Pw, and outputs the resultant signals as second rectangular wave signals Mu to Mw. An automated tube filling system provides a calibrated fill mechanism coordinated with a calibrated loading rope withdrawal mechanism to ensure loading consistency. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest.