An improved mobile fluid storage tank having a base, substantially vertical front wall, a substantially rear wall, a pair of substantially parallel side walls and a roof structure. Preferably, in the breath-holding measurement, low-frequency data of the k space is measured. A PDL component receives the image and determines a location, a color and a designation for each of the one or more pixels. The processing portion also compensates for volumetric differences between the gas flow during inspiration and the gas flow during expiration to maximize the accuracy in the measurements made using such a system and method. By changing the ratio of the length of a sub-period to the length of another sub-period or the range of the driving voltage, the dynamic range of the display can be further increased.