Quality control to maintain quantitativity and stability of positron emission tomographic study

We examined factors effecting on quantitation of positron emission tomographic (PET) study in our institute. Routine maintenance for positron emission tomograph consists of normalizing scan for normalizing the efficiency of individual coincidence data, blank scan for the attenuation correction and cross-calibration between PET and well counter to measure blood radioactivity concentration. The errors included in these corrections were kept less than few percent. In the second year of operation of our PET (HEADTOME-III) a transient decrease of sensitivity occurred. However, the errors due to these unstabilities were eliminated from the final physiological data by performing the accurate procedure of the cross-calibration. Still the following problems remain to achieve quantitative measurement; a more accurate correction for the scattered even and a higher fidelity to high count rate. (author)