<prompt> CT SCAN is based on?piezoelectric effectlinear attenuation of xraysCoincidence ImagingPulse Echo principle  <response>: CT scan is based on Linear attenuation of Xraysstopping power of various tissues, which is based on its density and is measured in Hounsfield Units. Pulse-Echo principle and Piezoelectric effect are used in USG. Coincidence imaging is used in PET scan. 