The effect of calibration factors and recovery coefficients on 177Lu SPECT activity quantification accuracy: a Monte Carlo study

Abstract Background Different gamma camera calibration factor (CF) geometries have been proposed to convert SPECT data into units of activity concentration. However, no consensus has reached on a standardised geometry. The CF is dependent the selected geometry and further affected by partial volume effects. This study investigated effect two their corresponding recovery coefficients (RCs) quantification accuracy 177 Lu images using Monte Carlo simulations. Methods were (i) radioactive-sphere surrounded non-radioactive water (sphere-CF) (ii) cylindrical phantom uniformly filled with radioactive (cylinder-CF). Recovery obtained sphere-CF cylinder-CF, yielding sphere-RC cylinder-RC values, respectively, for correction (PVC). was evaluated four different-sized spheres (15.6–65.4 ml) kidney model known concentrations inside cylindrical, torso patient phantom. Images reconstructed 3D OS-EM algorithm incorporating attenuation, scatter detector-response corrections. Segmentation performed physical size small cylinder respectively. Results sphere error (without PVC) better (≤ − 5.54%) compared cylinder-CF 20.90%), attributed similar quantified spheres. Partial yielded comparable results sphere-CF-RC 3.47%) cylinder-CF-RC 3.53%). poorer 22.34%) without PVC 2.44%). With PVC, improved well 3.50%) 3.45%). Conclusion demonstrated that upon careful selection CF-RC combinations, errors 3.53%) between cylinder-CF-RC, when all corrections applied.