[en] Accuracy and reliability of absorbed dose calculations in therapeutic nuclear medicine are directly related to the accuracy of the activity concentration estimates obtained from each of the imaging time points. An increasing number of clinical dosimetry protocols currently include SPECT/CT imaging studies because of their superior accuracy. Multi SPECT/CT based imaging technique known to best because of all necessary corrections i e. attenuation, scatter and over-lapping activity contribution Various technical parameters influence the quantitative accuracy of dosimetry are mainly related to technique used, data acquisition, data processing, photon attenuation, Compton scatter, collimator detector response and activity quantification. Technique used for the curve fitting and time integrated activity estimation i e. least square analysis, mono-bi exponential or trapezoidal integration can also lead to variation in cumulative activity and absorbed dose estimation. Hence proper selection of technical parameters like Collimator selection, crystal thickness, selection of number of time points, imaging me, integration of time activity data and and necessary corrections like scatter correction, background activity correction, Attenuation correction, dead time correction, resolution recovery is utmost important to determine more reliable and reproducible dosimetry results